Packet inspector gui (#238)

Fixes #235

## Description

A GUI Project for the packet inspector

## Test Plan

Steps:
1. Start (any) server
2. Start the proxy `cargo r -r -p packet_inspector_gui --
127.0.0.1:25560 127.0.0.1:25565`
3. Join server (127.0.0.1:25560)
4. Magic

.github/workflows/ci.yml

@@ -38,6 +38,9 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-cargo-target-${{ hashFiles('**/Cargo.toml') }}
             ${{ runner.os }}-cargo-target
+      - name: Install Dependencies (Linux)
+        run: sudo apt-get update && sudo apt-get install -y libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev libxkbcommon-dev libssl-dev libclang-dev libgtk-3-dev
+        if: matrix.os == 'ubuntu-latest'
       - name: Validate formatting
         run: cargo fmt --all -- --check
       - name: Validate documentation

crates/packet_inspector/Cargo.toml

@@ -4,11 +4,33 @@ version = "0.1.0"
 edition = "2021"
 description = "A simple Minecraft proxy for inspecting packets."
 
+[features]
+default = ["syntax_highlighting"]
+syntax_highlighting = ["syntect"]
+
 [dependencies]
 anyhow = "1"
 clap = { version = "4.0.30", features = ["derive"] }
-owo-colors = "3.5.0"
 regex = "1.6.0"
 tokio = { version = "1", features = ["full"] }
 tracing-subscriber = "0.3.16"
-valence_protocol = { path = "../valence_protocol", version = "0.1.0", features = ["compression"] }
+valence_protocol = { path = "../valence_protocol", version = "0.1.0", features = [
+    "compression",
+] }
+
+egui = "0.21.0"
+eframe = { version = "0.21.0", default-features = false, features = [
+    "default_fonts", # Embed the default egui fonts.
+    "glow",          # Use the glow rendering backend. Alternative: "wgpu".
+] }
+enum-map = "2.4.2"
+syntect = { version = "5", optional = true, default-features = false, features = [
+    "default-fancy",
+] }
+time = { version = "0.3.17", features = ["local-offset"] }
+rfd = "0.11"
+owo-colors = "3.5.0"
+atty = "0.2"
+directories = "4.0"
+serde = { version = "1.0.152", features = ["derive"] }
+toml = "0.7.2"

crates/packet_inspector/README.md

@@ -1,44 +1,87 @@
 # What's This?
 
-The packet inspector is a very simple Minecraft proxy for viewing the contents of packets as they are sent/received.
-It uses Valence's protocol facilities to print packet contents.
-This was made for three purposes:
+The packet inspector is a Minecraft proxy for viewing the contents of packets as
+they are sent/received. It uses Valence's protocol facilities to display packet
+contents. This was made for three purposes:
 
 - Check that packets between Valence and client are matching your expectations.
-- Check that packets between vanilla server and client are parsed correctly by Valence.
+- Check that packets between vanilla server and client are parsed correctly by
+  Valence.
 - Understand how the protocol works between the vanilla server and client.
 
 # Usage
 
-First, start a server
+Firstly, we should have a server running that we're going to be
+proxying/inspecting.
 
 ```sh
 cargo r -r --example conway
 ```
 
-In a separate terminal, start the packet inspector.
+Next up, we need to run the proxy server, this can be done in 2 different ways,
+either using the GUI application (default) or using the `--nogui` flag to log
+the packets to a terminal instance.
 
-```sh
-cargo r -r -p packet_inspector -- 127.0.0.1:25566 127.0.0.1:25565
+To assist, `--help` will produce the following:
+
+```
+A simple Minecraft proxy for inspecting packets.
+
+Usage: packet_inspector [OPTIONS] [CLIENT_ADDR] [SERVER_ADDR]
+
+Arguments:
+  [CLIENT_ADDR]  The socket address to listen for connections on. This is the address clients should connect to
+  [SERVER_ADDR]  The socket address the proxy will connect to. This is the address of the server
+
+Options:
+  -m, --max-connections <MAX_CONNECTIONS>
+          The maximum number of connections allowed to the proxy. By default, there is no limit
+      --nogui
+          Disable the GUI. Logging to stdout
+  -i, --include-filter <INCLUDE_FILTER>
+          Only show packets that match the filter
+  -e, --exclude-filter <EXCLUDE_FILTER>
+          Hide packets that match the filter. Note: Only in effect if nogui is set
+  -h, --help
+          Print help
+  -V, --version
+          Print version
 ```
 
-The client must connect to `localhost:25566`. You should see the packets in `stdout`.
+To launch in a Gui environment, simply launch `packet_inspector[.exe]` (or
+`cargo r -r -p packet_inspector` to run from source). The gui will prompt you
+for the `CLIENT_ADDR` and `SERVER_ADDR` if they have not been supplied via the
+command line arguments.
 
-The `-i` and `-e` flags accept a regex to filter packets according to their name. The `-i` regex includes matching
-packets while the `-e` regex excludes matching packets.
+In a terminal only environment, use the `--nogui` option and supply
+`CLIENT_ADDR` and `SERVER_ADDR` as arguments.
 
-For instance, if you only want to print the packets `Foo`, `Bar`, and `Baz`, you can use a regex such
-as `^(Foo|Bar|Baz)$` with the `-i` flag.
-
-```sh
-cargo r -r -p packet_inspector -- 127.0.0.1:25566 127.0.0.1:25565 -i '^(Foo|Bar|Baz)$'
+```bash
+cargo r -r -p packet_inspector -- --nogui 127.0.0.1:25566 127.0.0.1:25565
 ```
 
-Packets are printed to `stdout` while errors are printed to `stderr`. If you only want to see errors in your terminal,
-direct `stdout` elsewhere.
+The client must connect to `localhost:25566`. You should see the packets in
+`stdout` when running in `--nogui`, or you should see packets streaming in on
+the Gui.
+
+The `-i` and `-e` flags accept a regex to filter packets according to their
+name. The `-i` regex includes matching packets while the `-e` regex excludes
+matching packets. Do note that `-e` only applies in `--nogui` environment, as
+the Gui has a "packet selector" to enable/disable packets dynamically. The `-i`
+parameter value will be included in the `Filter` input field on the Gui.
+
+For instance, if you only want to print the packets `Foo`, `Bar`, and `Baz`, you
+can use a regex such as `^(Foo|Bar|Baz)$` with the `-i` flag.
 
 ```sh
-cargo r -r -p packet_inspector -- 127.0.0.1:25566 127.0.0.1:25565 > log.txt
+cargo r -r -p packet_inspector -- --nogui 127.0.0.1:25566 127.0.0.1:25565 -i '^(Foo|Bar|Baz)$'
+```
+
+Packets are printed to `stdout` while errors are printed to `stderr`. If you
+only want to see errors in your terminal, direct `stdout` elsewhere.
+
+```sh
+cargo r -r -p packet_inspector -- --nogui 127.0.0.1:25566 127.0.0.1:25565 > log.txt
 ```
 
 ## Quick start with Vanilla Server via Docker
@@ -64,7 +107,7 @@ docker exec -i mc rcon-cli
 In a separate terminal, start the packet inspector.
 
 ```sh
-cargo r -r -p packet_inspector -- 127.0.0.1:25566 127.0.0.1:25565
+cargo r -r -p packet_inspector -- --nogui 127.0.0.1:25566 127.0.0.1:25565
 ```
 
 Open Minecraft and connect to `localhost:25566`.

crates/packet_inspector/src/config.rs

@@ -0,0 +1,131 @@
+use std::collections::BTreeMap;
+use std::net::SocketAddr;
+use std::path::PathBuf;
+
+use directories::ProjectDirs;
+use serde::{Deserialize, Serialize};
+
+use crate::MetaPacket;
+
+#[derive(Serialize, Deserialize)]
+pub struct ApplicationConfig {
+    server_addr: SocketAddr,
+    client_addr: SocketAddr,
+    max_connections: Option<usize>,
+    filter: Option<String>,
+    selected_packets: Option<BTreeMap<MetaPacket, bool>>,
+
+    #[serde(skip_serializing, skip_deserializing)]
+    must_save: bool,
+}
+
+impl Default for ApplicationConfig {
+    fn default() -> Self {
+        Self {
+            server_addr: "127.0.0.1:25565".parse().unwrap(),
+            client_addr: "127.0.0.1:25566".parse().unwrap(),
+            max_connections: None,
+            filter: None,
+            selected_packets: None,
+            must_save: false,
+        }
+    }
+}
+
+impl ApplicationConfig {
+    pub fn load() -> Result<ApplicationConfig, Box<dyn std::error::Error>> {
+        let config_dir = get_or_create_project_dirs()?;
+
+        let config_file = config_dir.join("config.toml");
+
+        if config_file.exists() {
+            let config = std::fs::read_to_string(config_file)?;
+
+            toml::from_str(&config).map_err(|e| e.into())
+        } else {
+            let config = toml::to_string(&ApplicationConfig::default()).unwrap();
+            std::fs::write(config_file, config)?;
+            Ok(ApplicationConfig::default())
+        }
+    }
+
+    pub fn server_addr(&self) -> SocketAddr {
+        self.server_addr
+    }
+
+    pub fn client_addr(&self) -> SocketAddr {
+        self.client_addr
+    }
+
+    pub fn max_connections(&self) -> Option<usize> {
+        self.max_connections
+    }
+
+    pub fn filter(&self) -> &Option<String> {
+        &self.filter
+    }
+
+    pub fn selected_packets(&self) -> &Option<BTreeMap<MetaPacket, bool>> {
+        &self.selected_packets
+    }
+
+    pub fn set_server_addr(&mut self, addr: SocketAddr) {
+        self.must_save = true;
+        self.server_addr = addr;
+    }
+
+    pub fn set_client_addr(&mut self, addr: SocketAddr) {
+        self.must_save = true;
+        self.client_addr = addr;
+    }
+
+    pub fn set_max_connections(&mut self, max: Option<usize>) {
+        self.must_save = true;
+        self.max_connections = max;
+    }
+
+    pub fn set_filter(&mut self, filter: Option<String>) {
+        self.must_save = true;
+        self.filter = filter;
+    }
+
+    pub fn set_selected_packets(&mut self, packets: BTreeMap<MetaPacket, bool>) {
+        self.must_save = true;
+        self.selected_packets = Some(packets);
+    }
+
+    pub fn save(&mut self) -> Result<(), Box<dyn std::error::Error>> {
+        if !self.must_save {
+            return Ok(());
+        }
+
+        self.must_save = false;
+
+        let config_dir = match get_or_create_project_dirs() {
+            Ok(dir) => dir,
+            Err(e) => {
+                eprintln!("Could not find config directory: {}", e);
+                return Ok(());
+            }
+        };
+
+        let config_file = config_dir.join("config.toml");
+
+        let config = toml::to_string(&self).unwrap();
+        std::fs::write(config_file, config).unwrap();
+        Ok(())
+    }
+}
+
+fn get_or_create_project_dirs() -> Result<PathBuf, Box<dyn std::error::Error>> {
+    if let Some(proj_dirs) = ProjectDirs::from("com", "valence", "inspector") {
+        // check if the directory exists, if not create it
+        if !proj_dirs.config_dir().exists() {
+            std::fs::create_dir_all(proj_dirs.config_dir())?;
+        }
+
+        Ok(proj_dirs.config_dir().to_owned())
+    } else {
+        Err("Could not find project directories".into())
+    }
+}

crates/packet_inspector/src/context.rs

@@ -0,0 +1,386 @@
+use std::path::PathBuf;
+use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
+use std::sync::RwLock;
+
+use owo_colors::{OwoColorize, Style};
+use regex::Regex;
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+use valence_protocol::codec::PacketDecoder;
+use valence_protocol::packet::c2s::handshake::HandshakeC2s;
+use valence_protocol::packet::c2s::login::{LoginHelloC2s, LoginKeyC2s};
+use valence_protocol::packet::c2s::status::{QueryPingC2s, QueryRequestC2s};
+use valence_protocol::packet::s2c::login::LoginSuccessS2c;
+use valence_protocol::packet::s2c::status::{QueryPongS2c, QueryResponseS2c};
+use valence_protocol::packet::{C2sPlayPacket, S2cLoginPacket, S2cPlayPacket};
+use valence_protocol::raw::RawPacket;
+
+use crate::packet_widget::{systemtime_strftime, PacketDirection};
+
+#[derive(Clone, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
+pub enum Stage {
+    HandshakeC2s,
+    QueryRequestC2s,
+    QueryResponseS2c,
+    QueryPingC2s,
+    QueryPongS2c,
+    LoginHelloC2s,
+    S2cLoginPacket,
+    LoginKeyC2s,
+    LoginSuccessS2c,
+    C2sPlayPacket,
+    S2cPlayPacket,
+}
+
+impl From<Stage> for usize {
+    fn from(stage: Stage) -> Self {
+        match stage {
+            Stage::HandshakeC2s => 0,
+            Stage::QueryRequestC2s => 1,
+            Stage::QueryResponseS2c => 2,
+            Stage::QueryPingC2s => 3,
+            Stage::QueryPongS2c => 4,
+            Stage::LoginHelloC2s => 5,
+            Stage::S2cLoginPacket => 6,
+            Stage::LoginKeyC2s => 7,
+            Stage::LoginSuccessS2c => 8,
+            Stage::C2sPlayPacket => 9,
+            Stage::S2cPlayPacket => 10,
+        }
+    }
+}
+
+impl TryFrom<usize> for Stage {
+    type Error = anyhow::Error;
+
+    fn try_from(value: usize) -> anyhow::Result<Self> {
+        match value {
+            0 => Ok(Stage::HandshakeC2s),
+            1 => Ok(Stage::QueryRequestC2s),
+            2 => Ok(Stage::QueryResponseS2c),
+            3 => Ok(Stage::QueryPingC2s),
+            4 => Ok(Stage::QueryPongS2c),
+            5 => Ok(Stage::LoginHelloC2s),
+            6 => Ok(Stage::S2cLoginPacket),
+            7 => Ok(Stage::LoginKeyC2s),
+            8 => Ok(Stage::LoginSuccessS2c),
+            9 => Ok(Stage::C2sPlayPacket),
+            10 => Ok(Stage::S2cPlayPacket),
+            _ => Err(anyhow::anyhow!("Invalid stage")),
+        }
+    }
+}
+
+#[derive(Clone)]
+pub struct Packet {
+    pub(crate) id: usize,
+    pub(crate) direction: PacketDirection,
+    pub(crate) selected: bool,
+    pub(crate) use_compression: bool,
+    pub(crate) packet_data: Vec<u8>,
+    pub(crate) stage: Stage,
+    pub(crate) packet_type: i32,
+    pub(crate) packet_name: String,
+    pub(crate) created_at: OffsetDateTime,
+}
+
+impl Packet {
+    pub(crate) fn selected(&mut self, value: bool) {
+        self.selected = value;
+    }
+
+    pub fn get_raw_packet(&self) -> Vec<u8> {
+        let mut dec = PacketDecoder::new();
+        dec.set_compression(self.use_compression);
+        dec.queue_slice(&self.packet_data);
+
+        let pkt = match dec.try_next_packet::<RawPacket>() {
+            Ok(Some(pkt)) => pkt,
+            Ok(None) => return vec![],
+            Err(e) => {
+                eprintln!("Error decoding packet: {e}");
+                return vec![];
+            }
+        };
+
+        pkt.0.to_vec()
+    }
+
+    pub fn get_packet_string(&self, formatted: bool) -> String {
+        let mut dec = PacketDecoder::new();
+        dec.set_compression(self.use_compression);
+        dec.queue_slice(&self.packet_data);
+
+        match self.stage {
+            Stage::HandshakeC2s => {
+                let pkt = match dec.try_next_packet::<HandshakeC2s>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "HandshakeC2s".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+            Stage::QueryRequestC2s => {
+                let pkt = match dec.try_next_packet::<QueryRequestC2s>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "QueryRequestC2s".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+            Stage::QueryResponseS2c => {
+                let pkt = match dec.try_next_packet::<QueryResponseS2c>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "QueryResponseS2c".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+            Stage::QueryPingC2s => {
+                let pkt = match dec.try_next_packet::<QueryPingC2s>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "QueryPingC2s".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+            Stage::QueryPongS2c => {
+                let pkt = match dec.try_next_packet::<QueryPongS2c>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "QueryPongS2c".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+            Stage::LoginHelloC2s => {
+                let pkt = match dec.try_next_packet::<LoginHelloC2s>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "LoginHelloC2s".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+            Stage::S2cLoginPacket => {
+                let pkt = match dec.try_next_packet::<S2cLoginPacket>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "S2cLoginPacket".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+            Stage::LoginKeyC2s => {
+                let pkt = match dec.try_next_packet::<LoginKeyC2s>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "LoginKeyC2s".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+            Stage::LoginSuccessS2c => {
+                let pkt = match dec.try_next_packet::<LoginSuccessS2c>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "LoginSuccessS2c".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+            Stage::C2sPlayPacket => {
+                let pkt = match dec.try_next_packet::<C2sPlayPacket>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "C2sPlayPacket".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+            Stage::S2cPlayPacket => {
+                let pkt = match dec.try_next_packet::<S2cPlayPacket>() {
+                    Ok(Some(pkt)) => pkt,
+                    Ok(None) => return "S2cPlayPacket".to_string(),
+                    Err(err) => return format!("{:?}", err),
+                };
+
+                if formatted {
+                    format!("{pkt:#?}")
+                } else {
+                    format!("{pkt:?}")
+                }
+            }
+        }
+    }
+}
+
+pub struct Logger {
+    pub include_filter: Option<Regex>,
+    pub exclude_filter: Option<Regex>,
+}
+
+pub enum ContextMode {
+    Gui(egui::Context),
+    Cli(Logger),
+}
+
+pub struct Context {
+    pub mode: ContextMode,
+    pub last_packet: AtomicUsize,
+    pub selected_packet: RwLock<Option<usize>>,
+    pub(crate) packets: RwLock<Vec<Packet>>,
+    pub(crate) packet_count: RwLock<usize>,
+    pub(crate) has_encryption_enabled_error: AtomicBool,
+    pub filter: RwLock<String>,
+    c2s_style: Style,
+    s2c_style: Style,
+}
+
+impl Context {
+    pub fn new(mode: ContextMode) -> Self {
+        Self {
+            mode,
+            last_packet: AtomicUsize::new(0),
+            selected_packet: RwLock::new(None),
+            packets: RwLock::new(Vec::new()),
+            filter: RwLock::new("".into()),
+            packet_count: RwLock::new(0),
+
+            has_encryption_enabled_error: AtomicBool::new(false),
+
+            c2s_style: Style::new().green(),
+            s2c_style: Style::new().purple(),
+        }
+    }
+
+    pub fn clear(&self) {
+        self.last_packet.store(0, Ordering::Relaxed);
+        *self.selected_packet.write().expect("Poisoned RwLock") = None;
+        self.packets.write().expect("Poisoned RwLock").clear();
+        if let ContextMode::Gui(ctx) = &self.mode {
+            ctx.request_repaint();
+        }
+    }
+
+    pub fn add(&self, mut packet: Packet) {
+        match &self.mode {
+            ContextMode::Gui(ctx) => {
+                packet.id = self.last_packet.fetch_add(1, Ordering::Relaxed);
+                self.packets.write().expect("Poisoned RwLock").push(packet);
+                ctx.request_repaint();
+            }
+            ContextMode::Cli(logger) => {
+                if let Some(include_filter) = &logger.include_filter {
+                    if !include_filter.is_match(&packet.packet_name) {
+                        return;
+                    }
+                }
+                if let Some(exclude_filter) = &logger.exclude_filter {
+                    if exclude_filter.is_match(&packet.packet_name) {
+                        return;
+                    }
+                }
+
+                let arrow = match &packet.direction {
+                    PacketDirection::ClientToServer => "↑",
+                    PacketDirection::ServerToClient => "↓",
+                };
+
+                if atty::is(atty::Stream::Stdout) {
+                    let style = match &packet.direction {
+                        PacketDirection::ClientToServer => self.c2s_style,
+                        PacketDirection::ServerToClient => self.s2c_style,
+                    };
+
+                    println!(
+                        "[{}] ({}) {}",
+                        systemtime_strftime(packet.created_at),
+                        arrow.style(style),
+                        packet.get_packet_string(false).style(style)
+                    );
+                } else {
+                    println!(
+                        "[{}] ({}) {}",
+                        systemtime_strftime(packet.created_at),
+                        arrow,
+                        packet.get_packet_string(false)
+                    );
+                }
+            }
+        }
+    }
+
+    pub fn set_selected_packet(&self, idx: usize) {
+        *self.selected_packet.write().expect("Poisoned RwLock") = Some(idx);
+    }
+
+    pub fn set_filter(&self, filter: String) {
+        *self.filter.write().expect("Posisoned RwLock") = filter;
+        *self.selected_packet.write().expect("Poisoned RwLock") = None;
+    }
+
+    pub fn save(&self, path: PathBuf) -> Result<(), std::io::Error> {
+        let packets = self
+            .packets
+            .read()
+            .expect("Poisoned RwLock")
+            .iter()
+            .map(|packet| {
+                format!(
+                    "[{}] {}",
+                    systemtime_strftime(packet.created_at),
+                    packet.get_packet_string(false)
+                )
+            })
+            .collect::<Vec<String>>()
+            .join("\n");
+
+        std::fs::write(path, packets)?;
+
+        Ok(())
+    }
+}

crates/packet_inspector/src/hex_viewer.rs

@@ -0,0 +1,45 @@
+use std::io::Read;
+
+use egui::Color32;
+
+pub fn hex_view_ui(ui: &mut egui::Ui, mut file: &[u8]) {
+    let mut buf = [0u8; 16];
+    let mut count = 0;
+
+    egui::Grid::new("hex_grid")
+        .spacing([4.0, 1.5])
+        .striped(true)
+        .min_col_width(0.0)
+        .show(ui, |ui| {
+            ui.label(" ");
+            for i in 0..16 {
+                ui.label(format!("{:02X}", i));
+            }
+            ui.end_row();
+            loop {
+                let bytes_read = file.read(&mut buf).unwrap();
+                if bytes_read == 0 {
+                    break;
+                }
+
+                ui.label(format!("{:08X}", count));
+                for b in buf.iter().take(bytes_read) {
+                    ui.colored_label(Color32::from_rgb(255, 255, 255), format!("{:02X}", b));
+                }
+                for _ in 0..16 - bytes_read {
+                    ui.label(" ");
+                }
+                ui.label(" ");
+                for b in buf.iter().take(bytes_read) {
+                    if *b >= 0x20 && *b <= 0x7e {
+                        ui.label(format!("{}", *b as char));
+                    } else {
+                        ui.label(".");
+                    }
+                }
+
+                ui.end_row();
+                count += bytes_read;
+            }
+        });
+}

crates/packet_inspector/src/main.rs

@@ -1,14 +1,25 @@
-use std::error::Error;
-use std::fmt::Write;
-use std::io;
-use std::io::ErrorKind;
+mod config;
+mod context;
+mod hex_viewer;
+mod packet_widget;
+mod state;
+mod syntax_highlighting;
+
+use std::collections::BTreeMap;
 use std::net::SocketAddr;
-use std::sync::Arc;
+use std::str::FromStr;
+use std::sync::atomic::Ordering;
+use std::sync::{Arc, RwLock};
 
 use anyhow::bail;
 use clap::Parser;
-use owo_colors::OwoColorize;
+use config::ApplicationConfig;
+use context::{Context, Packet};
+use egui::{Align2, RichText};
+use hex_viewer::hex_view_ui;
 use regex::Regex;
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+use syntax_highlighting::code_view_ui;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::net::tcp::{OwnedReadHalf, OwnedWriteHalf};
 use tokio::net::{TcpListener, TcpStream};
@@ -23,107 +34,79 @@ use valence_protocol::packet::c2s::status::{QueryPingC2s, QueryRequestC2s};
 use valence_protocol::packet::s2c::login::LoginSuccessS2c;
 use valence_protocol::packet::s2c::status::{QueryPongS2c, QueryResponseS2c};
 use valence_protocol::packet::{C2sPlayPacket, S2cLoginPacket, S2cPlayPacket};
-use valence_protocol::Packet;
+
+use crate::context::{ContextMode, Stage};
+use crate::packet_widget::PacketDirection;
+use crate::state::State;
 
 #[derive(Parser, Clone, Debug)]
 #[clap(author, version, about)]
 struct Cli {
     /// The socket address to listen for connections on. This is the address
     /// clients should connect to.
-    client_addr: SocketAddr,
+    #[arg(required_if_eq("nogui", "true"))]
+    client_addr: Option<SocketAddr>,
+
     /// The socket address the proxy will connect to. This is the address of the
     /// server.
-    server_addr: SocketAddr,
-    /// An optional regular expression to use on packet names. Packet names
-    /// matching the regex are printed while those that don't are ignored.
-    ///
-    /// If no regex is provided, all packets are considered matching.
-    #[clap(short, long)]
-    include_regex: Option<Regex>,
-    /// An optional regular expression to use on packet names. Packet names
-    /// matching the regex are ignored while those are don't are printed.
-    ///
-    /// If no regex is provided, all packets are not considered matching.
-    #[clap(short, long)]
-    exclude_regex: Option<Regex>,
+    #[arg(required_if_eq("nogui", "true"))]
+    server_addr: Option<SocketAddr>,
+
     /// The maximum number of connections allowed to the proxy. By default,
     /// there is no limit.
     #[clap(short, long)]
     max_connections: Option<usize>,
-}
 
-struct State {
-    cli: Arc<Cli>,
-    enc: PacketEncoder,
-    dec: PacketDecoder,
-    read: OwnedReadHalf,
-    write: OwnedWriteHalf,
-    buf: String,
-    style: owo_colors::Style,
-}
+    /// Disable the GUI. Logging to stdout.
+    #[clap(long)]
+    nogui: bool,
 
-impl State {
-    pub async fn rw_packet<'a, P>(&'a mut self) -> anyhow::Result<P>
-    where
-        P: Packet<'a>,
-    {
-        while !self.dec.has_next_packet()? {
-            self.dec.reserve(4096);
-            let mut buf = self.dec.take_capacity();
+    /// Only show packets that match the filter.
+    #[clap(short, long)]
+    include_filter: Option<Regex>,
 
-            if self.read.read_buf(&mut buf).await? == 0 {
-                return Err(io::Error::from(ErrorKind::UnexpectedEof).into());
-            }
-
-            self.dec.queue_bytes(buf);
-        }
-
-        let pkt: P = self.dec.try_next_packet()?.unwrap();
-
-        self.enc.append_packet(&pkt)?;
-
-        let bytes = self.enc.take();
-        self.write.write_all(&bytes).await?;
-
-        self.buf.clear();
-        write!(&mut self.buf, "{pkt:?}")?;
-
-        let packet_name = self
-            .buf
-            .split_once(|ch: char| !ch.is_ascii_alphabetic())
-            .map(|(fst, _)| fst)
-            .unwrap_or(&self.buf);
-
-        if let Some(r) = &self.cli.include_regex {
-            if !r.is_match(packet_name) {
-                return Ok(pkt);
-            }
-        }
-
-        if let Some(r) = &self.cli.exclude_regex {
-            if r.is_match(packet_name) {
-                return Ok(pkt);
-            }
-        }
-
-        println!("{}", self.buf.style(self.style));
-
-        Ok(pkt)
-    }
+    /// Hide packets that match the filter. Note: Only in effect if nogui is
+    /// set.
+    #[clap(short, long)]
+    exclude_filter: Option<Regex>,
 }
 
 #[tokio::main]
-async fn main() -> Result<(), Box<dyn Error>> {
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
     tracing_subscriber::fmt()
         .with_max_level(LevelFilter::DEBUG)
         .init();
 
     let cli = Arc::new(Cli::parse());
 
+    match cli.nogui {
+        true => start_cli(cli).await?,
+        false => start_gui(cli)?,
+    };
+
+    Ok(())
+}
+
+async fn start_cli(cli: Arc<Cli>) -> Result<(), Box<dyn std::error::Error>> {
+    let context = Arc::new(Context::new(ContextMode::Cli(context::Logger {
+        include_filter: cli.include_filter.clone(),
+        exclude_filter: cli.exclude_filter.clone(),
+    })));
+
     let sema = Arc::new(Semaphore::new(cli.max_connections.unwrap_or(100_000)));
 
-    eprintln!("Waiting for connections on {}", cli.client_addr);
-    let listen = TcpListener::bind(cli.client_addr).await?;
+    let client_addr = match cli.client_addr {
+        Some(addr) => addr,
+        None => return Err("Missing Client Address".into()),
+    };
+
+    let server_addr = match cli.server_addr {
+        Some(addr) => addr,
+        None => return Err("Missing Server Address".into()),
+    };
+
+    eprintln!("Waiting for connections on {}", client_addr);
+    let listen = TcpListener::bind(client_addr).await?;
 
     while let Ok(permit) = sema.clone().acquire_owned().await {
         let (client, remote_client_addr) = listen.accept().await?;
@@ -133,9 +116,9 @@ async fn main() -> Result<(), Box<dyn Error>> {
             eprintln!("Failed to set TCP_NODELAY: {e}");
         }
 
-        let cli = cli.clone();
+        let context = context.clone();
         tokio::spawn(async move {
-            if let Err(e) = handle_connection(client, cli).await {
+            if let Err(e) = handle_connection(client, server_addr, context).await {
                 eprintln!("Connection to {remote_client_addr} ended with: {e:#}");
             } else {
                 eprintln!("Connection to {remote_client_addr} ended.");
@@ -147,10 +130,50 @@ async fn main() -> Result<(), Box<dyn Error>> {
     Ok(())
 }
 
-async fn handle_connection(client: TcpStream, cli: Arc<Cli>) -> anyhow::Result<()> {
-    eprintln!("Connecting to {}", cli.server_addr);
+fn start_gui(cli: Arc<Cli>) -> Result<(), Box<dyn std::error::Error>> {
+    let native_options = eframe::NativeOptions {
+        initial_window_size: Some(egui::Vec2::new(800.0, 600.0)),
+        decorated: true,
+        ..Default::default()
+    };
 
-    let server = TcpStream::connect(cli.server_addr).await?;
+    let server_addr = cli.server_addr;
+    let client_addr = cli.client_addr;
+    let max_connections = cli.max_connections.unwrap_or(100_000);
+
+    let filter = cli
+        .include_filter
+        .clone()
+        .map(|f| f.to_string())
+        .unwrap_or("".to_string());
+
+    eframe::run_native(
+        "Valence Packet Inspector",
+        native_options,
+        Box::new(move |cc| {
+            let gui_app = GuiApp::new(cc, filter);
+
+            if let Some(server_addr) = server_addr {
+                if let Some(client_addr) = client_addr {
+                    gui_app.start_listening(client_addr, server_addr, max_connections);
+                }
+            }
+
+            Box::new(gui_app)
+        }),
+    )?;
+
+    Ok(())
+}
+
+async fn handle_connection(
+    client: TcpStream,
+    server_addr: SocketAddr,
+    context: Arc<Context>,
+) -> anyhow::Result<()> {
+    eprintln!("Connecting to {}", server_addr);
+
+    let server = TcpStream::connect(server_addr).await?;
 
     if let Err(e) = server.set_nodelay(true) {
         eprintln!("Failed to set TCP_NODELAY: {e}");
@@ -160,48 +183,55 @@ async fn handle_connection(client: TcpStream, cli: Arc<Cli>) -> anyhow::Result<(
     let (server_read, server_write) = server.into_split();
 
     let mut s2c = State {
-        cli: cli.clone(),
         enc: PacketEncoder::new(),
         dec: PacketDecoder::new(),
         read: server_read,
         write: client_write,
-        buf: String::new(),
-        style: owo_colors::Style::new().purple(),
+        direction: PacketDirection::ServerToClient,
+        context: context.clone(),
     };
 
     let mut c2s = State {
-        cli,
         enc: PacketEncoder::new(),
         dec: PacketDecoder::new(),
         read: client_read,
         write: server_write,
-        buf: String::new(),
-        style: owo_colors::Style::new().green(),
+        direction: PacketDirection::ClientToServer,
+        context: context.clone(),
     };
 
-    let handshake: HandshakeC2s = c2s.rw_packet().await?;
+    let handshake: HandshakeC2s = c2s.rw_packet(Stage::HandshakeC2s).await?;
 
     match handshake.next_state {
         NextState::Status => {
-            c2s.rw_packet::<QueryRequestC2s>().await?;
-            s2c.rw_packet::<QueryResponseS2c>().await?;
-            c2s.rw_packet::<QueryPingC2s>().await?;
-            s2c.rw_packet::<QueryPongS2c>().await?;
+            c2s.rw_packet::<QueryRequestC2s>(Stage::QueryRequestC2s)
+                .await?;
+            s2c.rw_packet::<QueryResponseS2c>(Stage::QueryResponseS2c)
+                .await?;
+            c2s.rw_packet::<QueryPingC2s>(Stage::QueryPingC2s).await?;
+            s2c.rw_packet::<QueryPongS2c>(Stage::QueryPongS2c).await?;
 
             Ok(())
         }
         NextState::Login => {
-            c2s.rw_packet::<LoginHelloC2s>().await?;
+            c2s.rw_packet::<LoginHelloC2s>(Stage::LoginHelloC2s).await?;
 
-            match s2c.rw_packet::<S2cLoginPacket>().await? {
+            match s2c
+                .rw_packet::<S2cLoginPacket>(Stage::S2cLoginPacket)
+                .await?
+            {
                 S2cLoginPacket::LoginHelloS2c(_) => {
-                    c2s.rw_packet::<LoginKeyC2s>().await?;
+                    c2s.rw_packet::<LoginKeyC2s>(Stage::LoginKeyC2s).await?;
 
                     eprintln!(
-                        "Encryption was enabled! Packet contents are inaccessible to the proxy. \
-                         Disable online_mode to fix this."
+                        "Encryption is enabled! Packet contents are inaccessible to the proxy. \
+                         Disable online mode to fix this."
                     );
 
+                    context
+                        .has_encryption_enabled_error
+                        .store(true, Ordering::Relaxed);
+
                     return tokio::select! {
                         c2s_res = passthrough(c2s.read, c2s.write) => c2s_res,
                         s2c_res = passthrough(s2c.read, s2c.write) => s2c_res,
@@ -215,30 +245,31 @@ async fn handle_connection(client: TcpStream, cli: Arc<Cli>) -> anyhow::Result<(
                     c2s.enc.set_compression(Some(threshold));
                     c2s.dec.set_compression(true);
 
-                    s2c.rw_packet::<LoginSuccessS2c>().await?;
+                    s2c.rw_packet::<LoginSuccessS2c>(Stage::LoginSuccessS2c)
+                        .await?;
                 }
                 S2cLoginPacket::LoginSuccessS2c(_) => {}
                 S2cLoginPacket::LoginDisconnectS2c(_) => return Ok(()),
                 S2cLoginPacket::LoginQueryRequestS2c(_) => {
-                    bail!("got login query request. Don't know how to proceed.")
+                    bail!("got login plugin request. Don't know how to proceed.")
                 }
             }
 
             let c2s_fut: JoinHandle<anyhow::Result<()>> = tokio::spawn(async move {
                 loop {
-                    c2s.rw_packet::<C2sPlayPacket>().await?;
+                    c2s.rw_packet::<C2sPlayPacket>(Stage::C2sPlayPacket).await?;
                 }
             });
 
-            let s2c_fut = async move {
+            let s2c_fut: JoinHandle<anyhow::Result<()>> = tokio::spawn(async move {
                 loop {
-                    s2c.rw_packet::<S2cPlayPacket>().await?;
+                    s2c.rw_packet::<S2cPlayPacket>(Stage::S2cPlayPacket).await?;
                 }
-            };
+            });
 
             tokio::select! {
                 c2s = c2s_fut => Ok(c2s??),
-                s2c = s2c_fut => s2c,
+                s2c = s2c_fut => Ok(s2c??),
             }
         }
     }
@@ -257,3 +288,607 @@ async fn passthrough(mut read: OwnedReadHalf, mut write: OwnedWriteHalf) -> anyh
         write.write_all(bytes).await?;
     }
 }
+
+#[derive(Clone)]
+pub struct MetaPacket {
+    id: i32,
+    stage: Stage,
+    direction: PacketDirection,
+    name: String,
+}
+
+// manually implement Serialize and Deserialize that use the ToString and
+// FromStr implementaions for keys
+impl Serialize for MetaPacket {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&self.to_string())
+    }
+}
+
+impl<'de> Deserialize<'de> for MetaPacket {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let s = String::deserialize(deserializer)?;
+        MetaPacket::from_str(&s).map_err(serde::de::Error::custom)
+    }
+}
+
+impl From<(Stage, i32, PacketDirection, String)> for MetaPacket {
+    fn from((stage, id, direction, name): (Stage, i32, PacketDirection, String)) -> Self {
+        Self {
+            stage,
+            id,
+            direction,
+            name,
+        }
+    }
+}
+
+// to string and from string to be used in toml
+impl ToString for MetaPacket {
+    fn to_string(&self) -> String {
+        let stage: usize = self.stage.clone().into();
+
+        format!(
+            "{}:{}:{}:{}",
+            stage,
+            self.id,
+            match self.direction {
+                PacketDirection::ClientToServer => 0,
+                PacketDirection::ServerToClient => 1,
+            },
+            self.name
+        )
+    }
+}
+
+impl FromStr for MetaPacket {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut split = s.split(':');
+        let stage = match split.next().unwrap().parse::<usize>() {
+            Ok(stage) => Stage::try_from(stage)?,
+            Err(_) => bail!("invalid stage"),
+        };
+        let id = split.next().unwrap().parse::<i32>()?;
+        let direction = match split.next().unwrap().parse::<i32>()? {
+            0 => PacketDirection::ClientToServer,
+            1 => PacketDirection::ServerToClient,
+            _ => bail!("invalid direction"),
+        };
+        let name = split.next().unwrap().to_string();
+
+        Ok(Self {
+            stage,
+            id,
+            direction,
+            name,
+        })
+    }
+}
+
+impl Ord for MetaPacket {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        #[derive(PartialEq, Eq, PartialOrd, Ord)]
+        struct OrdMetaPacket {
+            stage: Stage,
+            id: i32,
+            direction: PacketDirection,
+        }
+
+        let left = OrdMetaPacket {
+            stage: self.stage.clone(),
+            id: self.id,
+            direction: self.direction.clone(),
+        };
+
+        let right = OrdMetaPacket {
+            stage: other.stage.clone(),
+            id: other.id,
+            direction: other.direction.clone(),
+        };
+
+        left.cmp(&right)
+    }
+}
+
+impl PartialOrd for MetaPacket {
+    fn partial_cmp(&self, other: &Self) -> std::option::Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl PartialEq for MetaPacket {
+    fn eq(&self, other: &Self) -> bool {
+        self.stage == other.stage && self.id == other.id && self.direction == other.direction
+    }
+}
+
+impl Eq for MetaPacket {}
+
+struct GuiApp {
+    config: ApplicationConfig,
+    temp_server_addr: String,
+    temp_client_addr: String,
+    temp_max_connections: String,
+
+    server_addr_error: bool,
+    client_addr_error: bool,
+    max_connections_error: bool,
+
+    context: Arc<Context>,
+    filter: String,
+    selected_packets: BTreeMap<MetaPacket, bool>,
+    buffer: String,
+    is_listening: RwLock<bool>,
+    window_open: bool,
+    encryption_error_dialog_open: bool,
+
+    config_load_error: Option<String>,
+    config_load_error_window_open: bool,
+
+    raw_packet: Vec<u8>,
+    view_hex: bool,
+}
+
+impl GuiApp {
+    fn new(cc: &eframe::CreationContext<'_>, filter: String) -> Self {
+        let ctx = cc.egui_ctx.clone();
+
+        let context = Context::new(ContextMode::Gui(ctx));
+
+        let mut config_load_error: Option<String> = None;
+
+        let mut config = match ApplicationConfig::load() {
+            Ok(config) => config,
+            Err(e) => {
+                config_load_error = Some(format!("Failed to load config:\n{}", e));
+                ApplicationConfig::default()
+            }
+        };
+
+        let mut filter = filter;
+
+        if filter.is_empty() {
+            if let Some(c_filter) = config.filter() {
+                filter = c_filter.to_string();
+            }
+        } else {
+            config.set_filter(Some(filter.clone()));
+        }
+
+        {
+            let mut f = context.filter.write().expect("Poisoned filter");
+            *f = filter.clone();
+        }
+
+        let context = Arc::new(context);
+
+        let temp_server_addr = config.server_addr().to_string();
+        let temp_client_addr = config.client_addr().to_string();
+        let temp_max_connections = match config.max_connections() {
+            Some(max_connections) => max_connections.to_string(),
+            None => String::new(),
+        };
+
+        let selected_packets = match config.selected_packets().clone() {
+            Some(selected_packets) => selected_packets,
+            None => BTreeMap::new(),
+        };
+
+        Self {
+            config,
+            context,
+            filter,
+            selected_packets,
+            buffer: String::new(),
+            is_listening: RwLock::new(false),
+            window_open: false,
+            encryption_error_dialog_open: false,
+
+            temp_server_addr,
+            temp_client_addr,
+            temp_max_connections,
+
+            server_addr_error: false,
+            client_addr_error: false,
+            max_connections_error: false,
+
+            config_load_error,
+            config_load_error_window_open: false,
+
+            raw_packet: Vec::new(),
+            view_hex: false,
+        }
+    }
+
+    fn start_listening(
+        &self,
+        client_addr: SocketAddr,
+        server_addr: SocketAddr,
+        max_connections: usize,
+    ) {
+        let t_context = self.context.clone();
+        tokio::spawn(async move {
+            let sema = Arc::new(Semaphore::new(max_connections));
+
+            let listen = TcpListener::bind(client_addr).await?;
+            eprintln!("Waiting for connections on {}", client_addr);
+
+            while let Ok(permit) = sema.clone().acquire_owned().await {
+                let (client, remote_client_addr) = listen.accept().await?;
+                eprintln!("Accepted connection to {remote_client_addr}");
+
+                if let Err(e) = client.set_nodelay(true) {
+                    eprintln!("Failed to set TCP_NODELAY: {e}");
+                }
+
+                let t2_context = t_context.clone();
+                tokio::spawn(async move {
+                    if let Err(e) = handle_connection(client, server_addr, t2_context).await {
+                        eprintln!("Connection to {remote_client_addr} ended with: {e:#}");
+                    } else {
+                        eprintln!("Connection to {remote_client_addr} ended.");
+                    }
+                    drop(permit);
+                });
+            }
+
+            Ok::<(), anyhow::Error>(())
+        });
+        *self.is_listening.write().expect("Poisoned is_listening") = true;
+    }
+
+    fn nested_menus(&mut self, ui: &mut egui::Ui) {
+        let mut changed = false;
+        self.selected_packets
+            .iter_mut()
+            .for_each(|(m_packet, selected)| {
+                // todo: format, add arrows, etc
+                if ui.checkbox(selected, m_packet.name.clone()).changed() {
+                    changed = true;
+                    ui.ctx().request_repaint();
+                }
+            });
+
+        if changed {
+            self.config
+                .set_selected_packets(self.selected_packets.clone());
+        }
+    }
+}
+
+impl eframe::App for GuiApp {
+    fn on_close_event(&mut self) -> bool {
+        match self.config.save() {
+            Ok(_) => {}
+            Err(e) => {
+                eprintln!("Failed to save config: {e}");
+            }
+        }
+        true
+    }
+
+    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
+        if !*self.is_listening.read().expect("Poisoned is_listening") {
+            self.window_open = true;
+        }
+
+        if self
+            .context
+            .has_encryption_enabled_error
+            .load(Ordering::Relaxed)
+        {
+            self.encryption_error_dialog_open = true;
+        }
+
+        if self.encryption_error_dialog_open {
+            egui::Window::new("Encryption Error")
+                .anchor(Align2::CENTER_CENTER, [0.0, 0.0])
+                .open(&mut self.encryption_error_dialog_open)
+                .movable(false)
+                .collapsible(false)
+                .resizable(false)
+                .show(ctx, |ui| {
+                    ui.label(
+                        "Encryption is enabled! Packet contents are inaccessible to the proxy. \
+                         Disable online mode to fix this.",
+                    );
+                });
+
+            // it was true, now it's false, the user acknowledged the error, set it to false
+            if !self.encryption_error_dialog_open {
+                self.context
+                    .has_encryption_enabled_error
+                    .store(false, Ordering::Relaxed);
+            }
+        }
+
+        if self.config_load_error.is_some() {
+            self.config_load_error_window_open = true;
+        }
+
+        if self.config_load_error_window_open {
+            if let Some(err) = &self.config_load_error {
+                egui::Window::new("Config Error")
+                    .anchor(Align2::CENTER_CENTER, [0.0, 0.0])
+                    .open(&mut self.config_load_error_window_open)
+                    .movable(false)
+                    .collapsible(false)
+                    .resizable(false)
+                    .show(ctx, |ui| {
+                        ui.label(err);
+                    });
+            }
+
+            if !self.config_load_error_window_open {
+                self.config_load_error = None;
+            }
+
+            return;
+        }
+
+        if self.window_open {
+            egui::Window::new("Setup")
+                .anchor(Align2::CENTER_CENTER, [0.0, 0.0])
+                .movable(false)
+                .collapsible(false)
+                .resizable(false)
+                .show(ctx, |ui| {
+                    egui::Grid::new("setup_grid")
+                        .num_columns(2)
+                        .spacing([40.0, 4.0])
+                        .striped(true)
+                        .show(ui, |ui| {
+                            ui.label(RichText::new("Server address:").color(
+                                match self.server_addr_error {
+                                    true => egui::Color32::RED,
+                                    false => egui::Color32::WHITE,
+                                },
+                            ));
+                            if ui
+                                .text_edit_singleline(&mut self.temp_server_addr)
+                                .on_hover_text(
+                                    "The socket address the proxy will connect to. This is the \
+                                     address of the server.",
+                                )
+                                .changed()
+                            {
+                                self.server_addr_error = false;
+                            };
+                            ui.end_row();
+                            ui.label(RichText::new("Client address:").color(
+                                match self.client_addr_error {
+                                    true => egui::Color32::RED,
+                                    false => egui::Color32::WHITE,
+                                },
+                            ));
+                            ui.text_edit_singleline(&mut self.temp_client_addr)
+                                .on_hover_text(
+                                    "The socket address to listen for connections on. This is the \
+                                     address clients should connect to.",
+                                );
+                            ui.end_row();
+                            ui.label(RichText::new("Max Connections:").color(
+                                match self.max_connections_error {
+                                    true => egui::Color32::RED,
+                                    false => egui::Color32::WHITE,
+                                },
+                            ));
+                            ui.text_edit_singleline(&mut self.temp_max_connections)
+                                .on_hover_text(
+                                    "The maximum number of connections allowed to the proxy. By \
+                                     default, there is no limit.",
+                                );
+                            ui.end_row();
+                            if ui.button("Start Proxy").clicked() {
+                                self.window_open = false;
+                            }
+                        });
+                });
+
+            if !self.window_open {
+                let server_addr = self.temp_server_addr.parse::<SocketAddr>().map_err(|_| {
+                    self.server_addr_error = true;
+                });
+
+                let client_addr = self.temp_client_addr.parse::<SocketAddr>().map_err(|_| {
+                    self.client_addr_error = true;
+                });
+
+                let max_connections = if self.temp_max_connections.is_empty() {
+                    Ok(100_000)
+                } else {
+                    self.temp_max_connections.parse::<usize>().map_err(|_| {
+                        self.max_connections_error = true;
+                    })
+                };
+
+                if server_addr.is_err() || client_addr.is_err() || max_connections.is_err() {
+                    self.window_open = true;
+                    return;
+                }
+
+                self.config.set_server_addr(server_addr.unwrap());
+                self.config.set_client_addr(client_addr.unwrap());
+                self.config
+                    .set_max_connections(if self.temp_max_connections.is_empty() {
+                        None
+                    } else {
+                        Some(self.temp_max_connections.parse::<usize>().unwrap())
+                    });
+
+                self.start_listening(
+                    client_addr.unwrap(),
+                    server_addr.unwrap(),
+                    max_connections.unwrap(),
+                );
+            }
+
+            return;
+        }
+
+        egui::TopBottomPanel::top("header").show(ctx, |ui| {
+            ui.horizontal(|ui| {
+                ui.label("Filter:");
+                if ui.text_edit_singleline(&mut self.filter).changed() {
+                    self.context.set_filter(self.filter.clone());
+
+                    self.config.set_filter(match self.filter.is_empty() {
+                        true => None,
+                        false => Some(self.filter.clone()),
+                    });
+                }
+                ui.menu_button("Packets", |ui| {
+                    ui.set_max_width(250.0);
+                    ui.set_max_height(400.0);
+                    egui::ScrollArea::vertical()
+                        .auto_shrink([true, true])
+                        .show(ui, |ui| {
+                            self.nested_menus(ui);
+                        });
+                });
+            });
+        });
+
+        egui::SidePanel::left("side_panel")
+            .min_width(150.0)
+            .default_width(250.0)
+            .show(ctx, |ui| {
+                ui.horizontal(|ui| {
+                    ui.heading("Packets");
+
+                    let count = self.context.packet_count.read().expect("Poisoned RwLock");
+                    let total = self.context.packets.read().expect("Poisoned RwLock").len();
+
+                    let all_selected = self.selected_packets.values().all(|v| *v);
+
+                    if self.filter.is_empty() && all_selected {
+                        ui.label(format!("({total})"));
+                    } else {
+                        ui.label(format!("({count}/{total})"));
+                    }
+
+                    if ui.button("Clear").clicked() {
+                        self.context.clear();
+                        self.buffer = String::new();
+                        self.raw_packet = vec![];
+                    }
+
+                    if ui.button("Export").clicked() {
+                        if let Some(path) = rfd::FileDialog::new()
+                            .add_filter("Text Document", &["txt"])
+                            .save_file()
+                        {
+                            match self.context.save(path) {
+                                Ok(_) => {}
+                                Err(err) => {
+                                    eprintln!("Failed to save: {}", err);
+                                }
+                            }
+                        }
+                    }
+                });
+                egui::ScrollArea::vertical()
+                    .auto_shrink([false, false])
+                    .stick_to_bottom(true)
+                    .show(ui, |ui| {
+                        let mut f = self.context.packets.write().expect("Poisoned RwLock");
+
+                        let f: Vec<&mut Packet> = f
+                            .iter_mut()
+                            .filter(|p| {
+                                let m_packet = MetaPacket {
+                                    stage: p.stage.clone(),
+                                    id: p.packet_type,
+                                    direction: p.direction.clone(),
+                                    name: p.packet_name.clone(),
+                                };
+
+                                if !self.selected_packets.contains_key(&m_packet) {
+                                    self.selected_packets.insert(m_packet.clone(), true);
+                                    self.config
+                                        .set_selected_packets(self.selected_packets.clone());
+                                } else {
+                                    // if it does exist, check if the names are the same, if not
+                                    // update the key
+                                    let (existing, value) =
+                                        self.selected_packets.get_key_value(&m_packet).unwrap();
+                                    if existing.name != m_packet.name {
+                                        let value = *value; // keep the old value
+                                        self.selected_packets.remove(&m_packet);
+                                        self.selected_packets.insert(m_packet.clone(), value);
+                                        self.config
+                                            .set_selected_packets(self.selected_packets.clone());
+                                    }
+                                }
+
+                                if let Some(selected) = self.selected_packets.get(&m_packet) {
+                                    if !*selected {
+                                        return false;
+                                    }
+                                }
+
+                                if self.filter.is_empty() {
+                                    return true;
+                                }
+
+                                if let Ok(re) = regex::Regex::new(&self.filter) {
+                                    return re.is_match(&p.packet_name);
+                                }
+
+                                false
+                            })
+                            .collect();
+
+                        *self.context.packet_count.write().expect("Poisoned RwLock") = f.len();
+
+                        for packet in f {
+                            {
+                                let selected = self
+                                    .context
+                                    .selected_packet
+                                    .read()
+                                    .expect("Poisoned RwLock");
+                                if let Some(idx) = *selected {
+                                    if idx == packet.id {
+                                        packet.selected(true);
+                                        self.buffer = packet.get_packet_string(true);
+                                        self.raw_packet = packet.get_raw_packet();
+                                    } else {
+                                        packet.selected(false);
+                                    }
+                                } else {
+                                    packet.selected(false);
+                                }
+                            }
+
+                            if ui.add(packet.clone()).clicked() {
+                                self.context.set_selected_packet(packet.id);
+                            }
+                        }
+                    });
+            });
+        egui::CentralPanel::default().show(ctx, |ui| {
+            ui.horizontal(|ui| {
+                ui.checkbox(&mut self.view_hex, "Hex View");
+            });
+
+            egui::ScrollArea::both()
+                .auto_shrink([false, false])
+                .show(ui, |ui| {
+                    if self.view_hex {
+                        hex_view_ui(ui, &self.raw_packet);
+                    } else {
+                        code_view_ui(ui, &self.buffer);
+                    }
+                });
+        });
+    }
+}

crates/packet_inspector/src/packet_widget.rs

@@ -0,0 +1,151 @@
+use eframe::epaint::{PathShape, RectShape};
+use egui::{
+    Pos2, Rect, Response, Rgba, Rounding, Sense, Shape, Stroke, TextStyle, Ui, Vec2, Widget,
+    WidgetText,
+};
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+
+use crate::context::Packet;
+
+pub fn systemtime_strftime(odt: OffsetDateTime) -> String {
+    let hour = odt.hour();
+    let minute = odt.minute();
+    let second = odt.second();
+    let millis = odt.millisecond();
+
+    format!("{hour:0>2}:{minute:0>2}:{second:0>2}.{millis:0>4}")
+}
+
+#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Serialize, Deserialize)]
+pub enum PacketDirection {
+    ClientToServer,
+    ServerToClient,
+}
+
+impl PacketDirection {
+    fn get_shape(&self, outer_rect: &Rect) -> PathShape {
+        let rect = Rect::from_min_size(
+            Pos2 {
+                x: outer_rect.left() + 6.0,
+                y: outer_rect.top() + 8.0,
+            },
+            Vec2 { x: 8.0, y: 8.0 },
+        );
+
+        let color = match self {
+            PacketDirection::ServerToClient => Rgba::from_rgb(255.0, 0.0, 0.0),
+            PacketDirection::ClientToServer => Rgba::from_rgb(0.0, 255.0, 0.0),
+        };
+
+        let points = match self {
+            PacketDirection::ServerToClient => vec![
+                Pos2 {
+                    x: rect.left() + (rect.width() / 2.0),
+                    y: rect.top() + rect.height(),
+                },
+                Pos2 {
+                    x: rect.left() + 0.0,
+                    y: rect.top(),
+                },
+                Pos2 {
+                    x: rect.left() + rect.width(),
+                    y: rect.top(),
+                },
+            ],
+            PacketDirection::ClientToServer => vec![
+                Pos2 {
+                    x: rect.left() + (rect.width() / 2.0),
+                    y: rect.top() + 0.0,
+                },
+                Pos2 {
+                    x: rect.left() + 0.0,
+                    y: rect.top() + rect.height(),
+                },
+                Pos2 {
+                    x: rect.left() + rect.width(),
+                    y: rect.top() + rect.height(),
+                },
+            ],
+        };
+
+        let mut shape = PathShape::closed_line(points, Stroke::new(2.0, color));
+        shape.fill = color.into();
+
+        shape
+    }
+}
+
+impl Widget for Packet {
+    fn ui(self, ui: &mut Ui) -> Response {
+        let (mut rect, response) = ui.allocate_at_least(
+            Vec2 {
+                x: ui.available_width(),
+                y: 24.0,
+            },
+            Sense::click(),
+        );
+
+        let fill = match self.selected {
+            true => Rgba::from_rgba_premultiplied(0.0, 0.0, 0.0, 0.4),
+            false => Rgba::from_rgba_premultiplied(0.0, 0.0, 0.0, 0.0),
+        };
+
+        if ui.is_rect_visible(rect) {
+            ui.painter().add(Shape::Rect(RectShape {
+                rect,
+                rounding: Rounding::none(),
+                fill: fill.into(),
+                stroke: Stroke::new(1.0, Rgba::BLACK),
+            }));
+
+            let shape = self.direction.get_shape(&rect);
+            ui.painter().add(Shape::Path(shape));
+
+            let identifier: WidgetText = format!("0x{:0>2X?}", self.packet_type).into();
+
+            let identifier =
+                identifier.into_galley(ui, Some(false), rect.width() - 21.0, TextStyle::Button);
+
+            let label: WidgetText = self.packet_name.into();
+            let label = label.into_galley(ui, Some(false), rect.width() - 60.0, TextStyle::Button);
+
+            let timestamp: WidgetText = systemtime_strftime(self.created_at).into();
+            let timestamp =
+                timestamp.into_galley(ui, Some(false), rect.width() - 60.0, TextStyle::Button);
+
+            identifier.paint_with_fallback_color(
+                ui.painter(),
+                Pos2 {
+                    x: rect.left() + 21.0,
+                    y: rect.top() + 6.0,
+                },
+                ui.visuals().weak_text_color(),
+            );
+
+            rect.set_width(rect.width() - 5.0);
+
+            let label_width = label.size().x + 50.0;
+
+            label.paint_with_fallback_color(
+                &ui.painter().with_clip_rect(rect),
+                Pos2 {
+                    x: rect.left() + 55.0,
+                    y: rect.top() + 6.0,
+                },
+                ui.visuals().strong_text_color(),
+            );
+
+            timestamp.paint_with_fallback_color(
+                &ui.painter().with_clip_rect(rect),
+                Pos2 {
+                    x: rect.left() + label_width + 8.0,
+                    y: rect.top() + 6.0,
+                },
+                ui.visuals().weak_text_color(),
+            );
+        }
+
+        response
+    }
+}

crates/packet_inspector/src/state.rs

@@ -0,0 +1,65 @@
+use std::io::ErrorKind;
+use std::sync::Arc;
+
+use time::OffsetDateTime;
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tokio::net::tcp::{OwnedReadHalf, OwnedWriteHalf};
+use valence_protocol::codec::{PacketDecoder, PacketEncoder};
+use valence_protocol::Packet as ValencePacket;
+
+use crate::context::{Context, Packet, Stage};
+use crate::packet_widget::PacketDirection;
+
+pub struct State {
+    pub direction: PacketDirection,
+    pub context: Arc<Context>,
+    pub enc: PacketEncoder,
+    pub dec: PacketDecoder,
+    pub read: OwnedReadHalf,
+    pub write: OwnedWriteHalf,
+}
+
+impl State {
+    pub async fn rw_packet<'a, P>(&'a mut self, stage: Stage) -> anyhow::Result<P>
+    where
+        P: ValencePacket<'a>,
+    {
+        while !self.dec.has_next_packet()? {
+            self.dec.reserve(4096);
+            let mut buf = self.dec.take_capacity();
+
+            if self.read.read_buf(&mut buf).await? == 0 {
+                return Err(std::io::Error::from(ErrorKind::UnexpectedEof).into());
+            }
+
+            self.dec.queue_bytes(buf);
+        }
+
+        let has_compression = self.dec.compression();
+        let pkt: P = self.dec.try_next_packet()?.unwrap();
+
+        self.enc.append_packet(&pkt)?;
+
+        let bytes = self.enc.take();
+        self.write.write_all(&bytes).await?;
+
+        let time = match OffsetDateTime::now_local() {
+            Ok(time) => time,
+            Err(_) => OffsetDateTime::now_utc(),
+        };
+
+        self.context.add(Packet {
+            id: 0, // updated when added to context
+            direction: self.direction.clone(),
+            use_compression: has_compression,
+            packet_data: bytes.to_vec(),
+            stage,
+            created_at: time,
+            selected: false,
+            packet_type: pkt.packet_id(),
+            packet_name: pkt.packet_name().to_string(),
+        });
+
+        Ok(pkt)
+    }
+}

crates/packet_inspector/src/syntax_highlighting.rs

@@ -0,0 +1,513 @@
+// From: https://github.com/emilk/egui/blob/master/crates/egui_demo_lib/src/syntax_highlighting.rs
+
+use egui::text::LayoutJob;
+
+/// View some code with syntax highlighting and selection.
+pub fn code_view_ui(ui: &mut egui::Ui, mut code: &str) {
+    let language = "rs";
+    let theme = CodeTheme::from_memory(ui.ctx());
+
+    let mut layouter = |ui: &egui::Ui, string: &str, wrap_width: f32| {
+        let mut layout_job = highlight(ui.ctx(), &theme, string, language);
+        layout_job.wrap.max_width = wrap_width; // no wrapping
+        ui.fonts(|f| f.layout_job(layout_job))
+    };
+
+    ui.add(
+        egui::TextEdit::multiline(&mut code)
+            .font(egui::TextStyle::Monospace) // for cursor height
+            .code_editor()
+            .desired_width(ui.available_width())
+            .desired_rows(24)
+            .lock_focus(true)
+            .layouter(&mut layouter),
+    );
+}
+
+/// Memoized Code highlighting
+pub fn highlight(ctx: &egui::Context, theme: &CodeTheme, code: &str, language: &str) -> LayoutJob {
+    impl egui::util::cache::ComputerMut<(&CodeTheme, &str, &str), LayoutJob> for Highlighter {
+        fn compute(&mut self, (theme, code, lang): (&CodeTheme, &str, &str)) -> LayoutJob {
+            self.highlight(theme, code, lang)
+        }
+    }
+
+    type HighlightCache = egui::util::cache::FrameCache<LayoutJob, Highlighter>;
+
+    ctx.memory_mut(|mem| {
+        mem.caches
+            .cache::<HighlightCache>()
+            .get((theme, code, language))
+    })
+}
+
+// ----------------------------------------------------------------------------
+
+#[cfg(not(feature = "syntect"))]
+#[derive(Clone, Copy, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+#[derive(enum_map::Enum)]
+enum TokenType {
+    Comment,
+    Keyword,
+    Literal,
+    StringLiteral,
+    Punctuation,
+    Whitespace,
+}
+
+#[cfg(feature = "syntect")]
+#[derive(Clone, Copy, Hash, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+#[allow(unused)]
+enum SyntectTheme {
+    Base16EightiesDark,
+    Base16MochaDark,
+    Base16OceanDark,
+    Base16OceanLight,
+    InspiredGitHub,
+    SolarizedDark,
+    SolarizedLight,
+}
+
+#[allow(unused)]
+#[cfg(feature = "syntect")]
+impl SyntectTheme {
+    fn all() -> impl ExactSizeIterator<Item = Self> {
+        [
+            Self::Base16EightiesDark,
+            Self::Base16MochaDark,
+            Self::Base16OceanDark,
+            Self::Base16OceanLight,
+            Self::InspiredGitHub,
+            Self::SolarizedDark,
+            Self::SolarizedLight,
+        ]
+        .iter()
+        .copied()
+    }
+
+    fn name(&self) -> &'static str {
+        match self {
+            Self::Base16EightiesDark => "Base16 Eighties (dark)",
+            Self::Base16MochaDark => "Base16 Mocha (dark)",
+            Self::Base16OceanDark => "Base16 Ocean (dark)",
+            Self::Base16OceanLight => "Base16 Ocean (light)",
+            Self::InspiredGitHub => "InspiredGitHub (light)",
+            Self::SolarizedDark => "Solarized (dark)",
+            Self::SolarizedLight => "Solarized (light)",
+        }
+    }
+
+    fn syntect_key_name(&self) -> &'static str {
+        match self {
+            Self::Base16EightiesDark => "base16-eighties.dark",
+            Self::Base16MochaDark => "base16-mocha.dark",
+            Self::Base16OceanDark => "base16-ocean.dark",
+            Self::Base16OceanLight => "base16-ocean.light",
+            Self::InspiredGitHub => "InspiredGitHub",
+            Self::SolarizedDark => "Solarized (dark)",
+            Self::SolarizedLight => "Solarized (light)",
+        }
+    }
+
+    pub fn is_dark(&self) -> bool {
+        match self {
+            Self::Base16EightiesDark
+            | Self::Base16MochaDark
+            | Self::Base16OceanDark
+            | Self::SolarizedDark => true,
+
+            Self::Base16OceanLight | Self::InspiredGitHub | Self::SolarizedLight => false,
+        }
+    }
+}
+
+#[derive(Clone, Hash, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+#[cfg_attr(feature = "serde", serde(default))]
+pub struct CodeTheme {
+    dark_mode: bool,
+
+    #[cfg(feature = "syntect")]
+    syntect_theme: SyntectTheme,
+
+    #[cfg(not(feature = "syntect"))]
+    formats: enum_map::EnumMap<TokenType, egui::TextFormat>,
+}
+
+impl Default for CodeTheme {
+    fn default() -> Self {
+        Self::dark()
+    }
+}
+
+#[allow(unused)]
+impl CodeTheme {
+    pub fn from_style(style: &egui::Style) -> Self {
+        if style.visuals.dark_mode {
+            Self::dark()
+        } else {
+            Self::light()
+        }
+    }
+
+    pub fn from_memory(ctx: &egui::Context) -> Self {
+        if ctx.style().visuals.dark_mode {
+            ctx.data_mut(|d| {
+                d.get_persisted(egui::Id::new("dark"))
+                    .unwrap_or_else(CodeTheme::dark)
+            })
+        } else {
+            ctx.data_mut(|d| {
+                d.get_persisted(egui::Id::new("light"))
+                    .unwrap_or_else(CodeTheme::light)
+            })
+        }
+    }
+
+    pub fn store_in_memory(self, ctx: &egui::Context) {
+        if self.dark_mode {
+            ctx.data_mut(|d| d.insert_persisted(egui::Id::new("dark"), self));
+        } else {
+            ctx.data_mut(|d| d.insert_persisted(egui::Id::new("light"), self));
+        }
+    }
+}
+
+#[allow(unused)]
+#[cfg(feature = "syntect")]
+impl CodeTheme {
+    pub fn dark() -> Self {
+        Self {
+            dark_mode: true,
+            syntect_theme: SyntectTheme::SolarizedDark,
+        }
+    }
+
+    pub fn light() -> Self {
+        Self {
+            dark_mode: false,
+            syntect_theme: SyntectTheme::SolarizedLight,
+        }
+    }
+
+    pub fn ui(&mut self, ui: &mut egui::Ui) {
+        egui::widgets::global_dark_light_mode_buttons(ui);
+
+        for theme in SyntectTheme::all() {
+            if theme.is_dark() == self.dark_mode {
+                ui.radio_value(&mut self.syntect_theme, theme, theme.name());
+            }
+        }
+    }
+}
+
+#[cfg(not(feature = "syntect"))]
+impl CodeTheme {
+    pub fn dark() -> Self {
+        let font_id = egui::FontId::monospace(10.0);
+        use egui::{Color32, TextFormat};
+        Self {
+            dark_mode: true,
+            formats: enum_map::enum_map![
+                TokenType::Comment => TextFormat::simple(font_id.clone(), Color32::from_gray(120)),
+                TokenType::Keyword => TextFormat::simple(font_id.clone(), Color32::from_rgb(255, 100, 100)),
+                TokenType::Literal => TextFormat::simple(font_id.clone(), Color32::from_rgb(87, 165, 171)),
+                TokenType::StringLiteral => TextFormat::simple(font_id.clone(), Color32::from_rgb(109, 147, 226)),
+                TokenType::Punctuation => TextFormat::simple(font_id.clone(), Color32::LIGHT_GRAY),
+                TokenType::Whitespace => TextFormat::simple(font_id.clone(), Color32::TRANSPARENT),
+            ],
+        }
+    }
+
+    pub fn light() -> Self {
+        let font_id = egui::FontId::monospace(10.0);
+        use egui::{Color32, TextFormat};
+        Self {
+            dark_mode: false,
+            #[cfg(not(feature = "syntect"))]
+            formats: enum_map::enum_map![
+                TokenType::Comment => TextFormat::simple(font_id.clone(), Color32::GRAY),
+                TokenType::Keyword => TextFormat::simple(font_id.clone(), Color32::from_rgb(235, 0, 0)),
+                TokenType::Literal => TextFormat::simple(font_id.clone(), Color32::from_rgb(153, 134, 255)),
+                TokenType::StringLiteral => TextFormat::simple(font_id.clone(), Color32::from_rgb(37, 203, 105)),
+                TokenType::Punctuation => TextFormat::simple(font_id.clone(), Color32::DARK_GRAY),
+                TokenType::Whitespace => TextFormat::simple(font_id.clone(), Color32::TRANSPARENT),
+            ],
+        }
+    }
+
+    pub fn ui(&mut self, ui: &mut egui::Ui) {
+        ui.horizontal_top(|ui| {
+            let selected_id = egui::Id::null();
+            let mut selected_tt: TokenType =
+                ui.data_mut(|d| *d.get_persisted_mut_or(selected_id, TokenType::Comment));
+
+            ui.vertical(|ui| {
+                ui.set_width(150.0);
+                egui::widgets::global_dark_light_mode_buttons(ui);
+
+                ui.add_space(8.0);
+                ui.separator();
+                ui.add_space(8.0);
+
+                ui.scope(|ui| {
+                    for (tt, tt_name) in [
+                        (TokenType::Comment, "// comment"),
+                        (TokenType::Keyword, "keyword"),
+                        (TokenType::Literal, "literal"),
+                        (TokenType::StringLiteral, "\"string literal\""),
+                        (TokenType::Punctuation, "punctuation ;"),
+                        // (TokenType::Whitespace, "whitespace"),
+                    ] {
+                        let format = &mut self.formats[tt];
+                        ui.style_mut().override_font_id = Some(format.font_id.clone());
+                        ui.visuals_mut().override_text_color = Some(format.color);
+                        ui.radio_value(&mut selected_tt, tt, tt_name);
+                    }
+                });
+
+                let reset_value = if self.dark_mode {
+                    CodeTheme::dark()
+                } else {
+                    CodeTheme::light()
+                };
+
+                if ui
+                    .add_enabled(*self != reset_value, egui::Button::new("Reset theme"))
+                    .clicked()
+                {
+                    *self = reset_value;
+                }
+            });
+
+            ui.add_space(16.0);
+
+            ui.data_mut(|d| d.insert_persisted(selected_id, selected_tt));
+
+            egui::Frame::group(ui.style())
+                .inner_margin(egui::Vec2::splat(2.0))
+                .show(ui, |ui| {
+                    // ui.group(|ui| {
+                    ui.style_mut().override_text_style = Some(egui::TextStyle::Small);
+                    ui.spacing_mut().slider_width = 128.0; // Controls color picker size
+                    egui::widgets::color_picker::color_picker_color32(
+                        ui,
+                        &mut self.formats[selected_tt].color,
+                        egui::color_picker::Alpha::Opaque,
+                    );
+                });
+        });
+    }
+}
+
+// ----------------------------------------------------------------------------
+
+#[cfg(feature = "syntect")]
+struct Highlighter {
+    ps: syntect::parsing::SyntaxSet,
+    ts: syntect::highlighting::ThemeSet,
+}
+
+#[cfg(feature = "syntect")]
+impl Default for Highlighter {
+    fn default() -> Self {
+        Self {
+            ps: syntect::parsing::SyntaxSet::load_defaults_newlines(),
+            ts: syntect::highlighting::ThemeSet::load_defaults(),
+        }
+    }
+}
+
+#[cfg(feature = "syntect")]
+impl Highlighter {
+    #[allow(clippy::unused_self, clippy::unnecessary_wraps)]
+    fn highlight(&self, theme: &CodeTheme, code: &str, lang: &str) -> LayoutJob {
+        self.highlight_impl(theme, code, lang).unwrap_or_else(|| {
+            // Fallback:
+            LayoutJob::simple(
+                code.into(),
+                egui::FontId::monospace(12.0),
+                if theme.dark_mode {
+                    egui::Color32::LIGHT_GRAY
+                } else {
+                    egui::Color32::DARK_GRAY
+                },
+                f32::INFINITY,
+            )
+        })
+    }
+
+    fn highlight_impl(&self, theme: &CodeTheme, text: &str, language: &str) -> Option<LayoutJob> {
+        use syntect::easy::HighlightLines;
+        use syntect::highlighting::FontStyle;
+        use syntect::util::LinesWithEndings;
+
+        let syntax = self
+            .ps
+            .find_syntax_by_name(language)
+            .or_else(|| self.ps.find_syntax_by_extension(language))?;
+
+        let theme = theme.syntect_theme.syntect_key_name();
+        let mut h = HighlightLines::new(syntax, &self.ts.themes[theme]);
+
+        use egui::text::{LayoutSection, TextFormat};
+
+        let mut job = LayoutJob {
+            text: text.into(),
+            ..Default::default()
+        };
+
+        for line in LinesWithEndings::from(text) {
+            for (style, range) in h.highlight_line(line, &self.ps).ok()? {
+                let fg = style.foreground;
+                let text_color = egui::Color32::from_rgb(fg.r, fg.g, fg.b);
+                let italics = style.font_style.contains(FontStyle::ITALIC);
+                let underline = style.font_style.contains(FontStyle::ITALIC);
+                let underline = if underline {
+                    egui::Stroke::new(1.0, text_color)
+                } else {
+                    egui::Stroke::NONE
+                };
+                job.sections.push(LayoutSection {
+                    leading_space: 0.0,
+                    byte_range: as_byte_range(text, range),
+                    format: TextFormat {
+                        font_id: egui::FontId::monospace(12.0),
+                        color: text_color,
+                        italics,
+                        underline,
+                        ..Default::default()
+                    },
+                });
+            }
+        }
+
+        Some(job)
+    }
+}
+
+#[cfg(feature = "syntect")]
+fn as_byte_range(whole: &str, range: &str) -> std::ops::Range<usize> {
+    let whole_start = whole.as_ptr() as usize;
+    let range_start = range.as_ptr() as usize;
+    assert!(whole_start <= range_start);
+    assert!(range_start + range.len() <= whole_start + whole.len());
+    let offset = range_start - whole_start;
+    offset..(offset + range.len())
+}
+
+// ----------------------------------------------------------------------------
+
+#[cfg(not(feature = "syntect"))]
+#[derive(Default)]
+struct Highlighter {}
+
+#[cfg(not(feature = "syntect"))]
+impl Highlighter {
+    #[allow(clippy::unused_self, clippy::unnecessary_wraps)]
+    fn highlight(&self, theme: &CodeTheme, mut text: &str, _language: &str) -> LayoutJob {
+        // Extremely simple syntax highlighter for when we compile without syntect
+
+        let mut job = LayoutJob::default();
+
+        while !text.is_empty() {
+            if text.starts_with("//") {
+                let end = text.find('\n').unwrap_or(text.len());
+                job.append(&text[..end], 0.0, theme.formats[TokenType::Comment].clone());
+                text = &text[end..];
+            } else if text.starts_with('"') {
+                let end = text[1..]
+                    .find('"')
+                    .map(|i| i + 2)
+                    .or_else(|| text.find('\n'))
+                    .unwrap_or(text.len());
+                job.append(
+                    &text[..end],
+                    0.0,
+                    theme.formats[TokenType::StringLiteral].clone(),
+                );
+                text = &text[end..];
+            } else if text.starts_with(|c: char| c.is_ascii_alphanumeric()) {
+                let end = text[1..]
+                    .find(|c: char| !c.is_ascii_alphanumeric())
+                    .map_or_else(|| text.len(), |i| i + 1);
+                let word = &text[..end];
+                let tt = if is_keyword(word) {
+                    TokenType::Keyword
+                } else {
+                    TokenType::Literal
+                };
+                job.append(word, 0.0, theme.formats[tt].clone());
+                text = &text[end..];
+            } else if text.starts_with(|c: char| c.is_ascii_whitespace()) {
+                let end = text[1..]
+                    .find(|c: char| !c.is_ascii_whitespace())
+                    .map_or_else(|| text.len(), |i| i + 1);
+                job.append(
+                    &text[..end],
+                    0.0,
+                    theme.formats[TokenType::Whitespace].clone(),
+                );
+                text = &text[end..];
+            } else {
+                let mut it = text.char_indices();
+                it.next();
+                let end = it.next().map_or(text.len(), |(idx, _chr)| idx);
+                job.append(
+                    &text[..end],
+                    0.0,
+                    theme.formats[TokenType::Punctuation].clone(),
+                );
+                text = &text[end..];
+            }
+        }
+
+        job
+    }
+}
+
+#[cfg(not(feature = "syntect"))]
+fn is_keyword(word: &str) -> bool {
+    matches!(
+        word,
+        "as" | "async"
+            | "await"
+            | "break"
+            | "const"
+            | "continue"
+            | "crate"
+            | "dyn"
+            | "else"
+            | "enum"
+            | "extern"
+            | "false"
+            | "fn"
+            | "for"
+            | "if"
+            | "impl"
+            | "in"
+            | "let"
+            | "loop"
+            | "match"
+            | "mod"
+            | "move"
+            | "mut"
+            | "pub"
+            | "ref"
+            | "return"
+            | "self"
+            | "Self"
+            | "static"
+            | "struct"
+            | "super"
+            | "trait"
+            | "true"
+            | "type"
+            | "unsafe"
+            | "use"
+            | "where"
+            | "while"
+    )
+}