use palette16::{Palette16OptimisationResults, Palette16Optimiser};
use palette256::Palette256;
use proc_macro::TokenStream;
use proc_macro2::Literal;
use syn::parse::{Parse, Parser};
use syn::{parse_macro_input, punctuated::Punctuated, LitStr};
use syn::{Expr, ExprLit, Lit, Token};

use std::collections::HashMap;
use std::path::PathBuf;
use std::{iter, path::Path, str};

use quote::{format_ident, quote, ToTokens};

mod aseprite;
mod colour;
mod config;
mod font_loader;
mod image_loader;
mod palette16;
mod palette256;
mod rust_generator;

use image::GenericImageView;
use image_loader::Image;

use colour::Colour;

#[derive(Debug, Clone, Copy)]
pub(crate) enum Colours {
    Colours16,
    Colours256,
}

struct BackgroundGfxOption {
    module_name: String,
    file_name: String,
    colours: Colours,
    deduplicate: bool,
}

impl config::Image for BackgroundGfxOption {
    fn filename(&self) -> String {
        self.file_name.clone()
    }

    fn colours(&self) -> Colours {
        self.colours
    }

    fn deduplicate(&self) -> bool {
        self.deduplicate
    }
}

impl Parse for BackgroundGfxOption {
    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
        let module_name: syn::Ident = input.parse()?;
        let _: Token![=>] = input.parse()?;

        let lookahead = input.lookahead1();

        let colours = if lookahead.peek(syn::LitInt) {
            let num_colours: syn::LitInt = input.parse()?;

            match num_colours.base10_parse()? {
                16 => Colours::Colours16,
                256 => Colours::Colours256,
                _ => {
                    return Err(syn::Error::new_spanned(
                        num_colours,
                        "Number of colours must be 16 or 256",
                    ))
                }
            }
        } else {
            Colours::Colours16
        };

        let lookahead = input.lookahead1();

        let deduplicate = if lookahead.peek(syn::Ident) {
            let deduplicate: syn::Ident = input.parse()?;

            if deduplicate == "deduplicate" {
                true
            } else {
                return Err(syn::Error::new_spanned(
                    deduplicate,
                    "Must either be the literal deduplicate or missing",
                ));
            }
        } else {
            false
        };

        let file_name: syn::LitStr = input.parse()?;

        Ok(Self {
            module_name: module_name.to_string(),
            file_name: file_name.value(),
            colours,
            deduplicate,
        })
    }
}

struct IncludeBackgroundGfxInput {
    module_name: syn::Ident,
    crate_prefix: String,
    transparent_colour: Colour,
    background_gfx_options: Vec<BackgroundGfxOption>,
}

impl Parse for IncludeBackgroundGfxInput {
    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
        let lookahead = input.lookahead1();

        let crate_prefix: syn::Ident = if lookahead.peek(Token![crate]) {
            let _: Token![crate] = input.parse()?;
            let _: Token![,] = input.parse()?;
            format_ident!("crate")
        } else {
            format_ident!("agb")
        };

        let module_name: syn::Ident = input.parse()?;
        let _: Token![,] = input.parse()?;

        let lookahead = input.lookahead1();
        let transparent_colour: Colour = if lookahead.peek(syn::LitStr) {
            let colour_str: syn::LitStr = input.parse()?;
            let _: Token![,] = input.parse()?;
            colour_str
                .value()
                .parse()
                .map_err(|msg| syn::Error::new_spanned(colour_str, msg))?
        } else {
            Colour::from_rgb(255, 0, 255, 0)
        };

        let background_gfx_options =
            input.parse_terminated(BackgroundGfxOption::parse, Token![,])?;

        Ok(Self {
            module_name,
            crate_prefix: crate_prefix.to_string(),
            transparent_colour,
            background_gfx_options: background_gfx_options.into_iter().collect(),
        })
    }
}

impl config::Config for IncludeBackgroundGfxInput {
    fn crate_prefix(&self) -> String {
        self.crate_prefix.clone()
    }

    fn images(&self) -> HashMap<String, &dyn config::Image> {
        self.background_gfx_options
            .iter()
            .map(|options| (options.module_name.clone(), options as &dyn config::Image))
            .collect()
    }

    fn transparent_colour(&self) -> Option<Colour> {
        Some(self.transparent_colour)
    }
}

#[proc_macro]
pub fn include_background_gfx(input: TokenStream) -> TokenStream {
    let config = Box::new(parse_macro_input!(input as IncludeBackgroundGfxInput));

    let root = std::env::var("CARGO_MANIFEST_DIR").expect("Failed to get cargo manifest dir");

    let module_name = config.module_name.clone();
    include_gfx_from_config(config, module_name, Path::new(&root))
}

fn include_gfx_from_config(
    config: Box<dyn config::Config>,
    module_name: syn::Ident,
    parent: &Path,
) -> TokenStream {
    let images = config.images();

    let mut optimiser = Palette16Optimiser::new(config.transparent_colour());
    let mut assignment_offsets = HashMap::new();
    let mut assignment_offset = 0;

    let mut palette256 = Palette256::new();

    for (name, settings) in images.iter() {
        let image_filename = &parent.join(settings.filename());
        let image = Image::load_from_file(image_filename);

        match settings.colours() {
            Colours::Colours16 => {
                let tile_size = 8;
                if image.width % tile_size != 0 || image.height % tile_size != 0 {
                    panic!("Image size not a multiple of tile size");
                }

                add_to_optimiser(
                    &mut optimiser,
                    &image,
                    tile_size,
                    tile_size,
                    config.transparent_colour(),
                );

                let num_tiles = image.width * image.height / 8usize.pow(2);
                assignment_offsets.insert(name, assignment_offset);
                assignment_offset += num_tiles;
            }
            Colours::Colours256 => {
                palette256.add_image(&image);
            }
        }
    }

    let optimisation_results = optimiser.optimise_palettes();
    let optimisation_results = palette256.extend_results(&optimisation_results);

    let mut image_code = vec![];

    for (image_name, &image) in images.iter() {
        let assignment_offset = match image.colours() {
            Colours::Colours16 => Some(assignment_offsets[image_name]),
            _ => None,
        };

        image_code.push(convert_image(
            image,
            parent,
            image_name,
            &config.crate_prefix(),
            &optimisation_results,
            assignment_offset,
        ));
    }

    let palette_code =
        rust_generator::generate_palette_code(&optimisation_results, &config.crate_prefix());

    let module = quote! {
        mod #module_name {
            #palette_code

            #(#image_code)*
        }
    };

    TokenStream::from(module)
}

use quote::TokenStreamExt;
struct ByteString<'a>(&'a [u8]);
impl ToTokens for ByteString<'_> {
    fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
        tokens.append(Literal::byte_string(self.0));
    }
}

#[proc_macro]
pub fn include_colours_inner(input: TokenStream) -> TokenStream {
    let input_filename = parse_macro_input!(input as LitStr);
    let input_filename = input_filename.value();

    let root = std::env::var("CARGO_MANIFEST_DIR").expect("Failed to get cargo manifest dir");
    let input_filename = Path::new(&root).join(input_filename);

    let image = Image::load_from_file(Path::new(&input_filename));

    let mut palette_data = Vec::with_capacity(image.width * image.height);
    for y in 0..image.height {
        for x in 0..image.width {
            palette_data.push(image.colour(x, y).to_rgb15())
        }
    }

    let filename = input_filename.to_string_lossy();

    TokenStream::from(quote! {
        {
            const _: &[u8] = include_bytes!(#filename);
            [#(#palette_data),*]
        }
    })
}

#[proc_macro]
pub fn include_aseprite_inner(input: TokenStream) -> TokenStream {
    let parser = Punctuated::<LitStr, syn::Token![,]>::parse_terminated;
    let parsed = match parser.parse(input) {
        Ok(e) => e,
        Err(e) => return e.to_compile_error().into(),
    };

    let transparent_colour = Colour::from_rgb(255, 0, 255, 0);

    let mut optimiser = palette16::Palette16Optimiser::new(Some(transparent_colour));
    let mut images = Vec::new();
    let mut tags = Vec::new();

    let root = std::env::var("CARGO_MANIFEST_DIR").expect("Failed to get cargo manifest dir");

    let filenames: Vec<PathBuf> = parsed
        .iter()
        .map(|s| s.value())
        .map(|s| Path::new(&root).join(&*s))
        .collect();

    for filename in filenames.iter() {
        let (frames, tag) = aseprite::generate_from_file(filename);

        tags.push((tag, images.len()));

        for frame in frames {
            let width = frame.width();
            let height = frame.height();
            assert!(
                valid_sprite_size(width, height),
                "File {} contains sprites with size {}x{} which cannot be represented on the GameBoy Advance",
                filename.display(),
                width,
                height
            );

            let image = Image::load_from_dyn_image(frame);
            add_to_optimiser(
                &mut optimiser,
                &image,
                width as usize,
                height as usize,
                Some(transparent_colour),
            );
            images.push(image);
        }
    }

    let optimised_results = optimiser.optimise_palettes();

    let (palette_data, tile_data, assignments) = palette_tile_data(&optimised_results, &images);

    let palette_data = palette_data.iter().map(|colours| {
        quote! {
            Palette16::new([
                #(#colours),*
            ])
        }
    });

    let mut pre = 0;
    let sprites = images
        .iter()
        .zip(assignments.iter())
        .map(|(f, assignment)| {
            let start: usize = pre;
            let end: usize = pre + (f.width / 8) * (f.height / 8) * 32;
            let data = ByteString(&tile_data[start..end]);
            pre = end;
            let width = f.width;
            let height = f.height;
            quote! {
                unsafe {
                        Sprite::new(
                        &PALETTES[#assignment],
                        align_bytes!(u16, #data),
                        Size::from_width_height(#width, #height)
                    )
                }
            }
        });

    let tags = tags.iter().flat_map(|(tag, num_images)| {
        tag.iter().map(move |tag| {
            let start = tag.from_frame() as usize + num_images;
            let end = tag.to_frame() as usize + num_images;
            let direction = tag.animation_direction() as usize;

            let name = tag.name();
            assert!(start <= end, "Tag {name} has start > end");

            quote! {
                (#name, Tag::new(SPRITES, #start, #end, #direction))
            }
        })
    });

    let include_paths = filenames.iter().map(|s| {
        let s = s.as_os_str().to_string_lossy();
        quote! {
            const _: &[u8] = include_bytes!(#s);
        }
    });

    let module = quote! {
        #(#include_paths)*


        const PALETTES: &[Palette16] = &[
            #(#palette_data),*
        ];

        pub const SPRITES: &[Sprite] = &[
            #(#sprites),*
        ];

        const TAGS: &TagMap = &TagMap::new(
            &[
                #(#tags),*
            ]
        );

    };

    TokenStream::from(module)
}

fn convert_image(
    settings: &dyn config::Image,
    parent: &Path,
    variable_name: &str,
    crate_prefix: &str,
    optimisation_results: &Palette16OptimisationResults,
    assignment_offset: Option<usize>,
) -> proc_macro2::TokenStream {
    let image_filename = &parent.join(settings.filename());
    let image = Image::load_from_file(image_filename);

    rust_generator::generate_code(
        variable_name,
        optimisation_results,
        &image,
        &image_filename.to_string_lossy(),
        crate_prefix.to_owned(),
        assignment_offset,
    )
}

fn add_to_optimiser(
    palette_optimiser: &mut palette16::Palette16Optimiser,
    image: &Image,
    tile_width: usize,
    tile_height: usize,
    transparent_colour: Option<Colour>,
) {
    let tiles_x = image.width / tile_width;
    let tiles_y = image.height / tile_height;

    for y in 0..tiles_y {
        for x in 0..tiles_x {
            let mut palette = palette16::Palette16::new();

            for j in 0..tile_height {
                for i in 0..tile_width {
                    let colour = image.colour(x * tile_width + i, y * tile_height + j);

                    palette.add_colour(match (colour.is_transparent(), transparent_colour) {
                        (true, Some(transparent_colour)) => transparent_colour,
                        _ => colour,
                    });
                }
            }

            palette_optimiser.add_palette(palette);
        }
    }
}

fn palette_tile_data(
    optimiser: &Palette16OptimisationResults,
    images: &[Image],
) -> (Vec<Vec<u16>>, Vec<u8>, Vec<usize>) {
    let palette_data: Vec<Vec<u16>> = optimiser
        .optimised_palettes
        .iter()
        .map(|palette| {
            palette
                .clone()
                .into_iter()
                .map(|colour| colour.to_rgb15())
                .chain(iter::repeat(0))
                .take(16)
                .collect()
        })
        .collect();

    let mut tile_data = Vec::new();

    for (image_idx, image) in images.iter().enumerate() {
        add_image_to_tile_data(&mut tile_data, image, optimiser, image_idx, true)
    }

    let tile_data = collapse_to_4bpp(&tile_data);

    let assignments = optimiser.assignments.clone();

    (palette_data, tile_data, assignments)
}

fn collapse_to_4bpp(tile_data: &[u8]) -> Vec<u8> {
    tile_data
        .chunks(2)
        .map(|chunk| chunk[0] | (chunk[1] << 4))
        .collect()
}

fn add_image_to_tile_data(
    tile_data: &mut Vec<u8>,
    image: &Image,
    optimiser: &Palette16OptimisationResults,
    assignment_offset: usize,
    is_sprite: bool,
) {
    let tile_size = 8;
    let tiles_x = image.width / tile_size;
    let tiles_y = image.height / tile_size;

    for y in 0..tiles_y {
        for x in 0..tiles_x {
            let assignment = if is_sprite {
                assignment_offset
            } else {
                y * tiles_x + x + assignment_offset
            };

            let palette_index = optimiser.assignments[assignment];
            let palette = &optimiser.optimised_palettes[palette_index];

            for inner_y in 0..tile_size / 8 {
                for inner_x in 0..tile_size / 8 {
                    for j in inner_y * 8..inner_y * 8 + 8 {
                        for i in inner_x * 8..inner_x * 8 + 8 {
                            let colour = image.colour(x * tile_size + i, y * tile_size + j);
                            tile_data.push(palette.colour_index(colour));
                        }
                    }
                }
            }
        }
    }
}

fn add_image_256_to_tile_data(
    tile_data: &mut Vec<u8>,
    image: &Image,
    optimiser: &Palette16OptimisationResults,
) {
    let tile_size = 8;
    let tiles_x = image.width / tile_size;
    let tiles_y = image.height / tile_size;

    let all_colours: Vec<_> = optimiser
        .optimised_palettes
        .iter()
        .flat_map(|p| p.colours())
        .collect();

    for y in 0..tiles_y {
        for x in 0..tiles_x {
            for inner_y in 0..tile_size / 8 {
                for inner_x in 0..tile_size / 8 {
                    for j in inner_y * 8..inner_y * 8 + 8 {
                        for i in inner_x * 8..inner_x * 8 + 8 {
                            let colour = image.colour(x * tile_size + i, y * tile_size + j);
                            tile_data.push(all_colours.iter().position(|c| **c == colour).unwrap() as u8);
                        }
                    }
                }
            }
        }
    }
}

fn flatten_group(expr: &Expr) -> &Expr {
    match expr {
        Expr::Group(group) => &group.expr,
        _ => expr,
    }
}

#[proc_macro]
pub fn include_font(input: TokenStream) -> TokenStream {
    let parser = Punctuated::<Expr, syn::Token![,]>::parse_separated_nonempty;
    let parsed = match parser.parse(input) {
        Ok(e) => e,
        Err(e) => return e.to_compile_error().into(),
    };

    let all_args: Vec<_> = parsed.into_iter().collect();
    if all_args.len() != 2 {
        panic!("Include_font requires 2 arguments, got {}", all_args.len());
    }

    let filename = match flatten_group(&all_args[0]) {
        Expr::Lit(ExprLit {
            lit: Lit::Str(str_lit),
            ..
        }) => str_lit.value(),
        _ => panic!("Expected literal string as first argument to include_font"),
    };

    let font_size = match flatten_group(&all_args[1]) {
        Expr::Lit(ExprLit {
            lit: Lit::Float(value),
            ..
        }) => value.base10_parse::<f32>().expect("Invalid float literal"),
        Expr::Lit(ExprLit {
            lit: Lit::Int(value),
            ..
        }) => value
            .base10_parse::<i32>()
            .expect("Invalid integer literal") as f32,
        _ => panic!("Expected literal float or integer as second argument to include_font"),
    };

    let root = std::env::var("CARGO_MANIFEST_DIR").expect("Failed to get cargo manifest dir");
    let path = Path::new(&root).join(&*filename);

    let file_content = std::fs::read(&path).expect("Failed to read ttf file");

    let rendered = font_loader::load_font(&file_content, font_size);

    let include_path = path.to_string_lossy();

    quote!({
        let _ = include_bytes!(#include_path);

        #rendered
    })
    .into()
}

fn valid_sprite_size(width: u32, height: u32) -> bool {
    match (width, height) {
        (8, 8) => true,
        (16, 16) => true,
        (32, 32) => true,
        (64, 64) => true,
        (16, 8) => true,
        (32, 8) => true,
        (32, 16) => true,
        (64, 32) => true,
        (8, 16) => true,
        (8, 32) => true,
        (16, 32) => true,
        (32, 64) => true,
        (_, _) => false,
    }
}

#[cfg(test)]
mod tests {
    use asefile::AnimationDirection;

    #[test]
    // These directions defined in agb and have these values. This is important
    // when outputting code for agb. If more animation directions are added then
    // we will have to support them there.
    fn directions_to_agb() {
        assert_eq!(AnimationDirection::Forward as usize, 0);
        assert_eq!(AnimationDirection::Reverse as usize, 1);
        assert_eq!(AnimationDirection::PingPong as usize, 2);
    }
}