use anyhow::{Context, Result};
use metrics::{describe_gauge, gauge, Gauge, Unit};
use metrics_prometheus::Recorder;
use serde::{Deserialize, Serialize};
use std::{
    path::PathBuf,
    sync::{Arc, RwLock},
    time::{Duration, Instant},
};
use teslatte::{
    auth::{AccessToken, RefreshToken},
    vehicles::{Endpoint, GetVehicleData},
    FleetApi, FleetVehicleApi, VehicleId,
};

use crate::{errors::*, types::CarState};

struct Metrics {
    battery_level: Gauge,
    charge_rate: Gauge,
    inside_temp: Gauge,
}

impl Metrics {
    fn new() -> (Self, Recorder) {
        let recorder = metrics_prometheus::install();

        describe_gauge!("tesla_battery_level", Unit::Percent, "Battery level");
        let battery_level = gauge!("tesla_battery_level");
        describe_gauge!("tesla_charge_rate", "Charge rate");
        let charge_rate = gauge!("tesla_charge_rate");
        describe_gauge!("tesla_inside_temp", "Inside temperature");
        let inside_temp = gauge!("tesla_inside_temp");

        (
            Self {
                battery_level,
                charge_rate,
                inside_temp,
            },
            recorder,
        )
    }
}

pub struct TeslaInterface {
    pub state: Arc<RwLock<CarState>>,
    api: FleetApi,
    vehicle: Box<teslatte::vehicles::VehicleData>,
    last_refresh: Instant,
    auth_path: PathBuf,
    metrics: Metrics,
}

#[derive(Serialize, Deserialize, Clone)]
struct AuthInfo {
    access_token: AccessToken,
    refresh_token: Option<RefreshToken>,
}

#[derive(Clone, Copy, Debug)]
// these are the messages that the webserver can send the api thread
pub enum InterfaceRequest {
    FlashLights,
}

const KEY_REFRESH_INTERVAL: Duration = Duration::from_secs(12 * 60 * 60);

impl TeslaInterface {
    pub async fn load(auth_path: PathBuf) -> Result<Self, AuthLoadError> {
        let key: AuthInfo = ron::from_str(&std::fs::read_to_string(&auth_path)?)?;
        let mut api = FleetApi::new(key.access_token, key.refresh_token);
        api.refresh().await?;
        let last_refresh = Instant::now();
        info!("Refreshed auth key");
        let vehicle = api
            .products()
            .await?
            .into_iter()
            .filter_map(|v| match v {
                teslatte::products::Product::Vehicle(vehicle) => Some(vehicle),
                _ => None,
            })
            .next()
            .context("No vehicles attached to account!")?;

        let (metrics, _recorder) = Metrics::new();

        let interface = Self {
            state: Arc::new(RwLock::new(Default::default())),
            api,
            last_refresh,
            auth_path,
            vehicle,
            metrics,
        };
        interface.save_key()?;

        Ok(interface)
    }

    fn save_key(&self) -> Result<(), SaveError> {
        std::fs::write(
            self.auth_path.clone(),
            ron::ser::to_string(&AuthInfo {
                access_token: self.api.access_token.clone(),
                refresh_token: self.api.refresh_token.clone(),
            })?,
        )?;
        info!("Auth successfully saved");
        Ok(())
    }

    pub async fn refresh(&mut self) {
        info!("refreshing keys...");
        self.refresh_keys().await;
        self.refresh_state().await;
    }

    pub async fn process_request(&mut self, request: InterfaceRequest) {
        match request {
            InterfaceRequest::FlashLights => {
                let _ = self.api.flash_lights(&self.vehicle.vin).await;
            }
        }
    }

    async fn refresh_state(&mut self) {
        match get_state(&self.api, self.vehicle.id).await {
            Ok(new_state) => {
                self.last_refresh = Instant::now();
                let mut state = self.state.write().expect("State handler panicked!!");

                if let Some(new_charge_state) = new_state.charge_state {
                    self.metrics
                        .battery_level
                        .set(new_charge_state.battery_level as f64);
                    self.metrics.charge_rate.set(new_charge_state.charge_rate);
                    state.charge_state = Some(new_charge_state);
                }
                if let Some(new_location_data) = new_state.location_data {
                    state.location_data = Some(new_location_data);
                }
                if let Some(new_climate_state) = new_state.climate_state {
                    self.metrics.inside_temp.set(new_climate_state.inside_temp);
                    state.climate_state = Some(new_climate_state);
                }
            }
            Err(e) => error!("Error getting state: {e:#?}"),
        }
    }

    async fn refresh_keys(&mut self) {
        // refresh our Tesla (the company's web servers, not the car) access token
        if Instant::now().duration_since(self.last_refresh) >= KEY_REFRESH_INTERVAL {
            match self.api.refresh().await {
                Ok(_) => {
                    let now = Instant::now();
                    match self.save_key() {
                        Ok(_) => self.last_refresh = now,
                        Err(e) => error!("error saving auth token: {e:?}"),
                    }
                }
                Err(e) => error!("error refreshing auth token: {e:?}"),
            }
        }
    }
}

async fn get_state(api: &FleetApi, vehicle_id: VehicleId) -> Result<CarState> {
    // Endpoint::VehicleDataCombo or multiple Endpoints in one request
    // doesn't seem to reliably get them all,
    // so for each endpoint we do a new request
    let charge_state = api
        .vehicle_data(&GetVehicleData {
            vehicle_id,
            endpoints: vec![Endpoint::ChargeState].into(),
        })
        .await?
        .charge_state
        .map(|v| v.into());

    let location_data = api
        .vehicle_data(&GetVehicleData {
            vehicle_id,
            endpoints: vec![Endpoint::LocationData].into(),
        })
        .await?
        .drive_state
        .and_then(|v| v.try_into().ok());

    let climate_state = api
        .vehicle_data(&GetVehicleData {
            vehicle_id,
            endpoints: vec![Endpoint::ClimateState].into(),
        })
        .await?
        .climate_state
        .and_then(|v| v.try_into().ok());

    Ok(CarState {
        charge_state,
        location_data,
        climate_state,
    })
}