use ggez::graphics::spritebatch::{SpriteBatch, SpriteIdx};
use ggez::graphics::{DrawParam, Drawable, Image};
use ggez::{Context, GameError};
use specs::WorldExt;
use std::path::Path;

#[derive(Eq, PartialEq, Debug, Copy, Clone)]
pub enum Color {
    Red,
    Green,
    Blue,
}

impl From<Color> for ggez::graphics::Color {
    fn from(color: Color) -> ggez::graphics::Color {
        match color {
            Color::Red => [1.0, 0.0, 0.0, 1.0].into(),
            Color::Green => [0.0, 1.0, 0.0, 1.0].into(),
            Color::Blue => [0.0, 0.0, 1.0, 1.0].into(),
        }
    }
}


/// The `Tile` trait is used to identify which tile we care about on a
/// tilesheet, and also to provide a sensible 'blank' tile. The tile
/// identifiers we care about should at least be `Clone`, but often
/// they'll be (wrappers over) small identifiers (like a `u8` or a
/// `u16`) and could probably be `Copy`.
pub trait Tile: Clone + Send + Sync {
    fn to_location(self) -> [f32;4];
    fn blank() -> Self;
}

/// This represents a character from DOS codepage 437
#[derive(Debug, Copy, Clone)]
pub struct CP437(u8);

impl CP437 {
    pub fn from_u8(ch: u8) -> CP437 {
        CP437(ch)
    }

    pub fn from_char(ch: char) -> CP437 {
        CP437(match ch as u32 {
            // happy faces
            0x263A => 1,
            0x263B => 2,
            // card suits
            0x2665 => 3,
            0x2666 => 4,
            0x2663 => 5,
            0x2660 => 6,
            0x2022 => 7,
            // fill this in some time later
            // standard ASCII mappings
            0x20 ..= 0x7e => ch as u8,
            0x2302 => 0x7f,
            _ => panic!("Character {} does not have a CP437 equivalent", ch),
        })
    }
}

impl Tile for CP437 {
    fn to_location(self) -> [f32;4] {
        const TILE_SIZE: f32 = 1.0 / 16.0;
        let u = f32::from(self.0 % 16) * TILE_SIZE;
        let v = f32::from(self.0 / 16) * TILE_SIZE;
        [u, v, TILE_SIZE, TILE_SIZE]
    }

    fn blank() -> Self {
        CP437(0)
    }
}


pub struct Board<Idx: Tile> {
    size: Size,
    contents: Vec<(Idx, SpriteIdx)>,
    tileset: Tileset<Idx>,
}

pub struct Tileset<Idx: Tile> {
    tile_size: Size,
    batch: SpriteBatch,
    idx: std::marker::PhantomData<Idx>,
}

impl<Idx: Tile> Tileset<Idx> {
    pub fn from_file(
        ctx: &mut Context,
        tile_size: impl Into<Size>,
        file: impl AsRef<Path>,
    ) -> Result<Tileset<Idx>, GameError> {
        let tile_size = tile_size.into();
        let image = Image::new(ctx, file)?;
        let mut batch = SpriteBatch::new(image);
        batch.set_filter(ggez::graphics::FilterMode::Nearest);
        Ok(Tileset {
            tile_size,
            batch,
            idx: std::marker::PhantomData,
        })
    }

    fn to_screen(&self, coord: impl Into<Coord>) -> [f32; 2] {
        let Coord { x, y } = coord.into();
        [
            (x * self.tile_size.width) as f32,
            (y * self.tile_size.height) as f32,
        ]
    }
}

#[derive(Debug, PartialEq, Eq, Hash)]
pub struct Size {
    width: usize,
    height: usize,
}

impl From<[usize; 2]> for Size {
    fn from([width, height]: [usize; 2]) -> Size {
        Size { width, height }
    }
}

#[derive(Debug, PartialEq, Eq, Hash)]
pub struct Coord {
    x: usize,
    y: usize,
}

impl From<[usize; 2]> for Coord {
    fn from([x, y]: [usize; 2]) -> Coord {
        Coord { x, y }
    }
}

impl<Idx: Tile> Board<Idx> {
    pub fn new(size: impl Into<Size>, mut tileset: Tileset<Idx>) -> Board<Idx> {
        let size = size.into();
        let mut contents = Vec::new();
        for y in 0..size.height {
            for x in 0..size.width {
                let param = DrawParam::new()
                    .src(Idx::blank().to_location().into())
                    .dest(tileset.to_screen([x, y]));
                let idx = tileset.batch.add(param);
                contents.push((Idx::blank(), idx));
            }
        }
        Board {
            size,
            contents,
            tileset,
        }
    }

    // fn sprite_location(ch: u8) -> [f32; 4] {
    //     let u = f32::from(ch % 16) * TILE_SIZE;
    //     let v = f32::from(ch / 16) * TILE_SIZE;
    //     [u, v, TILE_SIZE, TILE_SIZE]
    // }

    pub fn draw(&self, ctx: &mut Context) -> Result<(), ggez::GameError> {
        self.tileset.batch.draw(ctx, DrawParam::new())
    }

    pub fn set(&mut self, at: impl Into<Coord>, ch: Idx) {
        let at = at.into();
        let idx = at.x + at.y * self.size.width;
        let param = DrawParam::new()
            .src(ch.to_location().into())
            .dest(self.tileset.to_screen(at));
        self.tileset.batch.set(self.contents[idx].1, param).unwrap();
    }

    pub fn set_with_color(
        &mut self,
        at: impl Into<Coord>,
        ch: Idx,
        color: impl Into<ggez::graphics::Color>,
    ) {
        let at = at.into();
        let idx = at.x + at.y * self.size.width;
        let param = DrawParam::new()
            .src(ch.to_location().into())
            .dest(self.tileset.to_screen(at))
            .color(color.into());
        self.tileset.batch.set(self.contents[idx].1, param).unwrap();
    }

    pub fn get(&self, at: impl Into<Coord>) -> Idx {
        let at = at.into();
        let idx = at.x + at.y * self.size.width;
        self.contents[idx].0.clone()
    }

    pub fn clear(&mut self) {
        for (n, contents) in self.contents.iter_mut().enumerate() {
            let x = n % self.size.width;
            let y = n / self.size.width;
            let param = DrawParam::new()
                .src(Idx::blank().to_location().into())
                .dest(self.tileset.to_screen([x, y]));
            contents.0 = Idx::blank();
            self.tileset.batch.set(contents.1, param).unwrap();
        }
    }
}

impl Board<CP437> {
    pub fn print(&mut self, at: impl Into<Coord>, msg: &str) {
        let Coord { x, y } = at.into();
        for (idx, ch) in msg.chars().enumerate() {
            self.set([idx + x, y], CP437::from_char(ch));
        }
    }
}



pub struct Game<Idx> {
    pub world: specs::World,
    idx: std::marker::PhantomData<Idx>,
}


impl<Idx: Tile + 'static> Game<Idx> {
    pub fn create(_name: &str, _author: &str, board: Board<Idx>) -> Result<Game<Idx>, ggez::GameError> {
        let mut world = specs::World::new();
        world.insert(board);
        Ok(Game {
            world,
            idx: std::marker::PhantomData,
        })
    }

    pub fn set(&mut self, at: impl Into<Coord>, ch: Idx) {
        self.world.fetch_mut::<Board<Idx>>().set(at, ch)
    }

    pub fn set_with_color(
        &mut self,
        at: impl Into<Coord>,
        ch: Idx,
        color: impl Into<ggez::graphics::Color>,
    ) {
        self.world
            .fetch_mut::<Board<Idx>>()
            .set_with_color(at, ch, color)
    }

    pub fn get(&self, at: impl Into<Coord>) -> Idx {
        self.world.fetch::<Board<Idx>>().get(at)
    }
}

impl Game<CP437> {
    pub fn print(&mut self, at: impl Into<Coord>, msg: &str) {
        self.world.fetch_mut::<Board<CP437>>().print(at, msg)
    }
}


impl<Idx: 'static + Tile> ggez::event::EventHandler for Game<Idx> {
    fn draw(&mut self, ctx: &mut Context) -> Result<(), ggez::GameError> {
        ggez::graphics::clear(ctx, ggez::graphics::BLACK);
        self.world.fetch::<Board<Idx>>().draw(ctx)?;
        ggez::graphics::present(ctx)
    }

    fn update(&mut self, _ctx: &mut Context) -> Result<(), ggez::GameError> {
        Ok(())
    }
}