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

pub use ggez::input::keyboard::KeyMods;
pub use winit::VirtualKeyCode;

mod board;
mod types;
pub use board::{Board, BoardIter};
pub use types::{Coord, Rect, Size};

#[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 GameBoard<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,
        ]
    }
}

impl<Idx: Tile> GameBoard<Idx> {
    pub fn new(size: impl Into<Size>, mut tileset: Tileset<Idx>) -> GameBoard<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));
            }
        }
        GameBoard {
            size,
            contents,
            tileset,
        }
    }

    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 GameBoard<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));
        }
    }
}

type Updater = Box<dyn FnMut(&mut specs::World)>;
type Keycode = (winit::VirtualKeyCode, ggez::event::KeyMods);
type EventMap = std::collections::HashMap<Keycode, Updater>;
pub struct World<Idx> {
    pub world: specs::World,
    updater: Updater,
    events: EventMap,
    idx: std::marker::PhantomData<Idx>,
}

fn do_nothing() -> Updater {
    Box::new(|_| {})
}

impl<Idx: Tile + 'static> World<Idx> {
    pub fn new(board: GameBoard<Idx>) -> World<Idx> {
        let mut world = specs::World::new();
        world.insert(board);
        let updater = do_nothing();
        let events = std::collections::HashMap::new();
        World {
            world,
            updater,
            events,
            idx: std::marker::PhantomData,
        }
    }
    pub fn set(&mut self, at: impl Into<Coord>, ch: Idx) {
        self.world.fetch_mut::<GameBoard<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::<GameBoard<Idx>>()
            .set_with_color(at, ch, color)
    }

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

    pub fn on_update(&mut self, update: impl FnMut(&mut specs::World) + 'static) {
        self.updater = Box::new(update) as Updater;
    }

    pub fn on_keycode(&mut self, kc: Keycode, update: impl FnMut(&mut specs::World) + 'static) {
        self.events.insert(kc, Box::new(update) as Updater);
    }
}

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

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

    fn update(&mut self, _ctx: &mut Context) -> Result<(), ggez::GameError> {
        let mut updater = do_nothing();
        std::mem::swap(&mut updater, &mut self.updater);
        updater(&mut self.world);
        std::mem::swap(&mut updater, &mut self.updater);
        Ok(())
    }

    fn key_down_event(
        &mut self,
        ctx: &mut Context,
        keycode: winit::VirtualKeyCode,
        keymod: ggez::event::KeyMods,
        _repeat: bool,
    ) {
        if keycode == VirtualKeyCode::Escape {
            ggez::event::quit(ctx);
        }
        if let Some(cb) = self.events.get_mut(&(keycode, keymod)) {
            cb(&mut self.world);
        }
    }
}

//

pub struct Game<Idx> {
    pub ctx: ggez::Context,
    pub evloop: ggez::event::EventsLoop,
    pub world: World<Idx>,
}

impl<Idx: Tile + 'static> Game<Idx> {
    pub fn create(
        board: GameBoard<Idx>,
        ctx: ggez::Context,
        evloop: ggez::event::EventsLoop,
    ) -> Result<Game<Idx>, ggez::GameError> {
        let world = World::new(board);
        Ok(Game { world, ctx, evloop })
    }

    pub fn register<C>(&mut self)
    where
        C: specs::Component,
        <C as specs::Component>::Storage: std::default::Default,
    {
        self.world.world.register::<C>();
    }

    pub fn insert(&mut self, r: impl specs::prelude::Resource) {
        self.world.world.insert(r);
    }

    pub fn create_entity(&mut self) -> specs::world::EntityBuilder {
        self.world.world.create_entity()
    }

    pub fn on_key(&mut self, kc: Keycode, update: impl FnMut(&mut specs::World) + 'static) {
        self.world.on_keycode(kc, update);
    }

    pub fn run(self) -> ggez::GameResult<()> {
        let Game {
            mut world,
            mut ctx,
            mut evloop,
        } = self;
        ggez::event::run(&mut ctx, &mut evloop, &mut world)
    }

    pub fn run_with_systems(
        self,
        update: impl FnMut(&mut specs::World) + 'static,
    ) -> ggez::GameResult<()> {
        let Game {
            mut world,
            mut ctx,
            mut evloop,
        } = self;
        world.on_update(update);
        ggez::event::run(&mut ctx, &mut evloop, &mut world)
    }
}

// game builder
use std::path::PathBuf;

pub struct GameBuilder<Idx: Tile> {
    name: String,
    author: String,
    resource_path: Option<PathBuf>,
    tile_size: Option<[usize; 2]>,
    tile_path: Option<PathBuf>,
    map_size: Option<[usize; 2]>,
    idx: std::marker::PhantomData<Idx>,
}

impl<Idx: Tile + 'static> GameBuilder<Idx> {
    pub fn new() -> GameBuilder<Idx> {
        GameBuilder {
            name: "Carpet Game".to_owned(),
            author: "unknown author".to_owned(),
            resource_path: None,
            tile_size: None,
            tile_path: None,
            map_size: None,
            idx: std::marker::PhantomData,
        }
    }

    pub fn name(mut self, name: impl Into<String>) -> GameBuilder<Idx> {
        self.name = name.into();
        self
    }

    pub fn author(mut self, author: impl Into<String>) -> GameBuilder<Idx> {
        self.author = author.into();
        self
    }

    pub fn resource_path(mut self, path: impl AsRef<Path>) -> GameBuilder<Idx> {
        self.resource_path = Some(path.as_ref().to_path_buf());
        self
    }

    pub fn tileset(
        mut self,
        image: impl AsRef<Path>,
        size: impl Into<[usize; 2]>,
    ) -> GameBuilder<Idx> {
        self.tile_path = Some(image.as_ref().to_path_buf());
        self.tile_size = Some(size.into());
        self
    }

    pub fn map_size(mut self, width: usize, height: usize) -> GameBuilder<Idx> {
        self.map_size = Some([width, height]);
        self
    }

    pub fn build(self) -> ggez::GameResult<Game<Idx>> {
        use ggez::error::GameError::ResourceLoadError;
        let resource_path = self
            .resource_path
            .ok_or_else(|| ResourceLoadError("No resource path specified".to_owned()))?;
        let tile_path = self
            .tile_path
            .ok_or_else(|| ResourceLoadError("No tile path specified".to_owned()))?;
        let tile_size = self
            .tile_size
            .ok_or_else(|| ResourceLoadError("No tile size specified".to_owned()))?;
        let map_size = self
            .map_size
            .ok_or_else(|| ResourceLoadError("No map size specified".to_owned()))?;
        let (mut ctx, evloop) = ggez::ContextBuilder::new(&self.name, &self.author)
            .add_resource_path(resource_path)
            .window_mode(ggez::conf::WindowMode {
                width: (tile_size[0] * map_size[0]) as f32,
                height: (tile_size[1] * map_size[1]) as f32,
                ..ggez::conf::WindowMode::default()
            })
            .build()?;
        let tileset = Tileset::from_file(&mut ctx, tile_size, tile_path)?;
        let board = GameBoard::new(map_size, tileset);
        Game::create(board, ctx, evloop)
    }
}