#[macro_use] extern crate itertools;

use ggez::{Context, ContextBuilder, GameResult};
use ggez::event::{self, EventHandler};
use ggez::graphics;

use std::path::Path;

#[allow(dead_code)]
mod consts {
    pub const SPEED: u32 = 2;
    pub const TILE_SIZE: u32 = 24;
    pub const HALF_TILE: u32 = TILE_SIZE / 2;
    pub const QUARTER_TILE: u32 = TILE_SIZE / 4;
    pub const BOARD_WIDTH: usize = 16;
    pub const BOARD_HEIGHT: usize = 12;
    pub const SCALE: u32 = 3;
    pub const TILED_TRUE: tiled::PropertyValue =
        tiled::PropertyValue::BoolValue(true);
}

#[derive(Debug)]
struct Board {
    tiles: Vec<Option<Tile>>,
    entities: Vec<Option<Tile>>,
    decoration: Vec<Option<Tile>>,
}

impl Board {
    fn from_file(path: &Path) -> Board {
        let tiled::Map {
            tilesets,
            layers,
            ..
        } = tiled::parse_file(path).unwrap();
        let read_layer = |idx: usize| {
            layers[idx].tiles.iter()
                .flat_map(|row| row)
                .map(|&n| if n > 0 {
                    Some(Tile::from_tileset(n, &tilesets[0]))
                } else {
                    None
                })
                .collect()
        };
        let tiles = read_layer(0);
        let entities = read_layer(1);
        let decoration = read_layer(2);
        Board {
            tiles,
            entities,
            decoration,
        }
    }

    fn draw() {
        
    }
}

#[derive(Debug, Clone)]
struct Tile {
    action: Action,
    sprite: (u8, u8),
    pass: bool,
}

impl Tile {
    fn from_tileset(n: u32, tileset: &tiled::Tileset) -> Tile {
        let x = (n - 1) % 32;
        let y = (n - x - 1) / 32;
        let pass = tileset.tiles[n as usize].properties.get("pass").eq(
            &Some(&consts::TILED_TRUE));
        Tile {
            action: Action::NoAction,
            sprite: (x as u8, y as u8),
            pass: pass,
        }
    }

    fn draw(&self, (y, x): (usize, usize)) -> graphics::DrawParam {
        let (tx, ty) = self.sprite;
        graphics::DrawParam {
            src: graphics::Rect {
                x: (1.0 / 32.0) * tx as f32,
                y: (1.0 / 32.0) * ty as f32,
                w: 1.0 / 32.0,
                h: 1.0 / 32.0,
            },
            dest: ggez::nalgebra::Point2::new(
                x as f32 * 24.0, y as f32 * 24.0),
            ..Default::default()
        }
    }
}

#[derive(Debug, Clone)]
enum Action {
    NoAction,
}

struct MyGame {
    board: Board,
    sprites: graphics::spritebatch::SpriteBatch,
}

impl EventHandler for MyGame {
    fn update(&mut self, _ctx: &mut Context) -> GameResult<()> {
        Ok(())
    }

    fn draw(&mut self, ctx: &mut Context) -> GameResult<()> {
        use ggez::graphics as g;
        use ggez::nalgebra as n;
        g::set_background_color(ctx, g::BLACK);
        g::clear(ctx);
        for layer in [ &self.board.tiles, &self.board.entities, &self.board.decoration ].iter() {
            for (pt, t) in iproduct!((0..consts::BOARD_HEIGHT),
                                     (0..consts::BOARD_WIDTH)).zip(
                layer.iter()) {
                if let Some(t) = t {
                    self.sprites.add(t.draw(pt));
                }
            }
        }
        g::draw(ctx, &self.sprites, n::Point2::new(0.0, 0.0), 0.0)?;
        self.sprites.clear();
        g::present(ctx);
        Ok(())
    }
}

fn main() -> Result<(), ggez::error::GameError> {
    // Make a Context and an EventLoop.
    let board = Board::from_file(&Path::new("assets/main.tmx"));
    let mut ctx = ContextBuilder::new("game", "me")
        .add_resource_path({
            let base = std::env::var("CARGO_MANIFEST_DIR").unwrap();
            let mut path = std::path::PathBuf::from(base);
            path.push("assets");
            path
        })
        .build()?;
    let image = graphics::Image::new(&mut ctx, "/spritesheet.png")?;
    let sprites = graphics::spritebatch::SpriteBatch::new(image);

    let mut my_game = MyGame {
        board,
        sprites,
    };

    event::run(&mut ctx, &mut my_game)
}