#[macro_use]
extern crate specs_derive;
#[macro_use]
extern crate specs_system_macro;

use carpet::Coord;
use ggez::GameError;
use rand::Rng;
use specs::prelude::*;

#[derive(PartialEq, Clone, Copy, Debug)]
pub enum TileType {
    Wall,
    Floor,
}

impl TileType {
    fn glyph(&self) -> carpet::CP437 {
        match self {
            TileType::Wall => carpet::CP437::from_char('#'),
            TileType::Floor => carpet::CP437::from_u8(0),
        }
    }
}

pub struct Map {
    tiles: carpet::Board<TileType>,
    rooms: Vec<carpet::Rect>,
}

impl Map {
    fn new() -> Map {
        let mut rng = rand::thread_rng();
        let mut map = Map {
            tiles: carpet::Board::new_with_default(80, 50, TileType::Wall),
            rooms: Vec::new(),
        };

        const MAX_ROOMS: usize = 30;
        const MIN_SIZE: usize = 6;
        const MAX_SIZE: usize = 10;

        for _ in 0..MAX_ROOMS {
            let w = rng.gen_range(MIN_SIZE, MAX_SIZE);
            let h = rng.gen_range(MIN_SIZE, MAX_SIZE);
            let x = rng.gen_range(1, 80 - w);
            let y = rng.gen_range(1, 50 - h);
            let room = carpet::Rect::new([x, y], [w, h]);
            if map.rooms.iter().any(|r| r.overlaps(room)) {
                continue;
            }
            map.carve(room);
            if let Some(prev) = map.rooms.first() {
                let c1 = room.center();
                let c2 = prev.center();
                let join = if rng.gen() {
                    carpet::Coord { x: c1.x, y: c2.y }
                } else {
                    carpet::Coord { x: c2.x, y: c1.y }
                };
                map.carve(carpet::Rect::from_points(c1, join));
                map.carve(carpet::Rect::from_points(join, c2));
            }

            map.rooms.push(room);
        }

        map
    }

    fn carve(&mut self, rect: carpet::Rect) {
        let iter = self
            .tiles
            .window_iter_mut(rect)
            .expect(&format!("Rect {:?} of map bounds", rect));
        for (_, _, t) in iter {
            *t = TileType::Floor;
        }
    }

    fn passable(&self, (x, y): (usize, usize)) -> bool {
        Some(&TileType::Floor) == self.tiles.get(x, y)
    }
}

#[derive(Component)]
pub struct Renderable {
    glyph: carpet::CP437,
    color: carpet::Color,
}

#[derive(Component)]
pub struct Player;

impl Player {
    fn get_entity(world: &mut specs::World) -> Entity {
        let storage = (&world.read_component::<Player>(), &world.entities());
        storage
            .join()
            .next()
            .expect("No entities tagged as Player")
            .1
    }
}

#[derive(Component)]
pub struct Motion {
    down: i8,
    right: i8,
}

impl Motion {
    fn move_player(world: &mut specs::World, down: i8, right: i8) {
        let player = Player::get_entity(world);
        world
            .write_component::<Motion>()
            .insert(player, Motion { down, right })
            .unwrap();
    }
}

system_impl! {
    Draw(
        resource mut game_board: carpet::GameBoard<carpet::CP437>,
        resource map: Map,
        renderable: Renderable,
        pos: Coord,
    ) {
        game_board.clear();
        for (x, y, t) in map.tiles.iter() {
            game_board.set([x, y], t.glyph());
        }
        for (p, r) in (&pos, &renderable).join() {
            game_board.set_with_color([p.x, p.y], r.glyph, r.color);
        }
    }
}

system! {
    Move (
        resource map: Map,
        mut motion: Motion,
        mut pos: Coord,
    ) {
        let tgt_x = (pos.x as i8 + motion.right) as usize;
        let tgt_y = (pos.y as i8 + motion.down) as usize;
        if map.passable((tgt_x, tgt_y)) {
            pos.x = tgt_x;
            pos.y = tgt_y;
        }
    } finally {
        motion.clear();
    }
}

fn main() -> Result<(), GameError> {
    let mut game: carpet::Game<carpet::CP437> = carpet::GameBuilder::new()
        .name("game")
        .author("me")
        .resource_path({
            let base = std::env::var("CARGO_MANIFEST_DIR").unwrap();
            let mut path = std::path::PathBuf::from(base);
            path.pop();
            path.push("resources");
            path
        })
        .tileset("/haberdash.gif", [12, 12])
        .map_size(80, 50)
        .build()?;

    game.register::<Coord>();
    game.register::<Renderable>();
    game.register::<Motion>();
    game.register::<Player>();

    let map = Map::new();
    let player_start = map
        .rooms
        .first()
        .map(|r| r.center())
        .unwrap_or([40, 25].into());
    game.insert(map);

    game.create_entity()
        .with(player_start)
        .with(Player)
        .with(Renderable {
            glyph: carpet::CP437::from_char('@'),
            color: carpet::Color::Blue,
        })
        .build();

    {
        // set up all the keybindings
        use carpet::VirtualKeyCode::*;
        let none = carpet::KeyMods::NONE;
        game.on_key((W, none), |world| Motion::move_player(world, -1, 0));
        game.on_key((A, none), |world| Motion::move_player(world, 0, -1));
        game.on_key((S, none), |world| Motion::move_player(world, 1, 0));
        game.on_key((D, none), |world| Motion::move_player(world, 0, 1));
    }

    game.run_with_systems(|world| {
        Draw.run_now(&world);
        Move.run_now(&world);
    })
}