bracket_terminal::add_wasm_support!();
use bracket_random::prelude::*;
use bracket_terminal::prelude::*;
use std::collections::HashMap;

// We'll allow map tiles to be either a wall or a floor. We're deriving PartialEq so we don't
// have to match on it every time. We'll make it a copy type because it's really just an int.
#[derive(PartialEq, Copy, Clone)]
enum TileType {
    Wall,
    Floor,
}

// We're extending State to include a minimal map and player coordinates.
struct State {
    map: Vec<TileType>,
    player_position: usize,
    keymap: HashMap<VirtualKeyCode, (i32, i32)>,
}

// We're storing all the tiles in one big array, so we need a way to map an X,Y coordinate to
// a tile. Each row is stored sequentially (so 0..80, 81..160, etc.). This takes an x/y and returns
// the array index.
pub fn xy_idx(x: i32, y: i32) -> usize {
    (y as usize * 80) + x as usize
}

// It's a great idea to have a reverse mapping for these coordinates. This is as simple as
// index % 80 (mod 80), and index / 80
pub fn idx_xy(idx: usize) -> (i32, i32) {
    (idx as i32 % 80, idx as i32 / 80)
}

// Since we have some content, we should also include a map builder. A 'new'
// function is a common Rust way to do this.
impl State {
    pub fn new() -> State {
        let mut state = State {
            map: vec![TileType::Floor; 80 * 50],
            player_position: xy_idx(40, 25),
            keymap: HashMap::new(),
        };

        // Make the keyboard mappings
        state.keymap.insert(VirtualKeyCode::Numpad8, (0, -1));
        state.keymap.insert(VirtualKeyCode::Numpad4, (-1, 0));
        state.keymap.insert(VirtualKeyCode::Numpad6, (1, 0));
        state.keymap.insert(VirtualKeyCode::Numpad2, (0, 1));
        state.keymap.insert(VirtualKeyCode::Numpad7, (-1, -1));
        state.keymap.insert(VirtualKeyCode::Numpad9, (1, -1));
        state.keymap.insert(VirtualKeyCode::Numpad1, (-1, 1));
        state.keymap.insert(VirtualKeyCode::Numpad3, (1, 1));
        state.keymap.insert(VirtualKeyCode::Up, (0, -1));
        state.keymap.insert(VirtualKeyCode::Down, (0, 1));
        state.keymap.insert(VirtualKeyCode::Left, (-1, 0));
        state.keymap.insert(VirtualKeyCode::Right, (1, 0));

        // Make the boundaries walls
        for x in 0..80 {
            state.map[xy_idx(x, 0)] = TileType::Wall;
            state.map[xy_idx(x, 49)] = TileType::Wall;
        }
        for y in 0..50 {
            state.map[xy_idx(0, y)] = TileType::Wall;
            state.map[xy_idx(79, y)] = TileType::Wall;
        }

        // Now we'll randomly splat a bunch of walls. It won't be pretty, but it's a decent illustration.
        // First, obtain the thread-local RNG:
        let mut rng = RandomNumberGenerator::new();

        for _ in 0..400 {
            // rand provides a gen_range function to get numbers in a range.
            let x = rng.roll_dice(1, 80) - 1;
            let y = rng.roll_dice(1, 50) - 1;
            let idx = xy_idx(x, y);
            // We don't want to add a wall on top of the player
            if state.player_position != idx {
                state.map[idx] = TileType::Wall;
            }
        }

        // We'll return the state with the short-hand
        state
    }

    // Handle player movement. Delta X and Y are the relative move
    // requested by the player. We calculate the new coordinates,
    // and if it is a floor - move the player there.
    pub fn move_player(&mut self, delta_x: i32, delta_y: i32) {
        let current_position = idx_xy(self.player_position);
        let new_position = (current_position.0 + delta_x, current_position.1 + delta_y);
        let new_idx = xy_idx(new_position.0, new_position.1);
        if self.map[new_idx] == TileType::Floor {
            self.player_position = new_idx;
        }
    }
}

// Implement the game loop
impl GameState for State {
    fn tick(&mut self, ctx: &mut BTerm) {
        // New: handle keyboard inputs.
        let mut delta = (0, 0);
        let input = INPUT.lock();
        self.keymap.iter().for_each(|(key, key_delta)| {
            if input.is_key_pressed(*key) {
                delta = *key_delta;
            }
        });
        self.move_player(delta.0, delta.1);

        // Clear the screen
        ctx.cls();

        // Iterate the map array, incrementing coordinates as we go.
        let mut y = 0;
        let mut x = 0;
        for tile in &self.map {
            // Render a tile depending upon the tile type
            match tile {
                TileType::Floor => {
                    ctx.print_color(
                        x,
                        y,
                        RGB::from_f32(0.5, 0.5, 0.5),
                        RGB::from_f32(0., 0., 0.),
                        ".",
                    );
                }
                TileType::Wall => {
                    ctx.print_color(
                        x,
                        y,
                        RGB::from_f32(0.0, 1.0, 0.0),
                        RGB::from_f32(0., 0., 0.),
                        "#",
                    );
                }
            }

            // Move the coordinates
            x += 1;
            if x > 79 {
                x = 0;
                y += 1;
            }
        }

        // Render the player @ symbol
        let ppos = idx_xy(self.player_position);
        ctx.print_color(
            ppos.0,
            ppos.1,
            RGB::from_f32(1.0, 1.0, 0.0),
            RGB::from_f32(0., 0., 0.),
            "@",
        );
    }
}

fn main() -> BError {
    let context = BTermBuilder::simple80x50()
        .with_title("Bracket Terminal Example - Walking")
        .build()?;
    let gs = State::new();
    main_loop(context, gs)
}