use ggez::event::EventHandler;
use ggez::graphics::{self, Color, DrawMode, Mesh, MeshBuilder};
use ggez::input::mouse::{self, MouseButton};
use ggez::{Context, GameResult};

use crate::actor;
use crate::behaviour;
use crate::board;

pub struct Apr {
    board: board::Board,
    grid: Mesh,
    should_update_grid: bool,
    dragging: bool,

    actors: Vec<actor::Actor>,

    #[allow(dead_code)]
    behaviours: Vec<behaviour::Behaviour>,
}

pub fn make_grid(ctx: &mut Context, r: u8, c: u8, board: &[Vec<u8>]) -> GameResult<Mesh> {
    let mut builder = MeshBuilder::new();

    for row in 0..r {
        for col in 0..c {
            builder.rectangle(
                DrawMode::fill(),
                graphics::Rect {
                    x: board::START_X + (board::BOARD_SQUARE_SIZE * col as f32),
                    y: board::START_Y + (board::BOARD_SQUARE_SIZE * row as f32),
                    w: board::BOARD_SQUARE_SIZE,
                    h: board::BOARD_SQUARE_SIZE,
                },
                match board[row as usize][col as usize] % 2 {
                    0 => Color::WHITE,
                    1 => Color::BLACK,
                    _ => Color::BLACK, //impossible
                },
            )?;
        }
    }

    builder.build(ctx)
}

impl Apr {
    pub fn new(_ctx: &mut Context, r: u8, c: u8) -> GameResult<Apr> {
        // Load/create resources such as images here.
        let board = board::make_board(r, c);
        let mut actors: Vec<actor::Actor> = Vec::new();
        for i in 0..r {
            // white side
            actors.push(actor::Actor::new(_ctx, "/pawn.png", i, 1, 0));
        }
        for i in 0..r {
            // black side
            actors.push(actor::Actor::new(_ctx, "/pawn2.png", i, c - 2, 0));
        }
        Ok(Apr {
            grid: make_grid(_ctx, r, c, board.board.as_slice())?,
            board,
            should_update_grid: false,
            actors,
            dragging: false,
            behaviours: vec![behaviour::Behaviour { // 4-tile-corner leaper pawn behaviour
                moves: vec![(1, 1)],
				dirs: (1, 0, 0, 0),
            }], //the pawn can go TWO diagonally and to the right and only upwards
        })
    }

    #[allow(dead_code)]
    pub fn set_colour(&mut self, r: usize, c: usize, clr: u8) {
        //You should only modify self.board through this method.
        self.board.board[r][c] = clr; //Making a getter for self.board would sadly break borrowing in the same way that closest_square_coords does.
        self.should_update_grid = true; //Similar solutions apply.
    }
}

impl EventHandler for Apr {
    fn update(&mut self, ctx: &mut Context) -> GameResult<()> {
        let posn = mouse::position(ctx);
        for actor in self.actors.iter_mut() {
            match actor.posn {
                actor::ActorPosn::FloatingPosn {
                    x: _,
                    y: _,
                    held_x,
                    held_y,
                } => {
                    if !mouse::button_pressed(ctx, MouseButton::Left) {
                        // no long clicking and dragging
                        let (x, y) = self.board.closest_square_coords(posn.x, posn.y);
                        actor.posn = actor::ActorPosn::BoardPosn { x, y };
                        self.dragging = false;
                    } else {
                        actor.posn = actor::ActorPosn::FloatingPosn {
                            x: posn.x + held_x,
                            y: posn.y + held_y,
                            held_x,
                            held_y,
                        };
                    }
                }
                actor::ActorPosn::BoardPosn { x, y } => {
                    if mouse::button_pressed(ctx, MouseButton::Left) && !self.dragging {
                        let (posx, posy) = self.board.closest_square_coords(posn.x, posn.y);
                        if posx == x && posy == y {
                            let x = board::START_X + board::BOARD_SQUARE_SIZE * (x as f32);
                            let y = board::START_Y + board::BOARD_SQUARE_SIZE * (y as f32);
                            self.dragging = true;
                            actor.posn = actor::ActorPosn::FloatingPosn {
                                x,
                                y,
                                held_x: x - posn.x,
                                held_y: y - posn.y,
                            };
                        }
                    }
                }
            }
        }
        Ok(())
    }

    fn draw(&mut self, ctx: &mut Context) -> GameResult<()> {
        graphics::clear(ctx, Color::new(0.5, 0.5, 0.5, 1.0));
        let drawparams = graphics::DrawParam::new();

        if self.should_update_grid {
            self.grid = make_grid(
                ctx,
                self.board.row,
                self.board.col,
                self.board.board.as_slice(),
            )?;
            self.should_update_grid = false;
        }
        graphics::draw(ctx, &self.grid, drawparams)?;
        for actor in &self.actors {
            match actor.posn {
                actor::ActorPosn::FloatingPosn { x, y, .. } => {
                    graphics::draw(ctx, &actor.image, drawparams.dest([x, y]))?
                }
                actor::ActorPosn::BoardPosn { x, y } => graphics::draw(
                    ctx,
                    &actor.image,
                    drawparams.dest([
                        board::START_X + board::BOARD_SQUARE_SIZE * (x as f32),
                        board::START_Y + board::BOARD_SQUARE_SIZE * (y as f32),
                    ]),
                )?,
            }
        }
        // Draw code here...
        graphics::present(ctx)
    }
}