use sfml::system::Vector2;
use sfml::graphics::IntRect;

use engine::texture::Texture;
use engine::renderer::Drawable;
use engine::math::Matrix;

/// This struct represents the different type of tiles that can exist in our maps.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum CollisionTile {
    /// A tile that contains nothing.
    Empty,

    /// A solid tile.
    Solid
}

impl CollisionTile {
    /// Creates a tile from a u8.
    pub fn from_u8(id: u8) -> Option<CollisionTile> {
        match id {
            0 => Some(CollisionTile::Empty),
            1 => Some(CollisionTile::Solid),
            _ => None,
        }
    }
}

/// This struct represents a renderable tile linking to its part in the tileset texture.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum GraphicTile {
    /// There is nothing to draw.
    Hidden,

    /// Top left corner of a solid tile.
    TopLeft,

    /// Top of a solid tile.
    Top,

    /// Top right corner of a solid tile.
    TopRight,

    /// Left of a solid tile.
    Left,

    /// Center of a solid tile.
    Center,

    /// Right of a solid tile.
    Right,

    /// Bottom left corner of a solid tile.
    BottomLeft,

    /// Bottom of a solid tile.
    Bottom,

    /// Bottom right corner of a solid tile.
    BottomRight,
}

impl GraphicTile {

    /// Checks if a graphic tile has a top border.
    pub fn is_top(&self) -> bool {
        match *self {
            GraphicTile::TopLeft | GraphicTile::Top | GraphicTile::TopRight => true,
            _ => false,
        }
    }

    /// Checks if a graphic tile has a left border.
    pub fn is_left(&self) -> bool {
        match *self {
            GraphicTile::TopLeft | GraphicTile::Left | GraphicTile::BottomLeft => true,
            _ => false,
        }
    }

    /// Checks if a graphic tile has a right border.
    pub fn is_right(&self) -> bool {
        match *self {
            GraphicTile::TopRight | GraphicTile::Right | GraphicTile::BottomRight => true,
            _ => false,
        }
    }

    /// Checks if a graphic tile has a bottom border.
    pub fn is_bottom(&self) -> bool {
        match *self {
            GraphicTile::BottomLeft | GraphicTile::Bottom | GraphicTile::BottomRight => true,
            _ => false,
        }
    }



    /// Creates a vec containing all the non hidden graphic tiles.
    pub fn all() -> Vec<GraphicTile> {
        vec![
            GraphicTile::TopLeft,
            GraphicTile::Top,
            GraphicTile::TopRight,
            GraphicTile::Left,
            GraphicTile::Center,
            GraphicTile::Right,
            GraphicTile::BottomLeft,
            GraphicTile::Bottom,
            GraphicTile::BottomRight,
        ]
    }

    /// Creates the correct graphic tile depending on the neighbours.
    ///
    /// A none will be considered solid.
    pub fn from_neighbour_options(
        top: Option<CollisionTile>,
        left: Option<CollisionTile>,
        right: Option<CollisionTile>,
        bottom: Option<CollisionTile>) -> GraphicTile {

        GraphicTile::from_neighbours(
            top.unwrap_or(CollisionTile::Solid),
            left.unwrap_or(CollisionTile::Solid),
            right.unwrap_or(CollisionTile::Solid),
            bottom.unwrap_or(CollisionTile::Solid),
        )
    }

    /// Creates the correct graphic tile depending on the neighbours.
    pub fn from_neighbours(
        top: CollisionTile,
        left: CollisionTile,
        right: CollisionTile,
        bottom: CollisionTile) -> GraphicTile {

        let mut all = GraphicTile::all()
            .into_iter()
            .map(|x| (x, true))
            .collect::<Vec<_>>();

        for (ref mut tile, ref mut possible) in &mut all {

            if tile.is_top() == (top == CollisionTile::Solid) {
                *possible = false;
            }

            if tile.is_left() == (left == CollisionTile::Solid) {
                *possible = false;
            }

            if tile.is_right() == (right == CollisionTile::Solid) {
                *possible = false;
            }

            if tile.is_bottom() == (bottom == CollisionTile::Solid) {
                *possible = false;
            }

        }

        for (tile, possible) in all {
            if possible {
                return tile;
            }
        }

        panic!("Did not find a tile, implementation error");
    }

    /// Returns the offset to the corresponding graphic tile in the texture.
    pub fn offset(&self) -> (i32, i32) {
        let vertical = match *self {
            GraphicTile::TopLeft | GraphicTile::Top | GraphicTile::TopRight => 0,
            GraphicTile::Left | GraphicTile::Center | GraphicTile::Right => 16,
            GraphicTile::BottomLeft | GraphicTile::Bottom | GraphicTile::BottomRight => 32,
            _ => 0,
        };

        let horizontal = match *self {
            GraphicTile::TopLeft | GraphicTile::Left | GraphicTile::BottomLeft => 0,
            GraphicTile::Top | GraphicTile::Center | GraphicTile::Bottom => 16,
            GraphicTile::TopRight | GraphicTile::Right | GraphicTile::BottomRight => 32,
            _ => 0,
        };

        // (horizontal, vertical)
        (vertical, horizontal)
    }
}

/// A tile and its position.
pub struct PositionedTile {
    /// The graphic representation of the positioned tile.
    pub graphic: GraphicTile,

    /// The collision representation of the positioned tile.
    pub collision: CollisionTile,

    /// The position of the positioned tile.
    pub position: (f32, f32),
}

impl Drawable for PositionedTile {
    fn texture(&self) -> Texture {
        Texture::Overworld
    }

    fn texture_rect(&self) -> IntRect {
        let offset = self.graphic.offset();
        IntRect::new(offset.0, offset.1, 16, 16)
    }

    fn position(&self) -> Vector2<f32> {
        self.position.into()
    }
}

/// The map represents the tiles contained in a level.
pub struct Map {

    /// The tiles contained in the level.
    tiles: Matrix<(CollisionTile, GraphicTile)>,

}

impl Map {

    /// Creates a map full of nothing, with a ground at the bottom.
    pub fn new(rows: usize, cols: usize) -> Map {

        let mut tiles = Matrix::from_size(rows, cols, CollisionTile::Empty);
        let rows = tiles.rows();

        for i in 0 .. tiles.cols() {
            tiles[(rows - 1, i)] = CollisionTile::Solid;
        }

        tiles[(25, 12)] = CollisionTile::Solid;
        tiles[(25, 13)] = CollisionTile::Solid;
        tiles[(25, 14)] = CollisionTile::Solid;
        tiles[(25, 15)] = CollisionTile::Solid;

        Map::from_collision_tiles(tiles)

    }

    /// Creates a map from a txt file.
    pub fn from_str(text: &str) -> Result<Map, ()> {
        let split = text.split('\n').collect::<Vec<_>>();

        // First two usize are the size of the map
        let size = split[0]
            .split_whitespace()
            .map(|x| x.parse::<usize>().unwrap())
            .collect::<Vec<_>>();

        let mut tiles = Matrix::from_size(size[0], size[1], CollisionTile::Empty);

        for (row, line) in split.iter().skip(1).enumerate() {
            for (col, tile) in line.split_whitespace().enumerate() {
                tiles[(row, col)] = CollisionTile::from_u8(tile.parse::<u8>().unwrap()).unwrap();
            }
        }

        Ok(Map::from_collision_tiles(tiles))
    }

    /// Creates a map from its tiles.
    pub fn from_collision_tiles(tiles: Matrix<CollisionTile>) -> Map {
        let rows = tiles.rows();
        let cols = tiles.cols();

        let mut matrix = Matrix::from_size(rows, cols,
            (CollisionTile::Empty, GraphicTile::Hidden)
        );

        for i in 0 .. rows {
            for j in 0 .. cols {

                let graphic = if tiles[(i, j)] == CollisionTile::Solid {

                    // TODO This is uggly
                    // If there is an overflow, we should give None instead
                    let (i, j) = (i as isize, j as isize);

                    GraphicTile::from_neighbour_options(
                        tiles.get(((i  ) as usize, (j-1) as usize)).map(|x| *x),
                        tiles.get(((i-1) as usize, (j  ) as usize)).map(|x| *x),
                        tiles.get(((i+1) as usize, (j  ) as usize)).map(|x| *x),
                        tiles.get(((i  ) as usize, (j+1) as usize)).map(|x| *x),
                    )
                } else {
                    GraphicTile::Hidden
                };

                matrix[(i, j)] = (tiles[(i, j)], graphic);
            }
        }

        Map {
            tiles: matrix,
        }
    }

    /// Returns an iterator to the positioned tiles.
    pub fn at(&self, row: usize, col: usize) -> PositionedTile {
        PositionedTile {
            collision: self.tiles[(row, col)].0,
            graphic: self.tiles[(row, col)].1,
            position: (col as f32 * 16.0, row as f32 * 16.0),
        }
    }

    /// Returns the number of rows of the map.
    pub fn rows(&self) -> usize {
        self.tiles.rows()
    }

    /// Returns the number of columns of the map.
    pub fn cols(&self) -> usize {
        self.tiles.cols()
    }

    /// Checks whether the vector (old, new) collides with an element of the map.
    ///
    /// Returns the height of the collision if any.
    pub fn collides(&self, old: Vector2<f32>, new: Vector2<f32>) -> Option<f32> {

        let height = new.y - old.y;
        let mut y = (old.y / 16.0).ceil() * 16.0;

        while y < new.y {

            let current_height = y - old.y;
            let x = old.x + (new.x - old.x) * current_height / height;

            // Find tile on x, y
            if x > 0.0 && y > 0.0 {

                let row = (y / 16.0) as usize + 2;
                let col = (x / 16.0) as usize + 1;

                if let Some((CollisionTile::Solid, _)) = self.tiles.get((row, col)) {
                    return Some(y);
                }

            }

            y += 16.0;
        }

        None
    }
}