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use crate::{reader::AseReader, tilemap::TileBitmaskHeader, Result};
use std::{io::Read, ops::Index};

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub(crate) struct TileId(pub u32);

/// A tile is a reference to a single tile in a tilemap.
///
/// Note that the Aseprite file format also enables rotating or flipping tiles.
/// But since the GUI does not yet support those (as of v1.3-beta5) we do not
/// yet expose these attributes.
#[derive(Debug, Clone)]
#[allow(unused)]
pub struct Tile {
    pub(crate) id: TileId,
    // These are currently (Aseprite v1.3-beta5) not supported by the GUI.
    pub(crate) flip_x: bool,
    pub(crate) flip_y: bool,
    pub(crate) rotate_90cw: bool,
}

pub(crate) static EMPTY_TILE: Tile = Tile {
    id: TileId(0),
    flip_x: false,
    flip_y: false,
    rotate_90cw: false,
};

impl Tile {
    /// The ID of the tile, i.e., the index into the corresponding tileset.
    pub fn id(&self) -> u32 {
        self.id.0
    }

    pub(crate) fn new(chunk: &[u8], header: &TileBitmaskHeader) -> Result<Self> {
        AseReader::new(chunk)
            .dword()
            .map(|bits| Self::parse(bits, header))
    }

    fn parse(bits: u32, header: &TileBitmaskHeader) -> Self {
        Self {
            id: TileId(bits & header.tile_id),
            flip_x: as_bool(bits & header.x_flip),
            flip_y: as_bool(bits & header.y_flip),
            rotate_90cw: as_bool(bits & header.rotate_90cw),
        }
    }
}

#[derive(Debug)]
pub(crate) struct Tiles(Vec<Tile>);

impl Tiles {
    pub(crate) fn unzip<T: Read>(
        reader: AseReader<T>,
        expected_tile_count: usize,
        header: &TileBitmaskHeader,
    ) -> Result<Self> {
        // Only 32-bit tiles supported for now
        let expected_output_size = 4 * expected_tile_count;
        let bytes = reader.unzip(expected_output_size)?;
        let tiles: Result<Vec<Tile>> = bytes
            .chunks_exact(4)
            .map(|bytes| Tile::new(bytes, header))
            .collect();
        Ok(Self(tiles?))
    }
}

impl Index<usize> for Tiles {
    type Output = Tile;

    fn index(&self, index: usize) -> &Self::Output {
        &self.0[index]
    }
}

fn as_bool(bitwise_and: u32) -> bool {
    bitwise_and != 0
}