using System.Collections.Generic;
using System.Linq;
using Godot;

/// <summary>
///     图块映射辅助类
/// </summary>
public partial class TileMapping : Node {
    /// <summary>
    ///     从图块坐标到像素坐标的映射。如果不为空，则使用此映射。
    /// </summary>
    private readonly Dictionary<Vector2I, Vector2I> _pixelMap;

    /// <summary>
    ///     如果 pixelMap 为空，使用此偏移量将图块坐标转换为像素坐标。
    /// </summary>
    private Vector2I _pixelOffset;

    /// <summary>
    ///     图块区域
    /// </summary>
    private Rect2I _tileRect;

    /// <summary>
    ///     构造函数，使用坐标映射字典
    /// </summary>
    /// <param name="map">坐标映射字典</param>
    public TileMapping(Dictionary<Vector2I, Vector2I> map) {
        _pixelMap = map;
        _pixelOffset = new Vector2I(-int.MaxValue, -int.MaxValue);
    }

    /// <summary>
    ///     构造函数，使用偏移量和区域
    /// </summary>
    /// <param name="offset">偏移量</param>
    /// <param name="rect">区域</param>
    public TileMapping(Vector2I offset, Rect2I rect) {
        _pixelMap = null;
        _pixelOffset = offset;
        _tileRect = rect;
    }

    public TileMapping() { }

    /// <summary>
    ///     应用映射到TileMapLayer
    /// </summary>
    /// <param name="layer">TileMapLayer</param>
    public void Apply(TileMapLayer layer) {
        // if pixelMap is not null, use all the pairs in pixelMap to set the tiles.
        if (_pixelMap != null) {
            var sourceId = layer.GetCellSourceId(_pixelMap.Keys.First());
            foreach (var pair in _pixelMap) layer.SetCell(pair.Key, sourceId, pair.Value);
        }
        else {
            var sourceId = layer.GetCellSourceId(_tileRect.Position);
            GD.Print(_tileRect);
            for (var x = _tileRect.Position.X; x < _tileRect.End.X; x++)
            for (var y = _tileRect.Position.Y; y < _tileRect.End.Y; y++) {
                var pos = new Vector2I(x, y);
                layer.SetCell(pos, sourceId, pos + _pixelOffset);
            }
        }
    }
}