#region Copyright & License Information
/*
 * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
 * This file is part of OpenRA, which is free software. It is made
 * available to you under the terms of the GNU General Public License
 * as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version. For more
 * information, see COPYING.
 */
#endregion

using System.Collections.Generic;
using OpenRA.Graphics;
using OpenRA.Primitives;
using OpenRA.Traits;

namespace OpenRA.Mods.Common.Traits
{
	public class TerrainRendererInfo : TraitInfo, ITiledTerrainRendererInfo
	{
		public override object Create(ActorInitializer init) { return new TerrainRenderer(init.World); }
	}

	public sealed class TerrainRenderer : IRenderTerrain, IWorldLoaded, INotifyActorDisposing, ITiledTerrainRenderer
	{
		readonly Map map;
		readonly Dictionary<string, TerrainSpriteLayer> spriteLayers = new Dictionary<string, TerrainSpriteLayer>();
		readonly Theater theater;
		bool disposed;

		public TerrainRenderer(World world)
		{
			map = world.Map;
			theater = new Theater(world.Map.Rules.TileSet);
		}

		void IWorldLoaded.WorldLoaded(World world, WorldRenderer wr)
		{
			foreach (var template in map.Rules.TileSet.Templates)
			{
				var palette = template.Value.Palette ?? TileSet.TerrainPaletteInternalName;
				spriteLayers.GetOrAdd(palette, pal =>
					new TerrainSpriteLayer(world, wr, theater.Sheet, BlendMode.Alpha, wr.Palette(palette), world.Type != WorldType.Editor));
			}

			foreach (var cell in map.AllCells)
				UpdateCell(cell);

			map.Tiles.CellEntryChanged += UpdateCell;
			map.Height.CellEntryChanged += UpdateCell;
		}

		public void UpdateCell(CPos cell)
		{
			var tile = map.Tiles[cell];
			var palette = TileSet.TerrainPaletteInternalName;
			if (map.Rules.TileSet.Templates.ContainsKey(tile.Type))
				palette = map.Rules.TileSet.Templates[tile.Type].Palette ?? palette;

			foreach (var kv in spriteLayers)
				kv.Value.Update(cell, palette == kv.Key ? theater.TileSprite(tile) : null, false);
		}

		void IRenderTerrain.RenderTerrain(WorldRenderer wr, Viewport viewport)
		{
			foreach (var kv in spriteLayers.Values)
				kv.Draw(wr.Viewport);

			foreach (var r in wr.World.WorldActor.TraitsImplementing<IRenderOverlay>())
				r.Render(wr);
		}

		void INotifyActorDisposing.Disposing(Actor self)
		{
			if (disposed)
				return;

			map.Tiles.CellEntryChanged -= UpdateCell;
			map.Height.CellEntryChanged -= UpdateCell;

			foreach (var kv in spriteLayers.Values)
				kv.Dispose();

			theater.Dispose();
			disposed = true;
		}

		Sheet ITiledTerrainRenderer.Sheet { get { return theater.Sheet; } }

		Sprite ITiledTerrainRenderer.TileSprite(TerrainTile r, int? variant)
		{
			return theater.TileSprite(r, variant);
		}

		Rectangle ITiledTerrainRenderer.TemplateBounds(TerrainTemplateInfo template)
		{
			Rectangle? templateRect = null;
			var tileSize = map.Grid.TileSize;

			var i = 0;
			for (var y = 0; y < template.Size.Y; y++)
			{
				for (var x = 0; x < template.Size.X; x++)
				{
					var tile = new TerrainTile(template.Id, (byte)(i++));
					if (!map.Rules.TileSet.TryGetTileInfo(tile, out var tileInfo))
						continue;

					var sprite = theater.TileSprite(tile);
					var u = map.Grid.Type == MapGridType.Rectangular ? x : (x - y) / 2f;
					var v = map.Grid.Type == MapGridType.Rectangular ? y : (x + y) / 2f;

					var tl = new float2(u * tileSize.Width, (v - 0.5f * tileInfo.Height) * tileSize.Height) - 0.5f * sprite.Size;
					var rect = new Rectangle((int)(tl.X + sprite.Offset.X), (int)(tl.Y + sprite.Offset.Y), (int)sprite.Size.X, (int)sprite.Size.Y);
					templateRect = templateRect.HasValue ? Rectangle.Union(templateRect.Value, rect) : rect;
				}
			}

			return templateRect ?? Rectangle.Empty;
		}
	}
}