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

using Hjg.Pngcs;

using Vintagestory.API.Client;
using Vintagestory.API.Common;
using Vintagestory.API.MathTools;
using Vintagestory.Common;

namespace Automap
{
	public class StandardRenderer : AChunkRenderer
	{
		public const string Name = @"Standard";

		/// <summary>
		/// Renders shards similar to the Default VS version, plus P.O.I. markings.
		/// </summary>
		/// <param name="clientAPI">Client API.</param>
		/// <param name="logger">Logger.</param>
		public StandardRenderer(ICoreClientAPI clientAPI, ILogger logger, bool seasonalColor) : base(clientAPI, logger, seasonalColor)
		{
			
		}

		public override void GenerateChunkPngShard(Vec2i chunkPos, IMapChunk mc, ColumnMeta targetColMeta, ref ColumnsMetadata allCols, out uint pixelCount)
		{
		pixelCount = 0;
		BlockPos tmpPos = new BlockPos( );
		Vec2i localpos = new Vec2i( );

		var chunksColumn = new IWorldChunk[ClientAPI.World.BlockAccessor.MapSizeY / chunkSize];

		//pre-create PNG line slices...
		ImageLine[ ] lines = Enumerable.Repeat(new object( ), chunkSize).Select(l => new ImageLine(this.PngWriter.ImgInfo)).ToArray( );

		int topChunkY = targetColMeta.YMax / chunkSize;

		for (int chunkY = 0; chunkY <= topChunkY; chunkY++) {
		chunksColumn[chunkY] = ClientAPI.World.BlockAccessor.GetChunk(chunkPos.X, chunkY, chunkPos.Y);
		WorldChunk ownChunk = chunksColumn[chunkY] as WorldChunk;
		if (ownChunk != null) {
		if (ownChunk.IsPacked( )) ownChunk.Unpack( );//Gah - probably done already by chunk processor
		}
		else {
		Logger.Warning("CHUNK A.W.O.L. : X{0} Y{1} Z{2}	- Missing slice FOR COLUMN", chunkPos.X, chunkY, chunkPos.Y);
		//return;
		}
		}

		// Prefetch map chunks, in pattern
		var mapCornerChunks = new List<ColumnMeta>(3);

		var south_west = new Vec2i(chunkPos.X - 1, chunkPos.Y - 1);
		var west = new Vec2i(chunkPos.X - 1, chunkPos.Y);
		var south = new Vec2i(chunkPos.X, chunkPos.Y - 1);

		bool nullSouthWest = false, nullSouth = false, nullWest = false;

		/* 
 		For missing corners / cardinal heightmaps...
		make fake heightmap dummy
		*/

		if (allCols.Contains(south_west)) {
		mapCornerChunks.Add(allCols[south_west]);		
		}
		else {
		nullSouthWest = true;
		mapCornerChunks.Add(targetColMeta);//Temporary!
		}

		if (allCols.Contains(south)) {
		mapCornerChunks.Add(allCols[south]);
		}
		else {
		nullSouth = true;
		mapCornerChunks.Add(targetColMeta);//Temporary!
		}

		if (allCols.Contains(west)) {
		mapCornerChunks.Add(allCols[west]);
		}
		else {
		nullWest = true;
		mapCornerChunks.Add(targetColMeta);//Temporary!
		}


		for (int pixelIndex = 0; pixelIndex < (chunkSize * chunkSize); pixelIndex++) {
		MapUtil.PosInt2d(pixelIndex, chunkSize, localpos);
		int localX = localpos.X;
		int localZ = localpos.Y;
		ushort localY = targetColMeta.HeightMap[localX, localZ];

		int localChunkY = localY / chunkSize;
		if (localChunkY >= (chunksColumn.Length)) continue;//Out of range!
		if (chunksColumn[localChunkY] == null) continue;//BIG Gaps!
		//if (mapCornerChunks.Any(chks => chks == null)) {
		//Logger.Warning("mapCornerChunks A.W.O.L. near : X{0} Y{1} Z{2}	- ", localX, localY, localZ);
		//continue;
		//}

		float slopeBoost = 1;
		int leftTop, rightTop, leftBot;

		ColumnMeta leftTopMapChunk = targetColMeta;
		ColumnMeta rightTopMapChunk = targetColMeta;
		ColumnMeta leftBotMapChunk = targetColMeta;

		int topX = localX - 1;
		int botX = localX;
		int leftZ = localZ - 1;
		int rightZ = localZ;

		if (topX < 0 && leftZ < 0) {
		leftTopMapChunk = mapCornerChunks[0];
		rightTopMapChunk = mapCornerChunks[1];
		leftBotMapChunk = mapCornerChunks[2];
		}
		else {
		if (topX < 0) {
		leftTopMapChunk = mapCornerChunks[1];
		rightTopMapChunk = mapCornerChunks[1];
		}
		if (leftZ < 0) {
		leftTopMapChunk = mapCornerChunks[2];
		leftBotMapChunk = mapCornerChunks[2];
		}
		}

		topX = GameMath.Mod(topX, chunkSize);
		leftZ = GameMath.Mod(leftZ, chunkSize);
		
		leftTop = nullSouthWest ? 0 : Math.Sign(localY - leftTopMapChunk.HeightMap[topX, leftZ]);
		rightTop = nullSouth ? 0 : Math.Sign(localY - rightTopMapChunk.HeightMap[topX, rightZ]);
		leftBot = nullWest ? 0 : Math.Sign(localY - leftBotMapChunk.HeightMap[botX, leftZ]);

		float slopeness = (leftTop + rightTop + leftBot);

		if (slopeness > 0) slopeBoost = 1.2f;
		if (slopeness < 0) slopeBoost = 0.8f;

		slopeBoost -= 0.15f; //Slope boost value 

		int blockId = chunksColumn[localChunkY].MaybeBlocks[MapUtil.Index3d(localX, (localY % chunkSize), localZ, chunkSize, chunkSize)];

		Block block = ClientAPI.World.Blocks[blockId];

		tmpPos.Set(chunkSize * chunkPos.X + localpos.X, localY, chunkSize * chunkPos.Y + localpos.Y);

		int red = 0, green = 0, blue = 0;

		ExtractBlockColor(tmpPos, block, slopeBoost, out red, out green, out blue);

		//============ POI Population =================
		if (BlockID_Designators.ContainsKey(blockId)) {
		var desig = BlockID_Designators[blockId];

			if (desig.Enabled) 
			{
			red = desig.OverwriteColor.R;
			green = desig.OverwriteColor.G;
			blue = desig.OverwriteColor.B;
			}
		}

		ImageLineHelper.SetPixel(lines[localZ], localX, red, green, blue);
		pixelCount++;
		}

		for (int row = 0; row < this.PngWriter.ImgInfo.Rows; row++) {
		this.PngWriter.WriteRow(lines[row], row);
		}

		this.PngWriter.End( );
		}
	}
}