using System;
using System.Collections.Generic;
//using System.Linq;
//using System.Text;
using MinecraftClient.Mapping;

namespace MinecraftClient.Protocol.Handlers
{
    /// <summary>
    /// Terrain Decoding handler for Protocol18
    /// </summary>
    class Protocol18Terrain
    {
        private int protocolversion;
        private DataTypes dataTypes;
        private IMinecraftComHandler handler;

        /// <summary>
        /// Initialize a new Terrain Decoder
        /// </summary>
        /// <param name="protocolVersion">Minecraft Protocol Version</param>
        /// <param name="dataTypes">Minecraft Protocol Data Types</param>
        public Protocol18Terrain(int protocolVersion, DataTypes dataTypes, IMinecraftComHandler handler)
        {
            this.protocolversion = protocolVersion;
            this.dataTypes = dataTypes;
            this.handler = handler;
        }

        /// <summary>
        /// Process chunk column data from the server and (un)load the chunk from the Minecraft world
        /// </summary>
        /// <param name="chunkX">Chunk X location</param>
        /// <param name="chunkZ">Chunk Z location</param>
        /// <param name="chunkMask">Chunk mask for reading data</param>
        /// <param name="chunkMask2">Chunk mask for some additional 1.7 metadata</param>
        /// <param name="hasSkyLight">Contains skylight info</param>
        /// <param name="chunksContinuous">Are the chunk continuous</param>
        /// <param name="currentDimension">Current dimension type (0 = overworld)</param>
        /// <param name="cache">Cache for reading chunk data</param>
        public void ProcessChunkColumnData(int chunkX, int chunkZ, ushort chunkMask, ushort chunkMask2, bool hasSkyLight, bool chunksContinuous, int currentDimension, Queue<byte> cache)
        {
            if (protocolversion >= Protocol18Handler.MC_1_9_Version)
            {
                // 1.9 and above chunk format
                // Unloading chunks is handled by a separate packet
                for (int chunkY = 0; chunkY < ChunkColumn.ColumnSize; chunkY++)
                {
                    if ((chunkMask & (1 << chunkY)) != 0)
                    {
                        // 1.14 and above Non-air block count inside chunk section, for lighting purposes
                        if (protocolversion >= Protocol18Handler.MC_1_14_Version)
                            dataTypes.ReadNextShort(cache);

                        byte bitsPerBlock = dataTypes.ReadNextByte(cache);
                        bool usePalette = (bitsPerBlock <= 8);

                        // Vanilla Minecraft will use at least 4 bits per block
                        if (bitsPerBlock < 4)
                            bitsPerBlock = 4;

                        // MC 1.9 to 1.12 will set palette length field to 0 when palette
                        // is not used, MC 1.13+ does not send the field at all in this case
                        int paletteLength = 0; // Assume zero when length is absent
                        if (usePalette || protocolversion < Protocol18Handler.MC_1_13_Version)
                            paletteLength = dataTypes.ReadNextVarInt(cache);

                        int[] palette = new int[paletteLength];
                        for (int i = 0; i < paletteLength; i++)
                        {
                            palette[i] = dataTypes.ReadNextVarInt(cache);
                        }

                        // Bit mask covering bitsPerBlock bits
                        // EG, if bitsPerBlock = 5, valueMask = 00011111 in binary
                        uint valueMask = (uint)((1 << bitsPerBlock) - 1);

                        // Block IDs are packed in the array of 64-bits integers
                        ulong[] dataArray = dataTypes.ReadNextULongArray(cache);

                        Chunk chunk = new Chunk();

                        if (dataArray.Length > 0)
                        {
                            int longIndex = 0;
                            int startOffset = 0 - bitsPerBlock;

                            for (int blockY = 0; blockY < Chunk.SizeY; blockY++)
                            {
                                for (int blockZ = 0; blockZ < Chunk.SizeZ; blockZ++)
                                {
                                    for (int blockX = 0; blockX < Chunk.SizeX; blockX++)
                                    {
                                        // NOTICE: In the future a single ushort may not store the entire block id;
                                        // the Block class may need to change if block state IDs go beyond 65535
                                        ushort blockId;

                                        // Calculate location of next block ID inside the array of Longs
                                        startOffset += bitsPerBlock;
                                        bool overlap = false;

                                        if ((startOffset + bitsPerBlock) > 64)
                                        {
                                            if (protocolversion >= Protocol18Handler.MC_1_16_Version)
                                            {
                                                // In MC 1.16+, padding is applied to prevent overlapping between Longs:
                                                // [      LONG INTEGER      ][      LONG INTEGER      ]
                                                // [Block][Block][Block]XXXXX[Block][Block][Block]XXXXX

                                                // When overlapping, move forward to the beginning of the next Long
                                                startOffset = 0;
                                                longIndex++;
                                            }
                                            else
                                            {
                                                // In MC 1.15 and lower, block IDs can overlap between Longs:
                                                // [      LONG INTEGER      ][      LONG INTEGER      ]
                                                // [Block][Block][Block][Blo  ck][Block][Block][Block][

                                                // Detect when we reached the next Long or switch to overlap mode
                                                if (startOffset >= 64)
                                                {
                                                    startOffset -= 64;
                                                    longIndex++;
                                                }
                                                else overlap = true;
                                            }
                                        }

                                        // Extract Block ID
                                        if (overlap)
                                        {
                                            int endOffset = 64 - startOffset;
                                            blockId = (ushort)((dataArray[longIndex] >> startOffset | dataArray[longIndex + 1] << endOffset) & valueMask);
                                        }
                                        else
                                        {
                                            blockId = (ushort)((dataArray[longIndex] >> startOffset) & valueMask);
                                        }

                                        // Map small IDs to actual larger block IDs
                                        if (usePalette)
                                        {
                                            if (paletteLength <= blockId)
                                            {
                                                int blockNumber = (blockY * Chunk.SizeZ + blockZ) * Chunk.SizeX + blockX;
                                                throw new IndexOutOfRangeException(String.Format("Block ID {0} is outside Palette range 0-{1}! (bitsPerBlock: {2}, blockNumber: {3})",
                                                    blockId,
                                                    paletteLength - 1,
                                                    bitsPerBlock,
                                                    blockNumber));
                                            }

                                            blockId = (ushort)palette[blockId];
                                        }

                                        // We have our block, save the block into the chunk
                                        chunk[blockX, blockY, blockZ] = new Block(blockId);
                                    }
                                }
                            }
                        }

                        //We have our chunk, save the chunk into the world
                        handler.InvokeOnMainThread(() =>
                        {
                            if (handler.GetWorld()[chunkX, chunkZ] == null)
                                handler.GetWorld()[chunkX, chunkZ] = new ChunkColumn();
                            handler.GetWorld()[chunkX, chunkZ][chunkY] = chunk;
                        });

                        //Pre-1.14 Lighting data
                        if (protocolversion < Protocol18Handler.MC_1_14_Version)
                        {
                            //Skip block light
                            dataTypes.ReadData((Chunk.SizeX * Chunk.SizeY * Chunk.SizeZ) / 2, cache);

                            //Skip sky light
                            if (currentDimension == 0)
                                // Sky light is not sent in the nether or the end
                                dataTypes.ReadData((Chunk.SizeX * Chunk.SizeY * Chunk.SizeZ) / 2, cache);
                        }
                    }
                }

                // Don't worry about skipping remaining data since there is no useful data afterwards in 1.9
                // (plus, it would require parsing the tile entity lists' NBT)
            }
            else if (protocolversion >= Protocol18Handler.MC_1_8_Version)
            {
                // 1.8 chunk format
                if (chunksContinuous && chunkMask == 0)
                {
                    //Unload the entire chunk column
                    handler.InvokeOnMainThread(() =>
                    {
                        handler.GetWorld()[chunkX, chunkZ] = null;
                    });
                }
                else
                {
                    //Load chunk data from the server
                    for (int chunkY = 0; chunkY < ChunkColumn.ColumnSize; chunkY++)
                    {
                        if ((chunkMask & (1 << chunkY)) != 0)
                        {
                            Chunk chunk = new Chunk();

                            //Read chunk data, all at once for performance reasons, and build the chunk object
                            Queue<ushort> queue = new Queue<ushort>(dataTypes.ReadNextUShortsLittleEndian(Chunk.SizeX * Chunk.SizeY * Chunk.SizeZ, cache));
                            for (int blockY = 0; blockY < Chunk.SizeY; blockY++)
                                for (int blockZ = 0; blockZ < Chunk.SizeZ; blockZ++)
                                    for (int blockX = 0; blockX < Chunk.SizeX; blockX++)
                                        chunk[blockX, blockY, blockZ] = new Block(queue.Dequeue());

                            //We have our chunk, save the chunk into the world
                            handler.InvokeOnMainThread(() =>
                            {
                                if (handler.GetWorld()[chunkX, chunkZ] == null)
                                    handler.GetWorld()[chunkX, chunkZ] = new ChunkColumn();
                                handler.GetWorld()[chunkX, chunkZ][chunkY] = chunk;
                            });
                        }
                    }

                    //Skip light information
                    for (int chunkY = 0; chunkY < ChunkColumn.ColumnSize; chunkY++)
                    {
                        if ((chunkMask & (1 << chunkY)) != 0)
                        {
                            //Skip block light
                            dataTypes.ReadData((Chunk.SizeX * Chunk.SizeY * Chunk.SizeZ) / 2, cache);

                            //Skip sky light
                            if (hasSkyLight)
                                dataTypes.ReadData((Chunk.SizeX * Chunk.SizeY * Chunk.SizeZ) / 2, cache);
                        }
                    }

                    //Skip biome metadata
                    if (chunksContinuous)
                        dataTypes.ReadData(Chunk.SizeX * Chunk.SizeZ, cache);
                }
            }
            else
            {
                // 1.7 chunk format
                if (chunksContinuous && chunkMask == 0)
                {
                    //Unload the entire chunk column
                    handler.InvokeOnMainThread(() =>
                    {
                        handler.GetWorld()[chunkX, chunkZ] = null;
                    });
                }
                else
                {
                    //Count chunk sections
                    int sectionCount = 0;
                    int addDataSectionCount = 0;
                    for (int chunkY = 0; chunkY < ChunkColumn.ColumnSize; chunkY++)
                    {
                        if ((chunkMask & (1 << chunkY)) != 0)
                            sectionCount++;
                        if ((chunkMask2 & (1 << chunkY)) != 0)
                            addDataSectionCount++;
                    }

                    //Read chunk data, unpacking 4-bit values into 8-bit values for block metadata
                    Queue<byte> blockTypes = new Queue<byte>(dataTypes.ReadData(Chunk.SizeX * Chunk.SizeY * Chunk.SizeZ * sectionCount, cache));
                    Queue<byte> blockMeta = new Queue<byte>();
                    foreach (byte packed in dataTypes.ReadData((Chunk.SizeX * Chunk.SizeY * Chunk.SizeZ * sectionCount) / 2, cache))
                    {
                        byte hig = (byte)(packed >> 4);
                        byte low = (byte)(packed & (byte)0x0F);
                        blockMeta.Enqueue(hig);
                        blockMeta.Enqueue(low);
                    }

                    //Skip data we don't need
                    dataTypes.ReadData((Chunk.SizeX * Chunk.SizeY * Chunk.SizeZ * sectionCount) / 2, cache);          //Block light
                    if (hasSkyLight)
                        dataTypes.ReadData((Chunk.SizeX * Chunk.SizeY * Chunk.SizeZ * sectionCount) / 2, cache);      //Sky light
                    dataTypes.ReadData((Chunk.SizeX * Chunk.SizeY * Chunk.SizeZ * addDataSectionCount) / 2, cache);   //BlockAdd
                    if (chunksContinuous)
                        dataTypes.ReadData(Chunk.SizeX * Chunk.SizeZ, cache);                                         //Biomes

                    //Load chunk data
                    for (int chunkY = 0; chunkY < ChunkColumn.ColumnSize; chunkY++)
                    {
                        if ((chunkMask & (1 << chunkY)) != 0)
                        {
                            Chunk chunk = new Chunk();

                            for (int blockY = 0; blockY < Chunk.SizeY; blockY++)
                                for (int blockZ = 0; blockZ < Chunk.SizeZ; blockZ++)
                                    for (int blockX = 0; blockX < Chunk.SizeX; blockX++)
                                        chunk[blockX, blockY, blockZ] = new Block(blockTypes.Dequeue(), blockMeta.Dequeue());

                            handler.InvokeOnMainThread(() =>
                            {
                                if (handler.GetWorld()[chunkX, chunkZ] == null)
                                    handler.GetWorld()[chunkX, chunkZ] = new ChunkColumn();
                                handler.GetWorld()[chunkX, chunkZ][chunkY] = chunk;
                            });
                        }
                    }
                }
            }
        }
    }
}