using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;

namespace System.Fire.Container {

    public partial class ContainerList {

        private long ChunkFile_Offset;
        private FileStream ChunkFile;
        private BinaryReader ChunkFileR;
        private BinaryWriter ChunkFileW;

        /*public bool ReadChunk(int pos, int ChunkNum, ref byte Group, ref byte Container, ref ushort ChunkIndex) {
            if (ChunkNum >= 0 && ChunkNum * 4 < this._chunks.Length - 4) {
                Group = this._chunks[pos * 4];
                Container = this._chunks[(pos * 4) + 1];
                ChunkIndex = (ushort)(this._chunks[(((pos * 4) + 2) * 256)] + this._chunks[(pos * 4) + 2]);
                return true;
            }
            return true;
        }

        public bool ReadChunk(int pos, int ChunkNum, ref byte Group, ref byte Container, ref ushort ChunkIndex) {
            this.ChunkFile.Seek(pos + (ChunkNum * 4), IO.SeekOrigin.Begin);
            Group = this.ChunkFileR.ReadByte();
            Container = this.ChunkFileR.ReadByte();
            ChunkIndex = this.ChunkFileR.ReadUInt16();
            return true;
        }*/


            /// <summary>
            /// Returns the length of a container, given by chunkfile-position and chunk number
            /// </summary>
            /// <param name="pos"></param>
            /// <param name="ChunkNum"></param>
            /// <returns></returns>
        private int GetContainerLenFromChunk(long pos, int ChunkNum) {
            this.ChunkFile.Position = (ChunkNum * 4) + pos;
            byte Group = this.ChunkFileR.ReadByte();
            byte Container = this.ChunkFileR.ReadByte();
            return this._container[Group][Container].ChunkSize;
        }

        private byte[] ReadChunk(long pos, int ChunkNum) {
            this.ChunkFile.Position = (ChunkNum * 4) + pos;
            byte Group = this.ChunkFileR.ReadByte();
            byte Container = this.ChunkFileR.ReadByte();
            byte ci1 = this.ChunkFileR.ReadByte();
            byte ci2 = this.ChunkFileR.ReadByte();
            ushort ChunkIndex = (ushort)((ci1 * 256) + ci2);
            //ushort ChunkIndex = this.ChunkFileR.ReadUInt16();
            System.Diagnostics.Debug.WriteLine("Read Chunk: " +
                Group.ToString().PadLeft(3) + " | " +
                Container.ToString().PadLeft(3) + " | " +
                ChunkIndex.ToString().PadLeft(5) +
                " (" + pos + " | " + ChunkNum + ")"
            );
            return this._container[Group][Container].GetChunk(ChunkIndex);
        }

        private long WriteChunk(byte[] b) {
            this.ChunkFile.Seek(0, SeekOrigin.End);
            long pos = ChunkFile.Position;
            System.Diagnostics.Debug.WriteLine("Writ Chunk: " +
                " (" + pos + " | " + (b.Length / 4) + ")"
            );
            this.ChunkFileW.Write(b);
            return pos;
        }


        private void OpenChunkFile(string Path) {
            bool bHasFileInfo = false;
            if (System.IO.File.Exists(Path)) {
                this.ChunkFile = new FileStream(Path, FileMode.Open);
                if (this.ChunkFile.Length > 6) {
                    this.ChunkFileR = new BinaryReader(this.ChunkFile);
                    this.ChunkFileW = new BinaryWriter(this.ChunkFile);
                    byte[] Magic = this.ChunkFileR.ReadBytes(4);
                    if (
                        Magic[0] == 67 /* C */ &&
                        Magic[1] == 111 /* o */ &&
                        Magic[2] == 67 /* C */ &&
                        Magic[3] == 72 /* H */
                    ) {
                        ushort version = this.ChunkFileR.ReadUInt16();
                        bHasFileInfo = true;
                        this.ChunkFile_Offset = this.ChunkFile.Position;
                    }
                }
                if (bHasFileInfo == false) {
                    this.ChunkFile.Close();
                    File.Delete(Path);
                }
            }
            if (!bHasFileInfo) {
                this.ChunkFile = new FileStream(Path, FileMode.CreateNew);
                this.ChunkFileR = new BinaryReader(this.ChunkFile);
                this.ChunkFileW = new BinaryWriter(this.ChunkFile);
                this.ChunkFileW.Write(new byte[] { 67, 111, 67, 72 });
                this.ChunkFileW.Write(Version);
                this.ChunkFile_Offset = this.ChunkFile.Position;
            }
        }

        private void CloseChunkFile() {
            this.ChunkFile.Close();
        }
    }

}