//-----------------------------------------------------------------------
//-----------------------------------------------------------------------
//     file="SSDraw.cs"
//     Project: StgSharp
//     AuthorGroup: Nitload Space
//     Copyright (c) Nitload Space. All rights reserved.
//     
//     Permission is hereby granted, free of charge, to any person 
//     obtaining a copy of this software and associated documentation 
//     files (the “Software”), to deal in the Software without restriction, 
//     including without limitation the rights to use, copy, modify, merge,
//     publish, distribute, sublicense, and/or sell copies of the Software, 
//     and to permit persons to whom the Software is furnished to do so, 
//     subject to the following conditions:
//     
//     The above copyright notice and 
//     this permission notice shall be included in all copies 
//     or substantial portions of the Software.
//     
//     THE SOFTWARE IS PROVIDED “AS IS”, 
//     WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, 
//     INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
//     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
//     IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
//     DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 
//     ARISING FROM, OUT OF OR IN CONNECTION WITH 
//     THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//     
//-----------------------------------------------------------------------
//-----------------------------------------------------------------------
using StgSharp.Graphics.ShaderEdit;

using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;
using System.Xml.Serialization;

namespace StgSharp.Data.FileIO
{
    public class SSDraw
    {

        public const string FileType = "ssdraw";
        public const int SegmentCapacity = 16 * 16;

        private Area home;

        private SSDrawHead _head;
        private string _name; 
        private SSDSegment currentSegment;
        private int previousHash;
        private List<SSDSegment> segments;

        internal SSDraw()
        {
            segments = new List<SSDSegment>();
            ID = home.
        }

        public SSDraw(string name)
        {
            _name = name;
            segments = new List<SSDSegment>();
        }

        public int ID
        {
            get { return _head._head.globalID; }
            set { _head._head.globalID = value; }
        }

        internal SSDrawHead Head
        {
            get{return _head; }
        }

        //TODO 分析头，加载文件头，进一步加载全部的数据块

        /// <summary>
        /// 
        /// </summary>
        /// <param name="head"></param>
        /// <returns></returns>
        public static SSDraw AnalyzeHead(SSDrawHead head)
        {
            if (head._head.globalID == 0)
            {
                return null;
            }
            SSDraw ret = new SSDraw();
            foreach (var item in head)
            {

            }
        }

        public void CreateRawFile(string outputFolder, bool rewrite)
        {
            string route =
                $"{((outputFolder == string.Empty) ? " " : ($"{outputFolder}\\"))}{$"{_name}.{FileType}"}";
            if (File.Exists(route) && !rewrite)
            {
                throw new Exception("This SSDRAW has already existed.");
            }
            using (File.Create(route)) { }
            using (File.Open(route, FileMode.Truncate)) { }
            FileStream f = File.Open(route, FileMode.Open);
            int size = 0;
            f.Write(_head.GetBytes(out size), 0, size);
            foreach (var _head in segments)
            {
                f.Write(_head.GetBytes(), 0, 18 * 16);
            }
            f.Close();
        }

        //TODO read raw 没写完
        public static SSDraw readRaw(string route)
        {
            string[] routeFolders = route.Split('\\');
            if (!routeFolders.Last().Contains($".{FileType}"))
            {
                throw new Exception($"File to open is not a {FileType} file.");
            }
            FileStream stream = File.Open(route, FileMode.Open);
            return new SSDraw(string.Empty);
            
        }

        public void WriteRaw(byte[] dataStream)
        {
            previousHash = BuildRawHead(0);
            currentSegment = new SSDSegment(previousHash);
            int t = 0;
            for (int i = 0; i < dataStream.Length; i++, t++)
            {
                if (t == SegmentCapacity)
                {
                    currentSegment.GetDataHash();
                    currentSegment.Head.Size = 256;
                    currentSegment.Head.globalID = i;
                    segments.Add(currentSegment);
                    previousHash = currentSegment.GetHashCode();
                    currentSegment = new SSDSegment(previousHash);
                    t = 0;
                }
                currentSegment[i] = dataStream[i];
            }
            currentSegment.FillRandomBytes(t);
            currentSegment.GetDataHash();
            currentSegment.Head.Size = t;
            segments.Add(currentSegment);

        }

        private int BuildRawHead(int beginID)
        {
            SSDrawHead rawHead = new SSDrawHead(_name);
            _head = rawHead;
            return rawHead.GetHashCode();
        }

    }


    public unsafe class SSDrawHead : IEnumerable<int>
    {

        private List<int> freeSegments;
        private string name;

        private List<(int, int)> segmentRange;
        internal SSDSegmentHead _head;

        internal SSDrawHead(string name)
        {
            int hash;
            this.name = name;
            using (SHA256 sha256Hash = SHA256.Create())
            {
                byte[] bytes = sha256Hash.ComputeHash(Encoding.UTF8.GetBytes(name));

                hash = BitConverter.ToInt32(bytes, 0);
            }
            _head.previousHash = hash;
            segmentRange = new List<(int, int)>();
            freeSegments = new List<int>();
        }

        public SSDrawHead()
        {
            segmentRange = new List<(int, int)>();
            freeSegments = new List<int>();
        }

        public byte DiscIndex
        {
            get => _head.selfDefine_2;
            internal set => _head.selfDefine_2 = value;
        }

        public byte TypeCode
        {
            get => _head.selfDefine_1;
            internal set => _head.selfDefine_1 = value;
        }

        public void AddSingleSegment(int id)
        {
            freeSegments.Add(id);
        }

        public unsafe byte[] GetBytes(out int size)
        {
            byte[] namecode = Encoding.UTF8.GetBytes(name);
            size = 16 + 4 +
                (segmentRange.Count * 8) +
                (freeSegments.Count * 4) +
                namecode.Length;
            byte[] ret = new byte[size];
            fixed (byte* bptr = ret)
            {
                *(SSDSegmentHead*)bptr = _head;
                *(bptr + 16) = (byte)segmentRange.Count;
                *(bptr + 17) = (byte)namecode.Length;
                *(bptr + 18) = (byte)freeSegments.Count;
                int t = 20;
                for (int i = 0; i < segmentRange.Count; i++, t += 8)
                {
                    *(int*)(bptr + t) = segmentRange[i].Item1;
                    *(int*)(bptr + t + 4) = segmentRange[i].Item2;
                }
                for (int i = 0; i < freeSegments.Count; i++, t += 4)
                {
                    *(int*)(bptr + t) = freeSegments[i];
                }
                for (int i = 0; i < namecode.Length; i++, t++)
                {
                    *(bptr + t) = namecode[i];
                }
            }
            return ret;
        }

        public void WriteRange(int begin, int end)
        {
            segmentRange.Add((begin, end));
        }

        internal void MarkSegment(int id)
        {
            freeSegments.Add(id);
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            foreach (var tuple in segmentRange)
            {
                for (int i = tuple.Item1; i <= tuple.Item2; i++)
                {
                    yield return i;
                }
            }

            foreach (var item in freeSegments)
            {
                yield return item;
            }
        }

        IEnumerator<int> IEnumerable<int>.GetEnumerator()
        {
            foreach (var tuple in segmentRange)
            {
                for (int i = tuple.Item1; i <= tuple.Item2; i++)
                {
                    yield return i;
                }
            }

            foreach (var item in freeSegments)
            {
                yield return item;
            }
        }

    }


}