using LibXom.Blocks;
using LibXom.Data;
using LibXom.Streams;
using System.IO;
using System.Text;

namespace LibXom
{
    public class XomReader
    {
        private XomStreamReader xomStream;
        public bool bufferEndsWith(List<byte> buffer, byte[] search)
        {
            int len = search.Length;

            if (buffer.Count < len) return false;

            byte[] lastSection = new byte[len];

            int ii = 0;
            for (int i = 0; i < len; i++)
            {
                int pos = (buffer.Count - len) + i;
                lastSection[ii] = buffer[pos];
                ii++;
            }

            if (lastSection.SequenceEqual(search))
                return true;
            else
                return false;
        }
        public CtnrBlock readCtnr()
        {
            List<byte> buffer = new List<byte>();
            while (xomStream.BaseStream.Position < xomStream.BaseStream.Length)
            {
                buffer.Add(xomStream.ReadByte());
                if (bufferEndsWith(buffer, Encoding.UTF8.GetBytes("CTNR")))
                {
                    xomStream.Skip(-4);
                    int i = buffer.Count - 1;
                    int endAt = i - 4;
                    for (; i != endAt; i--)
                        buffer.RemoveAt(i);
                    return new CtnrBlock(buffer.ToArray());
                }
            }

            // remove last 2 for EOF
            buffer.RemoveAt(buffer.Count-1);
            buffer.RemoveAt(buffer.Count-1);

            return new CtnrBlock(buffer.ToArray());
        }

        public MoikBlock readMoik()
        {
            int version = xomStream.ReadInt32BE();
            xomStream.Skip(0x10);
            int numTypes = xomStream.ReadInt32();
            int numCtnr = xomStream.ReadInt32();
            int numCtnr2 = xomStream.ReadInt32();
            xomStream.Skip(0x1C);
            return new MoikBlock(version, numCtnr, numTypes);
        }
        public TypeBlock readType()
        {
            xomStream.Skip(0x4);
            int numCtnr = xomStream.ReadInt32();
            xomStream.Skip(0x4);
            byte[] md5 = xomStream.ReadBytes(0x10);
            string typeName = xomStream.ReadStrLen(0x20);
            return new TypeBlock(numCtnr, md5, typeName);
        }
        public SchmBlock readSchm()
        {
            int unk0 = xomStream.ReadInt32();
            int unk1 = xomStream.ReadInt32();
            int unk2 = xomStream.ReadInt32();
            return new SchmBlock(unk0, unk1, unk2);
        }
        public GuidBlock readGuid()
        {
            int unk0 = xomStream.ReadInt32();
            int unk1 = xomStream.ReadInt32();
            int unk2 = xomStream.ReadInt32();
            return new GuidBlock(unk0, unk1, unk2);
        }
        public StrsBlock readStrs()
        {
            int numStrs = xomStream.ReadInt32();
            int strsSz = xomStream.ReadInt32();

            int[] offsets = new int[numStrs];
            string[] strings = new string[numStrs];

            for (int i = 0; i < numStrs; i++)
            {
                offsets[i] = xomStream.ReadInt32();
            }
            for (int i = 0; i < numStrs; i++)
            {
                strings[i] = xomStream.ReadCStr();
            }
            return new StrsBlock(numStrs, strsSz, offsets, strings);
        }
        public XomBlock? readBlock()
        {
            string hdr = xomStream.ReadStrLen(0x4);

            switch (hdr)
            {
                case "MOIK":
                    return readMoik();
                case "TYPE":
                    return readType();
                case "SCHM":
                    return readSchm();
                case "GUID":
                    return readGuid();
                case "STRS":
                    return readStrs();
                case "CTNR":
                    return readCtnr();
            }

            return null;
        }
        private XomBlock[] readAllBlocks()
        {
            List<XomBlock> xomBlocks = new List<XomBlock>();
            while (xomStream.BaseStream.Position < xomStream.BaseStream.Length)
            {
                XomBlock? block = readBlock();
                if (block == null) break;
                xomBlocks.Add(block);
            }
            return xomBlocks.ToArray();
        }
        public static XomFile ReadXomFile(string xomFilename)
        {
            using(MemoryStream ms = new MemoryStream())
            {
                using(FileStream fs = File.OpenRead(xomFilename))
                   fs.CopyTo(ms);
                
                ms.Seek(0, SeekOrigin.Begin);
                return ReadXomFile(ms);
            }
        }
        public static XomFile ReadXomFile(Stream xomStream)
        {
            XomReader reader = new XomReader(xomStream);
            // Read all blocks
            XomBlock[] xomBlocks = reader.readAllBlocks();
            // Create the file object
            return new XomFile(xomBlocks);
        }
        internal XomReader(Stream xom)
        {
            this.xomStream = new XomStreamReader(xom);
        }
    }
}