using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace Tlk
{
    class TlkFile
    {
        public TLKHeader Header;
        public SortedList<int, TLKString> Strings = new SortedList<int, TLKString>();

        private TlkFile() { }
        public TlkFile(byte[] data)
        {
            byte[] entry = new byte[26];
            Header = Tools.ByteArrayToStructure<TLKHeader>(data);
            if (Header.Version.StartsWith("V1"))
            {
                Encoding enc = Encoding.GetEncoding(1252);
                for (int i = 0; i < Header.NumberOfStrings; i++)
                {
                    Array.Copy(data, 18 + i * 26, entry, 0, 26);
                    TLKV1Entry tlkEntry = Tools.ByteArrayToStructure<TLKV1Entry>(entry);
                    string s = enc.GetString(data, Header.Offset + tlkEntry.StringOffset, tlkEntry.StringLength);
                    Strings.Add(i, new TLKString(tlkEntry, s));
                }
            }
        }
    }

    #region TLKHeader
    [StructLayout(LayoutKind.Sequential, Size = 18, Pack = 1)]
    public struct TLKHeader
    {
        /// <summary>
        /// Signature ('TLK ')
        /// </summary>
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 4)]
        public string Signature;

        /// <summary>
        /// Version ('V1')
        /// </summary>
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 4)]
        public string Version;

        [MarshalAs(UnmanagedType.I2)]
        public Int16 Unknown;

        /// <summary>
        /// Number of Strref entries in this file.
        /// </summary>
        [MarshalAs(UnmanagedType.U4)]
        public uint NumberOfStrings;
        /// <summary>
        /// Offset to string data
        /// </summary>
        [MarshalAs(UnmanagedType.I4)]
        public int Offset;
    }
    #endregion
    #region TLKV1Entry
    [StructLayout(LayoutKind.Sequential, Size = 26, Pack = 1)]
    public struct TLKV1Entry
    {
        /// <summary>
        /// 2 == entry unused? (i.e. ignore other fields), 3 == normal?
        /// </summary>
        [MarshalAs(UnmanagedType.I2)]
        public Int16 Flag;

        /// <summary>
        /// Resource name of the associated sound, if any
        /// </summary>
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 8)]
        public string SoundRessourceName;

        /// <summary>
        /// Volume variance.
        /// </summary>
        [MarshalAs(UnmanagedType.I4)]
        public int VolumeVariance;

        /// <summary>
        /// Pitch variance.
        /// </summary>
        [MarshalAs(UnmanagedType.I4)]
        public int PitchVariance;

        /// <summary>
        /// Offset of this string relative to the strings section
        /// </summary>
        [MarshalAs(UnmanagedType.I4)]
        public int StringOffset;

        /// <summary>
        /// length of this string
        /// </summary>
        [MarshalAs(UnmanagedType.I4)]
        public int StringLength;
    }
    #endregion

    class TLKString
    {
        public TLKV1Entry Entry;
        public string Text;
        public TLKString(TLKV1Entry e, string t)
        {
            Entry = e;
            Text = t;
        }
    }

    static class Tools
    {
        public static T ByteArrayToStructure<T>(byte[] bytes) where T : struct
        {
            GCHandle handle = GCHandle.Alloc(bytes, GCHandleType.Pinned);
            T stuff = (T)Marshal.PtrToStructure(handle.AddrOfPinnedObject(),
                typeof(T));
            handle.Free();
            return stuff;
        }
    }
}