//! \file       ArcCircus.cs
//! \date       Mon Jun 15 16:11:56 2015
//! \brief      Circus archive format.
//
// Copyright (C) 2015-2016 by morkt
//
// 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 System;
using System.Collections.Generic;
using System.ComponentModel.Composition;
using System.IO;
using GameRes.Utility;

namespace GameRes.Formats.Circus
{
    [Export(typeof(ArchiveFormat))]
    public class DatOpener : ArchiveFormat
    {
        public override string         Tag { get { return "DAT/CIRCUS"; } }
        public override string Description { get { return "Circus resource archive"; } }
        public override uint     Signature { get { return 0; } }
        public override bool  IsHierarchic { get { return true; } }
        public override bool      CanWrite { get { return false; } }

        public DatOpener ()
        {
            Extensions = new string[] { "dat" };
        }

        public override ArcFile TryOpen (ArcView file)
        {
            var arcFile = TryOpenFromHeader(file);
            if (null != arcFile) 
            {
                return arcFile;
            }

            arcFile = TryOpenFromFooter(file);

            return arcFile;
        }

        public ArcFile TryOpenFromHeader(ArcView file) 
        {
            int count = file.View.ReadInt32(0);
            if (count <= 1 || count > 0xfffff)
                return null;
            var dir = ReadIndexV1(file, count, 0x24);
            if (null == dir)
                dir = ReadIndexV1(file, count, 0x30);
            if (null == dir)
                dir = ReadIndexV1(file, count, 0x3C);
            if (null == dir)
                return null;
            return new ArcFile(file, this, dir);
        }

        public ArcFile TryOpenFromFooter(ArcView file) 
        {
            int count = file.View.ReadInt32(file.MaxOffset - 4);
            if(count <= 1 || count > 0xfffff) 
            {
                return null;
            }

           var dir = ReadIndexV2(file, count, file.View.ReadInt32(file.MaxOffset - 0x8));

           return new ArcFile(file, this, dir);
        }

        private List<Entry> ReadIndexV1 (ArcView file, int count, int name_length)
        {
            long index_offset = 4;
            uint index_size = (uint)((name_length + 4) * count);
            if (index_size > file.View.Reserve (index_offset, index_size))
                return null;
            --count;
            uint next_offset = file.View.ReadUInt32 (index_offset+name_length);
            if (next_offset < 4+index_size)
                return null;
            uint first_size    = file.View.ReadUInt32 (index_offset+name_length-4);
            uint second_offset = file.View.ReadUInt32 (index_offset+name_length*2+4);
            if (second_offset - next_offset == first_size)
                return null;
            var dir = new List<Entry> (count);
            for (int i = 0; i < count; ++i)
            {
                string name = file.View.ReadString (index_offset, (uint)name_length);
                if (0 == name.Length)
                    return null;
                var entry = FormatCatalog.Instance.Create<Entry> (name);
                index_offset += name_length;
                uint offset = next_offset;
                if (i+1 == count)
                    next_offset = (uint)file.MaxOffset;
                else
                    next_offset = file.View.ReadUInt32 (index_offset+4+name_length);
                if (next_offset < offset)
                    return null;
                entry.Size = next_offset - offset;
                entry.Offset = offset;
                if (offset < index_size || !entry.CheckPlacement (file.MaxOffset))
                    return null;
                dir.Add (entry);
                index_offset += 4;
            }
            return dir;
        }

        private List<Entry> ReadIndexV2(ArcView file, int count, long start_offset) 
        {
            uint max_index_size = (uint)(count * 0x4C);
            long index_offset = start_offset;
            var dir = new List<Entry> (count);

            file.View.Reserve(start_offset, max_index_size);

            for (int i = 0; i < count; i++)
            {
                int name_length = file.View.ReadByte(index_offset);
                index_offset++;

                string name = file.View.ReadString(index_offset, (uint)name_length);
                index_offset += name_length;

                uint entry_size = file.View.ReadUInt32(index_offset);
                index_offset += 8;

                long entry_offset = file.View.ReadInt32(index_offset);
                index_offset += 4;

                var entry = FormatCatalog.Instance.Create<Entry>(name);
                entry.Size = entry_size;
                entry.Offset = entry_offset;
                dir.Add(entry);
            }

            return dir;
        }
    }
}