Penumbra/Penumbra/Import/TexToolsMeta.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using Penumbra.Meta.Manipulations;

namespace Penumbra.Import;

// TexTools provices custom generated *.meta files for its modpacks, that contain changes to
//     - imc files
//     - eqp files
//     - gmp files
//     - est files
//     - eqdp files
// made by the mod. The filename determines to what the changes are applied, and the binary file itself contains changes.
// We parse every *.meta file in a mod and combine all actual changes that do not keep data on default values and that can be applied to the game in a .json.
// TexTools may also generate files that contain non-existing changes, e.g. *.imc files for weapon offhands, which will be ignored.
// TexTools also provides .rgsp files, that contain changes to the racial scaling parameters in the human.cmp file.
public partial class TexToolsMeta
{
    // An empty TexToolsMeta.
    public static readonly TexToolsMeta Invalid = new(string.Empty, 0);

    // The info class determines the files or table locations the changes need to apply to from the filename.

    public readonly  uint                     Version;
    public readonly  string                   FilePath;
    public readonly  List< MetaManipulation > MetaManipulations = new();
    private readonly bool                     _keepDefault      = false;

    public TexToolsMeta( byte[] data, bool keepDefault )
    {
        _keepDefault = keepDefault;
        try
        {
            using var reader = new BinaryReader( new MemoryStream( data ) );
            Version  = reader.ReadUInt32();
            FilePath = ReadNullTerminated( reader );
            var metaInfo    = new MetaFileInfo( FilePath );
            var numHeaders  = reader.ReadUInt32();
            var headerSize  = reader.ReadUInt32();
            var headerStart = reader.ReadUInt32();
            reader.BaseStream.Seek( headerStart, SeekOrigin.Begin );

            List< (MetaManipulation.Type type, uint offset, int size) > entries = new();
            for( var i = 0; i < numHeaders; ++i )
            {
                var currentOffset = reader.BaseStream.Position;
                var type          = ( MetaManipulation.Type )reader.ReadUInt32();
                var offset        = reader.ReadUInt32();
                var size          = reader.ReadInt32();
                entries.Add( ( type, offset, size ) );
                reader.BaseStream.Seek( currentOffset + headerSize, SeekOrigin.Begin );
            }

            byte[]? ReadEntry( MetaManipulation.Type type )
            {
                var idx = entries.FindIndex( t => t.type == type );
                if( idx < 0 )
                {
                    return null;
                }

                reader.BaseStream.Seek( entries[ idx ].offset, SeekOrigin.Begin );
                return reader.ReadBytes( entries[ idx ].size );
            }

            DeserializeEqpEntry( metaInfo, ReadEntry( MetaManipulation.Type.Eqp ) );
            DeserializeGmpEntry( metaInfo, ReadEntry( MetaManipulation.Type.Gmp ) );
            DeserializeEqdpEntries( metaInfo, ReadEntry( MetaManipulation.Type.Eqdp ) );
            DeserializeEstEntries( metaInfo, ReadEntry( MetaManipulation.Type.Est ) );
            DeserializeImcEntries( metaInfo, ReadEntry( MetaManipulation.Type.Imc ) );
        }
        catch( Exception e )
        {
            FilePath = "";
            Penumbra.Log.Error( $"Error while parsing .meta file:\n{e}" );
        }
    }

    private TexToolsMeta( string filePath, uint version )
    {
        FilePath = filePath;
        Version  = version;
    }

    // Read a null terminated string from a binary reader.
    private static string ReadNullTerminated( BinaryReader reader )
    {
        var builder = new StringBuilder();
        for( var c = reader.ReadChar(); c != 0; c = reader.ReadChar() )
        {
            builder.Append( c );
        }

        return builder.ToString();
    }
}