/// <summary>
/// Holds the game process for us to manipulate.
/// Allows you to read/write memory, perform pattern scans, etc.
/// See libReloaded/GameProcess (folder)
/// </summary>
public static ReloadedProcess GameProcess;

/// <summary>
/// Specifies the full directory location that the game
/// is contained in.
/// </summary>
public static string GameDirectory;

/// <summary>
/// Specifies the full directory location that the current mod
/// is contained in.
/// </summary>
public static string ModDirectory;

public const string RESOURCE_PATH_ROOT = @"resource\gd_pc\";

/// <summary>
/// Function delegate for CreateFileA, the function the game uses to obtain handles to files it will load.
/// </summary>
/// <param name="filename"></param>
/// <param name="access"></param>
/// <param name="share"></param>
/// <param name="securityAttributes"></param>
/// <param name="creationDisposition"></param>
/// <param name="flagsAndAttributes"></param>
/// <param name="templateFile"></param>
/// <returns></returns>
[UnmanagedFunctionPointer( CallingConvention.Cdecl )]
[ReloadedFunction( CallingConventions.Stdcall )]
public delegate IntPtr CreateFileA
(
    [MarshalAs( UnmanagedType.LPStr )] string filename,
    [MarshalAs( UnmanagedType.U4 )] FileAccess access,
    [MarshalAs( UnmanagedType.U4 )] FileShare share,
    IntPtr securityAttributes,
    [MarshalAs( UnmanagedType.U4 )] FileMode creationDisposition,
    [MarshalAs( UnmanagedType.U4 )] FileAttributes flagsAndAttributes,
    IntPtr templateFile
);

public static FunctionHook<CreateFileA> CreateFileAHook;

/// <summary>
/// Your own user code starts here.
/// If this is your first time, do consider reading the notice above.
/// It contains some very useful information.
/// </summary>
public static void Init()
{
#if DEBUG
    Print("SA2CustomFileLoader [DEBUG] initialized!");
    Debugger.Launch();
#else
    Print( "SA2CustomFileLoader initialized!" );
#endif

    // Initialize CreateFileA hook
    var kernel32Handle = Native.LoadLibrary( "kernel32" );
    var createFileA = Native.GetProcAddress( kernel32Handle, "CreateFileA" );
    CreateFileAHook = FunctionHook<CreateFileA>.CreateFunctionHook( ( long )createFileA, CreateFileAHookImpl );
}

public static IntPtr CreateFileAHookImpl( string filename, FileAccess fileAccess, FileShare fileShare, IntPtr securityAttributes,
                                            FileMode creationDisposition, FileAttributes flagsAndAttributes, IntPtr templateFile )
{
    if ( TryGetRelativePath( filename, RESOURCE_PATH_ROOT, out var relativePath ) )
    {
        var customFilePath = Path.Combine( ModDirectory, relativePath );
        if ( File.Exists( customFilePath ) )
        {
            filename = customFilePath;
        }
    }

    return CreateFileAHook.OriginalFunction( filename, fileAccess, fileShare, securityAttributes, creationDisposition, flagsAndAttributes,
                                                templateFile );
}

public static bool TryGetRelativePath( string path, string pathRoot, out string relativePath )
{
    var normalizedPath = path.ToLowerInvariant();
    var index = normalizedPath.IndexOf( pathRoot );
    if ( index != -1 )
    {
        relativePath = normalizedPath.Substring( index );
        return true;
    }

    relativePath = null;
    return false;
}