namespace UnityDataTools.BinaryFormat;

/// <summary>

/// Helper class for converting Unity GUID data to string format.

/// </summary>

public static class GuidHelper

{

/// <summary>

/// Converts Unity GUID data array to string format matching Unity's GUIDToString function.

/// Unity stores GUIDs as 4 uint32 values and converts them to a 32-character hex string

/// with a specific byte ordering that differs from standard GUID/UUID formatting.

/// </summary>

/// <example>

/// data[0]=3856716653 (0xe60765cd) becomes "d63d0e5e"

/// </example>

public static string FormatUnityGuid(uint data0, uint data1, uint data2, uint data3)

{

char[] result = new char[32];

FormatUInt32Reversed(data0, result, 0);

FormatUInt32Reversed(data1, result, 8);

FormatUInt32Reversed(data2, result, 16);

FormatUInt32Reversed(data3, result, 24);

return new string(result);

}

/// <summary>

/// Formats a uint32 as 8 hex digits matching Unity's GUIDToString logic.

/// Unity's implementation extracts nibbles from most significant to least significant

/// (j=7 down to j=0) and writes them to output positions in the same order (offset+7 to offset+0),

/// which reverses the byte order compared to standard hex formatting.

/// </summary>

/// <example>

/// For example: 0xe60765cd becomes "d63d0e5e" (bytes reversed: cd,65,07,e6 → e6,07,65,cd)

/// </example>

private static void FormatUInt32Reversed(uint value, char[] output, int offset)

{

const string hexChars = "0123456789abcdef";

for (int j = 7; j >= 0; j--)

{

uint nibble = (value >> (j * 4)) & 0xF;

output[offset + j] = hexChars[(int)nibble];

}

}

}