using System;
using System.Runtime.InteropServices;
using Xtremegaida.DataStructures;

namespace MediaContainers;

public struct EBMLElementStruct
{
	public readonly EBMLElementDefiniton Definition;
	public readonly EBMLVInt DataSize;
	public readonly long DataOffset;
	public EBMLElementStructValue Value;
	public string String;
	public byte[] Binary;
	public IDataQueueReader Reader;
	public bool UseFloat32;

	public EBMLElementStruct(EBMLElementDefiniton definition, EBMLVInt dataSize, long dataOffset)
	{
		Definition = definition;
		DataSize = dataSize;
		DataOffset = dataOffset;
		Value = default;
		String = null;
		Binary = null;
		Reader = null;
		UseFloat32 = false;
	}

	public EBMLElement ToElement()
	{
		switch (Definition.Type)
		{
			case EBMLElementType.SignedInteger:
				return new EBMLSignedIntegerElement(Definition, DataSize, DataOffset, Value.SignedInteger);
			case EBMLElementType.UnsignedInteger:
				return new EBMLUnsignedIntegerElement(Definition, DataSize, DataOffset, Value.UnsignedInteger);
			case EBMLElementType.Float:
				if (UseFloat32) { return new EBMLFloatElement(Definition, DataSize, DataOffset, Value.Float32); }
				return new EBMLFloatElement(Definition, DataSize, DataOffset, Value.Float64);
			case EBMLElementType.Date:
				return new EBMLDateElement(Definition, DataSize, DataOffset, Value.Date);
			case EBMLElementType.String:
			case EBMLElementType.UTF8:
				return new EBMLStringElement(Definition, DataSize, DataOffset, String);
			case EBMLElementType.Master:
				return new EBMLMasterElement(Definition, DataSize, DataOffset);
			case EBMLElementType.Binary:
			default:
				if (Definition == EBMLElementDefiniton.Void)
				{
					if (Reader != null) { return new EBMLVoidElement(DataSize, DataOffset, Reader, true); }
					return new EBMLVoidElement(DataSize, DataOffset);
				}
				if (Reader != null) { return new EBMLBinaryElement(Definition, DataSize, DataOffset, Reader, true); }
				return new EBMLBinaryElement(Definition, DataSize, DataOffset, Binary);
		}
	}
}

[StructLayout(LayoutKind.Explicit)]
public struct EBMLElementStructValue
{
	[FieldOffset(0)] public long SignedInteger;
	[FieldOffset(0)] public ulong UnsignedInteger;
	[FieldOffset(0)] public double Float64;
	[FieldOffset(0)] public float Float32;
	[FieldOffset(0)] public DateTime Date;
}