/************************************************************************************
Copyright : Copyright (c) Facebook Technologies, LLC and its affiliates. All rights reserved.

Your use of this SDK or tool is subject to the Oculus SDK License Agreement, available at
https://developer.oculus.com/licenses/oculussdk/

Unless required by applicable law or agreed to in writing, the Utilities SDK distributed
under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
ANY KIND, either express or implied. See the License for the specific language governing
permissions and limitations under the License.
************************************************************************************/

using System.Collections;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System;

using UnityEngine;

// Class that manages loading of Ktx Textures through OVRPlugin
public class OVRKtxTexture
{
	private const uint KTX_TTF_BC7_RGBA = 6;
	private const uint KTX_TTF_ASTC_4x4_RGBA = 10;

	public static bool Load(byte[] data, ref OVRTextureData ktxData)
	{
		int unmanagedSize = Marshal.SizeOf(data[0]) * data.Length;
		IntPtr dataPtr = Marshal.AllocHGlobal(unmanagedSize);

		Marshal.Copy(data, 0, dataPtr, data.Length);
		IntPtr ktxTexturePtr = OVRPlugin.Ktx.LoadKtxFromMemory(dataPtr, (uint)data.Length);
		Marshal.FreeHGlobal(dataPtr);

		ktxData.width = (int)OVRPlugin.Ktx.GetKtxTextureWidth(ktxTexturePtr);
		ktxData.height = (int)OVRPlugin.Ktx.GetKtxTextureHeight(ktxTexturePtr);

		bool transcodeResult = false;
#if UNITY_ANDROID && !UNITY_EDITOR
		transcodeResult = OVRPlugin.Ktx.TranscodeKtxTexture(ktxTexturePtr, KTX_TTF_ASTC_4x4_RGBA);
		ktxData.transcodedFormat = TextureFormat.ASTC_4x4;
#else
		transcodeResult = OVRPlugin.Ktx.TranscodeKtxTexture(ktxTexturePtr, KTX_TTF_BC7_RGBA);
		ktxData.transcodedFormat = TextureFormat.BC7;
#endif
		if (!transcodeResult)
		{
			Debug.LogError("Failed to transcode KTX texture.");
			return false;
		}

		uint textureSize = OVRPlugin.Ktx.GetKtxTextureSize(ktxTexturePtr);
		IntPtr textureDataPtr = Marshal.AllocHGlobal(sizeof(byte) * (int)textureSize);
		if(!OVRPlugin.Ktx.GetKtxTextureData(ktxTexturePtr, textureDataPtr, textureSize))
		{
			Debug.LogError("Failed to get texture data from Ktx texture reference");
			return false;
		}

		byte[] textureData = new byte[textureSize];
		Marshal.Copy(textureDataPtr, textureData, 0, textureData.Length);
		Marshal.FreeHGlobal(textureDataPtr);
		ktxData.data = textureData;

		OVRPlugin.Ktx.DestroyKtxTexture(ktxTexturePtr);

		return true;
	}
}