#include "Mesh.h"
#include "Log.h"

#define TINYGLTF_IMPLEMENTATION
#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "../dependency/tinygltf/tiny_gltf.h"

namespace Game
{
	void LoadMesh(Model& mesh)
	{
		mesh.VertLayout.begin()
			.add(bgfx::Attrib::Position, 3, bgfx::AttribType::Float)
			.add(bgfx::Attrib::Color0, 4, bgfx::AttribType::Uint8, true)
			.add(bgfx::Attrib::TexCoord0, 2, bgfx::AttribType::Float)
			.end();

		tinygltf::Model model;
		tinygltf::TinyGLTF loader;
		std::string warn;
		std::string err;
		bool loadSuccess = loader.LoadASCIIFromFile(&model, &err, &warn, "models/cube.gltf");

		if (!warn.empty()) Log("WARN: %s", warn.c_str());
		if (!err.empty()) Log("ERR: %s", err.c_str());
		if (!loadSuccess) Log("Model load failed!");

		tinygltf::Primitive primitive = model.meshes[0].primitives[0];
		{
			tinygltf::Accessor accessor = model.accessors.at(primitive.indices);
			tinygltf::BufferView bufferView = model.bufferViews.at(accessor.bufferView);
			tinygltf::Buffer buffer = model.buffers[bufferView.buffer];
			const bgfx::Memory* ibMem = bgfx::alloc(bufferView.byteLength);
			bx::memCopy(ibMem->data, &buffer.data.at(bufferView.byteOffset), bufferView.byteLength);
			mesh.IndexBuffer = bgfx::createIndexBuffer(ibMem);
		}
		{
			tinygltf::Accessor posAccessor = model.accessors.at(primitive.attributes.at("POSITION"));
			tinygltf::Accessor uvAccessor = model.accessors.at(primitive.attributes.at("TEXCOORD_0"));
			tinygltf::BufferView posBufferView = model.bufferViews[posAccessor.bufferView];
			tinygltf::BufferView uvBufferView = model.bufferViews[uvAccessor.bufferView];
			int posStride = posAccessor.ByteStride(posBufferView);
			int uvStride = uvAccessor.ByteStride(uvBufferView);
			tinygltf::Buffer posBuffer = model.buffers[posBufferView.buffer];
			tinygltf::Buffer uvBuffer = model.buffers[uvBufferView.buffer];
		
			uint32_t vertexCount = posBufferView.byteLength / posStride;
			const bgfx::Memory* vbMem = bgfx::alloc(vertexCount * sizeof(PosColorVertex));
		
			for (uint32_t i = 0; i < vertexCount; ++i)
			{
				PosColorVertex& v = *reinterpret_cast<PosColorVertex*>(vbMem->data + i * sizeof(PosColorVertex));
				bx::memCopy(&v.x, &posBuffer.data.at(posBufferView.byteOffset + i * posStride), posStride);
				v.abgr = 0;
				bx::memCopy(&v.uv_x, &uvBuffer.data.at(uvBufferView.byteOffset + i * uvStride), uvStride);
			}
			mesh.VertexBuffer = bgfx::createVertexBuffer(vbMem, mesh.VertLayout);
		}
	}
}