#include "Mesh.hpp"

#include <algorithm>

GpuVertexBuffer::GpuVertexBuffer() {
	glGenBuffers(1, &handle);
}

GpuVertexBuffer::~GpuVertexBuffer() {
	glDeleteBuffers(1, &handle);
}

void GpuVertexBuffer::Upload(const std::byte* data, size_t sizeInBytes) {
	glBindBuffer(GL_ARRAY_BUFFER, handle);
	glBufferData(GL_ARRAY_BUFFER, sizeInBytes, data, GL_DYNAMIC_DRAW);
}

GpuIndexBuffer::GpuIndexBuffer() {
	glGenBuffers(1, &handle);
}

GpuIndexBuffer::~GpuIndexBuffer() {
	glDeleteBuffers(1, &handle);
}

void GpuIndexBuffer::Upload(const std::byte* data, size_t count) {
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, handle);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, count * Tags::SizeOf(indexType), data, GL_DYNAMIC_DRAW);
}

void GpuIndexBuffer::Upload(const std::byte* data, Tags::IndexType type, size_t count) {
	indexType = type;
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, handle);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, count * Tags::SizeOf(type), data, GL_DYNAMIC_DRAW);
}

int BufferBindings::GetMaxBindingIndex() const {
	return bindings.size() - 1;
}

GpuVertexBuffer* BufferBindings::GetBinding(int index) const {
	if (index >= 0 && index < bindings.size()) {
		return bindings[index].Get();
	} else {
		return nullptr;
	}
}

void BufferBindings::SetBinding(int index, GpuVertexBuffer* buffer) {
	int maxBindingIndex = GetMaxBindingIndex();
	if (index > maxBindingIndex) {
		int countDelta = index - maxBindingIndex;
		bindings.resize(bindings.size() + countDelta);
	}

	bindings[index].Attach(buffer);
	if (index == maxBindingIndex && buffer == nullptr) {
		bindings.pop_back();
	}
}

void BufferBindings::Clear() {
	bindings.clear();
}

int VertexElementFormat::GetStride() const {
	return Tags::SizeOf(type);
}

void VertexFormat::AddElement(VertexElementFormat element) {
	vertexSize += element.GetStride();
	elements.push_back(std::move(element));
}

void VertexFormat::RemoveElement(int index) {
	auto& element = elements[index];
	vertexSize -= element.GetStride();
	elements.erase(elements.begin() + index);
}

void VertexFormat::Sort() {
	std::sort(elements.begin(), elements.end());
}

void VertexFormat::CompactBindingIndex() {
	if (elements.empty()) {
		return;
	}

	Sort();

	int targetIdx = 0;
	int lastIdx = elements[0].bindingIndex;
	int c = 0;
	for (auto& elm : elements) {
		if (lastIdx != elm.bindingIndex) {
			targetIdx++;
			lastIdx = elm.bindingIndex;
		}
		if (targetIdx != elm.bindingIndex) {
			elements[c] = elm;
			elements[c].bindingIndex = targetIdx;
		}
		++c;
	}
}

GpuMesh::GpuMesh(VertexFormat* vertexFormat, BufferBindings* bindings, GpuIndexBuffer* indexBuffer)
	: vertFormat(vertexFormat)
	, vertBufBindings(bindings)
	, indexBuf(indexBuffer) {
}

bool GpuMesh::IsEmpty() const {
	return vertFormat != nullptr;
}

void GpuMesh::SetVertex(VertexFormat* vertexFormat, BufferBindings* bindings) {
	vertFormat.Attach(vertexFormat);
	vertBufBindings.Attach(bindings);
}

VertexFormat* GpuMesh::GetVertexFormat() const {
	return vertFormat.Get();
}

BufferBindings* GpuMesh::GetVertexBufferBindings() const {
	return vertBufBindings.Get();
}

GpuIndexBuffer* GpuMesh::GetIndexBuffer() const {
	return indexBuf.Get();
}