#include "opengl/data/point_cloud_data.hpp"

#include "opengl/type_utils.hpp"
#include "opengl/error.hpp"

#include <algorithm>
#include "GL/glew.h"

std::error_code zgl::point_cloud_data::build_from(
		std::span<const std::uint8_t> point_buffer,
		std::span<const GLenum> component_types,
		std::span<const GLint> component_lengths,
		GLsizei stride,
		point_cloud_data& data
) {
	if (not std::ranges::all_of(component_types, type_utils::is_valid_type))
	{
		return std::make_error_code(std::errc::invalid_argument);
	}

	const auto points_byte_count = point_buffer.size() * sizeof(std::uint8_t);
	if (points_byte_count > std::numeric_limits<GLsizeiptr>::max())
	{
		return std::make_error_code(std::errc::value_too_large);
	}

	auto error = std::error_code{};

	auto check_error = [&error, ec = static_cast<GLenum>(GL_NO_ERROR)]() mutable -> const std::error_code&
	{
		ec = glGetError();
		if (ec != GL_NO_ERROR) {
			error = make_error_code(ec);
		}
		return error;
	};

	ztu::u32 vao_id;
	glGenVertexArrays(1, &vao_id);
	if (check_error()) return error;

	glBindVertexArray(vao_id);
	if (check_error()) return error;

	ztu::u32 vertex_buffer_id;
	glGenBuffers(1, &vertex_buffer_id);
	if (check_error()) return error;

	glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_id);
	if (check_error()) return error;

	glBufferData(
		GL_ARRAY_BUFFER,
		static_cast<GLsizeiptr>(points_byte_count),
		point_buffer.data(),
		GL_STATIC_DRAW
	);
	if (check_error()) return error;


	glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_id);
	if (check_error()) return error;

	auto offset = GLsizei{ 0 };

	for (std::size_t i{}; i != component_types.size(); ++i)
	{
		const auto type = component_types[i];
		const auto length = component_lengths[i];
		const auto byte_count = type_utils::size_of(type);

		glVertexAttribPointer(
			i,
			length,
			type,
			GL_FALSE,
			stride,
			reinterpret_cast<GLvoid*>(offset)
		);
		if (check_error()) return error;
		glEnableVertexAttribArray(i);
		if (check_error()) return error;

		offset += length * byte_count;
	}

	glBindBuffer(GL_ARRAY_BUFFER, 0);
	if (check_error()) return error;
	glBindVertexArray(0);
	if (check_error()) return error;

	data = point_cloud_data(
		vertex_buffer_id,
		vao_id,
		point_buffer.size()
	);

	return {};
}