#include "opengl/data_managers/mesh_vertex_buffer_manager.hpp"

#include "util/logger.hpp"
#include "opengl/error.hpp"
#include "opengl/vertex_buffer_utils.hpp"


void zgl::mesh_vertex_buffer_manager::process(store_type& store)
{
	for (const auto& [ id, mesh ] : store)
	{
		if (not m_resource_manager.has_resource(id))
		{
			m_mesh_buffer.emplace_back(id, mesh);
		}
	}

	m_buffer_id_buffer.resize(m_mesh_buffer.size());

	glGenBuffers(m_buffer_id_buffer.size(), m_buffer_id_buffer.data());
	if (const auto e = get_error())
	{
		ztu::logger::error("Error while creating % vertex buffers: %.", m_buffer_id_buffer.size(), e.message());
		return;
	}

	for (auto [ entry, buffer_id ] : std::ranges::views::zip(m_mesh_buffer, m_buffer_id_buffer))
	{
		auto [ store_id, mesh ] = entry;

		m_byte_buffer.clear();

		std::apply(
			[&](const auto&... component_buffers)
			{
				vertex_buffer_utils::interlace(
					m_byte_buffer,
					mesh.component_flags,
					mesh.vertex_count,
					component_buffers...
				);
			},
			mesh.vertex_component_arrays
		);

		glBindBuffer(GL_ARRAY_BUFFER, buffer_id);
		if (const auto e = get_error())
		{
			ztu::logger::error("Error while binding vertex buffer %: %.", buffer_id, e.message());
			continue;
		}

		glBufferData(
			GL_ARRAY_BUFFER,
			static_cast<GLsizeiptr>(m_byte_buffer.size()),
			m_byte_buffer.data(),
			GL_STATIC_DRAW
		);
		if (const auto e = get_error())
		{
			ztu::logger::error("Error while setting vertex buffer data: %.", e.message());
			continue;
		}

		const auto meta = mesh_vertex_buffer_metadata{
			.component_flags = mesh.component_flags,
			.material_id = mesh.material_id
		};

		m_resource_manager.add_resource(store_id, buffer_id, meta);

		buffer_id = {};
	}

	glBindBuffer(GL_ARRAY_BUFFER, 0);

	const auto valid_buffer_ids = std::ranges::remove(
		m_buffer_id_buffer,
		0
	);

	const auto invalid_buffer_count = m_buffer_id_buffer.size() - valid_buffer_ids.size();

	glDeleteBuffers(
		invalid_buffer_count,
		m_buffer_id_buffer.data()
	);
	if (const auto e = get_error())
	{
		ztu::logger::error("Error while deleting % buffers: %.", invalid_buffer_count, e.message());
	}
}

std::optional<zgl::mesh_vertex_buffer_manager::handle_type> zgl::mesh_vertex_buffer_manager::get_handle(
	const store_id_type id
) {
	return m_resource_manager
		.get_resource(id)
		.transform(
			[](auto& resource)
			{
				return *reinterpret_cast<handle_type*>(resource);
			}
		);
}


void zgl::mesh_vertex_buffer_manager::collect_garbage(const bool force)
{
	m_resource_manager.collect_garbage();
	if (force or m_resource_manager.count_garbage() >= min_garbage_collection_count)
	{
		m_buffer_id_buffer.clear();
		m_resource_manager.extract_garbage(m_buffer_id_buffer);
		glDeleteBuffers(
			m_buffer_id_buffer.size(),
			m_buffer_id_buffer.data()
		);
	}
}