/*
 * Copyright (C) 2022 Riyyi
 *
 * SPDX-License-Identifier: MIT
 */

#include "glm/ext/matrix_clip_space.hpp" // glm::perspective, glm::ortho
#include "glm/ext/matrix_transform.hpp"  // glm::radians, glm::lookAt
#include "ruc/format/log.h"
#include "ruc/meta/assert.h"

#include "inferno/application.h"
#include "inferno/component/cameracomponent.h"
#include "inferno/component/transformcomponent.h"
#include "inferno/io/input.h"
#include "inferno/system/camerasystem.h"
#include "inferno/window.h"

namespace Inferno {

CameraSystem::CameraSystem(s)
{
	ruc::info("CameraSystem initialized");
}

CameraSystem::~CameraSystem()
{
}

void CameraSystem::update()
{
	auto view = m_registry->view<TransformComponent, CameraComponent>();

	for (auto [entity, transform, camera] : view.each()) {

		if (camera.type == CameraType::Orthographic) {
			updateOrthographic(transform, camera);
		}
		else if (camera.type == CameraType::Perspective) {
			updatePerspective(transform, camera);
		}
	}
}

glm::mat4 CameraSystem::projectionView()
{
	auto view = m_registry->view<TransformComponent, CameraComponent>();

	for (auto [entity, transform, camera] : view.each()) {
		return camera.projection * transform.transform;
	}

	VERIFY_NOT_REACHED();

	return glm::mat4 { 1.0f };
}

void CameraSystem::updateOrthographic(TransformComponent& transform, CameraComponent& camera)
{
	// Update camera matrix

	// Local space -> World space: model matrix
	// Is done in Object::update()

	// World space -> View space: view matrix
	transform.transform = {
		glm::translate(glm::mat4(1.0f), transform.translate) * glm::rotate(glm::mat4(1.0f), glm::radians(transform.rotate.z), camera.rotateAxis)
	};
	transform.transform = { glm::inverse(transform.transform) };

	// View space -> Clip space: projection matrix
	float aspectRatio = Application::the().getWindow().getAspect();
	camera.projection = {
		glm::ortho(-aspectRatio * camera.zoomLevel, aspectRatio * camera.zoomLevel,
		           -camera.zoomLevel, camera.zoomLevel, -1.0f, 1.0f)
	};

	// Clip space -> Screen space: viewport transform
	// Is done in the fragment shader using the settings of glViewport
}

void CameraSystem::updatePerspective(TransformComponent& transform, CameraComponent& camera)
{
	// Update camera matrix

	// Local space -> World space: model matrix
	// Is done in Object::update()

	// World space -> View space: view matrix
	transform.transform = { glm::lookAt(transform.translate, transform.translate + transform.rotate, camera.up) };

	// View space -> Clip space: projection matrix
	float aspect = Application::the().getWindow().getAspect();
	camera.projection = { glm::perspective(glm::radians(camera.fov), aspect, NEAR_PLANE, FAR_PLANE) };

	// Clip space -> Screen space: viewport transform
	// Is done in the fragment shader using the settings of glViewport

	// Souce: https://learnopengl.com/img/getting-started/coordinate_systems.png
}

} // namespace Inferno