//	Voxspatium Engine - Voxel Planets engine
//	Copyright (C) 2018  Evert "Diamond" Prants <evert@lunasqu.ee>
//
//	This program is free software: you can redistribute it and/or modify
//	it under the terms of the GNU General Public License as published by
//	the Free Software Foundation, either version 3 of the License, or
//	(at your option) any later version.
//
//	This program is distributed in the hope that it will be useful,
//	but WITHOUT ANY WARRANTY; without even the implied warranty of
//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//	GNU General Public License for more details.
//
//	You should have received a copy of the GNU General Public License
//	along with this program.  If not, see <https://www.gnu.org/licenses/>.

#ifndef __CAMERA_H__
#define __CAMERA_H__

#include "util/Common.h"
#include "Shader.h"

// Defines several possible options for camera movement. Used as abstraction to stay away from window-system specific input methods
enum Camera_Movement {
    FORWARD,
    BACKWARD,
    LEFT,
    RIGHT
};

// Default camera values
const GLfloat YAW        = -90.0f;
const GLfloat PITCH      =  0.0f;
const GLfloat ROLL       =  0.0f;
const GLfloat SPEED      =  100.0f;
const GLfloat SENSITIVTY =  0.25f;
const GLfloat ZOOM       =  45.0f;

class Camera
{
public:
	Camera(glm::vec3 position = glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3 up = glm::vec3(0.0f, 1.0f, 0.0f), GLfloat yaw = YAW, GLfloat pitch = PITCH, GLfloat roll = ROLL);
	Camera(GLfloat posX, GLfloat posY, GLfloat posZ, GLfloat upX, GLfloat upY, GLfloat upZ, GLfloat yaw, GLfloat pitch, GLfloat roll);
	~Camera();

	glm::mat4 getViewMatrix(void);
	void processKeyboard(Camera_Movement direction, GLfloat deltaTime);
	void processMouseMovement(GLfloat xoffset, GLfloat yoffset, GLboolean constrainPitch);
	void processMouseScroll(GLfloat yoffset);

	void shaderViewProjection(Shader& shader);

	inline GLfloat getFOV() const { return m_zoom; }
	inline glm::vec3 getPosition(void) const { return m_position; }
	
	bool frustumContainsPoint(const glm::vec3 &point) const;
	int frustumContainsSphere(const glm::vec3 &position, const double radius) const;
	int frustumContainsBox(const glm::vec3 &min, const glm::vec3 &max) const;
	int frustumContainsPolygon(const std::vector<glm::vec3> &points) const;

	void updateFrustum(glm::mat4 modelMatrix);
private:
	glm::vec3 m_position;
	glm::vec3 m_front;
	glm::vec3 m_up;
	glm::vec3 m_right;
	glm::vec3 m_worldUp;

	// Eular Angles
	GLfloat m_yaw;
	GLfloat m_pitch;
	GLfloat m_roll;

	// Camera options
	GLfloat m_movementSpeed;
	GLfloat m_mouseSensitivity;
	GLfloat m_zoom;

	// The Projection Matrix
	glm::mat4 m_projection;

	// Frustum Culling
	glm::vec4 m_planes[6];
	float frustumDistanceToPlane(const int plane, const glm::vec3 &point) const;

	void updateCameraVectors(void);
	void updateProjection(void);
};
#endif // __CAMERA_H__