#pragma once

// Std. Includes
#include <vector>

// GL Includes
#include <GL/glew.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>


// 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 SPEED = 30.0f;
const GLfloat SENSITIVTY = 0.2f;
const GLfloat ZOOM = 45.0f;

// An abstract camera class that processes input and calculates the corresponding Eular Angles, Vectors and Matrices for use in OpenGL
class Camera3D {
public:
    // Camera3D Attributes
    glm::vec3 Position;
    glm::vec3 Front;
    glm::vec3 Up;
    glm::vec3 Right;
    glm::vec3 WorldUp;
    // Eular Angles
    GLfloat Yaw;
    GLfloat Pitch;
    // Camera3D options
    GLfloat MovementSpeed;
    GLfloat MouseSensitivity;
    GLfloat Zoom;

    // Constructor with vectors
    explicit Camera3D(glm::vec3 position = glm::vec3(0.0f, 0.0f, 3.0f), glm::vec3 up = glm::vec3(0.0f, 1.0f, 0.0f),
           GLfloat yaw = YAW, GLfloat pitch = PITCH);

    // Constructor with scalar values
    Camera3D(GLfloat posX, GLfloat posY, GLfloat posZ, GLfloat upX, GLfloat upY, GLfloat upZ, GLfloat yaw, GLfloat pitch);

    // Returns the view matrix calculated using Eular Angles and the LookAt Matrix
    glm::mat4 GetViewMatrix();

    // Processes input received from any keyboard-like input system. Accepts input parameter in the form of camera defined ENUM (to abstract it from windowing systems)
    void ProcessKeyboard(Camera_Movement direction, GLfloat deltaTime);

    // Processes input received from a mouse input system. Expects the offset value in both the x and y direction.
    void ProcessMouseMovement(GLfloat xoffset, GLfloat yoffset, GLboolean constrainPitch = true);

    // Processes input received from a mouse scroll-wheel event. Only requires input on the vertical wheel-axis
    void ProcessMouseScroll(GLfloat yoffset);

private:
    // Calculates the front vector from the Camera3D's (updated) Eular Angles
    void updateCameraVectors();
};