#ifndef ENGINE2026_CAMERA_H
#define ENGINE2026_CAMERA_H

#include <glad/glad.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>

// Movement keys/buttons
enum Camera_Movement {
    FORWARD,
    BACKWARD,
    LEFT,
    RIGHT
};

// Default camera values
const float YAW         = -90.0f;
const float PITCH       =  0.0f;
const float SPEED       =  2.5f;
const float SENSITIVITY =  0.1f;
const float ZOOM        =  45.0f;

class Camera
{
public:
    glm::vec3 position, front, up, right, worldUp;
    float yaw, pitch;
    float movementSpeed, mouseSensitivity, zoom;

    // constructor with vectors
    Camera(glm::vec3 newPosition = glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3 up = glm::vec3(0.0f, 1.0f, 0.0f), float newYaw = YAW, float newPitch = PITCH) : front(glm::vec3(0.0f, 0.0f, -1.0f)), movementSpeed(SPEED), mouseSensitivity(SENSITIVITY), zoom(ZOOM)
    {
        position = newPosition;
        worldUp = up;
        yaw = newYaw;
        pitch = newPitch;
        updateCameraVectors();
    }
    // constructor with scalar values
    Camera(float posX, float posY, float posZ, float upX, float upY, float upZ, float newYaw, float newPitch) : front(glm::vec3(0.0f, 0.0f, -1.0f)), movementSpeed(SPEED), mouseSensitivity(SENSITIVITY), zoom(ZOOM)
    {
        position = glm::vec3(posX, posY, posZ);
        worldUp = glm::vec3(upX, upY, upZ);
        yaw = newYaw;
        pitch = newPitch;
        updateCameraVectors();
    }

    // returns the view matrix calculated using Euler Angles and the LookAt Matrix
    glm::mat4 GetViewMatrix()
    {
        return glm::lookAt(position, position + front, up);
    }

    // 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, float deltaTime)
    {
        float velocity = movementSpeed * deltaTime;
        if (direction == FORWARD)
            position += front * velocity;
        if (direction == BACKWARD)
            position -= front * velocity;
        if (direction == LEFT)
            position -= right * velocity;
        if (direction == RIGHT)
            position += right * velocity;
    }

    // processes input received from a mouse input system. Expects the offset value in both the x and y direction.
    void processMouseMovement(float xoffset, float yoffset, GLboolean constrainPitch = true)
    {
        xoffset *= mouseSensitivity;
        yoffset *= mouseSensitivity;

        yaw   += xoffset;
        pitch += yoffset;

        // make sure that when pitch is out of bounds, screen doesn't get flipped
        if (constrainPitch)
        {
            if (pitch > 89.0f)
                pitch = 89.0f;

            if (pitch < -89.0f)
                pitch = -89.0f;
        }

        // update Front, Right and Up Vectors using the updated Euler angles
        updateCameraVectors();
    }

    // processes input received from a mouse scroll-wheel event. Only requires input on the vertical wheel-axis
    void processMouseScroll(float yoffset)
    {
        zoom -= (float)yoffset;
        if (zoom < 1.0f)
            zoom = 1.0f;
        if (zoom > 45.0f)
            zoom = 45.0f;
    }


private:
    // calculates the front vector from the Camera's (updated) Euler Angles
    void updateCameraVectors()
    {
        // calculate the new Front vector
        glm::vec3 newFront;
        newFront.x = cos(glm::radians(yaw)) * cos(glm::radians(pitch));
        newFront.y = sin(glm::radians(pitch));
        newFront.z = sin(glm::radians(yaw)) * cos(glm::radians(pitch));
        front = glm::normalize(newFront);

        // also re-calculate the Right and Up vector
        right = glm::normalize(glm::cross(front, worldUp));  // normalize the vectors, because their length gets closer to 0 the more you look up or down which results in slower movement.
        up    = glm::normalize(glm::cross(right, front));
    }
};

#endif