#include "camera.h"

#include <glm/gtc/quaternion.hpp>

namespace Donut
{
    Camera::Camera(float fov, float aspect_ratio, float near_plane, float far_plane)
        : m_fov(fov), m_aspect_ratio(aspect_ratio), m_near_plane(near_plane), m_far_plane(far_plane)
    {
        recalculate_projection_matrix();
        recalculate_view_matrix();
    }

    void Camera::set_projection(float fov, float aspect_ratio, float near_plane, float far_plane)
    {
        m_fov = fov;
        m_aspect_ratio = aspect_ratio;
        m_near_plane = near_plane;
        m_far_plane = far_plane;
        recalculate_projection_matrix();
    }

    void Camera::recalculate_projection_matrix()
    {
        m_projection_matrix = glm::perspective(glm::radians(m_fov), m_aspect_ratio, m_near_plane, m_far_plane);
        m_view_projection_matrix = m_projection_matrix * m_view_matrix;
    }

    void Camera::recalculate_view_matrix()
    {
        float pitch = glm::radians(m_rotation.x);
        float yaw   = glm::radians(m_rotation.y);
        float roll  = glm::radians(m_rotation.z);

        glm::vec3 direction;
        direction.x = cos(yaw) * cos(pitch);
        direction.y = sin(pitch);
        direction.z = sin(yaw) * cos(pitch);

        glm::vec3 world_up(0.0f, 1.0f, 0.0f);
        glm::vec3 front = glm::normalize(direction);
        glm::vec3 right = glm::normalize(glm::cross(front, world_up));
        glm::vec3 up    = glm::normalize(glm::cross(right, front));

        m_view_matrix           = glm::lookAt(m_position, m_position + front, up);
        m_view_projection_matrix = m_projection_matrix * m_view_matrix;
    }

    glm::vec3 Camera::get_forward_direction() const
    {
        float pitch = glm::radians(m_rotation.x);
        float yaw   = glm::radians(m_rotation.y);

        glm::vec3 direction;
        direction.x = cos(yaw) * cos(pitch);
        direction.y = sin(pitch);
        direction.z = sin(yaw) * cos(pitch);

        return glm::normalize(direction);
    }

    glm::vec3 Camera::get_right_direction() const
    {
        glm::vec3 world_up(0.0f, 1.0f, 0.0f);
        return glm::normalize(glm::cross(get_forward_direction(), world_up));
    }

    glm::vec3 Camera::get_up_direction() const
    {
        return glm::normalize(glm::cross(get_right_direction(), get_forward_direction()));
    }

    void Camera::on_mouse_move(float x_offset, float y_offset, bool constrain_pitch)
    {
        x_offset *= m_mouse_sensitivity;
        y_offset *= m_mouse_sensitivity;

        m_rotation.y += x_offset;
        m_rotation.x += y_offset;

        if (constrain_pitch)
        {
            if (m_rotation.x > 89.0f)
                m_rotation.x = 89.0f;
            if (m_rotation.x < -89.0f)
                m_rotation.x = -89.0f;
        }

        recalculate_view_matrix();
    }

    void Camera::move_forward(float delta_time)
    {
        m_position += get_forward_direction() * m_movement_speed * delta_time;
        recalculate_view_matrix();
    }

    void Camera::move_backward(float delta_time)
    {
        m_position -= get_forward_direction() * m_movement_speed * delta_time;
        recalculate_view_matrix();
    }

    void Camera::move_right(float delta_time)
    {
        m_position += get_right_direction() * m_movement_speed * delta_time;
        recalculate_view_matrix();
    }

    void Camera::move_left(float delta_time)
    {
        m_position -= get_right_direction() * m_movement_speed * delta_time;
        recalculate_view_matrix();
    }

    void Camera::move_up(float delta_time)
    {
        glm::vec3 world_up(0.0f, 1.0f, 0.0f);
        m_position += world_up * m_movement_speed * delta_time;
        recalculate_view_matrix();
    }

    void Camera::move_down(float delta_time)
    {
        glm::vec3 world_up(0.0f, 1.0f, 0.0f);
        m_position -= world_up * m_movement_speed * delta_time;
        recalculate_view_matrix();
    }
}