#include "camera.h"
static void cameraUpdateVectors(struct Camera *camera);

Mat4
cameraGetViewMatrix(struct Camera camera)
{
    Vec3 target = linearVec3Add(camera.position, camera.front);
    return linearLookAt(camera.position, target, camera.up);
}

void
cameraProcessKeyboard(
    struct Camera *camera,
    enum CameraMovement direction,
    float deltaTime)
{
    float speed = camera->movementSpeed * deltaTime;
    Vec3 tmp;

    switch (direction) {
        case CAMDIR_FORWARD:
            // pos = pos + front * speed
            tmp = linearVec3ScalarMulp(camera->front, speed);
            camera->position = linearVec3Add(camera->position, tmp);
            break;

        case CAMDIR_BACKWARD:
            // pos = pos + front * (-speed)
            tmp = linearVec3ScalarMulp(camera->front, -speed);
            camera->position = linearVec3Add(camera->position, tmp);
            break;

        case CAMDIR_LEFT:
            // pos = pos + unit|(up x front)| * (speed)
            tmp = linearVec3CrossProduct(camera->front, camera->up);
            tmp = linearVec3Normalize(tmp);
            tmp = linearVec3ScalarMulp(tmp, -speed);
            camera->position = linearVec3Add(camera->position, tmp);
            break;

        case CAMDIR_RIGHT:
            // pos = pos + unit|(up x front)| * (-speed)
            tmp = linearVec3CrossProduct(camera->front, camera->up);
            tmp = linearVec3Normalize(tmp);
            tmp = linearVec3ScalarMulp(tmp, speed);
            camera->position = linearVec3Add(camera->position, tmp);
            break;

        default:
            break;
    }
}

void
cameraProcessMouseMovement(struct Camera *camera, float xoffset, float yoffset)
{
    camera->yaw += camera->mouseSensivity * xoffset;
    camera->pitch += camera->mouseSensivity * yoffset;

    if (camera->pitch > 89.0f)
        camera->pitch = 89.0f;
    else if (camera->pitch < -89.0f)
        camera->pitch = - 89.0f;
    cameraUpdateVectors(camera);
}

void
cameraUpdateVectors(struct Camera *camera)
{
    Vec3 tmp;
    float rpitch = M_PI / 180 * camera->pitch;
    float ryaw = M_PI / 180 * camera->yaw;

    tmp = linearVec3(
            cosf(ryaw) * cosf(-rpitch),
            sinf(-rpitch),
            sinf(ryaw) * cosf(-rpitch));
    camera->front = linearVec3Normalize(tmp);

}