#include "render/camera.h"

#define PITCH_LIMIT 89.0f

static void updateVectors(Camera *cam) {
    float yaw = deg2rad(cam->yaw), pitch = deg2rad(cam->pitch);
    cam->front = vec3_normalize(vec3(cosf(yaw) * cosf(pitch),
                                     sinf(pitch),
                                     sinf(yaw) * cosf(pitch)));
    cam->right = vec3_normalize(vec3_cross(cam->front, vec3(0, 1, 0)));
    cam->up    = vec3_normalize(vec3_cross(cam->right, cam->front));
}

void Camera_init(Camera *cam, Vec3 position, float yaw, float pitch, float fov) {
    *cam = (Camera){
        .position = position,
        .yaw      = yaw,
        .pitch    = pitch,
        .fov      = fov,
        .near_z   = 0.1f,
        .far_z    = 420.0f, /* across the whole site */
    };
    updateVectors(cam);
    Camera_updateMatrices(cam, 1.0f);
}

void Camera_rotate(Camera *cam, float yaw_delta, float pitch_delta) {
    cam->yaw   += yaw_delta;
    cam->pitch += pitch_delta;
    if (cam->pitch >  PITCH_LIMIT) cam->pitch =  PITCH_LIMIT;
    if (cam->pitch < -PITCH_LIMIT) cam->pitch = -PITCH_LIMIT;
    updateVectors(cam);
}

void Camera_updateMatrices(Camera *cam, float aspect) {
    cam->projection = mat4_perspective(cam->fov, aspect, cam->near_z, cam->far_z);

    /* Sway and roll only change what we see, not where we walk */
    float yaw   = deg2rad(cam->yaw + cam->sway_yaw);
    float pitch = deg2rad(clampf(cam->pitch + cam->sway_pitch, -PITCH_LIMIT, PITCH_LIMIT));
    Vec3 front = vec3(cosf(yaw) * cosf(pitch), sinf(pitch), sinf(yaw) * cosf(pitch));
    Vec3 right = vec3_normalize(vec3_cross(front, vec3(0, 1, 0)));
    Vec3 up    = vec3_cross(right, front);
    float roll = deg2rad(cam->roll);
    up = vec3_add(vec3_scale(up, cosf(roll)), vec3_scale(right, sinf(roll)));
    cam->view = mat4_look_at(cam->position, vec3_add(cam->position, front), up);
}