/** 3d scene camera */

module re.ng.camera.cam3d;

import re.ecs;
import re.time;
import re.math;
import re.gfx.raytypes;
import re.ng.camera.base;
import std.math;
static import raylib;

/// represents a camera for a 3D scene
class SceneCamera3D : SceneCamera {
    mixin Reflect;
    private raylib.Camera3D _camera;
    private ProjectionType _projection;

    /// the projection used for the camera
    public enum ProjectionType {
        Perspective,
        Orthographic
    }

    this() {
        _camera = raylib.Camera3D();
        // default settings
        up = Vector3(0, 1, 0); // unit vector y+
        fov = C_PI_4; // 45 deg
        projection = ProjectionType.Perspective;
    }

    /// gets the underlying camera object (used internally)
    @property ref raylib.Camera3D camera() return  {
        return _camera;
    }

    /// gets the projection type
    @property ProjectionType projection() {
        return _projection;
    }

    /// sets the projection type
    @property ProjectionType projection(ProjectionType value) {
        _projection = value;
        switch (_projection) {
        case ProjectionType.Perspective:
            _camera.projection = raylib.CameraProjection.CAMERA_PERSPECTIVE;
            break;
        case ProjectionType.Orthographic:
            _camera.projection = raylib.CameraProjection.CAMERA_ORTHOGRAPHIC;
            break;
        default:
            assert(0);
        }
        return value;
    }

    /// gets the Y-field-of-view in radians
    @property float fov() {
        return _camera.fovy * C_DEG2RAD;
    }

    /// sets the Y-field-of-view in radians
    @property float fov(float value) {
        return _camera.fovy = value * C_RAD2DEG;
    }

    /// gets the direction that is up relative to this camera
    @property Vector3 up() {
        return _camera.up;
    }

    /// sets the direction that is up relative to this camera
    @property Vector3 up(Vector3 value) {
        return _camera.up = value;
    }

    override void update() {
        super.update();

        // copy entity to camera transform
        _camera.position = entity.transform.position;

        // import std.stdio : writefln;
        // writefln("cam pos: %s", _camera.position);

        // update raylib camera
        raylib.UpdateCamera(&_camera);
    }

    /// orient the camera in the direction of a point
    public void look_at(Vector3 target) {
        _camera.target = target;
    }

    /// orient the camera in the direction of an entity
    public void look_at(Entity entity) {
        look_at(entity.position);
    }
}

abstract class CameraFollow3D : Component, Updatable {
    mixin Reflect;
    protected SceneCamera3D cam;
    /// the target entity
    public Entity target;
    public Vector3 target_offset;
    protected enum third_person_dist = 1.2f;
    protected Vector2 _angle; // xz plane camera angle
    protected float _target_dist;

    this(Entity target, Vector3 target_offset = Vector3.zero) {
        this.target = target;
        this.target_offset = target_offset;
    }

    override void setup() {
        cam = entity.get_component!SceneCamera3D();
        // cam.look_at(target); // start by looking at the target
        auto look_target = target.position + target_offset;
        cam.look_at(look_target); // start by looking at the target

        // distance between look target and camera entity position
        auto to_target = look_target - entity.position;

        _target_dist = raymath.Vector3Length(to_target);
        _angle = Vector2(atan2(to_target.x, to_target.z), // Camera angle in plane XZ (0 aligned with Z, move positive CCW)
                atan2(to_target.y,
                    sqrt(to_target.x * to_target.x + to_target.z * to_target.z))); // // Camera angle in plane XY (0 aligned with X, move positive CW)
    }
}

/// controls a camera by making it orbit an entity
class CameraOrbit : CameraFollow3D {
    mixin Reflect;
    /// the orbit speed, in radians per second
    public float speed;
    public bool pause = false;

    this(Entity target, float speed) {
        super(target);
        this.speed = speed;
    }

    public void set_xz_angle(float val) {
        _angle.x = val;
    }

    /// based on https://github.com/raysan5/raylib/blob/6fa6757a8bf90d4b2fd0ce82dace7c7223635efa/src/camera.h#L400
    void update() {
        if (!pause) {
            _angle.x += speed * Time.delta_time; // camera xz orbit angle
        }

        // camera distance clamp
        if (_target_dist < third_person_dist)
            _target_dist = third_person_dist;

        // update camera position with changes
        auto npos_x = sin(_angle.x) * _target_dist * cos(_angle.y) + target.position.x;
        auto npos_y = ((_angle.y <= 0.0f) ? 1 : -1) * sin(
                _angle.y) * _target_dist * sin(_angle.y) + target.position.y;
        auto npos_z = cos(_angle.x) * _target_dist * cos(_angle.y) + target.position.z;
        entity.position = Vector3(npos_x, npos_y, npos_z);
    }
}

/// third person look camera
class CameraThirdPerson : CameraFollow3D {
    import re.input : Keys, Input;

    mixin Reflect;
    public float move_sensitivity = 20;
    public float look_sensitivity = 0.003;
    protected enum third_person_min_clamp = 5;
    protected enum third_person_max_clamp = -85;

    this(Entity target) {
        super(target);
    }

    // based on https://github.com/raysan5/raylib/blob/6fa6757a8bf90d4b2fd0ce82dace7c7223635efa/src/camera.h#L458
    void update() {
        // bool direction[6] = {
        //     IsKeyDown(CAMERA.moveControl[MOVE_FRONT]), IsKeyDown(CAMERA.moveControl[MOVE_BACK]),
        //         IsKeyDown(CAMERA.moveControl[MOVE_RIGHT]), IsKeyDown(CAMERA.moveControl[MOVE_LEFT]),
        //         IsKeyDown(CAMERA.moveControl[MOVE_UP]), IsKeyDown(CAMERA.moveControl[MOVE_DOWN])
        // };
        // bool[6] direction = [false, false, false, false, false, false];
        // bool[6] direction = [
        //     Input.is_key_down(Keys.KEY_W), Input.is_key_down(Keys.KEY_S),
        //     Input.is_key_down(Keys.KEY_D), Input.is_key_down(Keys.KEY_A),
        //     Input.is_key_down(Keys.KEY_E), Input.is_key_down(Keys.KEY_Q)
        // ];
        // enum MOVE_FRONT = 0;
        // enum MOVE_BACK = 1;
        // enum MOVE_RIGHT = 2;
        // enum MOVE_LEFT = 3;
        // enum MOVE_UP = 4;
        // enum MOVE_DOWN = 5;

        // auto dpos_x = (sin(_angle.x) * direction[MOVE_BACK] - sin(
        //         _angle.x) * direction[MOVE_FRONT] - cos(
        //         _angle.x) * direction[MOVE_LEFT] + cos(_angle.x) * direction[MOVE_RIGHT]) / move_sensitivity;
        // auto npos_x = transform.position.x + dpos_x;

        // auto dpos_y = (sin(_angle.y) * direction[MOVE_FRONT] - sin(
        //         _angle.y) * direction[MOVE_BACK] + 1.0f * direction[MOVE_UP]
        //         - 1.0f * direction[MOVE_DOWN]) / move_sensitivity;
        // auto npos_y = transform.position.y + dpos_y;

        // auto dpos_z = (cos(_angle.x) * direction[MOVE_BACK] - cos(
        //         _angle.x) * direction[MOVE_FRONT] + sin(
        //         _angle.x) * direction[MOVE_LEFT] - sin(_angle.x) * direction[MOVE_RIGHT]) / move_sensitivity;
        // auto npos_z = transform.position.z + dpos_z;

        // transform.position = Vector3(npos_x, npos_y, npos_z);

        auto npos_x = transform.position.x;
        auto npos_y = transform.position.y;
        auto npos_z = transform.position.z;

        // CAMDATA orientation calculation
        _angle.x = _angle.x + (Input.mouse_delta.x * -look_sensitivity);
        _angle.y = _angle.y + (Input.mouse_delta.y * -look_sensitivity);

        // Angle clamp
        if (_angle.y > third_person_min_clamp * C_DEG2RAD)
            _angle.y = third_person_min_clamp * C_DEG2RAD;
        else if (_angle.y < third_person_max_clamp * C_DEG2RAD)
            _angle.y = third_person_max_clamp * C_DEG2RAD;

        // CAMDATA zoom
        // _target_dist -= (wheel_delta * CAMERA_MOUSE_SCROLL_SENSITIVITY);

        // CAMDATA distance clamp
        if (_target_dist < third_person_dist)
            _target_dist = third_person_dist;

        // TODO: It seems CAMDATA.position is not correctly updated or some rounding issue makes the CAMDATA move straight to target.transform.position...
        npos_x = sin(_angle.x) * _target_dist * cos(_angle.y) + target.transform.position.x;

        if (_angle.y <= 0.0f)
            npos_y = sin(_angle.y) * _target_dist * sin(_angle.y) + target.transform.position.y;
        else
            npos_y = -sin(_angle.y) * _target_dist * sin(_angle.y) + target.transform.position.y;

        npos_z = cos(_angle.x) * _target_dist * cos(_angle.y) + target.transform.position.z;

        transform.position = Vector3(npos_x, npos_y, npos_z);
    }
}

/// free-look camera
class CameraFreeLook : CameraFollow3D {
    import re.input : Keys, MouseButton, Input;

    mixin Reflect;
    // public float move_sensitivity = ;
    public float look_sensitivity = 0.003;
    public float zoom_sensitivity = 0.9;
    public float smooth_zoom_sensitivity = 0.05;
    protected enum free_min_clamp = 85;
    protected enum free_max_clamp = -85;
    protected enum free_dist_min_clamp = 0.3;
    protected enum free_dist_max_clamp = 120;
    protected enum free_pan_divider = 5.1;

    this(Entity target) {
        super(target);
    }

    // based on https://github.com/raysan5/raylib/blob/6fa6757a8bf90d4b2fd0ce82dace7c7223635efa/src/camera.h#L314
    void update() {
        auto npos_x = transform.position.x;
        auto npos_y = transform.position.y;
        auto npos_z = transform.position.z;

        auto wheel_delta = Input.scroll_delta();
        auto mouse_delta = Input.mouse_delta;

        auto key_pan = Input.is_mouse_down(MouseButton.MOUSE_BUTTON_RIGHT)
            || Input.is_key_down(Keys.KEY_LEFT_ALT);
        auto key_alternate = !Input.is_key_down(Keys.KEY_LEFT_SHIFT);
        auto key_smooth = Input.is_key_down(Keys.KEY_LEFT_CONTROL);

        auto tpos_x = cam.camera.target.x;
        auto tpos_y = cam.camera.target.y;
        auto tpos_z = cam.camera.target.z;

        // Camera zoom
        if ((_target_dist < free_dist_max_clamp) && (wheel_delta < 0)) {
            _target_dist -= (wheel_delta * zoom_sensitivity);
            if (_target_dist > free_dist_max_clamp)
                _target_dist = free_dist_max_clamp;
        }  // Camera looking down
        else if ((entity.position.y > tpos_y)
                && (_target_dist == free_dist_max_clamp) && (wheel_delta < 0)) {
            tpos_x += wheel_delta * (tpos_x - entity.position.x) * zoom_sensitivity / _target_dist;
            tpos_y += wheel_delta * (tpos_y - entity.position.y) * zoom_sensitivity / _target_dist;
            tpos_z += wheel_delta * (tpos_z - entity.position.z) * zoom_sensitivity / _target_dist;
        } else if ((entity.position.y > tpos_y) && (tpos_y >= 0)) {
            tpos_x += wheel_delta * (tpos_x - entity.position.x) * zoom_sensitivity / _target_dist;
            tpos_y += wheel_delta * (tpos_y - entity.position.y) * zoom_sensitivity / _target_dist;
            tpos_z += wheel_delta * (tpos_z - entity.position.z) * zoom_sensitivity / _target_dist;

            // if (tpos_y < 0) tpos_y = -0.001;
        } else if ((entity.position.y > tpos_y) && (tpos_y < 0) && (wheel_delta > 0)) {
            _target_dist -= (wheel_delta * zoom_sensitivity);
            if (_target_dist < free_dist_min_clamp)
                _target_dist = free_dist_min_clamp;
        }  // Camera looking up
        else if ((entity.position.y < tpos_y)
                && (_target_dist == free_dist_max_clamp) && (wheel_delta < 0)) {
            tpos_x += wheel_delta * (tpos_x - entity.position.x) * zoom_sensitivity / _target_dist;
            tpos_y += wheel_delta * (tpos_y - entity.position.y) * zoom_sensitivity / _target_dist;
            tpos_z += wheel_delta * (tpos_z - entity.position.z) * zoom_sensitivity / _target_dist;
        } else if ((entity.position.y < tpos_y) && (tpos_y <= 0)) {
            tpos_x += wheel_delta * (tpos_x - entity.position.x) * zoom_sensitivity / _target_dist;
            tpos_y += wheel_delta * (tpos_y - entity.position.y) * zoom_sensitivity / _target_dist;
            tpos_z += wheel_delta * (tpos_z - entity.position.z) * zoom_sensitivity / _target_dist;

            // if (tpos_y > 0) tpos_y = 0.001;
        } else if ((entity.position.y < tpos_y) && (tpos_y > 0) && (wheel_delta > 0)) {
            _target_dist -= (wheel_delta * zoom_sensitivity);
            if (_target_dist < free_dist_min_clamp)
                _target_dist = free_dist_min_clamp;
        }

        // Input keys checks
        if (key_pan) {
            if (key_alternate) // Alternative key behaviour
            {
                if (key_smooth) {
                    // Camera smooth zoom
                    _target_dist += (mouse_delta.y * smooth_zoom_sensitivity);
                } else {
                    // Camera rotation
                    _angle.x += mouse_delta.x * -look_sensitivity;
                    _angle.y += mouse_delta.y * -look_sensitivity;

                    // Angle clamp
                    if (_angle.y > free_min_clamp * C_DEG2RAD)
                        _angle.y = free_min_clamp * C_DEG2RAD;
                    else if (_angle.y < free_max_clamp * C_DEG2RAD)
                        _angle.y = free_max_clamp * C_DEG2RAD;
                }
            } else {
                // Camera panning
                tpos_x += ((mouse_delta.x * look_sensitivity) * cos(_angle.x) + (
                        mouse_delta.y * look_sensitivity) * sin(_angle.x) * sin(_angle.y)) * (
                        _target_dist / free_pan_divider);
                tpos_y += ((mouse_delta.y * look_sensitivity) * cos(_angle.y)) * (
                        _target_dist / free_pan_divider);
                tpos_z += ((mouse_delta.x * -look_sensitivity) * sin(_angle.x) + (
                        mouse_delta.y * look_sensitivity) * cos(_angle.x) * sin(_angle.y)) * (
                        _target_dist / free_pan_divider);
            }
        }

        // Update camera position with changes
        npos_x = -sin(_angle.x) * _target_dist * cos(_angle.y) + tpos_x;
        npos_y = -sin(_angle.y) * _target_dist + tpos_y;
        npos_z = -cos(_angle.x) * _target_dist * cos(_angle.y) + tpos_z;

        transform.position = Vector3(npos_x, npos_y, npos_z);
        cam.camera.target = Vector3(tpos_x, tpos_y, tpos_z);
    }
}