/**
 * Graphic instance for rendering face position, orientation, and landmarks within an associated
 * graphic overlay view.
 */
public class FaceGraphic extends Graphic {
  private static final float FACE_POSITION_RADIUS = 10.0f;
  private static final float ID_TEXT_SIZE = 40.0f;
  private static final float ID_Y_OFFSET = 50.0f;
  private static final float ID_X_OFFSET = -50.0f;
  private static final float BOX_STROKE_WIDTH = 5.0f;

  private static final int[] COLOR_CHOICES = {
    Color.BLUE, Color.CYAN, Color.GREEN, Color.MAGENTA, Color.RED, Color.WHITE, Color.YELLOW
  };
  private static int currentColorIndex = 0;

  private int facing;

  private final Paint facePositionPaint;
  private final Paint idPaint;
  private final Paint boxPaint;

  private volatile FirebaseVisionFace firebaseVisionFace;

  public FaceGraphic(GraphicOverlay overlay) {
    super(overlay);

    currentColorIndex = (currentColorIndex + 1) % COLOR_CHOICES.length;
    final int selectedColor = COLOR_CHOICES[currentColorIndex];

    facePositionPaint = new Paint();
    facePositionPaint.setColor(selectedColor);

    idPaint = new Paint();
    idPaint.setColor(selectedColor);
    idPaint.setTextSize(ID_TEXT_SIZE);

    boxPaint = new Paint();
    boxPaint.setColor(selectedColor);
    boxPaint.setStyle(Paint.Style.STROKE);
    boxPaint.setStrokeWidth(BOX_STROKE_WIDTH);
  }

  /**
   * Updates the face instance from the detection of the most recent frame. Invalidates the relevant
   * portions of the overlay to trigger a redraw.
   */
  public void updateFace(FirebaseVisionFace face, int facing) {
    firebaseVisionFace = face;
    this.facing = facing;
    postInvalidate();
  }

  /** Draws the face annotations for position on the supplied canvas. */
  @Override
  public void draw(Canvas canvas) {
    FirebaseVisionFace face = firebaseVisionFace;
    if (face == null) {
      return;
    }

    // Draws a circle at the position of the detected face, with the face's track id below.
    float x = translateX(face.getBoundingBox().centerX());
    float y = translateY(face.getBoundingBox().centerY());
    canvas.drawCircle(x, y, FACE_POSITION_RADIUS, facePositionPaint);
    canvas.drawText("id: " + face.getTrackingId(), x + ID_X_OFFSET, y + ID_Y_OFFSET, idPaint);
    canvas.drawText(
        "happiness: " + String.format("%.2f", face.getSmilingProbability()),
        x + ID_X_OFFSET * 3,
        y - ID_Y_OFFSET,
        idPaint);
    if (facing == CameraSource.CAMERA_FACING_FRONT) {
      canvas.drawText(
          "right eye: " + String.format("%.2f", face.getRightEyeOpenProbability()),
          x - ID_X_OFFSET,
          y,
          idPaint);
      canvas.drawText(
          "left eye: " + String.format("%.2f", face.getLeftEyeOpenProbability()),
          x + ID_X_OFFSET * 6,
          y,
          idPaint);
    } else {
      canvas.drawText(
          "left eye: " + String.format("%.2f", face.getLeftEyeOpenProbability()),
          x - ID_X_OFFSET,
          y,
          idPaint);
      canvas.drawText(
          "right eye: " + String.format("%.2f", face.getRightEyeOpenProbability()),
          x + ID_X_OFFSET * 6,
          y,
          idPaint);
    }

    // Draws a bounding box around the face.
    float xOffset = scaleX(face.getBoundingBox().width() / 2.0f);
    float yOffset = scaleY(face.getBoundingBox().height() / 2.0f);
    float left = x - xOffset;
    float top = y - yOffset;
    float right = x + xOffset;
    float bottom = y + yOffset;
    canvas.drawRect(left, top, right, bottom, boxPaint);

    // draw landmarks
    drawLandmarkPosition(canvas, face, FirebaseVisionFaceLandmark.BOTTOM_MOUTH);
    drawLandmarkPosition(canvas, face, FirebaseVisionFaceLandmark.LEFT_CHEEK);
    drawLandmarkPosition(canvas, face, FirebaseVisionFaceLandmark.LEFT_EAR);
    drawLandmarkPosition(canvas, face, FirebaseVisionFaceLandmark.LEFT_MOUTH);
    drawLandmarkPosition(canvas, face, FirebaseVisionFaceLandmark.LEFT_EYE);
    drawLandmarkPosition(canvas, face, FirebaseVisionFaceLandmark.NOSE_BASE);
    drawLandmarkPosition(canvas, face, FirebaseVisionFaceLandmark.RIGHT_CHEEK);
    drawLandmarkPosition(canvas, face, FirebaseVisionFaceLandmark.RIGHT_EAR);
    drawLandmarkPosition(canvas, face, FirebaseVisionFaceLandmark.RIGHT_EYE);
    drawLandmarkPosition(canvas, face, FirebaseVisionFaceLandmark.RIGHT_MOUTH);
  }

  private void drawLandmarkPosition(Canvas canvas, FirebaseVisionFace face, int landmarkID) {
    FirebaseVisionFaceLandmark landmark = face.getLandmark(landmarkID);
    if (landmark != null) {
      FirebaseVisionPoint point = landmark.getPosition();
      canvas.drawCircle(
              translateX(point.getX()),
              translateY(point.getY()),
              10f, idPaint);
    }
  }
}