// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package io.flutter.plugins.camera.features.focuspoint;

import android.hardware.camera2.CaptureRequest;
import android.hardware.camera2.params.MeteringRectangle;
import android.util.Size;
import androidx.annotation.NonNull;
import io.flutter.plugins.camera.CameraProperties;
import io.flutter.plugins.camera.CameraRegionUtils;
import io.flutter.plugins.camera.features.CameraFeature;
import io.flutter.plugins.camera.features.Point;

/** Focus point controls where in the frame focus will come from. */
public class FocusPointFeature extends CameraFeature<Point> {

  private Size cameraBoundaries;
  private Point focusPoint;
  private MeteringRectangle focusRectangle;

  /**
   * Creates a new instance of the {@link FocusPointFeature}.
   *
   * @param cameraProperties Collection of the characteristics for the current camera device.
   */
  public FocusPointFeature(CameraProperties cameraProperties) {
    super(cameraProperties);
  }

  /**
   * Sets the camera boundaries that are required for the focus point feature to function.
   *
   * @param cameraBoundaries - The camera boundaries to set.
   */
  public void setCameraBoundaries(@NonNull Size cameraBoundaries) {
    this.cameraBoundaries = cameraBoundaries;
    this.buildFocusRectangle();
  }

  @Override
  public String getDebugName() {
    return "FocusPointFeature";
  }

  @Override
  public Point getValue() {
    return focusPoint;
  }

  @Override
  public void setValue(Point value) {
    this.focusPoint = value == null || value.x == null || value.y == null ? null : value;
    this.buildFocusRectangle();
  }

  // Whether or not this camera can set the focus point.
  @Override
  public boolean checkIsSupported() {
    Integer supportedRegions = cameraProperties.getControlMaxRegionsAutoFocus();
    return supportedRegions != null && supportedRegions > 0;
  }

  @Override
  public void updateBuilder(CaptureRequest.Builder requestBuilder) {
    if (!checkIsSupported()) {
      return;
    }
    requestBuilder.set(
        CaptureRequest.CONTROL_AF_REGIONS,
        focusRectangle == null ? null : new MeteringRectangle[] {focusRectangle});
  }

  private void buildFocusRectangle() {
    if (this.cameraBoundaries == null) {
      throw new AssertionError(
          "The cameraBoundaries should be set (using `FocusPointFeature.setCameraBoundaries(Size)`) before updating the focus point.");
    }
    if (this.focusPoint == null) {
      this.focusRectangle = null;
    } else {
      this.focusRectangle =
          CameraRegionUtils.convertPointToMeteringRectangle(
              this.cameraBoundaries, this.focusPoint.x, this.focusPoint.y);
    }
  }
}