/*
 * Copyright 2020 Google LLC. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.nixsensor.nixexample.util.mlkit;

import android.content.Context;
import android.content.res.Configuration;
import android.util.AttributeSet;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.ViewGroup;

import com.google.android.gms.common.images.Size;

import java.io.IOException;

/** Preview the camera image in the screen. */
public class CameraSourcePreview extends ViewGroup {
    private static final String TAG = "MIDemoApp:Preview";

    private final Context context;
    private final SurfaceView surfaceView;
    private boolean startRequested;
    private boolean surfaceAvailable;
    private CameraSource cameraSource;

    private GraphicOverlay overlay;

    public CameraSourcePreview(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        startRequested = false;
        surfaceAvailable = false;

        surfaceView = new SurfaceView(context);
        surfaceView.getHolder().addCallback(new SurfaceCallback());
        addView(surfaceView);
    }

    private void start(CameraSource cameraSource) throws IOException {
        this.cameraSource = cameraSource;

        if (this.cameraSource != null) {
            startRequested = true;
            startIfReady();
        }
    }

    public void start(CameraSource cameraSource, GraphicOverlay overlay) throws IOException {
        this.overlay = overlay;
        start(cameraSource);
    }

    public void stop() {
        if (cameraSource != null) {
            cameraSource.stop();
        }
    }

    public void release() {
        if (cameraSource != null) {
            cameraSource.release();
            cameraSource = null;
        }
        surfaceView.getHolder().getSurface().release();
    }

    private void startIfReady() throws IOException, SecurityException {
        if (startRequested && surfaceAvailable) {
            cameraSource.start(surfaceView.getHolder());
            requestLayout();

            if (overlay != null) {
                Size size = cameraSource.getPreviewSize();
                int min = Math.min(size.getWidth(), size.getHeight());
                int max = Math.max(size.getWidth(), size.getHeight());
                boolean isImageFlipped = cameraSource.getCameraFacing() == CameraSource.CAMERA_FACING_FRONT;
                if (isPortraitMode()) {
                    // Swap width and height sizes when in portrait, since it will be rotated by 90 degrees.
                    // The camera preview and the image being processed have the same size.
                    overlay.setImageSourceInfo(min, max, isImageFlipped);
                } else {
                    overlay.setImageSourceInfo(max, min, isImageFlipped);
                }
                overlay.clear();
            }
            startRequested = false;
        }
    }

    private class SurfaceCallback implements SurfaceHolder.Callback {
        @Override
        public void surfaceCreated(SurfaceHolder surface) {
            surfaceAvailable = true;
            try {
                startIfReady();
            } catch (IOException e) {
                Log.e(TAG, "Could not start camera source.", e);
            }
        }

        @Override
        public void surfaceDestroyed(SurfaceHolder surface) {
            surfaceAvailable = false;
        }

        @Override
        public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        int width = 320;
        int height = 240;
        if (cameraSource != null) {
            Size size = cameraSource.getPreviewSize();
            if (size != null) {
                width = size.getWidth();
                height = size.getHeight();
            }
        }

        // Swap width and height sizes when in portrait, since it will be rotated 90 degrees
        if (isPortraitMode()) {
            int tmp = width;
            width = height;
            height = tmp;
        }

        float previewAspectRatio = (float) width / height;
        int layoutWidth = right - left;
        int layoutHeight = bottom - top;
        float layoutAspectRatio = (float) layoutWidth / layoutHeight;
        if (previewAspectRatio > layoutAspectRatio) {
            // The preview input is wider than the layout area. Fit the layout height and crop
            // the preview input horizontally while keep the center.
            int horizontalOffset = (int) (previewAspectRatio * layoutHeight - layoutWidth) / 2;
            surfaceView.layout(-horizontalOffset, 0, layoutWidth + horizontalOffset, layoutHeight);
        } else {
            // The preview input is taller than the layout area. Fit the layout width and crop the preview
            // input vertically while keep the center.
            int verticalOffset = (int) (layoutWidth / previewAspectRatio - layoutHeight) / 2;
            surfaceView.layout(0, -verticalOffset, layoutWidth, layoutHeight + verticalOffset);
        }
    }

    private boolean isPortraitMode() {
        int orientation = context.getResources().getConfiguration().orientation;
        if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
            return false;
        }
        if (orientation == Configuration.ORIENTATION_PORTRAIT) {
            return true;
        }

        Log.d(TAG, "isPortraitMode returning false by default");
        return false;
    }
}