/* 
 * Copyright (C) 2008 ZXing authors
 * Copyright 2011 Robert Theis
 * Copyright 2015 Jakub Kříž
 *
 * 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 cz.muni.fi.digitrecognition;

import android.content.Context;
import android.content.SharedPreferences;
import android.graphics.Point;
import android.graphics.Rect;
import android.hardware.Camera;
import android.os.Handler;
import android.preference.PreferenceManager;
import android.view.SurfaceHolder;

import java.io.IOException;

/**
 * This object wraps the Camera service object and expects to be the only one talking to it. The
 * implementation encapsulates the steps needed to take preview-sized images, which are used for
 * both preview and decoding.
 *
 * The code for this class was adapted from the ZXing project: http://code.google.com/p/zxing
 */
public final class CameraManager {

  private static final String TAG = CameraManager.class.getSimpleName();
  
  private static final int MIN_FRAME_WIDTH = 50; // originally 240
  private static final int MIN_FRAME_HEIGHT = 120; // originally 240
  private static final int MAX_FRAME_WIDTH = 800; // originally 480
  private static final int MAX_FRAME_HEIGHT = 600; // originally 360
  
  private final Context context;
  private final CameraConfigurationManager configManager;
  private Camera camera;
  private AutoFocusManager autoFocusManager;
  private Rect framingRect;
  private Rect framingRectInPreview;
  private boolean initialized;
  private boolean previewing;
  private boolean reverseImage;
  private int requestedFramingRectWidth;
  private int requestedFramingRectHeight;
  /**
   * Preview frames are delivered here, which we pass on to the registered handler. Make sure to
   * clear the handler so it will only receive one message.
   */
  private final PreviewCallback previewCallback;

  public CameraManager(Context context) {
    this.context = context;
    this.configManager = new CameraConfigurationManager(context);
    previewCallback = new PreviewCallback(configManager);
  }

  /**
   * Opens the camera driver and initializes the hardware parameters.
   *
   * @param holder The surface object which the camera will draw preview frames into.
   * @throws IOException Indicates the camera driver failed to open.
   */
  public synchronized void openDriver(SurfaceHolder holder) throws IOException {
    Camera theCamera = camera;
    if (theCamera == null) {
      theCamera = Camera.open();
      if (theCamera == null) {
        throw new IOException();
      }
      camera = theCamera;
    }
    camera.setPreviewDisplay(holder);
    if (!initialized) {
      initialized = true;
      configManager.initFromCameraParameters(theCamera);
      if (requestedFramingRectWidth > 0 && requestedFramingRectHeight > 0) {
        adjustFramingRect(requestedFramingRectWidth, requestedFramingRectHeight);
        requestedFramingRectWidth = 0;
        requestedFramingRectHeight = 0;
      }
    }
    configManager.setDesiredCameraParameters(theCamera);
    
    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
//    reverseImage = prefs.getBoolean(PreferencesActivity.KEY_REVERSE_IMAGE, false);
  }

  /**
   * Closes the camera driver if still in use.
   */
  public synchronized void closeDriver() {
    if (camera != null) {
      camera.release();
      camera = null;

      // Make sure to clear these each time we close the camera, so that any scanning rect
      // requested by intent is forgotten.
      framingRect = null;
      framingRectInPreview = null;
    }
  }

  /**
   * Asks the camera hardware to begin drawing preview frames to the screen.
   */
  public synchronized void startPreview() {
    Camera theCamera = camera;
    if (theCamera != null && !previewing) {
      theCamera.startPreview();
      previewing = true;
      autoFocusManager = new AutoFocusManager(context, camera);
    }
  }

  /**
   * Tells the camera to stop drawing preview frames.
   */
  public synchronized void stopPreview() {
    if (autoFocusManager != null) {
    	autoFocusManager.stop();
    	autoFocusManager = null;
    }
  	if (camera != null && previewing) {
      camera.stopPreview();
      previewCallback.setHandler(null, 0);
      previewing = false;
    }
  }

  /**
   * A single preview frame will be returned to the handler supplied. The data will arrive as byte[]
   * in the message.obj field, with width and height encoded as message.arg1 and message.arg2,
   * respectively.
   *
   * @param handler The handler to send the message to.
   * @param message The what field of the message to be sent.
   */
  public synchronized void requestOcrDecode(Handler handler, int message) {
    Camera theCamera = camera;
    if (theCamera != null && previewing) {
      previewCallback.setHandler(handler, message);
      theCamera.setOneShotPreviewCallback(previewCallback);
    }
  }
  
  /**
   * Asks the camera hardware to perform an autofocus.
   * @param delay Time delay to send with the request
   */
  public synchronized void requestAutoFocus(long delay) {
  	autoFocusManager.start(delay);
  }
  
  /**
   * Calculates the framing rect which the UI should draw to show the user where to place the
   * barcode. This target helps with alignment as well as forces the user to hold the device
   * far enough away to ensure the image will be in focus.
   *
   * @return The rectangle to draw on screen in window coordinates.
   */
  public synchronized Rect getFramingRect() {
    if (framingRect == null) {
      if (camera == null) {
        return null;
      }
      Point screenResolution = configManager.getScreenResolution();
      if (screenResolution == null) {
        // Called early, before init even finished
        return null;
      }
      int width = screenResolution.x * 3/5;
      if (width < MIN_FRAME_WIDTH) {
        width = MIN_FRAME_WIDTH;
      } else if (width > MAX_FRAME_WIDTH) {
        width = MAX_FRAME_WIDTH;
      }
      int height = screenResolution.y * 1/5;
      if (height < MIN_FRAME_HEIGHT) {
        height = MIN_FRAME_HEIGHT;
      } else if (height > MAX_FRAME_HEIGHT) {
        height = MAX_FRAME_HEIGHT;
      }
      int leftOffset = (screenResolution.x - width) / 2;
      int topOffset = (screenResolution.y - height) / 2;
      framingRect = new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);
    }
    return framingRect;
  }

  /**
   * Like {@link #getFramingRect} but coordinates are in terms of the preview frame,
   * not UI / screen.
   */
  public synchronized Rect getFramingRectInPreview() {
    if (framingRectInPreview == null) {
      Rect rect = new Rect(getFramingRect());
      Point cameraResolution = configManager.getCameraResolution();
      Point screenResolution = configManager.getScreenResolution();
      if (cameraResolution == null || screenResolution == null) {
        // Called early, before init even finished
        return null;
      }
      rect.left = rect.left * cameraResolution.x / screenResolution.x;
      rect.right = rect.right * cameraResolution.x / screenResolution.x;
      rect.top = rect.top * cameraResolution.y / screenResolution.y;
      rect.bottom = rect.bottom * cameraResolution.y / screenResolution.y;
      framingRectInPreview = rect;
    }
    return framingRectInPreview;
  }

  /**
   * Changes the size of the framing rect.
   * 
   * @param deltaWidth Number of pixels to adjust the width
   * @param deltaHeight Number of pixels to adjust the height
   */
  public synchronized void adjustFramingRect(int deltaWidth, int deltaHeight) {
    if (initialized) {
      Point screenResolution = configManager.getScreenResolution();

      // Set maximum and minimum sizes
      if ((framingRect.width() + deltaWidth > screenResolution.x - 4) || (framingRect.width() + deltaWidth < 50)) {
        deltaWidth = 0;
      }
      if ((framingRect.height() + deltaHeight > screenResolution.y - 4) || (framingRect.height() + deltaHeight < 50)) {
        deltaHeight = 0;
      }

      int newWidth = framingRect.width() + deltaWidth;
      int newHeight = framingRect.height() + deltaHeight;
      int leftOffset = (screenResolution.x - newWidth) / 2;
      int topOffset = (screenResolution.y - newHeight) / 2;
      framingRect = new Rect(leftOffset, topOffset, leftOffset + newWidth, topOffset + newHeight);
      framingRectInPreview = null;
    } else {
      requestedFramingRectWidth = deltaWidth;
      requestedFramingRectHeight = deltaHeight;
    }
  }

  /**
   * A factory method to build the appropriate LuminanceSource object based on the format
   * of the preview buffers, as described by Camera.Parameters.
   *
   * @param data A preview frame.
   * @param width The width of the image.
   * @param height The height of the image.
   * @return A PlanarYUVLuminanceSource instance.
   */
  public PlanarYUVLuminanceSource buildLuminanceSource(byte[] data, int width, int height) {
    Rect rect = getFramingRectInPreview();
    if (rect == null) {
      return null;
    }
    // Go ahead and assume it's YUV rather than die.
    return new PlanarYUVLuminanceSource(data, width, height, rect.left, rect.top,
                                        rect.width(), rect.height(), reverseImage);
  }

}
