package com.hyphenate.helpdesk.easeui.util;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.TransitionDrawable;
import android.os.AsyncTask;
import android.widget.ImageView;

import androidx.fragment.app.FragmentManager;

import java.lang.ref.WeakReference;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;


public abstract class ImageWorker {
	private static final String TAG = "ImageWorker";
	private static final int FADE_IN_TIME = 200;

	private ImageCache mImageCache;
	private Bitmap mLoadingBitmap;
	private boolean mFadeInBitmap = true;
	private boolean mExitTasksEarly = false;
	protected boolean mPauseWork = false;
	private final Object mPauseWorkLock = new Object();

	protected Resources mResources;

	private static final int MESSAGE_CLEAR = 0;
	private static final int MESSAGE_INIT_DISK_CACHE = 1;
	private static final int MESSAGE_FLUSH = 2;
	private static final int MESSAGE_CLOSE = 3;

	public static final Executor DUAL_THREAD_EXECUTOR = Executors
			.newFixedThreadPool(2);

	protected ImageWorker(Context context) {
		mResources = context.getResources();
	}

	/**
	 * Load an image specified by the data parameter into an ImageView (override
	 * { ImageWorker#processBitmap(Object)} to define the processing logic). A memory and
	 * disk cache will be used if an { ImageCache} has been added using
	 * { ImageWorker#addImageCache(android.support.v4.app.FragmentManager, ImageCache.ImageCacheParams)}. If the
	 * image is found in the memory cache, it is set immediately, otherwise an { AsyncTask}
	 * will be created to asynchronously load the bitmap.
	 *
	 * @param data The URL of the image to download.
	 * @param imageView The ImageView to bind the downloaded image to.
	 */
	public void loadImage(Object data, ImageView imageView) {
		if (data == null) {
			return;
		}

		BitmapDrawable value = null;

		if (mImageCache != null) {
			value = mImageCache.getBitmapFromMemCache(String.valueOf(data));
		}

		if (value != null) {
			// Bitmap found in memory cache
			imageView.setImageDrawable(value);
		} else if (cancelPotentialWork(data, imageView)) {
			//BEGIN_INCLUDE(execute_background_task)
			final BitmapWorkerTask task = new BitmapWorkerTask(data, imageView);
			final AsyncDrawable asyncDrawable =
					new AsyncDrawable(mResources, mLoadingBitmap, task);
			imageView.setImageDrawable(asyncDrawable);

			// NOTE: This uses a custom version of AsyncTask that has been pulled from the
			// framework and slightly modified. Refer to the docs at the top of the class
			// for more info on what was changed.
			task.executeOnExecutor(DUAL_THREAD_EXECUTOR);
			//END_INCLUDE(execute_background_task)
		}
	}

	/**
	 * Set placeholder bitmap that shows when the the background thread is running.
	 *
	 * @param bitmap
	 */
	public void setLoadingImage(Bitmap bitmap) {
		mLoadingBitmap = bitmap;
	}

	/**
	 * Set placeholder bitmap that shows when the the background thread is running.
	 *
	 * @param resId
	 */
	public void setLoadingImage(int resId) {
		mLoadingBitmap = BitmapFactory.decodeResource(mResources, resId);
	}

	/**
	 * Adds an {@link ImageCache} to this {@link ImageWorker} to handle disk and memory bitmap
	 * caching.
	 * @param fragmentManager
	 * @param cacheParams The cache parameters to use for the image cache.
	 */
	public void addImageCache(FragmentManager fragmentManager,
							  ImageCache.ImageCacheParams cacheParams) {
		mImageCache = ImageCache.getInstance(fragmentManager, cacheParams);
		new CacheAsyncTask().execute(MESSAGE_INIT_DISK_CACHE);
	}


	/**
	 * If set to true, the image will fade-in once it has been loaded by the background thread.
	 */
	public void setImageFadeIn(boolean fadeIn) {
		mFadeInBitmap = fadeIn;
	}

	public void setExitTasksEarly(boolean exitTasksEarly) {
		mExitTasksEarly = exitTasksEarly;
		setPauseWork(false);
	}

	/**
	 * Subclasses should override this to define any processing or work that must happen to produce
	 * the final bitmap. This will be executed in a background thread and be long running. For
	 * example, you could resize a large bitmap here, or pull down an image from the network.
	 *
	 * @param data The data to identify which image to process, as provided by
	 *            {@link ImageWorker#loadImage(Object, android.widget.ImageView)}
	 * @return The processed bitmap
	 */
	protected abstract Bitmap processBitmap(Object data);

	/**
	 * @return The {@link ImageCache} object currently being used by this ImageWorker.
	 */
	protected ImageCache getImageCache() {
		return mImageCache;
	}

	/**
	 * Cancels any pending work attached to the provided ImageView.
	 * @param imageView
	 */
	public static void cancelWork(ImageView imageView) {
		final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView);
		if (bitmapWorkerTask != null) {
			bitmapWorkerTask.cancel(true);
//			if (BuildConfig.DEBUG) {
//				final Object bitmapData = bitmapWorkerTask.mData;
//				Log.d(TAG, "cancelWork - cancelled work for " + bitmapData);
//			}
		}
	}

	/**
	 * Returns true if the current work has been canceled or if there was no work in
	 * progress on this image view.
	 * Returns false if the work in progress deals with the same data. The work is not
	 * stopped in that case.
	 */
	public static boolean cancelPotentialWork(Object data, ImageView imageView) {
		//BEGIN_INCLUDE(cancel_potential_work)
		final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView);

		if (bitmapWorkerTask != null) {
			final Object bitmapData = bitmapWorkerTask.mData;
			if (bitmapData == null || !bitmapData.equals(data)) {
				bitmapWorkerTask.cancel(true);
//				if (BuildConfig.DEBUG) {
//					Log.d(TAG, "cancelPotentialWork - cancelled work for " + data);
//				}
			} else {
				// The same work is already in progress.
				return false;
			}
		}
		return true;
		//END_INCLUDE(cancel_potential_work)
	}

	/**
	 * @param imageView Any imageView
	 * @return Retrieve the currently active work task (if any) associated with this imageView.
	 * null if there is no such task.
	 */
	private static BitmapWorkerTask getBitmapWorkerTask(ImageView imageView) {
		if (imageView != null) {
			final Drawable drawable = imageView.getDrawable();
			if (drawable instanceof AsyncDrawable) {
				final AsyncDrawable asyncDrawable = (AsyncDrawable) drawable;
				return asyncDrawable.getBitmapWorkerTask();
			}
		}
		return null;
	}

	/**
	 * The actual AsyncTask that will asynchronously process the image.
	 */
	private class BitmapWorkerTask extends AsyncTask<Void, Void, BitmapDrawable> {
		private Object mData;
		private final WeakReference<ImageView> imageViewReference;

		public BitmapWorkerTask(Object data, ImageView imageView) {
			mData = data;
			imageViewReference = new WeakReference<ImageView>(imageView);
		}

		/**
		 * Background processing.
		 */
		@Override
		protected BitmapDrawable doInBackground(Void... params) {
			//BEGIN_INCLUDE(load_bitmap_in_background)
//			if (BuildConfig.DEBUG) {
//				Log.d(TAG, "doInBackground - starting work");
//			}

			final String dataString = String.valueOf(mData);
			Bitmap bitmap = null;
			BitmapDrawable drawable = null;

			// Wait here if work is paused and the task is not cancelled
			synchronized (mPauseWorkLock) {
				while (mPauseWork && !isCancelled()) {
					try {
						mPauseWorkLock.wait();
					} catch (InterruptedException ignored) {}
				}
			}



			// If the bitmap was not found in the cache and this task has not been cancelled by
			// another thread and the ImageView that was originally bound to this task is still
			// bound back to this task and our "exit early" flag is not set, then call the main
			// process method (as implemented by a subclass)
			if (!isCancelled() && getAttachedImageView() != null && !mExitTasksEarly) {
				bitmap = processBitmap(mData);
			}

			// If the bitmap was processed and the image cache is available, then add the processed
			// bitmap to the cache for future use. Note we don't check if the task was cancelled
			// here, if it was, and the thread is still running, we may as well add the processed
			// bitmap to our cache as it might be used again in the future
			if (bitmap != null) {
				if (Utils.hasHoneycomb()) {
					// Running on Honeycomb or newer, so wrap in a standard BitmapDrawable
					drawable = new BitmapDrawable(mResources, bitmap);
				} else {
					// Running on Gingerbread or older, so wrap in a RecyclingBitmapDrawable
					// which will recycle automagically
					drawable = new RecyclingBitmapDrawable(mResources, bitmap);
				}

				if (mImageCache != null) {
					mImageCache.addBitmapToCache(dataString, drawable);
				}
			}

//			if (BuildConfig.DEBUG) {
//				Log.d(TAG, "doInBackground - finished work");
//			}

			return drawable;
			//END_INCLUDE(load_bitmap_in_background)
		}

		/**
		 * Once the image is processed, associates it to the imageView
		 */
		@Override
		protected void onPostExecute(BitmapDrawable value) {
			//BEGIN_INCLUDE(complete_background_work)
			// if cancel was called on this task or the "exit early" flag is set then we're done
			if (isCancelled() || mExitTasksEarly) {
				value = null;
			}

			final ImageView imageView = getAttachedImageView();
			if (value != null && imageView != null) {
//				if (BuildConfig.DEBUG) {
//					Log.d(TAG, "onPostExecute - setting bitmap");
//				}
				setImageDrawable(imageView, value);
			}
			//END_INCLUDE(complete_background_work)
		}

		@Override
		protected void onCancelled(BitmapDrawable value) {
			super.onCancelled(value);
			synchronized (mPauseWorkLock) {
				mPauseWorkLock.notifyAll();
			}
		}

		/**
		 * Returns the ImageView associated with this task as long as the ImageView's task still
		 * points to this task as well. Returns null otherwise.
		 */
		private ImageView getAttachedImageView() {
			final ImageView imageView = imageViewReference.get();
			final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView);

			if (this == bitmapWorkerTask) {
				return imageView;
			}

			return null;
		}
	}

	/**
	 * A custom Drawable that will be attached to the imageView while the work is in progress.
	 * Contains a reference to the actual worker task, so that it can be stopped if a new binding is
	 * required, and makes sure that only the last started worker process can bind its result,
	 * independently of the finish order.
	 */
	private static class AsyncDrawable extends BitmapDrawable {
		private final WeakReference<BitmapWorkerTask> bitmapWorkerTaskReference;

		public AsyncDrawable(Resources res, Bitmap bitmap, BitmapWorkerTask bitmapWorkerTask) {
			super(res, bitmap);
			bitmapWorkerTaskReference =
					new WeakReference<BitmapWorkerTask>(bitmapWorkerTask);
		}

		public BitmapWorkerTask getBitmapWorkerTask() {
			return bitmapWorkerTaskReference.get();
		}
	}

	/**
	 * Called when the processing is complete and the final drawable should be
	 * set on the ImageView.
	 *
	 * @param imageView
	 * @param drawable
	 */
	private void setImageDrawable(ImageView imageView, Drawable drawable) {
		if (mFadeInBitmap) {
			// Transition drawable with a transparent drawable and the final drawable
			final TransitionDrawable td =
					new TransitionDrawable(new Drawable[] {
							new ColorDrawable(Color.parseColor("#00000000")),
							drawable
					});
			// Set background to loading bitmap
			imageView.setBackgroundDrawable(
					new BitmapDrawable(mResources, mLoadingBitmap));

			imageView.setImageDrawable(td);
			td.startTransition(FADE_IN_TIME);
		} else {
			imageView.setImageDrawable(drawable);
		}
	}

	/**
	 * Pause any ongoing background work. This can be used as a temporary
	 * measure to improve performance. For example background work could
	 * be paused when a ListView or GridView is being scrolled using a
	 * {@link android.widget.AbsListView.OnScrollListener} to keep
	 * scrolling smooth.
	 * <p>
	 * If work is paused, be sure setPauseWork(false) is called again
	 * before your fragment or activity is destroyed (for example during
	 * {@link android.app.Activity# onPause()}), or there is a risk the
	 * background thread will never finish.
	 */
	public void setPauseWork(boolean pauseWork) {
		synchronized (mPauseWorkLock) {
			mPauseWork = pauseWork;
			if (!mPauseWork) {
				mPauseWorkLock.notifyAll();
			}
		}
	}

	protected class CacheAsyncTask extends AsyncTask<Object, Void, Void> {

		@Override
		protected Void doInBackground(Object... params) {
			switch ((Integer)params[0]) {
				case MESSAGE_CLEAR:
					clearCacheInternal();
					break;
				default:
					break;
			}
			return null;
		}
	}


	protected void clearCacheInternal() {
		if (mImageCache != null) {
			mImageCache.clearCache();
		}
	}


	public void clearCache() {
		new CacheAsyncTask().execute(MESSAGE_CLEAR);
	}

	public void flushCache() {
		new CacheAsyncTask().execute(MESSAGE_FLUSH);
	}

	public void closeCache() {
		new CacheAsyncTask().execute(MESSAGE_CLOSE);
	}
}
