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/*
 * Copyright 2013 serso aka se.solovyev
 *
 * 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.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 * Contact details
 *
 * Email: [email protected]
 * Site:  http://se.solovyev.org
 */

package org.solovyev.android.async;

import android.content.Context;
import android.os.AsyncTask;
import android.util.Log;
import org.solovyev.common.collections.Collections;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.lang.ref.WeakReference;
import java.util.List;

public abstract class CommonAsyncTask extends AsyncTask> {

	@Nonnull
	private static final String TAG = "CommonAsyncTask";

	@Nonnull
	private final WeakReference contextRef;

	protected CommonAsyncTask() {
		this.contextRef = new WeakReference(null);
	}

	protected CommonAsyncTask(@Nonnull Context context) {
		this.contextRef = new WeakReference(context);
	}

	@Override
	protected void onPreExecute() {
		super.onPreExecute();
	}

	@Override
	protected final Result doInBackground(PARAM... params) {
		try {
			return new CommonResult(doWork(Collections.asList(params)));
		} catch (CommonAsyncTaskRuntimeException e) {
			return new CommonResult(e.getException());
		} catch (Exception e) {
			return new CommonResult(e);
		}
	}

	protected abstract RESULT doWork(@Nonnull List params);

	@Override
	protected void onPostExecute(@Nonnull Result r) {
		super.onPostExecute(r);

		if (r.isFailure()) {
			onFailurePostExecute(r.getFailureResult());
		} else {
			onSuccessPostExecute(r.getSuccessResult());
		}

	}

	@Nullable
	protected Context getContext() {
		return contextRef.get();
	}

	protected abstract void onSuccessPostExecute(@Nullable RESULT result);

	protected abstract void onFailurePostExecute(@Nonnull Exception e);

	private static class CommonResult implements Result {

		@Nullable
		private SR successResult;

		@Nullable
		private Exception failureResult;

		public CommonResult(@Nullable SR result) {
			this.successResult = result;
		}

		public CommonResult(@Nonnull Exception e) {
			this.failureResult = e;
		}

		@Override
		@Nullable
		public SR getSuccessResult() {
			return successResult;
		}

		@Nullable
		@Override
		public Exception getFailureResult() {
			return this.failureResult;
		}

		@Override
		public boolean isFailure() {
			return this.failureResult != null;
		}
	}

	protected static interface Result {

		boolean isFailure();

		@Nullable
		Exception getFailureResult();

		@Nullable
		SR getSuccessResult();
	}

	protected void throwException(@Nonnull Exception e) {
		throw new CommonAsyncTaskRuntimeException(e);
	}

	protected void defaultOnFailurePostExecute(@Nonnull Exception e) {
		if (e instanceof RuntimeException) {
			throw (RuntimeException) e;
		} else {
			Log.e(TAG, e.getMessage(), e);
		}
	}

	private static class CommonAsyncTaskRuntimeException extends RuntimeException {

		@Nonnull
		private Exception exception;

		public CommonAsyncTaskRuntimeException(@Nonnull Exception exception) {
			this.exception = exception;
		}

		@Nonnull
		public Exception getException() {
			return exception;
		}
	}
}