/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * 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.android.phone.common;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Looper;
import android.provider.CallLog.Calls;

/**
 * Class to access the call log asynchronously to avoid carrying out database operations on the
 * UI thread, using an {@link AsyncTask}.
 *
 * <pre class="prettyprint">
 * Typical usage:
 * ==============
 *
 *  // From an activity...
 *  String mLastNumber = "";
 *
 *  CallLogAsync log = new CallLogAsync();
 *
 *  CallLogAsync.GetLastOutgoingCallArgs lastCallArgs = new CallLogAsync.GetLastOutgoingCallArgs(
 *      this, new CallLogAsync.OnLastOutgoingCallComplete() {
 *               public void lastOutgoingCall(String number) { mLastNumber = number; }
 *            });
 *  log.getLastOutgoingCall(lastCallArgs);
 * </pre>
 *
 */

public class CallLogAsync {
    private static final String TAG = "CallLogAsync";

    /**
     * Parameter object to hold the args to get the last outgoing call
     * from the call log DB.
     */
    public static class GetLastOutgoingCallArgs {
        public GetLastOutgoingCallArgs(Context context,
                                       OnLastOutgoingCallComplete callback) {
            this.context = context;
            this.callback = callback;
        }
        public final Context context;
        public final OnLastOutgoingCallComplete callback;
    }

    /** Interface to retrieve the last dialed number asynchronously. */
    public interface OnLastOutgoingCallComplete {
        /** @param number The last dialed number or an empty string if
         *                none exists yet. */
        void lastOutgoingCall(String number);
    }

    /**
     * CallLog.getLastOutgoingCall(...)
     */
    public AsyncTask getLastOutgoingCall(GetLastOutgoingCallArgs args) {
        assertUiThread();
        return new GetLastOutgoingCallTask(args.callback).execute(args);
    }

    /**
     * AsyncTask to get the last outgoing call from the DB.
     */
    private class GetLastOutgoingCallTask extends AsyncTask<GetLastOutgoingCallArgs, Void, String> {
        private final OnLastOutgoingCallComplete mCallback;
        private String mNumber;
        public GetLastOutgoingCallTask(OnLastOutgoingCallComplete callback) {
            mCallback = callback;
        }

        // Happens on a background thread. We cannot run the callback
        // here because only the UI thread can modify the view
        // hierarchy (e.g enable/disable the dial button). The
        // callback is ran rom the post execute method.
        @Override
        protected String doInBackground(GetLastOutgoingCallArgs... list) {
            int count = list.length;
            String number = "";
            for (GetLastOutgoingCallArgs args : list) {
                // May block. Select only the last one.
                number = Calls.getLastOutgoingCall(args.context);
            }
            return number;  // passed to the onPostExecute method.
        }

        // Happens on the UI thread, it is safe to run the callback
        // that may do some work on the views.
        @Override
        protected void onPostExecute(String number) {
            assertUiThread();
            mCallback.lastOutgoingCall(number);
        }
    }

    private void assertUiThread() {
        if (!Looper.getMainLooper().equals(Looper.myLooper())) {
            throw new RuntimeException("Not on the UI thread!");
        }
    }
}