/*
 * Copyright (C) 2012 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 android.app;

import android.annotation.NonNull;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.os.Bundle;
import android.os.UserHandle;
import android.util.Log;

import java.util.ArrayList;

Utility class for constructing synthetic back stacks for cross-task navigation
on Android 3.0 and newer.
In API level 11 (Android 3.0/Honeycomb) the recommended conventions for
app navigation using the back key changed. The back key's behavior is local
to the current task and does not capture navigation across different tasks.
Navigating across tasks and easily reaching the previous task is accomplished
through the "recents" UI, accessible through the software-provided Recents key
on the navigation or system bar. On devices with the older hardware button configuration
the recents UI can be accessed with a long press on the Home key.
When crossing from one task stack to another post-Android 3.0,
the application should synthesize a back stack/history for the new task so that
the user may navigate out of the new task and back to the Launcher by repeated
presses of the back key. Back key presses should not navigate across task stacks.
TaskStackBuilder provides a way to obey the correct conventions
around cross-task navigation.

About Navigation
For more detailed information about tasks, the back stack, and navigation design guidelines,
please read
Tasks and Back Stack
from the developer guide and Navigation
from the design guide.

/**
 * Utility class for constructing synthetic back stacks for cross-task navigation
 * on Android 3.0 and newer.
 *
 * <p>In API level 11 (Android 3.0/Honeycomb) the recommended conventions for
 * app navigation using the back key changed. The back key's behavior is local
 * to the current task and does not capture navigation across different tasks.
 * Navigating across tasks and easily reaching the previous task is accomplished
 * through the "recents" UI, accessible through the software-provided Recents key
 * on the navigation or system bar. On devices with the older hardware button configuration
 * the recents UI can be accessed with a long press on the Home key.</p>
 *
 * <p>When crossing from one task stack to another post-Android 3.0,
 * the application should synthesize a back stack/history for the new task so that
 * the user may navigate out of the new task and back to the Launcher by repeated
 * presses of the back key. Back key presses should not navigate across task stacks.</p>
 *
 * <p>TaskStackBuilder provides a way to obey the correct conventions
 * around cross-task navigation.</p>
 *
 * <div class="special reference">
 * <h3>About Navigation</h3>
 * For more detailed information about tasks, the back stack, and navigation design guidelines,
 * please read
 * <a href="{@docRoot}guide/topics/fundamentals/tasks-and-back-stack.html">Tasks and Back Stack</a>
 * from the developer guide and <a href="{@docRoot}design/patterns/navigation.html">Navigation</a>
 * from the design guide.
 * </div>
 */
public class TaskStackBuilder {
    private static final String TAG = "TaskStackBuilder";

    private final ArrayList<Intent> mIntents = new ArrayList<Intent>();
    private final Context mSourceContext;

    private TaskStackBuilder(Context a) {
        mSourceContext = a;
    }

    
Return a new TaskStackBuilder for launching a fresh task stack consisting
of a series of activities.
Params:
context – The context that will launch the new task stack or generate a PendingIntent
Returns:
A new TaskStackBuilder/**
     * Return a new TaskStackBuilder for launching a fresh task stack consisting
     * of a series of activities.
     *
     * @param context The context that will launch the new task stack or generate a PendingIntent
     * @return A new TaskStackBuilder
     */
    public static TaskStackBuilder create(Context context) {
        return new TaskStackBuilder(context);
    }

    
Add a new Intent to the task stack. The most recently added Intent will invoke
the Activity at the top of the final task stack.
Params:
nextIntent – Intent for the next Activity in the synthesized task stack
Returns:
This TaskStackBuilder for method chaining/**
     * Add a new Intent to the task stack. The most recently added Intent will invoke
     * the Activity at the top of the final task stack.
     *
     * @param nextIntent Intent for the next Activity in the synthesized task stack
     * @return This TaskStackBuilder for method chaining
     */
    public TaskStackBuilder addNextIntent(Intent nextIntent) {
        mIntents.add(nextIntent);
        return this;
    }

    
Add a new Intent with the resolved chain of parents for the target activity to
the task stack.
This is equivalent to calling addParentStack with the resolved ComponentName of nextIntent (if it can be resolved), followed by addNextIntent with nextIntent.
Params:
nextIntent – Intent for the topmost Activity in the synthesized task stack.
                  Its chain of parents as specified in the manifest will be added.
Returns:
This TaskStackBuilder for method chaining./**
     * Add a new Intent with the resolved chain of parents for the target activity to
     * the task stack.
     *
     * <p>This is equivalent to calling {@link #addParentStack(ComponentName) addParentStack}
     * with the resolved ComponentName of nextIntent (if it can be resolved), followed by
     * {@link #addNextIntent(Intent) addNextIntent} with nextIntent.</p>
     *
     * @param nextIntent Intent for the topmost Activity in the synthesized task stack.
     *                   Its chain of parents as specified in the manifest will be added.
     * @return This TaskStackBuilder for method chaining.
     */
    public TaskStackBuilder addNextIntentWithParentStack(Intent nextIntent) {
        ComponentName target = nextIntent.getComponent();
        if (target == null) {
            target = nextIntent.resolveActivity(mSourceContext.getPackageManager());
        }
        if (target != null) {
            addParentStack(target);
        }
        addNextIntent(nextIntent);
        return this;
    }

    
Add the activity parent chain as specified by the getParentActivityIntent() method of the activity specified and the parentActivityName attributes of each successive activity (or activity-alias) element in the application's manifest to the task stack builder. 
Params:
sourceActivity – All parents of this activity will be added
Returns:
This TaskStackBuilder for method chaining/**
     * Add the activity parent chain as specified by the
     * {@link Activity#getParentActivityIntent() getParentActivityIntent()} method of the activity
     * specified and the {@link android.R.attr#parentActivityName parentActivityName} attributes
     * of each successive activity (or activity-alias) element in the application's manifest
     * to the task stack builder.
     *
     * @param sourceActivity All parents of this activity will be added
     * @return This TaskStackBuilder for method chaining
     */
    public TaskStackBuilder addParentStack(Activity sourceActivity) {
        final Intent parent = sourceActivity.getParentActivityIntent();
        if (parent != null) {
            // We have the actual parent intent, build the rest from static metadata
            // then add the direct parent intent to the end.
            ComponentName target = parent.getComponent();
            if (target == null) {
                target = parent.resolveActivity(mSourceContext.getPackageManager());
            }
            addParentStack(target);
            addNextIntent(parent);
        }
        return this;
    }

    
Add the activity parent chain as specified by the parentActivityName attribute of the activity (or activity-alias) element in the application's manifest to the task stack builder. 
Params:
sourceActivityClass – All parents of this activity will be added
Returns:
This TaskStackBuilder for method chaining/**
     * Add the activity parent chain as specified by the
     * {@link android.R.attr#parentActivityName parentActivityName} attribute of the activity
     * (or activity-alias) element in the application's manifest to the task stack builder.
     *
     * @param sourceActivityClass All parents of this activity will be added
     * @return This TaskStackBuilder for method chaining
     */
    public TaskStackBuilder addParentStack(Class<?> sourceActivityClass) {
        return addParentStack(new ComponentName(mSourceContext, sourceActivityClass));
    }

    
Add the activity parent chain as specified by the parentActivityName attribute of the activity (or activity-alias) element in the application's manifest to the task stack builder. 
Params:
sourceActivityName – Must specify an Activity component. All parents of
                          this activity will be added
Returns:
This TaskStackBuilder for method chaining/**
     * Add the activity parent chain as specified by the
     * {@link android.R.attr#parentActivityName parentActivityName} attribute of the activity
     * (or activity-alias) element in the application's manifest to the task stack builder.
     *
     * @param sourceActivityName Must specify an Activity component. All parents of
     *                           this activity will be added
     * @return This TaskStackBuilder for method chaining
     */
    public TaskStackBuilder addParentStack(ComponentName sourceActivityName) {
        final int insertAt = mIntents.size();
        PackageManager pm = mSourceContext.getPackageManager();
        try {
            ActivityInfo info = pm.getActivityInfo(sourceActivityName, 0);
            String parentActivity = info.parentActivityName;
            while (parentActivity != null) {
                final ComponentName target = new ComponentName(info.packageName, parentActivity);
                info = pm.getActivityInfo(target, 0);
                parentActivity = info.parentActivityName;
                final Intent parent = parentActivity == null && insertAt == 0
                        ? Intent.makeMainActivity(target)
                        : new Intent().setComponent(target);
                mIntents.add(insertAt, parent);
            }
        } catch (NameNotFoundException e) {
            Log.e(TAG, "Bad ComponentName while traversing activity parent metadata");
            throw new IllegalArgumentException(e);
        }
        return this;
    }

    
Returns:
the number of intents added so far./**
     * @return the number of intents added so far.
     */
    public int getIntentCount() {
        return mIntents.size();
    }

    
Return the intent at the specified index for modification. Useful if you need to modify the flags or extras of an intent that was previously added, for example with addParentStack(Activity). 
Params:
index – Index from 0-getIntentCount()
Returns:
the intent at position index/**
     * Return the intent at the specified index for modification.
     * Useful if you need to modify the flags or extras of an intent that was previously added,
     * for example with {@link #addParentStack(Activity)}.
     *
     * @param index Index from 0-getIntentCount()
     * @return the intent at position index
     */
    public Intent editIntentAt(int index) {
        return mIntents.get(index);
    }

    
Start the task stack constructed by this builder.
/**
     * Start the task stack constructed by this builder.
     */
    public void startActivities() {
        startActivities(null);
    }

    
Start the task stack constructed by this builder.
@hide
/**
     * Start the task stack constructed by this builder.
     * @hide
     */
    public int startActivities(Bundle options, UserHandle userHandle) {
        if (mIntents.isEmpty()) {
            throw new IllegalStateException(
                    "No intents added to TaskStackBuilder; cannot startActivities");
        }

        return mSourceContext.startActivitiesAsUser(getIntents(), options, userHandle);
    }

    
Start the task stack constructed by this builder.
Params:
options – Additional options for how the Activity should be started. See Context.startActivity(Intent, Bundle) Context.startActivity(Intent, Bundle)} for more details./**
     * Start the task stack constructed by this builder.
     *
     * @param options Additional options for how the Activity should be started.
     * See {@link android.content.Context#startActivity(Intent, Bundle)}
     * Context.startActivity(Intent, Bundle)} for more details.
     */
    public void startActivities(Bundle options) {
        startActivities(options, mSourceContext.getUser());
    }

    
Obtain a PendingIntent for launching the task constructed by this builder so far. 
Params:
requestCode – Private request code for the sender
flags – May be PendingIntent.FLAG_ONE_SHOT, PendingIntent.FLAG_NO_CREATE, PendingIntent.FLAG_CANCEL_CURRENT, PendingIntent.FLAG_UPDATE_CURRENT, or any of the flags supported by Intent.fillIn(Intent, int) to control which unspecified parts of the intent that can be supplied when the actual send happens.
Returns:
The obtained PendingIntent/**
     * Obtain a {@link PendingIntent} for launching the task constructed by this builder so far.
     *
     * @param requestCode Private request code for the sender
     * @param flags May be {@link PendingIntent#FLAG_ONE_SHOT},
     *              {@link PendingIntent#FLAG_NO_CREATE}, {@link PendingIntent#FLAG_CANCEL_CURRENT},
     *              {@link PendingIntent#FLAG_UPDATE_CURRENT}, or any of the flags supported by
     *              {@link Intent#fillIn(Intent, int)} to control which unspecified parts of the
     *              intent that can be supplied when the actual send happens.
     *
     * @return The obtained PendingIntent
     */
    public PendingIntent getPendingIntent(int requestCode, @PendingIntent.Flags int flags) {
        return getPendingIntent(requestCode, flags, null);
    }

    
Obtain a PendingIntent for launching the task constructed by this builder so far. 
Params:
requestCode – Private request code for the sender
flags – May be PendingIntent.FLAG_ONE_SHOT, PendingIntent.FLAG_NO_CREATE, PendingIntent.FLAG_CANCEL_CURRENT, PendingIntent.FLAG_UPDATE_CURRENT, or any of the flags supported by Intent.fillIn(Intent, int) to control which unspecified parts of the intent that can be supplied when the actual send happens.
options – Additional options for how the Activity should be started. See Context.startActivity(Intent, Bundle) Context.startActivity(Intent, Bundle)} for more details.
Returns:
The obtained PendingIntent/**
     * Obtain a {@link PendingIntent} for launching the task constructed by this builder so far.
     *
     * @param requestCode Private request code for the sender
     * @param flags May be {@link PendingIntent#FLAG_ONE_SHOT},
     *              {@link PendingIntent#FLAG_NO_CREATE}, {@link PendingIntent#FLAG_CANCEL_CURRENT},
     *              {@link PendingIntent#FLAG_UPDATE_CURRENT}, or any of the flags supported by
     *              {@link Intent#fillIn(Intent, int)} to control which unspecified parts of the
     *              intent that can be supplied when the actual send happens.
     * @param options Additional options for how the Activity should be started.
     * See {@link android.content.Context#startActivity(Intent, Bundle)}
     * Context.startActivity(Intent, Bundle)} for more details.
     *
     * @return The obtained PendingIntent
     */
    public PendingIntent getPendingIntent(int requestCode, @PendingIntent.Flags int flags,
            Bundle options) {
        if (mIntents.isEmpty()) {
            throw new IllegalStateException(
                    "No intents added to TaskStackBuilder; cannot getPendingIntent");
        }

        return PendingIntent.getActivities(mSourceContext, requestCode, getIntents(),
                flags, options);
    }

    
@hide
/**
     * @hide
     */
    public PendingIntent getPendingIntent(int requestCode, int flags, Bundle options,
            UserHandle user) {
        if (mIntents.isEmpty()) {
            throw new IllegalStateException(
                    "No intents added to TaskStackBuilder; cannot getPendingIntent");
        }

        return PendingIntent.getActivitiesAsUser(mSourceContext, requestCode, getIntents(), flags,
                options, user);
    }

    
Return an array containing the intents added to this builder. The intent at the
root of the task stack will appear as the first item in the array and the
intent at the top of the stack will appear as the last item.
Returns:
An array containing the intents added to this builder./**
     * Return an array containing the intents added to this builder. The intent at the
     * root of the task stack will appear as the first item in the array and the
     * intent at the top of the stack will appear as the last item.
     *
     * @return An array containing the intents added to this builder.
     */
    @NonNull
    public Intent[] getIntents() {
        Intent[] intents = new Intent[mIntents.size()];
        if (intents.length == 0) return intents;

        intents[0] = new Intent(mIntents.get(0)).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK |
                Intent.FLAG_ACTIVITY_CLEAR_TASK |
                Intent.FLAG_ACTIVITY_TASK_ON_HOME);
        for (int i = 1; i < intents.length; i++) {
            intents[i] = new Intent(mIntents.get(i));
        }
        return intents;
    }
}