/*
 * Copyright (C) 2018 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.systemui.statusbar;

import android.annotation.NonNull;
import android.annotation.Nullable;
import android.os.Handler;
import android.os.Looper;
import android.os.SystemClock;
import android.util.ArrayMap;
import android.util.ArraySet;
import android.util.Log;
import android.view.accessibility.AccessibilityEvent;

import com.android.internal.annotations.VisibleForTesting;
import com.android.systemui.statusbar.notification.collection.NotificationEntry;
import com.android.systemui.statusbar.notification.row.NotificationContentInflater.InflationFlag;

import java.util.stream.Stream;

/**
 * A manager which contains notification alerting functionality, providing methods to add and
 * remove notifications that appear on screen for a period of time and dismiss themselves at the
 * appropriate time.  These include heads up notifications and ambient pulses.
 */
public abstract class AlertingNotificationManager implements NotificationLifetimeExtender {
    private static final String TAG = "AlertNotifManager";
    protected final Clock mClock = new Clock();
    protected final ArrayMap<String, AlertEntry> mAlertEntries = new ArrayMap<>();

    /**
     * This is the list of entries that have already been removed from the
     * NotificationManagerService side, but we keep it to prevent the UI from looking weird and
     * will remove when possible. See {@link NotificationLifetimeExtender}
     */
    protected final ArraySet<NotificationEntry> mExtendedLifetimeAlertEntries = new ArraySet<>();

    protected NotificationSafeToRemoveCallback mNotificationLifetimeFinishedCallback;
    protected int mMinimumDisplayTime;
    protected int mAutoDismissNotificationDecay;
    @VisibleForTesting
    public Handler mHandler = new Handler(Looper.getMainLooper());

    /**
     * Called when posting a new notification that should alert the user and appear on screen.
     * Adds the notification to be managed.
     * @param entry entry to show
     */
    public void showNotification(@NonNull NotificationEntry entry) {
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "showNotification");
        }
        addAlertEntry(entry);
        updateNotification(entry.key, true /* alert */);
        entry.setInterruption();
    }

    /**
     * Try to remove the notification.  May not succeed if the notification has not been shown long
     * enough and needs to be kept around.
     * @param key the key of the notification to remove
     * @param releaseImmediately force a remove regardless of earliest removal time
     * @return true if notification is removed, false otherwise
     */
    public boolean removeNotification(@NonNull String key, boolean releaseImmediately) {
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "removeNotification");
        }
        AlertEntry alertEntry = mAlertEntries.get(key);
        if (alertEntry == null) {
            return true;
        }
        if (releaseImmediately || canRemoveImmediately(key)) {
            removeAlertEntry(key);
        } else {
            alertEntry.removeAsSoonAsPossible();
            return false;
        }
        return true;
    }

    /**
     * Called when the notification state has been updated.
     * @param key the key of the entry that was updated
     * @param alert whether the notification should alert again and force reevaluation of
     *              removal time
     */
    public void updateNotification(@NonNull String key, boolean alert) {
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "updateNotification");
        }

        AlertEntry alertEntry = mAlertEntries.get(key);
        if (alertEntry == null) {
            // the entry was released before this update (i.e by a listener) This can happen
            // with the groupmanager
            return;
        }

        alertEntry.mEntry.sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED);
        if (alert) {
            alertEntry.updateEntry(true /* updatePostTime */);
        }
    }

    /**
     * Clears all managed notifications.
     */
    public void releaseAllImmediately() {
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "releaseAllImmediately");
        }
        // A copy is necessary here as we are changing the underlying map.  This would cause
        // undefined behavior if we iterated over the key set directly.
        ArraySet<String> keysToRemove = new ArraySet<>(mAlertEntries.keySet());
        for (String key : keysToRemove) {
            removeAlertEntry(key);
        }
    }

    /**
     * Returns the entry if it is managed by this manager.
     * @param key key of notification
     * @return the entry
     */
    @Nullable
    public NotificationEntry getEntry(@NonNull String key) {
        AlertEntry entry = mAlertEntries.get(key);
        return entry != null ? entry.mEntry : null;
    }

    /**
     * Returns the stream of all current notifications managed by this manager.
     * @return all entries
     */
    @NonNull
    public Stream<NotificationEntry> getAllEntries() {
        return mAlertEntries.values().stream().map(headsUpEntry -> headsUpEntry.mEntry);
    }

    /**
     * Whether or not there are any active alerting notifications.
     * @return true if there is an alert, false otherwise
     */
    public boolean hasNotifications() {
        return !mAlertEntries.isEmpty();
    }

    /**
     * Whether or not the given notification is alerting and managed by this manager.
     * @return true if the notification is alerting
     */
    public boolean isAlerting(@NonNull String key) {
        return mAlertEntries.containsKey(key);
    }

    /**
     * Gets the flag corresponding to the notification content view this alert manager will show.
     *
     * @return flag corresponding to the content view
     */
    public abstract @InflationFlag int getContentFlag();

    /**
     * Add a new entry and begin managing it.
     * @param entry the entry to add
     */
    protected final void addAlertEntry(@NonNull NotificationEntry entry) {
        AlertEntry alertEntry = createAlertEntry();
        alertEntry.setEntry(entry);
        mAlertEntries.put(entry.key, alertEntry);
        onAlertEntryAdded(alertEntry);
        entry.sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED);
    }

    /**
     * Manager-specific logic that should occur when an entry is added.
     * @param alertEntry alert entry added
     */
    protected abstract void onAlertEntryAdded(@NonNull AlertEntry alertEntry);

    /**
     * Remove a notification and reset the alert entry.
     * @param key key of notification to remove
     */
    protected final void removeAlertEntry(@NonNull String key) {
        AlertEntry alertEntry = mAlertEntries.get(key);
        if (alertEntry == null) {
            return;
        }
        NotificationEntry entry = alertEntry.mEntry;
        mAlertEntries.remove(key);
        onAlertEntryRemoved(alertEntry);
        entry.sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED);
        alertEntry.reset();
        if (mExtendedLifetimeAlertEntries.contains(entry)) {
            if (mNotificationLifetimeFinishedCallback != null) {
                mNotificationLifetimeFinishedCallback.onSafeToRemove(key);
            }
            mExtendedLifetimeAlertEntries.remove(entry);
        }
    }

    /**
     * Manager-specific logic that should occur when an alert entry is removed.
     * @param alertEntry alert entry removed
     */
    protected abstract void onAlertEntryRemoved(@NonNull AlertEntry alertEntry);

    /**
     * Returns a new alert entry instance.
     * @return a new AlertEntry
     */
    protected AlertEntry createAlertEntry() {
        return new AlertEntry();
    }

    /**
     * Whether or not the alert can be removed currently.  If it hasn't been on screen long enough
     * it should not be removed unless forced
     * @param key the key to check if removable
     * @return true if the alert entry can be removed
     */
    protected boolean canRemoveImmediately(String key) {
        AlertEntry alertEntry = mAlertEntries.get(key);
        return alertEntry == null || alertEntry.wasShownLongEnough()
                || alertEntry.mEntry.isRowDismissed();
    }

    ///////////////////////////////////////////////////////////////////////////////////////////////
    // NotificationLifetimeExtender Methods

    @Override
    public void setCallback(NotificationSafeToRemoveCallback callback) {
        mNotificationLifetimeFinishedCallback = callback;
    }

    @Override
    public boolean shouldExtendLifetime(NotificationEntry entry) {
        return !canRemoveImmediately(entry.key);
    }

    @Override
    public void setShouldManageLifetime(NotificationEntry entry, boolean shouldExtend) {
        if (shouldExtend) {
            mExtendedLifetimeAlertEntries.add(entry);
            // We need to make sure that entries are stopping to alert eventually, let's remove
            // this as soon as possible.
            AlertEntry alertEntry = mAlertEntries.get(entry.key);
            alertEntry.removeAsSoonAsPossible();
        } else {
            mExtendedLifetimeAlertEntries.remove(entry);
        }
    }
    ///////////////////////////////////////////////////////////////////////////////////////////////

    protected class AlertEntry implements Comparable<AlertEntry> {
        @Nullable public NotificationEntry mEntry;
        public long mPostTime;
        public long mEarliestRemovaltime;

        @Nullable protected Runnable mRemoveAlertRunnable;

        public void setEntry(@NonNull final NotificationEntry entry) {
            setEntry(entry, () -> removeAlertEntry(entry.key));
        }

        public void setEntry(@NonNull final NotificationEntry entry,
                @Nullable Runnable removeAlertRunnable) {
            mEntry = entry;
            mRemoveAlertRunnable = removeAlertRunnable;

            mPostTime = calculatePostTime();
            updateEntry(true /* updatePostTime */);
        }

        /**
         * Updates an entry's removal time.
         * @param updatePostTime whether or not to refresh the post time
         */
        public void updateEntry(boolean updatePostTime) {
            if (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, "updateEntry");
            }

            long currentTime = mClock.currentTimeMillis();
            mEarliestRemovaltime = currentTime + mMinimumDisplayTime;
            if (updatePostTime) {
                mPostTime = Math.max(mPostTime, currentTime);
            }
            removeAutoRemovalCallbacks();

            if (!isSticky()) {
                long finishTime = calculateFinishTime();
                long removeDelay = Math.max(finishTime - currentTime, mMinimumDisplayTime);
                mHandler.postDelayed(mRemoveAlertRunnable, removeDelay);
            }
        }

        /**
         * Whether or not the notification is "sticky" i.e. should stay on screen regardless
         * of the timer and should be removed externally.
         * @return true if the notification is sticky
         */
        protected boolean isSticky() {
            return false;
        }

        /**
         * Whether the notification has been on screen long enough and can be removed.
         * @return true if the notification has been on screen long enough
         */
        public boolean wasShownLongEnough() {
            return mEarliestRemovaltime < mClock.currentTimeMillis();
        }

        @Override
        public int compareTo(@NonNull AlertEntry alertEntry) {
            return (mPostTime < alertEntry.mPostTime)
                    ? 1 : ((mPostTime == alertEntry.mPostTime)
                            ? mEntry.key.compareTo(alertEntry.mEntry.key) : -1);
        }

        public void reset() {
            mEntry = null;
            removeAutoRemovalCallbacks();
            mRemoveAlertRunnable = null;
        }

        /**
         * Clear any pending removal runnables.
         */
        public void removeAutoRemovalCallbacks() {
            if (mRemoveAlertRunnable != null) {
                mHandler.removeCallbacks(mRemoveAlertRunnable);
            }
        }

        /**
         * Remove the alert at the earliest allowed removal time.
         */
        public void removeAsSoonAsPossible() {
            if (mRemoveAlertRunnable != null) {
                removeAutoRemovalCallbacks();
                mHandler.postDelayed(mRemoveAlertRunnable,
                        mEarliestRemovaltime - mClock.currentTimeMillis());
            }
        }

        /**
         * Calculate what the post time of a notification is at some current time.
         * @return the post time
         */
        protected long calculatePostTime() {
            return mClock.currentTimeMillis();
        }

        /**
         * Calculate when the notification should auto-dismiss itself.
         * @return the finish time
         */
        protected long calculateFinishTime() {
            return mPostTime + mAutoDismissNotificationDecay;
        }
    }

    protected final static class Clock {
        public long currentTimeMillis() {
            return SystemClock.elapsedRealtime();
        }
    }
}