/*
 * Copyright (C) 2019 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.services.telephony;

import android.annotation.NonNull;
import android.os.Bundle;
import android.telecom.Conference;
import android.telecom.Connection;
import android.telecom.PhoneAccountHandle;
import android.telecom.TelecomManager;
import android.telephony.ServiceState;

import java.util.Collections;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Base class for the various Telephony {@link Conference} implementations ({@link CdmaConference},
 * {@link TelephonyConference}, and {@link ImsConference}).  Adds some common listener code which
 * all of these conferences use.
 */
public class TelephonyConferenceBase extends Conference {
    private static final String TAG = "TelephonyConferenceBase";

    /**
     * Listener for conference events.
     */
    public abstract static class TelephonyConferenceListener {
        /**
         * Listener called when a connection is added or removed from a conference.
         * @param connection The connection.
         */
        public void onConferenceMembershipChanged(Connection connection) {}

        /**
         * Listener called when there conference call state changes.
         * @param conference The conference.
         * @param oldState previous state of conference call.
         * @param newState new state of conference call.
         */
        public void onStateChanged(Conference conference, int oldState, int newState) {}

        /**
         * Listener called when a conference is destroyed.
         * @param conference The conference.
         */
        public void onDestroyed(Conference conference) {}

        /**
         * Listener called when a conference either reaches capacity or is no longer at capacity.
         */
        public void onConferenceCapacityChanged() {}
    }

    private final Set<TelephonyConferenceListener> mListeners = Collections.newSetFromMap(
            new ConcurrentHashMap<>(8, 0.9f, 1));

    /**
     * Adds a listener to this conference.
     * @param listener The listener.
     */
    public void addTelephonyConferenceListener(@NonNull TelephonyConferenceListener listener) {
        mListeners.add(listener);
    }

    /**
     * Removes a listener from this conference.
     * @param listener The listener.
     */
    public void removeTelephonyConferenceListener(@NonNull TelephonyConferenceListener listener) {
        mListeners.remove(listener);
    }

    /**
     * Constructs a new Conference with a mandatory {@link PhoneAccountHandle}
     *
     * @param phoneAccount The {@code PhoneAccountHandle} associated with the conference.
     */
    public TelephonyConferenceBase(PhoneAccountHandle phoneAccount) {
        super(phoneAccount);
    }

    /**
     * Adds a connection to this {@link Conference}.
     * <p>
     * Should be used in place of {@link Conference#addConnection(Connection)} to ensure
     * {@link TelephonyConferenceListener}s are informed of the change.
     *
     * @param connection The connection.
     */
    public void addTelephonyConnection(@NonNull Connection connection) {
        addConnection(connection);
        notifyConferenceMembershipChanged(connection);
    }

    /**
     * Removes a {@link Connection} from this {@link Conference}.
     * <p>
     * Should be used instead of {@link Conference#removeConnection(Connection)} to ensure
     * {@link TelephonyConferenceListener}s are notified of the change.
     *
     * @param connection The connection.
     */
    public void removeTelephonyConnection(@NonNull Connection connection) {
        removeConnection(connection);
        notifyConferenceMembershipChanged(connection);
    }

    /**
     * Destroys the current {@link Conference} and notifies {@link TelephonyConferenceListener}s of
     * the change to conference membership.
     * <p>
     * Should be used instead of {@link Conference#destroy()} to ensure telephony listeners are
     * notified.
     */
    public void destroyTelephonyConference() {
        // Conference#removeConnection modifies the list of participants, so we need to use an
        // iterator here to ensure all participants are removed.
        // Technically Conference#destroy does this, but we want to notify listeners of the state
        // change so we'll do it here first.
        Iterator<Connection> connectionIterator = getConnections().iterator();
        while (connectionIterator.hasNext()) {
            removeTelephonyConnection(connectionIterator.next());
        }
        destroy();
        notifyDestroyed();
    }

    /**
     * Sets state to be on hold.
     */
     public final void setConferenceOnHold() {
         int oldState = getState();
         if (oldState == Connection.STATE_HOLDING) {
             return;
         }
         setOnHold();
         notifyStateChanged(oldState, getState());
     }

     /**
      * Sets state to be dialing.
      */
     public final void setConferenceOnDialing() {
         int oldState = getState();
         if (oldState == Connection.STATE_DIALING) {
             return;
         }
         setDialing();
         notifyStateChanged(oldState, getState());
     }

     /**
      * Sets state to be ringing.
      */
     public final void setConferenceOnRinging() {
         int oldState = getState();
         if (oldState == Connection.STATE_RINGING) {
             return;
         }
         setRinging();
         notifyStateChanged(oldState, getState());
     }

     /**
      * Sets state to be active.
      */
     public final void setConferenceOnActive() {
         int oldState = getState();
         if (oldState == Connection.STATE_ACTIVE) {
             return;
         }
         setActive();
         notifyStateChanged(oldState, getState());
     }

    /**
     * Updates RIL voice radio technology used for current conference after its creation.
     */
    public void updateCallRadioTechAfterCreation() {
        final Connection primaryConnection = getPrimaryConnection();
        if (primaryConnection != null && primaryConnection instanceof TelephonyConnection) {
            TelephonyConnection telephonyConnection = (TelephonyConnection) primaryConnection;
            Bundle newExtras = new Bundle();
            newExtras.putInt(TelecomManager.EXTRA_CALL_NETWORK_TYPE,
                    ServiceState.rilRadioTechnologyToNetworkType(
                            telephonyConnection.getCallRadioTech()));
            putExtras(newExtras);
        } else {
            Log.w(TAG, "No primary connection found while updateCallRadioTechAfterCreation");
        }
    }

    /**
     * Removes the specified capability from the set of capabilities of this {@code Conference}.
     *
     * @param capability The capability to remove from the set.
     */
    public void removeCapability(int capability) {
        int newCapabilities = getConnectionCapabilities();
        newCapabilities &= ~capability;

        setConnectionCapabilities(newCapabilities);
    }

    /**
     * Adds the specified capability to the set of capabilities of this {@code Conference}.
     *
     * @param capability The capability to add to the set.
     */
    public void addCapability(int capability) {
        int newCapabilities = getConnectionCapabilities();
        newCapabilities |= capability;

        setConnectionCapabilities(newCapabilities);
    }

    /**
     * Notifies {@link TelephonyConferenceListener}s of a connection being added or removed from
     * the conference.
     * @param connection The conference.
     */
    private void notifyConferenceMembershipChanged(@NonNull Connection connection) {
        for (TelephonyConferenceListener listener : mListeners) {
            listener.onConferenceMembershipChanged(connection);
        }
    }

    /**
     * Notifies the {@link TelephonyConferenceListener}s when the capacity of the conference has
     * changed.
     */
    public void notifyConferenceCapacityChanged() {
        mListeners.forEach(l -> l.onConferenceCapacityChanged());
    }

    /**
     * Notifies {@link TelephonyConferenceListener}s of a conference being destroyed
     */
    private void notifyDestroyed() {
        for (TelephonyConferenceListener listener : mListeners) {
            listener.onDestroyed(this);
        }
    }

    private void notifyStateChanged(int oldState, int newState) {
        if (oldState != newState) {
            for (TelephonyConferenceListener listener : mListeners) {
                listener.onStateChanged(this, oldState, newState);
            }
        }
    }
}