/*
 * Copyright (C) 2014 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.telecomm;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.net.Uri;
import android.os.UserHandle;
import android.telecomm.GatewayInfo;
import android.telecomm.PhoneAccount;
import android.telecomm.TelecommConstants;
import android.telecomm.VideoCallProfile;
import android.telephony.PhoneNumberUtils;
import android.telephony.TelephonyManager;
import android.text.TextUtils;

/**
 * OutgoingCallIntentBroadcaster receives CALL and CALL_PRIVILEGED Intents, and broadcasts the
 * ACTION_NEW_OUTGOING_CALL intent. ACTION_NEW_OUTGOING_CALL is an ordered broadcast intent which
 * contains the phone number being dialed. Applications can use this intent to (1) see which numbers
 * are being dialed, (2) redirect a call (change the number being dialed), or (3) prevent a call
 * from being placed.
 *
 * After the other applications have had a chance to see the ACTION_NEW_OUTGOING_CALL intent, it
 * finally reaches the {@link NewOutgoingCallBroadcastIntentReceiver}.
 *
 * Calls where no number is present (like for a CDMA "empty flash" or a nonexistent voicemail
 * number) are exempt from being broadcast.
 *
 * Calls to emergency numbers are still broadcast for informative purposes. The call is placed
 * prior to sending ACTION_NEW_OUTGOING_CALL and cannot be redirected nor prevented.
 */
class NewOutgoingCallIntentBroadcaster {
    /** Required permission for any app that wants to consume ACTION_NEW_OUTGOING_CALL. */
    private static final String PERMISSION = android.Manifest.permission.PROCESS_OUTGOING_CALLS;

    private static final String EXTRA_ACTUAL_NUMBER_TO_DIAL =
            "android.telecomm.extra.ACTUAL_NUMBER_TO_DIAL";

    /**
     * Legacy string constants used to retrieve gateway provider extras from intents. These still
     * need to be copied from the source call intent to the destination intent in order to
     * support third party gateway providers that are still using old string constants in
     * Telephony.
     */
    public static final String EXTRA_GATEWAY_PROVIDER_PACKAGE =
            "com.android.phone.extra.GATEWAY_PROVIDER_PACKAGE";
    public static final String EXTRA_GATEWAY_URI = "com.android.phone.extra.GATEWAY_URI";
    public static final String EXTRA_GATEWAY_ORIGINAL_URI =
            "com.android.phone.extra.GATEWAY_ORIGINAL_URI";

    private static final String SCHEME_TEL = "tel";
    private static final String SCHEME_SIP = "sip";

    private final CallsManager mCallsManager;
    private final ContactInfo mContactInfo;
    private final Intent mIntent;

    NewOutgoingCallIntentBroadcaster(CallsManager callsManager, ContactInfo contactInfo,
            Intent intent) {
        mCallsManager = callsManager;
        mContactInfo = contactInfo;
        mIntent = intent;
    }

    /**
     * Processes the result of the outgoing call broadcast intent, and performs callbacks to
     * the OutgoingCallIntentBroadcasterListener as necessary.
     */
    private class NewOutgoingCallBroadcastIntentReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            Log.v(this, "onReceive: %s", intent);

            // Once the NEW_OUTGOING_CALL broadcast is finished, the resultData is used as the
            // actual number to call. (If null, no call will be placed.)
            String resultHandle = getResultData();
            Log.v(this, "- got number from resultData: %s", Log.pii(resultHandle));

            if (resultHandle == null) {
                Log.v(this, "Call cancelled (null number), returning...");
                return;
            } else if (PhoneNumberUtils.isPotentialLocalEmergencyNumber(context, resultHandle)) {
                Log.w(this, "Cannot modify outgoing call to emergency number %s.", resultHandle);
                return;
            }

            Uri resultHandleUri = Uri.fromParts(
                    PhoneNumberUtils.isUriNumber(resultHandle) ? SCHEME_SIP : SCHEME_TEL,
                    resultHandle,
                    null);

            Uri originalUri = mIntent.getData();

            if (originalUri.getSchemeSpecificPart().equals(resultHandle)) {
                Log.v(this, "Call handle unmodified after new outgoing call intent broadcast.");
            } else {
                Log.v(this, "Retrieved modified handle after outgoing call intent broadcast: "
                        + "Original: %s, Modified: %s",
                        Log.pii(originalUri),
                        Log.pii(resultHandleUri));
            }

            GatewayInfo gatewayInfo = getGateWayInfoFromIntent(intent, resultHandleUri);
            PhoneAccount account = getAccountFromIntent(intent);
            mCallsManager.placeOutgoingCall(resultHandleUri, mContactInfo, gatewayInfo,
                    account,
                    mIntent.getBooleanExtra(TelecommConstants.EXTRA_START_CALL_WITH_SPEAKERPHONE,
                            false),
                    mIntent.getIntExtra(TelecommConstants.EXTRA_START_CALL_WITH_VIDEO_STATE,
                            VideoCallProfile.VIDEO_STATE_AUDIO_ONLY));
        }
    }

    /**
     * Processes the supplied intent and starts the outgoing call broadcast process relevant to the
     * intent.
     *
     * This method will handle three kinds of actions:
     *
     * - CALL (intent launched by all third party dialers)
     * - CALL_PRIVILEGED (intent launched by system apps e.g. system Dialer, voice Dialer)
     * - CALL_EMERGENCY (intent launched by lock screen emergency dialer)
     */
    void processIntent() {
        Log.v(this, "Processing call intent in OutgoingCallIntentBroadcaster.");

        final Context context = TelecommApp.getInstance();
        Intent intent = mIntent;

        String handle = PhoneNumberUtils.getNumberFromIntent(intent, context);

        if (TextUtils.isEmpty(handle)) {
            Log.w(this, "Empty handle obtained from the call intent.");
            return;
        }

        boolean isUriNumber = PhoneNumberUtils.isUriNumber(handle);

        if (!isUriNumber) {
            handle = PhoneNumberUtils.convertKeypadLettersToDigits(handle);
            handle = PhoneNumberUtils.stripSeparators(handle);
        }

        final boolean isPotentialEmergencyNumber = isPotentialEmergencyNumber(context, handle);
        Log.v(this, "isPotentialEmergencyNumber = %s", isPotentialEmergencyNumber);

        rewriteCallIntentAction(intent, isPotentialEmergencyNumber);
        // True for certain types of numbers that are not intended to be intercepted or modified
        // by third parties (e.g. emergency numbers).
        boolean callImmediately = false;

        String action = intent.getAction();
        if (Intent.ACTION_CALL.equals(action)) {
            if (isPotentialEmergencyNumber) {
                Log.w(this, "Cannot call potential emergency number %s with CALL Intent %s.",
                        handle, intent);
                launchSystemDialer(context, intent.getData());
            }
            callImmediately = false;
        } else if (Intent.ACTION_CALL_EMERGENCY.equals(action)) {
            if (!isPotentialEmergencyNumber) {
                Log.w(this, "Cannot call non-potential-emergency number %s with EMERGENCY_CALL "
                        + "Intent %s.", handle, intent);
                return;
            }
            callImmediately = true;
        } else {
            Log.w(this, "Unhandled Intent %s. Ignoring and not placing call.", intent);
            return;
        }

        if (callImmediately) {
            Log.i(this, "Placing call immediately instead of waiting for "
                    + " OutgoingCallBroadcastReceiver: %s", intent);
            String scheme = isUriNumber ? SCHEME_SIP : SCHEME_TEL;
            mCallsManager.placeOutgoingCall(
                    Uri.fromParts(scheme, handle, null), mContactInfo, null, null,
                    mIntent.getBooleanExtra(TelecommConstants.EXTRA_START_CALL_WITH_SPEAKERPHONE,
                            false),
                    mIntent.getIntExtra(TelecommConstants.EXTRA_START_CALL_WITH_VIDEO_STATE,
                            VideoCallProfile.VIDEO_STATE_AUDIO_ONLY));

            // Don't return but instead continue and send the ACTION_NEW_OUTGOING_CALL broadcast
            // so that third parties can still inspect (but not intercept) the outgoing call. When
            // the broadcast finally reaches the OutgoingCallBroadcastReceiver, we'll know not to
            // initiate the call again because of the presence of the EXTRA_ALREADY_CALLED extra.
        }

        broadcastIntent(intent, handle, context, !callImmediately);
    }

    /**
     * Sends a new outgoing call ordered broadcast so that third party apps can cancel the
     * placement of the call or redirect it to a different number.
     *
     * @param originalCallIntent The original call intent.
     * @param handle Call handle that was stored in the original call intent.
     * @param context Valid context to send the ordered broadcast using.
     * @param receiverRequired Whether or not the result from the ordered broadcast should be
     *     processed using a {@link NewOutgoingCallIntentBroadcaster}.
     */
    private void broadcastIntent(
            Intent originalCallIntent,
            String handle,
            Context context,
            boolean receiverRequired) {
        Intent broadcastIntent = new Intent(Intent.ACTION_NEW_OUTGOING_CALL);
        if (handle != null) {
            broadcastIntent.putExtra(Intent.EXTRA_PHONE_NUMBER, handle);
        }

        // Force receivers of this broadcast intent to run at foreground priority because we
        // want to finish processing the broadcast intent as soon as possible.
        broadcastIntent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
        Log.v(this, "Broadcasting intent: %s.", broadcastIntent);

        checkAndCopyProviderExtras(originalCallIntent, broadcastIntent);

        context.sendOrderedBroadcastAsUser(
                broadcastIntent,
                UserHandle.OWNER,
                PERMISSION,
                receiverRequired ? new NewOutgoingCallBroadcastIntentReceiver() : null,
                null,  // scheduler
                Activity.RESULT_OK,  // initialCode
                handle,  // initialData: initial value for the result data (number to be modified)
                null);  // initialExtras
    }

    /**
     * Copy all the expected extras set when a 3rd party gateway provider is to be used, from the
     * source intent to the destination one.
     *
     * @param src Intent which may contain the provider's extras.
     * @param dst Intent where a copy of the extras will be added if applicable.
     */
    public void checkAndCopyProviderExtras(Intent src, Intent dst) {
        if (src == null) {
            return;
        }
        if (hasGatewayProviderExtras(src)) {
            dst.putExtra(EXTRA_GATEWAY_PROVIDER_PACKAGE,
                    src.getStringExtra(EXTRA_GATEWAY_PROVIDER_PACKAGE));
            dst.putExtra(EXTRA_GATEWAY_URI,
                    src.getStringExtra(EXTRA_GATEWAY_URI));
            Log.d(this, "Found and copied gateway provider extras to broadcast intent.");
            return;
        }
        PhoneAccount extraAccount = src.getParcelableExtra(
                TelephonyManager.EXTRA_ACCOUNT);
        if (extraAccount != null) {
            dst.putExtra(TelephonyManager.EXTRA_ACCOUNT, extraAccount);
            Log.d(this, "Found and copied account extra to broadcast intent.");
        }

        Log.d(this, "No provider extras found in call intent.");
    }

    /**
     * Check if valid gateway provider information is stored as extras in the intent
     *
     * @param intent to check for
     * @return true if the intent has all the gateway information extras needed.
     */
    private boolean hasGatewayProviderExtras(Intent intent) {
        final String name = intent.getStringExtra(EXTRA_GATEWAY_PROVIDER_PACKAGE);
        final String uriString = intent.getStringExtra(EXTRA_GATEWAY_URI);

        return !TextUtils.isEmpty(name) && !TextUtils.isEmpty(uriString);
    }

    private static Uri getGatewayUriFromString(String gatewayUriString) {
        return TextUtils.isEmpty(gatewayUriString) ? null : Uri.parse(gatewayUriString);
    }

    /**
     * Extracts gateway provider information from a provided intent..
     *
     * @param intent to extract gateway provider information from.
     * @param trueHandle The actual call handle that the user is trying to dial
     * @return GatewayInfo object containing extracted gateway provider information as well as
     *     the actual handle the user is trying to dial.
     */
    public static GatewayInfo getGateWayInfoFromIntent(Intent intent, Uri trueHandle) {
        if (intent == null) {
            return null;
        }

        // Check if gateway extras are present.
        String gatewayPackageName = intent.getStringExtra(EXTRA_GATEWAY_PROVIDER_PACKAGE);
        Uri gatewayUri = getGatewayUriFromString(intent.getStringExtra(EXTRA_GATEWAY_URI));
        if (!TextUtils.isEmpty(gatewayPackageName) && gatewayUri != null) {
            return new GatewayInfo(gatewayPackageName, gatewayUri, trueHandle);
        }

        return null;
    }

    /**
     * Extracts account/connection provider information from a provided intent..
     *
     * @param intent to extract account information from.
     * @return Account object containing extracted account information
     */
    public static PhoneAccount getAccountFromIntent(Intent intent) {
        if (intent == null) {
            return null;
        }

        return intent.getParcelableExtra(TelephonyManager.EXTRA_ACCOUNT);
    }

    private void launchSystemDialer(Context context, Uri handle) {
        Intent systemDialerIntent = new Intent();
        final Resources resources = context.getResources();
        systemDialerIntent.setClassName(
                resources.getString(R.string.ui_default_package),
                resources.getString(R.string.dialer_default_class));
        systemDialerIntent.setAction(Intent.ACTION_DIAL);
        systemDialerIntent.setData(handle);
        systemDialerIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        Log.v(this, "calling startActivity for default dialer: %s", systemDialerIntent);
        context.startActivity(systemDialerIntent);
    }

    /**
     * Check whether or not this is an emergency number, in order to enforce the restriction
     * that only the CALL_PRIVILEGED and CALL_EMERGENCY intents are allowed to make emergency
     * calls.
     *
     * To prevent malicious 3rd party apps from making emergency calls by passing in an
     * "invalid" number like "9111234" (that isn't technically an emergency number but might
     * still result in an emergency call with some networks), we use
     * isPotentialLocalEmergencyNumber instead of isLocalEmergencyNumber.
     *
     * @param context Valid context
     * @param handle Handle to inspect in order to determine whether or not an emergency number
     * is potentially being dialed
     * @return True if the handle is potentially an emergency number.
     */
    private boolean isPotentialEmergencyNumber(Context context, String handle) {
        Log.v(this, "Checking restrictions for number : %s", Log.pii(handle));
        return (handle != null) && PhoneNumberUtils.isPotentialLocalEmergencyNumber(context,handle);
    }

    /**
     * Given a call intent and whether or not the number to dial is an emergency number, rewrite
     * the call intent action to an appropriate one.
     *
     * @param intent Intent to rewrite the action for
     * @param isPotentialEmergencyNumber Whether or not the handle is potentially an emergency
     * number.
     */
    private void rewriteCallIntentAction(Intent intent, boolean isPotentialEmergencyNumber) {
        if (CallActivity.class.getName().equals(intent.getComponent().getClassName())) {
            // If we were launched directly from the CallActivity, not one of its more privileged
            // aliases, then make sure that only the non-privileged actions are allowed.
            if (!Intent.ACTION_CALL.equals(intent.getAction())) {
                Log.w(this, "Attempt to deliver non-CALL action; forcing to CALL");
                intent.setAction(Intent.ACTION_CALL);
            }
        }

        String action = intent.getAction();

        /* Change CALL_PRIVILEGED into CALL or CALL_EMERGENCY as needed. */
        if (Intent.ACTION_CALL_PRIVILEGED.equals(action)) {
            if (isPotentialEmergencyNumber) {
                Log.i(this, "ACTION_CALL_PRIVILEGED is used while the number is a potential"
                        + " emergency number. Using ACTION_CALL_EMERGENCY as an action instead.");
                action = Intent.ACTION_CALL_EMERGENCY;
            } else {
                action = Intent.ACTION_CALL;
            }
            Log.v(this, " - updating action from CALL_PRIVILEGED to %s", action);
            intent.setAction(action);
        }
    }
}