/*
 * Copyright 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 android.telecom;

import android.content.Context;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Build;
import android.telecom.Logging.EventManager;
import android.telecom.Logging.Session;
import android.telecom.Logging.SessionManager;
import android.telephony.PhoneNumberUtils;
import android.text.TextUtils;

import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.util.IndentingPrintWriter;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.IllegalFormatException;
import java.util.Locale;

Manages logging for the entire module.
@hide
/**
 * Manages logging for the entire module.
 *
 * @hide
 */
public class Log {

    private static final long EXTENDED_LOGGING_DURATION_MILLIS = 60000 * 30; // 30 minutes

    private static final int EVENTS_TO_CACHE = 10;
    private static final int EVENTS_TO_CACHE_DEBUG = 20;

    // Generic tag for all Telecom logging
    @VisibleForTesting
    public static String TAG = "TelecomFramework";
    public static boolean DEBUG = isLoggable(android.util.Log.DEBUG);
    public static boolean INFO = isLoggable(android.util.Log.INFO);
    public static boolean VERBOSE = isLoggable(android.util.Log.VERBOSE);
    public static boolean WARN = isLoggable(android.util.Log.WARN);
    public static boolean ERROR = isLoggable(android.util.Log.ERROR);

    private static final boolean FORCE_LOGGING = false; /* STOP SHIP if true */
    private static final boolean USER_BUILD = Build.IS_USER;

    // Used to synchronize singleton logging lazy initialization
    private static final Object sSingletonSync = new Object();
    private static EventManager sEventManager;
    private static SessionManager sSessionManager;

    
Tracks whether user-activated extended logging is enabled.
/**
     * Tracks whether user-activated extended logging is enabled.
     */
    private static boolean sIsUserExtendedLoggingEnabled = false;

    
The time when user-activated extended logging should be ended.  Used to determine when
extended logging should automatically be disabled.
/**
     * The time when user-activated extended logging should be ended.  Used to determine when
     * extended logging should automatically be disabled.
     */
    private static long sUserExtendedLoggingStopTime = 0;

    private Log() {
    }

    public static void d(String prefix, String format, Object... args) {
        if (sIsUserExtendedLoggingEnabled) {
            maybeDisableLogging();
            android.util.Slog.i(TAG, buildMessage(prefix, format, args));
        } else if (DEBUG) {
            android.util.Slog.d(TAG, buildMessage(prefix, format, args));
        }
    }

    public static void d(Object objectPrefix, String format, Object... args) {
        if (sIsUserExtendedLoggingEnabled) {
            maybeDisableLogging();
            android.util.Slog.i(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
        } else if (DEBUG) {
            android.util.Slog.d(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
        }
    }

    public static void i(String prefix, String format, Object... args) {
        if (INFO) {
            android.util.Slog.i(TAG, buildMessage(prefix, format, args));
        }
    }

    public static void i(Object objectPrefix, String format, Object... args) {
        if (INFO) {
            android.util.Slog.i(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
        }
    }

    public static void v(String prefix, String format, Object... args) {
        if (sIsUserExtendedLoggingEnabled) {
            maybeDisableLogging();
            android.util.Slog.i(TAG, buildMessage(prefix, format, args));
        } else if (VERBOSE) {
            android.util.Slog.v(TAG, buildMessage(prefix, format, args));
        }
    }

    public static void v(Object objectPrefix, String format, Object... args) {
        if (sIsUserExtendedLoggingEnabled) {
            maybeDisableLogging();
            android.util.Slog.i(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
        } else if (VERBOSE) {
            android.util.Slog.v(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
        }
    }

    public static void w(String prefix, String format, Object... args) {
        if (WARN) {
            android.util.Slog.w(TAG, buildMessage(prefix, format, args));
        }
    }

    public static void w(Object objectPrefix, String format, Object... args) {
        if (WARN) {
            android.util.Slog.w(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
        }
    }

    public static void e(String prefix, Throwable tr, String format, Object... args) {
        if (ERROR) {
            android.util.Slog.e(TAG, buildMessage(prefix, format, args), tr);
        }
    }

    public static void e(Object objectPrefix, Throwable tr, String format, Object... args) {
        if (ERROR) {
            android.util.Slog.e(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args),
                    tr);
        }
    }

    public static void wtf(String prefix, Throwable tr, String format, Object... args) {
        android.util.Slog.wtf(TAG, buildMessage(prefix, format, args), tr);
    }

    public static void wtf(Object objectPrefix, Throwable tr, String format, Object... args) {
        android.util.Slog.wtf(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args),
                tr);
    }

    public static void wtf(String prefix, String format, Object... args) {
        String msg = buildMessage(prefix, format, args);
        android.util.Slog.wtf(TAG, msg, new IllegalStateException(msg));
    }

    public static void wtf(Object objectPrefix, String format, Object... args) {
        String msg = buildMessage(getPrefixFromObject(objectPrefix), format, args);
        android.util.Slog.wtf(TAG, msg, new IllegalStateException(msg));
    }

    
The ease of use methods below only act mostly as proxies to the Session and Event Loggers.
They also control the lazy loaders of the singleton instances, which will never be loaded if
the proxy methods aren't used.
Please see each method's documentation inside of their respective implementations in the
loggers.
/**
     * The ease of use methods below only act mostly as proxies to the Session and Event Loggers.
     * They also control the lazy loaders of the singleton instances, which will never be loaded if
     * the proxy methods aren't used.
     *
     * Please see each method's documentation inside of their respective implementations in the
     * loggers.
     */

    public static void setSessionContext(Context context) {
        getSessionManager().setContext(context);
    }

    public static void startSession(String shortMethodName) {
        getSessionManager().startSession(shortMethodName, null);
    }

    public static void startSession(Session.Info info, String shortMethodName) {
        getSessionManager().startSession(info, shortMethodName, null);
    }

    public static void startSession(String shortMethodName, String callerIdentification) {
        getSessionManager().startSession(shortMethodName, callerIdentification);
    }

    public static void startSession(Session.Info info, String shortMethodName,
            String callerIdentification) {
        getSessionManager().startSession(info, shortMethodName, callerIdentification);
    }

    public static Session createSubsession() {
        return getSessionManager().createSubsession();
    }

    public static Session.Info getExternalSession() {
        return getSessionManager().getExternalSession();
    }

    public static void cancelSubsession(Session subsession) {
        getSessionManager().cancelSubsession(subsession);
    }

    public static void continueSession(Session subsession, String shortMethodName) {
        getSessionManager().continueSession(subsession, shortMethodName);
    }

    public static void endSession() {
        getSessionManager().endSession();
    }

    public static void registerSessionListener(SessionManager.ISessionListener l) {
        getSessionManager().registerSessionListener(l);
    }

    public static String getSessionId() {
        // If the Session logger has not been initialized, then there have been no sessions logged.
        // Don't load it now!
        synchronized (sSingletonSync) {
            if (sSessionManager != null) {
                return getSessionManager().getSessionId();
            } else {
                return "";
            }
        }
    }

    public static void addEvent(EventManager.Loggable recordEntry, String event) {
        getEventManager().event(recordEntry, event, null);
    }

    public static void addEvent(EventManager.Loggable recordEntry, String event, Object data) {
        getEventManager().event(recordEntry, event, data);
    }

    public static void addEvent(EventManager.Loggable recordEntry, String event, String format,
            Object... args) {
        getEventManager().event(recordEntry, event, format, args);
    }

    public static void registerEventListener(EventManager.EventListener e) {
        getEventManager().registerEventListener(e);
    }

    public static void addRequestResponsePair(EventManager.TimedEventPair p) {
        getEventManager().addRequestResponsePair(p);
    }

    public static void dumpEvents(IndentingPrintWriter pw) {
        // If the Events logger has not been initialized, then there have been no events logged.
        // Don't load it now!
        synchronized (sSingletonSync) {
            if (sEventManager != null) {
                getEventManager().dumpEvents(pw);
            } else {
                pw.println("No Historical Events Logged.");
            }
        }
    }

    
Dumps the events in a timeline format.
Params:
pw – The IndentingPrintWriter to write to.
@hide
/**
     * Dumps the events in a timeline format.
     * @param pw The {@link IndentingPrintWriter} to write to.
     * @hide
     */
    public static void dumpEventsTimeline(IndentingPrintWriter pw) {
        // If the Events logger has not been initialized, then there have been no events logged.
        // Don't load it now!
        synchronized (sSingletonSync) {
            if (sEventManager != null) {
                getEventManager().dumpEventsTimeline(pw);
            } else {
                pw.println("No Historical Events Logged.");
            }
        }
    }

    
Enable or disable extended telecom logging.
Params:
isExtendedLoggingEnabled – true if extended logging should be enabled, false if it should be disabled./**
     * Enable or disable extended telecom logging.
     *
     * @param isExtendedLoggingEnabled {@code true} if extended logging should be enabled,
     *          {@code false} if it should be disabled.
     */
    public static void setIsExtendedLoggingEnabled(boolean isExtendedLoggingEnabled) {
        // If the state hasn't changed, bail early.
        if (sIsUserExtendedLoggingEnabled == isExtendedLoggingEnabled) {
            return;
        }

        if (sEventManager != null) {
            sEventManager.changeEventCacheSize(isExtendedLoggingEnabled ?
                    EVENTS_TO_CACHE_DEBUG : EVENTS_TO_CACHE);
        }

        sIsUserExtendedLoggingEnabled = isExtendedLoggingEnabled;
        if (sIsUserExtendedLoggingEnabled) {
            sUserExtendedLoggingStopTime = System.currentTimeMillis()
                    + EXTENDED_LOGGING_DURATION_MILLIS;
        } else {
            sUserExtendedLoggingStopTime = 0;
        }
    }

    private static EventManager getEventManager() {
        // Checking for null again outside of synchronization because we only need to synchronize
        // during the lazy loading of the events logger. We don't need to synchronize elsewhere.
        if (sEventManager == null) {
            synchronized (sSingletonSync) {
                if (sEventManager == null) {
                    sEventManager = new EventManager(Log::getSessionId);
                    return sEventManager;
                }
            }
        }
        return sEventManager;
    }

    @VisibleForTesting
    public static SessionManager getSessionManager() {
        // Checking for null again outside of synchronization because we only need to synchronize
        // during the lazy loading of the session logger. We don't need to synchronize elsewhere.
        if (sSessionManager == null) {
            synchronized (sSingletonSync) {
                if (sSessionManager == null) {
                    sSessionManager = new SessionManager();
                    return sSessionManager;
                }
            }
        }
        return sSessionManager;
    }

    public static void setTag(String tag) {
        TAG = tag;
        DEBUG = isLoggable(android.util.Log.DEBUG);
        INFO = isLoggable(android.util.Log.INFO);
        VERBOSE = isLoggable(android.util.Log.VERBOSE);
        WARN = isLoggable(android.util.Log.WARN);
        ERROR = isLoggable(android.util.Log.ERROR);
    }

    
If user enabled extended logging is enabled and the time limit has passed, disables the
extended logging.
/**
     * If user enabled extended logging is enabled and the time limit has passed, disables the
     * extended logging.
     */
    private static void maybeDisableLogging() {
        if (!sIsUserExtendedLoggingEnabled) {
            return;
        }

        if (sUserExtendedLoggingStopTime < System.currentTimeMillis()) {
            sUserExtendedLoggingStopTime = 0;
            sIsUserExtendedLoggingEnabled = false;
        }
    }

    public static boolean isLoggable(int level) {
        return FORCE_LOGGING || android.util.Log.isLoggable(TAG, level);
    }

    public static String piiHandle(Object pii) {
        if (pii == null || VERBOSE) {
            return String.valueOf(pii);
        }

        StringBuilder sb = new StringBuilder();
        if (pii instanceof Uri) {
            Uri uri = (Uri) pii;
            String scheme = uri.getScheme();

            if (!TextUtils.isEmpty(scheme)) {
                sb.append(scheme).append(":");
            }

            String textToObfuscate = uri.getSchemeSpecificPart();
            if (PhoneAccount.SCHEME_TEL.equals(scheme)) {
                for (int i = 0; i < textToObfuscate.length(); i++) {
                    char c = textToObfuscate.charAt(i);
                    sb.append(PhoneNumberUtils.isDialable(c) ? "*" : c);
                }
            } else if (PhoneAccount.SCHEME_SIP.equals(scheme)) {
                for (int i = 0; i < textToObfuscate.length(); i++) {
                    char c = textToObfuscate.charAt(i);
                    if (c != '@' && c != '.') {
                        c = '*';
                    }
                    sb.append(c);
                }
            } else {
                sb.append(pii(pii));
            }
        }

        return sb.toString();
    }

    
Redact personally identifiable information for production users.
If we are running in verbose mode, return the original string,
and return "***" otherwise.
/**
     * Redact personally identifiable information for production users.
     * If we are running in verbose mode, return the original string,
     * and return "***" otherwise.
     */
    public static String pii(Object pii) {
        if (pii == null || VERBOSE) {
            return String.valueOf(pii);
        }
        return "***";
    }

    private static String getPrefixFromObject(Object obj) {
        return obj == null ? "<null>" : obj.getClass().getSimpleName();
    }

    private static String buildMessage(String prefix, String format, Object... args) {
        // Incorporate thread ID and calling method into prefix
        String sessionName = getSessionId();
        String sessionPostfix = TextUtils.isEmpty(sessionName) ? "" : ": " + sessionName;

        String msg;
        try {
            msg = (args == null || args.length == 0) ? format
                    : String.format(Locale.US, format, args);
        } catch (IllegalFormatException ife) {
            e(TAG, ife, "Log: IllegalFormatException: formatString='%s' numArgs=%d", format,
                    args.length);
            msg = format + " (An error occurred while formatting the message.)";
        }
        return String.format(Locale.US, "%s: %s%s", prefix, msg, sessionPostfix);
    }
}