/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.gecko;

import org.mozilla.gecko.mozglue.RobocopTarget;
import org.mozilla.gecko.TelemetryContract.Event;
import org.mozilla.gecko.TelemetryContract.Method;
import org.mozilla.gecko.TelemetryContract.Reason;
import org.mozilla.gecko.TelemetryContract.Session;

import android.os.SystemClock;
import android.util.Log;

/**
 * All telemetry times are relative to one of two clocks:
 *
 * * Real time since the device was booted, including deep sleep. Use this
 *   as a substitute for wall clock.
 * * Uptime since the device was booted, excluding deep sleep. Use this to
 *   avoid timing a user activity when their phone is in their pocket!
 *
 * The majority of methods in this class are defined in terms of real time.
 */
@RobocopTarget
public class Telemetry {
    private static final String LOGTAG = "Telemetry";

    public static long uptime() {
        return SystemClock.uptimeMillis();
    }

    public static long realtime() {
        return SystemClock.elapsedRealtime();
    }

    // Define new histograms in:
    // toolkit/components/telemetry/Histograms.json
    public static void HistogramAdd(String name, int value) {
        GeckoEvent event = GeckoEvent.createTelemetryHistogramAddEvent(name, value);
        GeckoAppShell.sendEventToGecko(event);
    }

    public abstract static class Timer {
        private final long mStartTime;
        private final String mName;

        private volatile boolean mHasFinished = false;
        private volatile long mElapsed = -1;

        protected abstract long now();

        public Timer(String name) {
            mName = name;
            mStartTime = now();
        }

        public void cancel() {
            mHasFinished = true;
        }

        public long getElapsed() {
          return mElapsed;
        }

        public void stop() {
            // Only the first stop counts.
            if (mHasFinished) {
                return;
            }

            mHasFinished = true;

            final long elapsed = now() - mStartTime;
            if (elapsed < 0) {
                Log.e(LOGTAG, "Current time less than start time -- clock shenanigans?");
                return;
            }

            mElapsed = elapsed;
            if (elapsed > Integer.MAX_VALUE) {
                Log.e(LOGTAG, "Duration of " + elapsed + "ms is too great to add to histogram.");
                return;
            }

            HistogramAdd(mName, (int)(elapsed));
        }
    }

    public static class RealtimeTimer extends Timer {
        public RealtimeTimer(String name) {
            super(name);
        }

        @Override
        protected long now() {
            return Telemetry.realtime();
        }
    }

    public static class UptimeTimer extends Timer {
        public UptimeTimer(String name) {
            super(name);
        }

        @Override
        protected long now() {
            return Telemetry.uptime();
        }
    }

    public static void startUISession(final Session session, final String sessionNameSuffix) {
        final String sessionName = getSessionName(session, sessionNameSuffix);

        Log.d(LOGTAG, "StartUISession: " + sessionName);
        final GeckoEvent geckoEvent =
                GeckoEvent.createTelemetryUISessionStartEvent(sessionName, realtime());
        GeckoAppShell.sendEventToGecko(geckoEvent);
    }

    public static void startUISession(final Session session) {
        startUISession(session, null);
    }

    public static void stopUISession(final Session session, final String sessionNameSuffix,
            final Reason reason) {
        final String sessionName = getSessionName(session, sessionNameSuffix);

        Log.d(LOGTAG, "StopUISession: " + sessionName + ", reason=" + reason);
        final GeckoEvent geckoEvent = GeckoEvent.createTelemetryUISessionStopEvent(
                sessionName, reason.toString(), realtime());
        GeckoAppShell.sendEventToGecko(geckoEvent);
    }

    public static void stopUISession(final Session session, final Reason reason) {
        stopUISession(session, null, reason);
    }

    public static void stopUISession(final Session session, final String sessionNameSuffix) {
        stopUISession(session, sessionNameSuffix, Reason.NONE);
    }

    public static void stopUISession(final Session session) {
        stopUISession(session, null, Reason.NONE);
    }

    private static String getSessionName(final Session session, final String sessionNameSuffix) {
        if (sessionNameSuffix != null) {
            return session.toString() + ":" + sessionNameSuffix;
        } else {
            return session.toString();
        }
    }

    /**
     * @param method A non-null method (if null is desired, consider using Method.NONE)
     */
    private static void sendUIEvent(final String eventName, final Method method,
            final long timestamp, final String extras) {
        if (method == null) {
            throw new IllegalArgumentException("Expected non-null method - use Method.NONE?");
        }

        Log.d(LOGTAG, "SendUIEvent: event = " + eventName + " method = " + method +
                " timestamp = " + timestamp + " extras = " + extras);
        final GeckoEvent geckoEvent = GeckoEvent.createTelemetryUIEvent(
                eventName, method.toString(), timestamp, extras);
        GeckoAppShell.sendEventToGecko(geckoEvent);
    }

    public static void sendUIEvent(final Event event, final Method method, final long timestamp,
            final String extras) {
        sendUIEvent(event.toString(), method, timestamp, extras);
    }

    public static void sendUIEvent(final Event event, final Method method, final long timestamp) {
        sendUIEvent(event, method, timestamp, null);
    }

    public static void sendUIEvent(final Event event, final Method method, final String extras) {
        sendUIEvent(event, method, realtime(), extras);
    }

    public static void sendUIEvent(final Event event, final Method method) {
        sendUIEvent(event, method, realtime(), null);
    }

    public static void sendUIEvent(final Event event) {
        sendUIEvent(event, Method.NONE, realtime(), null);
    }

    /**
     * Sends a UIEvent with the given status appended to the event name.
     *
     * This method is a slight bend of the Telemetry framework so chances
     * are that you don't want to use this: please think really hard before you do.
     *
     * Intended for use with data policy notifications.
     */
    public static void sendUIEvent(final Event event, final boolean eventStatus) {
        final String eventName = event + ":" + eventStatus;
        sendUIEvent(eventName, Method.NONE, realtime(), null);
    }
}