/**
 * Tests that the balancer should not be moving chunks outside of the active window.
 * The outline of the test goes like this:
 * 1. Disable balancer to make sure that it will not try to move chunk on the setup phase.
 * 2. Setup the sharded collections by splitting it into 16 chunks. Since none of the chunks
 *    are being moved, all of them will end up on a single shard.
 * 3. Turn the balancer setting to on and set the active balancing window to a time that is
 *    outside of the current time at the same time.
 * 4. Make sure that no chunks have moved for at least one balancing round.
 * 5. Reset the active balancing window to a setting that overlaps the current time and make
 *    sure that some chunks are moved.
 */
(function() {
/**
 * Simple representation for wall clock time. Hour and minutes should be integers.
 */
var HourAndMinute = function(hour, minutes) {
    return {
        /**
         * Returns a new HourAndMinute object with the amount of hours added.
         * Amount can be negative.
         */
        addHour: function(amount) {
            var newHour = (hour + amount) % 24;
            if (newHour < 0) {
                newHour += 24;
            }

            return new HourAndMinute(newHour, minutes);
        },

        /**
         * Returns a string representation that is compatible with the format for the balancer
         * window settings.
         */
        toString: function() {
            var minStr = (minutes < 10) ? ('0' + minutes) : ('' + minutes);
            var hourStr = (hour < 10) ? ('0' + hour) : ('' + hour);
            return hourStr + ':' + minStr;
        }
    };
};

/**
 * Waits until at least one balancing round has passed.
 *
 * Note: This relies on the fact that the balancer pings the config.mongos document every round.
 */
var waitForAtLeastOneBalanceRound = function(mongosHost, timeoutMS) {
    var mongos = new Mongo(mongosHost);
    var configDB = mongos.getDB('config');

    // Wait for ts to change twice because:
    // 1st: for start of the balancing round.
    // 2nd: for the start of the next round, which implies that the previous one has ended.
    var waitForTSChangeNTimes = 2;
    var lastPing = new Date(0);

    assert.soon(function() {
        // Note: The balancer pings twice, once with { waiting: false } at the beginning
        // and another { waiting: true } at the end. Poll for the negative edge since
        // the smallest granurality should be a second, if for some reason the interval
        // became less than a second, it can cause this to miss the negative edge and
        // wake it wait longer than it should.
        var currentPing = configDB.mongos.findOne({ _id: mongosHost, waiting: true });
        if (currentPing == null) {
            return false;
        }

        if (currentPing.ping.valueOf() != lastPing.valueOf()) {
            waitForTSChangeNTimes--;
            lastPing = currentPing.ping;
        }

        return waitForTSChangeNTimes <= 0;
    }, 'Timed out waiting for mongos ping to change ' + waitForTSChangeNTimes + ' more times',
                timeoutMS, 500);
};

var st = new ShardingTest({ shards: 2 });
var configDB = st.s.getDB('config');
assert.commandWorked(configDB.adminCommand({ configureFailPoint: 'balancerRoundIntervalSetting',
                                             mode: 'alwaysOn',
                                             data: { sleepSecs: 1 }}));

configDB.adminCommand({ enableSharding: 'test' });
configDB.adminCommand({ shardCollection: 'test.user', key: { _id: 1 }});

// Disable balancer so it will not interfere with the chunk distribution setup.
st.stopBalancer();

for (var x = 0; x < 150; x += 10) {
    configDB.adminCommand({ split: 'test.user', middle: { _id: x }});
}

var shard0Chunks = configDB.chunks.find({ ns: 'test.user', shard: 'shard0000' }).count();

var startDate = new Date();
var hourMinStart = new HourAndMinute(startDate.getHours(), startDate.getMinutes());
configDB.settings.update({ _id: 'balancer' },
                         {
                             $set: {
                                 activeWindow: {
                                     start: hourMinStart.addHour(-2).toString(),
                                     stop: hourMinStart.addHour(-1).toString()
                                 },
                                 stopped: false
                             }
                         },
                         true);

waitForAtLeastOneBalanceRound(st.s.host, 60 * 1000);

var shard0ChunksAfter = configDB.chunks.find({ ns: 'test.user', shard: 'shard0000' }).count();
assert.eq(shard0Chunks, shard0ChunksAfter);

configDB.settings.update({ _id: 'balancer' },
                         {
                             $set: {
                                 activeWindow: {
                                     start: hourMinStart.toString(),
                                     stop: hourMinStart.addHour(2).toString()
                                 }
                             }
                         },
                         true);

waitForAtLeastOneBalanceRound(st.s.host, 60 * 1000);

shard0ChunksAfter = configDB.chunks.find({ ns: 'test.user', shard: 'shard0000' }).count();
assert.neq(shard0Chunks, shard0ChunksAfter);

st.stop();
})();