/**
 * Tests for the $$NOW and $$CLUSTER_TIME system variable on a replica set.
 */
// @tags: [requires_find_command]
(function() {
"use strict";

var replTest = new ReplSetTest({name: "now_and_cluster_time", nodes: 1});
replTest.startSet();
replTest.initiate();

var db = replTest.getPrimary().getDB("test");

const coll = db[jsTest.name()];
const otherColl = db[coll.getName() + "_other"];
otherColl.drop();
coll.drop();
db["viewWithNow"].drop();
db["viewWithClusterTime"].drop();

// Insert simple documents into the main test collection. Aggregation and view pipelines will
// augment these docs with time-based fields.
const numdocs = 1000;
let bulk = coll.initializeUnorderedBulkOp();
for (let i = 0; i < numdocs; ++i) {
    bulk.insert({_id: i});
}
assert.commandWorked(bulk.execute());

// Insert into another collection with pre-made fields for testing the find() command.
bulk = otherColl.initializeUnorderedBulkOp();
const timeFieldValue = new Date();
for (let i = 0; i < numdocs; ++i) {
    bulk.insert({_id: i, timeField: timeFieldValue, clusterTimeField: new Timestamp(0, 1)});
}
assert.commandWorked(bulk.execute());

assert.commandWorked(
    db.createView("viewWithNow", coll.getName(), [{$addFields: {timeField: "$$NOW"}}]));
const viewWithNow = db["viewWithNow"];

assert.commandWorked(db.createView(
    "viewWithClusterTime", coll.getName(), [{$addFields: {timeField: "$$CLUSTER_TIME"}}]));
const viewWithClusterTime = db["viewWithClusterTime"];

function toResultsArray(queryRes) {
    return Array.isArray(queryRes) ? queryRes : queryRes.toArray();
}

function runTests(query) {
    const results = toResultsArray(query());
    assert.eq(results.length, numdocs);

    // Make sure the values are the same for all documents
    for (let i = 0; i < numdocs; ++i) {
        assert.eq(results[0].timeField, results[i].timeField);
    }

    // Sleep for a while and then rerun.
    sleep(3000);

    const resultsLater = toResultsArray(query());
    assert.eq(resultsLater.length, numdocs);

    // Later results should be later in time.
    assert.lte(results[0].timeField, resultsLater[0].timeField);
}

function baseCollectionNowFind() {
    return otherColl.find({$expr: {$lte: ["$timeField", "$$NOW"]}});
}

function baseCollectionClusterTimeFind() {
    // The test validator examines 'timeField', so we copy clusterTimeField into timeField here.
    const results =
        otherColl.find({$expr: {$lt: ["$clusterTimeField", "$$CLUSTER_TIME"]}}).toArray();
    results.forEach((val, idx) => {
        results[idx].timeField = results[idx].clusterTimeField;
    });
    return results;
}

function baseCollectionNowAgg() {
    return coll.aggregate([{$addFields: {timeField: "$$NOW"}}]);
}

function baseCollectionClusterTimeAgg() {
    return coll.aggregate([{$addFields: {timeField: "$$CLUSTER_TIME"}}]);
}

function fromViewWithNow() {
    return viewWithNow.find();
}

function fromViewWithClusterTime() {
    return viewWithClusterTime.find();
}

function withExprNow() {
    return viewWithNow.find({$expr: {$eq: ["$timeField", "$$NOW"]}});
}

function withExprClusterTime() {
    return viewWithClusterTime.find({$expr: {$eq: ["$timeField", "$$CLUSTER_TIME"]}});
}

// $$NOW
runTests(baseCollectionNowFind);
runTests(baseCollectionNowAgg);
runTests(fromViewWithNow);
runTests(withExprNow);

// Test that $$NOW can be used in explain for both find and aggregate.
assert.commandWorked(coll.explain().find({$expr: {$lte: ["$timeField", "$$NOW"]}}).finish());
assert.commandWorked(viewWithNow.explain().find({$expr: {$eq: ["$timeField", "$$NOW"]}}).finish());
assert.commandWorked(coll.explain().aggregate([{$addFields: {timeField: "$$NOW"}}]));

// $$CLUSTER_TIME
runTests(baseCollectionClusterTimeFind);
runTests(baseCollectionClusterTimeAgg);
runTests(fromViewWithClusterTime);
runTests(withExprClusterTime);

// Test that $$CLUSTER_TIME can be used in explain for both find and aggregate.
assert.commandWorked(
    coll.explain().find({$expr: {$lte: ["$timeField", "$$CLUSTER_TIME"]}}).finish());
assert.commandWorked(
    viewWithNow.explain().find({$expr: {$eq: ["$timeField", "$$CLUSTER_TIME"]}}).finish());
assert.commandWorked(coll.explain().aggregate([{$addFields: {timeField: "$$CLUSTER_TIME"}}]));

replTest.stopSet();
}());