/**
 * Test that a legacy query via mongos retains the $comment query meta-operator when transformed
 * into a find command for the shards. In addition, verify that the find command comment parameter
 * and query operator are passed to the shards correctly, and that an attempt to attach a non-string
 * comment to the find command fails.
 * @tags: [requires_fcv_44]
 */
(function() {
"use strict";

// For profilerHasSingleMatchingEntryOrThrow.
load("jstests/libs/profiler.js");

const st = new ShardingTest({name: "mongos_comment_test", mongos: 1, shards: 1});

const shard = st.shard0;
const mongos = st.s;

// Need references to the database via both mongos and mongod so that we can enable profiling &
// test queries on the shard.
const mongosDB = mongos.getDB("mongos_comment");
const shardDB = shard.getDB("mongos_comment");

assert.commandWorked(mongosDB.dropDatabase());

const mongosColl = mongosDB.test;
const shardColl = shardDB.test;

const collNS = mongosColl.getFullName();

for (let i = 0; i < 5; ++i) {
    assert.commandWorked(mongosColl.insert({_id: i, a: i}));
}

// The profiler will be used to verify that comments are present on the shard.
assert.commandWorked(shardDB.setProfilingLevel(2));
const profiler = shardDB.system.profile;

//
// Set legacy read mode for the mongos and shard connections.
//
mongosDB.getMongo().forceReadMode("legacy");
shardDB.getMongo().forceReadMode("legacy");

// TEST CASE: A legacy string $comment meta-operator inside $query is propagated to the shards via
// mongos but not treated as a 'comment' field.
assert.eq(mongosColl.find({a: 1, $comment: "TEST"}).itcount(), 1);
profilerHasSingleMatchingEntryOrThrow({
    profileDB: shardDB,
    filter: {
        op: "query",
        ns: collNS,
        "command.filter": {a: 1, $comment: "TEST"},
        "command.comment": {$exists: false}
    }
});

// TEST CASE: A legacy string $comment meta-operator is propagated to the shards via mongos.
assert.eq(mongosColl.find({$query: {a: 1}, $comment: "TEST"}).itcount(), 1);
profilerHasSingleMatchingEntryOrThrow(
    {profileDB: shardDB, filter: {op: "query", ns: collNS, "command.comment": "TEST"}});

// TEST CASE: A legacy BSONObj $comment propagated via mongos.
assert.eq(mongosColl.find({$query: {a: 1}, $comment: {c: 2, d: {e: "TEST"}}}).itcount(), 1);
profilerHasSingleMatchingEntryOrThrow({
    profileDB: shardDB,
    filter: {
        op: "query",
        ns: collNS,
        "command.comment": {c: 2, d: {e: "TEST"}},
        "command.filter": {a: 1}
    }
});

// TEST CASE: Legacy BSONObj $comment when issued on the mongod.
assert.eq(shardColl.find({$query: {a: 1}, $comment: {c: 3, d: {e: "TEST"}}}).itcount(), 1);
profilerHasSingleMatchingEntryOrThrow({
    profileDB: shardDB,
    filter: {op: "query", ns: collNS, "command.comment": {c: 3, d: {e: "TEST"}}}
});

//
// Revert to "commands" read mode for the find command test cases below.
//
mongosDB.getMongo().forceReadMode("commands");
shardDB.getMongo().forceReadMode("commands");

// TEST CASE: Verify that find.comment and non-string find.filter.$comment propagate.
assert.eq(mongosColl.find({a: 1, $comment: {b: "TEST"}}).comment("TEST").itcount(), 1);
profilerHasSingleMatchingEntryOrThrow({
    profileDB: shardDB,
    filter:
        {op: "query", ns: collNS, "command.comment": "TEST", "command.filter.$comment": {b: "TEST"}}
});

// TEST CASE: Verify that find command with a non-string comment parameter gets propagated.
assert.commandWorked(mongosDB.runCommand(
    {"find": mongosColl.getName(), "filter": {a: 1}, "comment": {b: "TEST_BSONOBJ"}}));

profilerHasSingleMatchingEntryOrThrow({
    profileDB: shardDB,
    filter: {op: "query", ns: collNS, "command.comment": {b: "TEST_BSONOBJ"}}
});

st.stop();
})();