/**
 * Tests for the aggregate command's support for readConcern level "snapshot".
 *
 * @tags: [
 *   uses_transactions,
 * ]
 */
(function() {
"use strict";

const kAdminDB = "admin";
const kCollName = "coll";
const kConfigDB = "config";
const kDBName = "test";
const kWCMajority = {
    writeConcern: {w: "majority"}
};

let rst = new ReplSetTest({nodes: 1});
rst.startSet();
rst.initiate();
let session = rst.getPrimary().getDB(kDBName).getMongo().startSession({causalConsistency: false});
let sessionDB = session.getDatabase(kDBName);

let txnNumber = NumberLong(0);
assert.commandWorked(sessionDB.runCommand({create: kCollName, writeConcern: {w: "majority"}}));

function testSnapshotAggFailsWithCode(coll, pipeline, code) {
    let cmd = {aggregate: coll, pipeline: pipeline, cursor: {}};

    let cmdAsSnapshotRead = Object.extend({}, cmd);
    cmdAsSnapshotRead.txnNumber = NumberLong(++txnNumber);
    cmdAsSnapshotRead.readConcern = {level: "snapshot"};
    cmdAsSnapshotRead.autocommit = false;
    cmdAsSnapshotRead.startTransaction = true;
    assert.commandFailedWithCode(sessionDB.runCommand(cmdAsSnapshotRead), code);

    // As a sanity check, also make sure that the command succeeds when run without a txn number
    // and without a readConcern.
    assert.commandWorked(sessionDB.runCommand(cmd));
}

// Test that $changeStream is disallowed with transactions.
testSnapshotAggFailsWithCode(
    kCollName, [{$changeStream: {}}], ErrorCodes.OperationNotSupportedInTransaction);

// Test that $collStats is disallowed with transactions.
testSnapshotAggFailsWithCode(
    kCollName, [{$collStats: {}}], ErrorCodes.OperationNotSupportedInTransaction);

// Test that $indexStats is disallowed with transactions.
testSnapshotAggFailsWithCode(
    kCollName, [{$indexStats: {}}], ErrorCodes.OperationNotSupportedInTransaction);

// Test that $listLocalSessions is disallowed with transactions.
testSnapshotAggFailsWithCode(
    1, [{$listLocalSessions: {}}], ErrorCodes.OperationNotSupportedInTransaction);

// Test that $out is disallowed with transactions.
testSnapshotAggFailsWithCode(
    kCollName, [{$out: "out"}], ErrorCodes.OperationNotSupportedInTransaction);

// Test that $listSessions is disallowed with transactions. This stage must be run against
// 'system.sessions' in the config database, which cannot be queried in a transaction.
sessionDB = session.getDatabase(kConfigDB);
testSnapshotAggFailsWithCode(
    "system.sessions", [{$listSessions: {}}], ErrorCodes.OperationNotSupportedInTransaction);

// Test that $currentOp is disallowed with transactions. We have to reassign 'sessionDB' to
// refer to the admin database, because $currentOp pipelines are required to run against
// 'admin'. Queries against 'admin' are not permitted in a transaction.
sessionDB = session.getDatabase(kAdminDB);
testSnapshotAggFailsWithCode(1, [{$currentOp: {}}], ErrorCodes.OperationNotSupportedInTransaction);
sessionDB = session.getDatabase(kDBName);

// Helper for testing that aggregation stages which involve a local and foreign collection
// ($lookup and $graphLookup) obey the expected readConcern "snapshot" isolation semantics.
//
// Inserts 'localDocsPre' into the 'local' collection and 'foreignDocsPre' into the 'foreign'
// collection. Then runs the first batch of 'pipeline', before inserting 'localDocsPost' into
// 'local' and 'foreignDocsPost' into 'foreign'. Iterates the remainder of the aggregation
// cursor and verifies that the result set matches 'expectedResults'.
function testLookupReadConcernSnapshotIsolation(
    {localDocsPre, foreignDocsPre, localDocsPost, foreignDocsPost, pipeline, expectedResults}) {
    sessionDB.runCommand({drop: "local", writeConcern: {w: "majority"}});
    sessionDB.runCommand({drop: "foreign", writeConcern: {w: "majority"}});
    let localColl = sessionDB.local;
    let foreignColl = sessionDB.foreign;
    assert.commandWorked(localColl.insert(localDocsPre, kWCMajority));
    assert.commandWorked(foreignColl.insert(foreignDocsPre, kWCMajority));
    let cmdRes = sessionDB.runCommand({
        aggregate: localColl.getName(),
        pipeline: pipeline,
        cursor: {batchSize: 0},
        readConcern: {level: "snapshot"},
        txnNumber: NumberLong(++txnNumber),
        startTransaction: true,
        autocommit: false
    });
    assert.commandWorked(cmdRes);
    assert.neq(0, cmdRes.cursor.id);
    assert.eq(0, cmdRes.cursor.firstBatch.length);

    assert.commandWorked(localColl.insert(localDocsPost, kWCMajority));
    assert.commandWorked(foreignColl.insert(foreignDocsPost, kWCMajority));
    let results =
        new DBCommandCursor(sessionDB, cmdRes, undefined, undefined, NumberLong(txnNumber))
            .toArray();
    assert.eq(results, expectedResults);
    assert.commandWorked(sessionDB.adminCommand(
        {commitTransaction: 1, txnNumber: NumberLong(txnNumber), autocommit: false}));
}

// Test that snapshot isolation works with $lookup using localField/foreignField syntax.
testLookupReadConcernSnapshotIsolation({
    localDocsPre: [{_id: 0}, {_id: 1}, {_id: 2}],
    foreignDocsPre: [{_id: 1}],
    localDocsPost: [{_id: 3}],
    foreignDocsPost: [{_id: 2}, {_id: 3}],
    pipeline: [
        {$lookup: {from: "foreign", localField: "_id", foreignField: "_id", as: "as"}},
        {$sort: {_id: 1}}
    ],
    expectedResults: [{_id: 0, as: []}, {_id: 1, as: [{_id: 1}]}, {_id: 2, as: []}]
});

// Test that snapshot isolation works with $lookup into a nested pipeline.
testLookupReadConcernSnapshotIsolation({
        localDocsPre: [{_id: 0}, {_id: 1}, {_id: 2}],
        foreignDocsPre: [{_id: 1}],
        localDocsPost: [{_id: 3}],
        foreignDocsPost: [{_id: 2}, {_id: 3}],
        pipeline: [
            {
              $lookup: {
                  from: "foreign",
                  as: "as",
                  let : {localId: "$_id"},
                  pipeline: [{$match: {$expr: {$eq: ["$_id", "$$localId"]}}}]
              }
            },
            {$sort: {_id: 1}}
        ],
        expectedResults: [{_id: 0, as: []}, {_id: 1, as: [{_id: 1}]}, {_id: 2, as: []}]
    });

// Test that snapshot isolation works with $graphLookup.
testLookupReadConcernSnapshotIsolation({
        localDocsPre: [{_id: 0}, {_id: 1}, {_id: 2}],
        foreignDocsPre: [{_id: 1, linkTo: 2}],
        localDocsPost: [{_id: 3}],
        foreignDocsPost: [{_id: 2, linkTo: 3}, {_id: 3}],
        pipeline: [
            {
              $graphLookup: {
                  from: "foreign",
                  as: "as",
                  startWith: "$_id",
                  connectFromField: "linkTo",
                  connectToField: "_id"
              }
            },
            {$sort: {_id: 1}}
        ],
        expectedResults:
            [{_id: 0, as: []}, {_id: 1, as: [{_id: 1, linkTo: 2}]}, {_id: 2, as: []}]
    });

// Test that snapshot isolation works for $geoNear. Special care is taken to test snapshot
// isolation across getMore for $geoNear as it is an initial document source.
assert.commandWorked(sessionDB.runCommand({drop: kCollName, writeConcern: {w: "majority"}}));
assert.commandWorked(sessionDB.runCommand({
    createIndexes: kCollName,
    indexes: [{key: {geo: "2dsphere"}, name: "geo_2dsphere"}],
    writeConcern: {w: "majority"}
}));

const coll = sessionDB.getCollection(kCollName);
let bulk = coll.initializeUnorderedBulkOp();
const numInitialGeoInsert = 4;
for (let i = 0; i < numInitialGeoInsert; ++i) {
    bulk.insert({_id: i, geo: {type: "Point", coordinates: [0, 0]}});
}
assert.commandWorked(bulk.execute({w: "majority"}));

let cmdRes = assert.commandWorked(sessionDB.runCommand({
    aggregate: kCollName,
    pipeline: [{
        $geoNear:
            {spherical: true, near: {type: "Point", coordinates: [0, 0]}, distanceField: "distance"}
    }],
    txnNumber: NumberLong(++txnNumber),
    readConcern: {level: "snapshot"},
    autocommit: false,
    startTransaction: true,
    cursor: {batchSize: 0}
}));
assert(cmdRes.hasOwnProperty("cursor"));
const cursorId = cmdRes.cursor.id;
assert.neq(cursorId, 0);

assert.commandWorked(
    coll.insert({_id: numInitialGeoInsert, geo: {type: "Point", coordinates: [0, 0]}},
                {writeConcern: {w: "majority"}}));

cmdRes = assert.commandWorked(sessionDB.runCommand({
    getMore: NumberLong(cursorId),
    collection: kCollName,
    autocommit: false,
    txnNumber: NumberLong(txnNumber)
}));
assert.commandWorked(sessionDB.adminCommand(
    {commitTransaction: 1, txnNumber: NumberLong(txnNumber), autocommit: false}));
assert(cmdRes.hasOwnProperty("cursor"));
assert(cmdRes.cursor.hasOwnProperty("nextBatch"));
assert.eq(cmdRes.cursor.nextBatch.length, numInitialGeoInsert);

// Test that snapshot reads are legal for $facet.
assert.commandWorked(sessionDB.runCommand({drop: kCollName, writeConcern: {w: "majority"}}));
assert.commandWorked(coll.insert(
    [
        {group1: 1, group2: 1, val: 1},
        {group1: 1, group2: 2, val: 2},
        {group1: 2, group2: 2, val: 8}
    ],
    kWCMajority));

cmdRes = sessionDB.runCommand({
    aggregate: kCollName,
    pipeline: [
        {
            $facet: {
                g1: [{$group: {_id: "$group1", sum: {$sum: "$val"}}}, {$sort: {_id: 1}}],
                g2: [{$group: {_id: "$group2", sum: {$sum: "$val"}}}, {$sort: {_id: 1}}]
            }
        },
        {$unwind: "$g1"},
        {$unwind: "$g2"},
        {$sort: {"g1._id": 1, "g2._id": 1}}
    ],
    cursor: {},
    readConcern: {level: "snapshot"},
    txnNumber: NumberLong(++txnNumber),
    startTransaction: true,
    autocommit: false
});
assert.commandWorked(sessionDB.adminCommand(
    {commitTransaction: 1, txnNumber: NumberLong(txnNumber), autocommit: false}));
assert.commandWorked(cmdRes);
assert.eq(0, cmdRes.cursor.id);
assert.eq(cmdRes.cursor.firstBatch, [
    {g1: {_id: 1, sum: 3}, g2: {_id: 1, sum: 1}},
    {g1: {_id: 1, sum: 3}, g2: {_id: 2, sum: 10}},
    {g1: {_id: 2, sum: 8}, g2: {_id: 1, sum: 1}},
    {g1: {_id: 2, sum: 8}, g2: {_id: 2, sum: 10}}
]);

rst.stopSet();
}());