/**
 * Matching behavior for $elemMatch applied to a top level element.
 * Includes tests for bugs described in SERVER-1264 and SERVER-4180.
 */
(function() {
"use strict";

const collNamePrefix = 'jstests_arrayfind8_';
let collCount = 0;
let coll;

// May be changed during the test.
let currentIndexSpec = {a: 1};

/**
 * Check that the query results match the documents in the 'expected' array.
 */
function assertResults(expected, query, context) {
    assert.eq(expected.length, coll.count(query), 'unexpected count in ' + context);
    const results = coll.find(query).toArray();
    const resultsAOnly = results.map((r) => r.a);
    assert.sameMembers(resultsAOnly, expected);
}

/**
 * Check matching for different query types.
 * @param bothMatch - document matched by both standardQuery and elemMatchQuery
 * @param elemMatch - document matched by elemMatchQuery but not standardQuery
 * @param notElemMatch - document matched by standardQuery but not elemMatchQuery
 */
function checkMatch(bothMatch, elemMatch, nonElemMatch, standardQuery, elemMatchQuery, context) {
    function mayPush(arr, elt) {
        if (elt) {
            arr.push(elt);
        }
    }

    let expectedStandardQueryResults = [];
    mayPush(expectedStandardQueryResults, bothMatch);
    mayPush(expectedStandardQueryResults, nonElemMatch);
    assertResults(expectedStandardQueryResults, standardQuery, context + ' standard query');

    let expectedElemMatchQueryResults = [];
    mayPush(expectedElemMatchQueryResults, bothMatch);
    mayPush(expectedElemMatchQueryResults, elemMatch);
    assertResults(expectedElemMatchQueryResults, elemMatchQuery, context + ' elemMatch query');
}

/**
 * Check matching and for different query types.
 * @param subQuery - part of a query, to be provided as is for a standard query and within a
 *     $elemMatch clause for a $elemMatch query
 * @param bothMatch - document matched by both standardQuery and elemMatchQuery
 * @param elemMatch - document matched by elemMatchQuery but not standardQuery
 * @param notElemMatch - document matched by standardQuery but not elemMatchQuery
 * @param additionalConstraints - additional query parameters not generated from @param subQuery
 */
function checkQuery(subQuery, bothMatch, elemMatch, nonElemMatch, additionalConstraints) {
    const collNameSuffix = collCount++;
    coll = db.getCollection(collNamePrefix + 'noindex_' + collNameSuffix);
    coll.drop();
    additionalConstraints = additionalConstraints || {};

    // Construct standard and elemMatch queries from subQuery.
    const firstSubQueryKey = Object.keySet(subQuery)[0];
    let standardQuery = null;
    if (firstSubQueryKey[0] == '$') {
        standardQuery = {$and: [{a: subQuery}, additionalConstraints]};
    } else {
        // If the subQuery contains a field rather than operators, append to the 'a' field.
        let modifiedSubQuery = {};
        modifiedSubQuery['a.' + firstSubQueryKey] = subQuery[firstSubQueryKey];
        standardQuery = {$and: [modifiedSubQuery, additionalConstraints]};
    }
    const elemMatchQuery = {$and: [{a: {$elemMatch: subQuery}}, additionalConstraints]};

    function insertValueIfNotNull(val) {
        if (val) {
            assert.commandWorked(coll.insert({a: val}));
        }
    }

    // Save all documents and check matching without indexes.
    insertValueIfNotNull(bothMatch);
    insertValueIfNotNull(elemMatch);
    insertValueIfNotNull(nonElemMatch);

    checkMatch(bothMatch, elemMatch, nonElemMatch, standardQuery, elemMatchQuery, 'unindexed');

    // Check matching and index bounds for a single key index.

    coll = db.getCollection(collNamePrefix + 'index_' + collNameSuffix);
    coll.drop();
    insertValueIfNotNull(bothMatch);
    insertValueIfNotNull(elemMatch);
    // The nonElemMatch document is not tested here, as it will often make the index multikey.
    assert.commandWorked(coll.createIndex(currentIndexSpec));
    checkMatch(bothMatch, elemMatch, null, standardQuery, elemMatchQuery, 'single key index');

    // Check matching and index bounds for a multikey index.

    // Now the nonElemMatch document is tested.
    insertValueIfNotNull(nonElemMatch);
    // Force the index to be multikey.
    assert.commandWorked(coll.insert({a: [-1, -2]}));
    assert.commandWorked(coll.insert({a: {b: [-1, -2]}}));
    checkMatch(bothMatch, elemMatch, nonElemMatch, standardQuery, elemMatchQuery, 'multikey index');
}

// Basic test.
checkQuery({$gt: 4}, [5]);

// Multiple constraints within a $elemMatch clause.
checkQuery({$gt: 4, $lt: 6}, [5], null, [3, 7]);
checkQuery({$gt: 4, $not: {$gte: 6}}, [5]);
checkQuery({$gt: 4, $not: {$ne: 6}}, [6]);
checkQuery({$gte: 5, $lte: 5}, [5], null, [4, 6]);
checkQuery({$in: [4, 6], $gt: 5}, [6], null, [4, 7]);
checkQuery({$regex: '^a'}, ['a']);

// Some constraints within a $elemMatch clause and other constraints outside of it.
checkQuery({$gt: 4}, [5], null, null, {a: {$lt: 6}});
checkQuery({$gte: 5}, [5], null, null, {a: {$lte: 5}});
checkQuery({$in: [4, 6]}, [6], null, null, {a: {$gt: 5}});

// Constraints in different $elemMatch clauses.
checkQuery({$gt: 4}, [5], null, null, {a: {$elemMatch: {$lt: 6}}});
checkQuery({$gt: 4}, [3, 7], null, null, {a: {$elemMatch: {$lt: 6}}});
checkQuery({$gte: 5}, [5], null, null, {a: {$elemMatch: {$lte: 5}}});
checkQuery({$in: [4, 6]}, [6], null, null, {a: {$elemMatch: {$gt: 5}}});

checkQuery({$elemMatch: {$in: [5]}}, null, [[5]], [5], null);

currentIndexSpec = {
    "a.b": 1
};
checkQuery({$elemMatch: {b: {$gte: 1, $lte: 1}}}, null, [[{b: 1}]], [{b: 1}], null);
checkQuery({$elemMatch: {b: {$gte: 1, $lte: 1}}}, null, [[{b: [0, 2]}]], [{b: [0, 2]}], null);

// Constraints for a top level (SERVER-1264 style) $elemMatch nested within a non top level
// $elemMatch.
checkQuery({b: {$elemMatch: {$gte: 1, $lte: 1}}}, [{b: [1]}]);
checkQuery({b: {$elemMatch: {$gte: 1, $lte: 4}}}, [{b: [1]}]);

checkQuery({b: {$elemMatch: {$gte: 1, $lte: 4}}}, [{b: [2]}], null, null, {'a.b': {$in: [2, 5]}});
checkQuery(
    {b: {$elemMatch: {$in: [1, 2]}, $in: [2, 3]}}, [{b: [2]}], null, [{b: [1]}, {b: [3]}], null);
})();