sort source zset by target zset

sortzset.js

module.sortIt = function (params, callback) {
		var source = params.source;
		var target = params.target;
		var start = params.hasOwnProperty('start') ? params.start : 0;
		var stop = params.hasOwnProperty('stop') ? params.stop : -1;

		var limit = stop - start + 1;
		if (limit <= 0) {
			limit = 0;
		}
		var filter = {
			$or: [{ _key: target }],
		};
		if (params.min !== '-inf' || params.max !== '+inf') {
			var query = { _key: source };
			filter.$or.push(query);
			if (params.min !== '-inf') {
				query.score = { $gte: params.min };
			}
			if (params.max !== '+inf') {
				query.score = { $lte: params.max };
			}
		}

		var pipeline = [{ $match: filter }];
		pipeline.push({
			$project: {
				value: 1,
				score: {
					$cond: {
						if: {
							$eq: ['$_key', source],
						},
						then: {
							$multiply: ['$score', 0],
						},
						else: '$score',
					},
				},
			},
		});

		pipeline.push({ $group: { _id: { value: '$value' }, totalScore: { $sum: '$score' }, count: { $sum: 1 } } });
		pipeline.push({ $match: { count: 2 } });
		pipeline.push({ $sort: { totalScore: -1 } });

		if (start) {
			pipeline.push({ $skip: start });
		}

		if (limit > 0) {
			pipeline.push({ $limit: limit });
		}

		var project = { _id: 0, _key: 1, value: '$_id.value' };
		// project.score = '$totalScore';
		pipeline.push({ $project: project });

		db.collection('objects').aggregate(pipeline).toArray(function (err, data) {
			if (err || !data) {
				return callback(err);
			}

			callback(null, data);
		});
	};