/*
 * decaffeinate suggestions:
 * DS102: Remove unnecessary code created because of implicit returns
 * DS207: Consider shorter variations of null checks
 * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
 */
module.exports = {
	monitor(mongodb_require_path, logger) {

		let mongodb, mongodbCore;
		try {
			// for the v1 driver the methods to wrap are in the mongodb
			// module in lib/mongodb/db.js
			mongodb = require(`${mongodb_require_path}`);
		} catch (error) {}

		try {
			// for the v2 driver the relevant methods are in the mongodb-core
			// module in lib/topologies/{server,replset,mongos}.js
			const v2_path = mongodb_require_path.replace(/\/mongodb$/, '/mongodb-core');
			mongodbCore = require(v2_path);
		} catch (error1) {}

		const Metrics = require("./metrics");

		const monitorMethod = function(base, method, type) {
			let _method;
			if (base == null) { return; }
			if ((_method = base[method]) == null) { return; }
			const arglen = _method.length;

			const mongo_driver_v1_wrapper = function(db_command, options, callback) {
				let query;
				if (typeof callback === 'undefined') {
					callback = options;
					options = {};
				}

				const collection = db_command.collectionName;
				if (collection.match(/\$cmd$/)) {
					// Ignore noisy command methods like authenticating, ismaster and ping
					return _method.call(this, db_command, options, callback);
				}

				let key = `mongo-requests.${collection}.${type}`;
				if (db_command.query != null) {
					query = Object.keys(db_command.query).sort().join("_");
					key += "." + query;
				}

				const timer = new Metrics.Timer("mongo", {collection, query});
				const start = new Date();
				return _method.call(this, db_command, options, function() {
					timer.done();
					const time = new Date() - start;
					logger.log({
						query: db_command.query,
						query_type: type,
						collection,
						"response-time": new Date() - start
					},
						"mongo request");
					return callback.apply(this, arguments);
				});
			};

			const mongo_driver_v2_wrapper = function(ns, ops, options, callback) {
				let query;
				if (typeof callback === 'undefined') {
					callback = options;
					options = {};
				}

				if (ns.match(/\$cmd$/)) {
					// Ignore noisy command methods like authenticating, ismaster and ping
					return _method.call(this, ns, ops, options, callback);
				}

				let key = `mongo-requests.${ns}.${type}`;
				if (ops[0].q != null) {  // ops[0].q
					query = Object.keys(ops[0].q).sort().join("_");
					key += "." + query;
				}

				const timer = new Metrics.Timer(key);
				const start = new Date();
				return _method.call(this, ns, ops, options, function() {
					timer.done();
					const time = new Date() - start;
					logger.log({
						query: ops[0].q,
						query_type: type,
						collection: ns,
						"response-time": new Date() - start
					},
						"mongo request");
					return callback.apply(this, arguments);
				});
			};

			if (arglen === 3) {
				return base[method] = mongo_driver_v1_wrapper;
			} else if (arglen === 4) {
				return base[method] = mongo_driver_v2_wrapper;
			}
		};

		monitorMethod(mongodb != null ? mongodb.Db.prototype : undefined, "_executeQueryCommand",  "query");
		monitorMethod(mongodb != null ? mongodb.Db.prototype : undefined, "_executeRemoveCommand", "remove");
		monitorMethod(mongodb != null ? mongodb.Db.prototype : undefined, "_executeInsertCommand", "insert");
		monitorMethod(mongodb != null ? mongodb.Db.prototype : undefined, "_executeUpdateCommand", "update");

		monitorMethod(mongodbCore != null ? mongodbCore.Server.prototype : undefined, "command", "command");
		monitorMethod(mongodbCore != null ? mongodbCore.Server.prototype : undefined, "remove", "remove");
		monitorMethod(mongodbCore != null ? mongodbCore.Server.prototype : undefined, "insert", "insert");
		monitorMethod(mongodbCore != null ? mongodbCore.Server.prototype : undefined, "update", "update");

		monitorMethod(mongodbCore != null ? mongodbCore.ReplSet.prototype : undefined, "command", "command");
		monitorMethod(mongodbCore != null ? mongodbCore.ReplSet.prototype : undefined, "remove", "remove");
		monitorMethod(mongodbCore != null ? mongodbCore.ReplSet.prototype : undefined, "insert", "insert");
		monitorMethod(mongodbCore != null ? mongodbCore.ReplSet.prototype : undefined, "update", "update");

		monitorMethod(mongodbCore != null ? mongodbCore.Mongos.prototype : undefined, "command", "command");
		monitorMethod(mongodbCore != null ? mongodbCore.Mongos.prototype : undefined, "remove", "remove");
		monitorMethod(mongodbCore != null ? mongodbCore.Mongos.prototype : undefined, "insert", "insert");
		return monitorMethod(mongodbCore != null ? mongodbCore.Mongos.prototype : undefined, "update", "update");
	}
};