'use strict';

const events = require("events");

module.exports = function createDeduplicator(options) {
	let mergedOptions = Object.assign({
		historyLength: 10
	}, options);

	let seenMessages = {}; // FIXME: Use a Set instead?

	function tryMessage(client, data, callback) {
		if (client.socketId == null) {
			// FIXME: Warning!
			console.error("Not deduplicating message because client.socketId is null");
			callback();
		} else if (data.messageId == null) {
			// FIXME: Warning!
			console.error("Not deduplicating message because data.messageId is null");
			callback();
		} else {
			if (seenMessages[client.socketId] == null) {
				seenMessages[client.socketId] = [];
			}

			let clientSeenMessages = seenMessages[client.socketId];

			if (clientSeenMessages.indexOf(data.messageId) !== 1) {
				clientSeenMessages.push(data);

				if (clientSeenMessages.length > mergedOptions.historyLength) {
					clientSeenMessages.shift();
				}

				callback();
			}
		}
	}

	tryMessage.forgetClient = function forgetClient(client) {
		delete seenMessages[client.socketId];
	}
}