utils.js

/**
 * Utility function to get a deep property value without all the && this && that malarkey
 * 
 * @param {Object} obj the object
 * @param {String} key the deep property key
 * 
 * @return {Object} the deep property value
 */
function get(obj, key) {
    return key.split(".").reduce(function (o, x) {
        return (typeof o == "undefined" || o === null) ? o : o[x];
    }, obj);
}

/**
 * Calls a vote in a text channel.
 * 
 * @param {String} subject The subject to be voted on
 * @param {TextChannel} channel The text channel to run the vote in
 * @param {Object} options Vote options
 * @param {Array} [options.selections] The available selections. Defaults to agree/disagree
 * @param {Number} [options.time] Time to listen for reactions in ms. Defaults to 5 seconds.
 * @param {Array} [options.targetUsers] Users to limit the vote to.
 * 
 */
function vote(subject, channel, options) {
    let {
        selections = [{
            name: 'agree',
            emoji: '✅'
        }, {
            name: 'disagree',
            emoji: '❌'
        }],  
        time = 5000,
        targetUsers
    } = options;

    //Alert target users via mentions
    if (targetUsers && targetUsers.length > 0) {
        let mentions = [];

        targetUsers.forEach(user => {
            mentions.push(user.toString());
        });

        subject = mentions.join(' ') + '\n\n' + subject;
    }

    return new Promise((resolve, reject) => {

        channel.send(subject).then(message => {
            let promise = new Promise(resolve => {
                resolve();
            });

            selections.forEach(selection => {
                promise = promise.then(() => {
                    return message.react(selection.emoji);
                });
            });

            promise = promise.then(() => {
                //Wait the configured time for user reactions.
                // Only accept requested reactions from targeted users.
                return message.awaitReactions((reaction, user) => {
                    let include = selections.findIndex((selection) => {
                        return reaction.emoji.name === selection.emoji;
                    }) !== -1;

                    if (targetUsers && targetUsers.length > 0) {
                        include = include && targetUsers.findIndex((targetUser) => {
                            return targetUser.id === user.id;
                        }) !== -1;
                    }

                    return include;
                }, {
                    time: time
                });
            });

            promise.then(reactions => {
                //Tally reactions, then resolve the vote promise with the results
                let results = {};

                selections.forEach(selection => {
                    let reaction = reactions.get(selection.emoji),
                        result = {
                            count: 0,
                            users: []
                        };

                    if (reaction) {
                        reaction.users.forEach(user => {
                            result.count++;
                            result.users.push(user);
                        });
                    }

                    results[selection.name] = result;
                });

                resolve(results);
            });
        });
    });
}

module.exports = {
    get: get,
    vote: vote
};