const { WebClient, IncomingWebhook } = require('@slack/client');
const humanizeDuration = require('humanize-duration');
const { sprintf } = require('sprintf-js');

const EMAIL_REGEX = /^(.*)@(.*)$/;

function generateAnnoyMessage(config, now, usersList, phrases) {
    if (!usersList.length) {
        const isMonday = now.weekday() === 1;
        if (isMonday) {
            return config.completeMessage;
        }

        return null;
    }

    let phrase = config.annoyMessage;

    if (phrases.length) {
        phrase = phrases[Math.floor(Math.random() * phrases.length)].phrase;
    }

    return sprintf(phrase, usersList.join(', '));
}

function annoySlackUsers(config, logger, now, users, phrases) {
    const usersList = users.map(({ id }) => `<@${id}>`);

    const message = generateAnnoyMessage(config, now, usersList, phrases);

    if (!message) {
        logger.info('[SLACK] No users to annoy');

        return null;
    }

    logger.info('[SLACK] Annoying users:', users.map(({ name }) => name));

    const t0 = Date.now();

    const webhook = new IncomingWebhook(config.slack.webhookUrl);

    return new Promise((resolve, reject) => {
        webhook.send(message, err => {
            const t1 = Date.now();
            logger.debug(`[SLACK] Took ${humanizeDuration(t1 - t0)} to send message to Slack channel`);

            if (err) {
                return reject(err);
            }

            return resolve(message);
        });
    });
}

function getAllSlackUsersWithNames(config, logger) {
    return new Promise((resolve, reject) => {
        logger.debug('[SLACK] Getting all Slack user details...');
        const t0 = Date.now();

        const webClient = new WebClient(config.slack.token);

        webClient.users.list({}, (err, info) => {
            if (err) {
                return reject(err);
            }

            const users = info.members
                .filter(user => user &&
                    !user.deleted &&
                    user.name &&
                    user.profile &&
                    user.profile.email &&
                    user.profile.email.match(EMAIL_REGEX)
                )
                .map(user => {
                    const [, shortName] = user.profile.email.match(EMAIL_REGEX);

                    return {
                        id: user.id,
                        name: user.name,
                        shortName,
                        email: user.profile.email.toLowerCase()
                    };
                });

            const t1 = Date.now();
            logger.debug(`[SLACK] Took ${humanizeDuration(t1 - t0)} to fetch slack user details`);

            return resolve(users);
        });
    });
}

module.exports = {
    annoySlackUsers,
    getAllSlackUsersWithNames
};