const moment = require('moment-timezone');
const semver = require('semver');
const Promise = require('bluebird');
const _ = require('lodash');
const settingsCache = require('../settings/cache');
const ghostVersion = require('../../lib/ghost-version');
const {i18n} = require('../../lib/common');
const errors = require('@tryghost/errors');
const ObjectId = require('bson-objectid');

const fetchAllNotifications = () => {
    let allNotifications = settingsCache.get('notifications');

    allNotifications.forEach((notification) => {
        notification.addedAt = moment(notification.addedAt).toDate();
    });

    return allNotifications;
};

const wasSeen = (notification, user) => {
    if (notification.seenBy === undefined) {
        return notification.seen;
    } else {
        return notification.seenBy.includes(user.id);
    }
};

const browse = ({user}) => {
    let allNotifications = fetchAllNotifications();
    allNotifications = _.orderBy(allNotifications, 'addedAt', 'desc');

    allNotifications = allNotifications.filter((notification) => {
        // NOTE: Filtering by version below is just a patch for bigger problem - notifications are not removed
        //       after Ghost update. Logic below should be removed when Ghost upgrade detection
        //       is done (https://github.com/TryGhost/Ghost/issues/10236) and notifications are
        //       be removed permanently on upgrade event.
        const ghost20RegEx = /Ghost 2.0 is now available/gi;

        // CASE: do not return old release notification
        if (notification.message && (!notification.custom || notification.message.match(ghost20RegEx))) {
            let notificationVersion = notification.message.match(/(\d+\.)(\d+\.)(\d+)/);

            if (notification.message.match(ghost20RegEx)) {
                notificationVersion = '2.0.0';
            } else if (notificationVersion){
                notificationVersion = notificationVersion[0];
            }

            const blogVersion = ghostVersion.full.match(/^(\d+\.)(\d+\.)(\d+)/);

            if (notificationVersion && blogVersion && semver.gt(notificationVersion, blogVersion[0])) {
                return true;
            } else {
                return false;
            }
        }

        return !wasSeen(notification, user);
    });

    return allNotifications;
};

const add = ({notifications}) => {
    const defaults = {
        dismissible: true,
        location: 'bottom',
        status: 'alert',
        id: ObjectId.generate()
    };

    const overrides = {
        seen: false,
        addedAt: moment().toDate()
    };

    let notificationsToCheck = notifications;
    let notificationsToAdd = [];

    const allNotifications = fetchAllNotifications();

    notificationsToCheck.forEach((notification) => {
        const isDuplicate = allNotifications.find((n) => {
            return n.id === notification.id;
        });

        if (!isDuplicate) {
            notificationsToAdd.push(Object.assign({}, defaults, notification, overrides));
        }
    });

    const hasReleaseNotification = notificationsToCheck.find((notification) => {
        return !notification.custom;
    });

    // CASE: remove any existing release notifications if a new release notification comes in
    if (hasReleaseNotification) {
        _.remove(allNotifications, (el) => {
            return !el.custom;
        });
    }

    // CASE: nothing to add, skip
    if (!notificationsToAdd.length) {
        return Promise.resolve();
    }

    const releaseNotificationsToAdd = notificationsToAdd.filter((notification) => {
        return !notification.custom;
    });

    // CASE: reorder notifications before save
    if (releaseNotificationsToAdd.length > 1) {
        notificationsToAdd = notificationsToAdd.filter((notification) => {
            return notification.custom;
        });
        notificationsToAdd.push(_.orderBy(releaseNotificationsToAdd, 'created_at', 'desc')[0]);
    }

    return {allNotifications, notificationsToAdd};
};

const destroy = ({notificationId, user}) => {
    const allNotifications = fetchAllNotifications();

    const notificationToMarkAsSeen = allNotifications.find((notification) => {
        return notification.id === notificationId;
    });

    const notificationToMarkAsSeenIndex = allNotifications.findIndex((notification) => {
        return notification.id === notificationId;
    });

    if (notificationToMarkAsSeenIndex > -1 && !notificationToMarkAsSeen.dismissible) {
        return Promise.reject(new errors.NoPermissionError({
            message: i18n.t('errors.api.notifications.noPermissionToDismissNotif')
        }));
    }

    if (notificationToMarkAsSeenIndex < 0) {
        return Promise.reject(new errors.NotFoundError({
            message: i18n.t('errors.api.notifications.notificationDoesNotExist')
        }));
    }

    if (wasSeen(notificationToMarkAsSeen, user)) {
        return Promise.resolve();
    }

    // @NOTE: We don't remove the notifications, because otherwise we will receive them again from the service.
    allNotifications[notificationToMarkAsSeenIndex].seen = true;

    if (!allNotifications[notificationToMarkAsSeenIndex].seenBy) {
        allNotifications[notificationToMarkAsSeenIndex].seenBy = [];
    }

    allNotifications[notificationToMarkAsSeenIndex].seenBy.push(user.id);

    return allNotifications;
};

const destroyAll = () => {
    const allNotifications = fetchAllNotifications();

    allNotifications.forEach((notification) => {
        // @NOTE: We don't remove the notifications, because otherwise we will receive them again from the service.
        notification.seen = true;
    });

    return allNotifications;
};

module.exports.browse = browse;
module.exports.add = add;
module.exports.destroy = destroy;
module.exports.destroyAll = destroyAll;