const { makeUserUrl } = require('./util');
const ActivityPubObject = require('./object');
const apDb = require('../database').dbs.activitypub;
const { getISOTimestampString } = require('../database');

const { isString, get } = require('lodash');

module.exports = class Collection extends ActivityPubObject {
    constructor(obj) {
        super(obj);
    }

    static followers(owningUser, page, webServer, cb) {
        return Collection.getOrdered(
            'followers',
            owningUser,
            false,
            page,
            e => e.id,
            webServer,
            cb
        );
    }

    static following(owningUser, page, webServer, cb) {
        return Collection.getOrdered(
            'following',
            owningUser,
            false,
            page,
            e => get(e, 'object.id'),
            webServer,
            cb
        );
    }

    static addFollower(owningUser, followingActor, cb) {
        return Collection.addToCollection(
            'followers',
            owningUser,
            followingActor.id,
            followingActor,
            false,
            cb
        );
    }

    static outbox(owningUser, page, webServer, cb) {
        return Collection.getOrdered(
            'outbox',
            owningUser,
            false,
            page,
            null,
            webServer,
            cb
        );
    }

    static addOutboxItem(owningUser, outboxItem, cb) {
        return Collection.addToCollection(
            'outbox',
            owningUser,
            outboxItem.id,
            outboxItem,
            false,
            cb
        );
    }

    static getOrdered(name, owningUser, includePrivate, page, mapper, webServer, cb) {
        const privateQuery = includePrivate ? '' : ' AND is_private = FALSE';
        const followersUrl =
            makeUserUrl(webServer, owningUser, '/ap/users/') + `/${name}`;

        if (!page) {
            return apDb.get(
                `SELECT COUNT(id) AS count
                FROM collection
                WHERE user_id = ? AND name = ?${privateQuery};`,
                [owningUser.userId, name],
                (err, row) => {
                    if (err) {
                        return cb(err);
                    }

                    //
                    //  Mastodon for instance, will never follow up for the
                    //  actual data from some Collections such as 'followers';
                    //  Instead, they only use the |totalItems| to form an
                    //  approximate follower count.
                    //
                    let obj;
                    if (row.count > 0) {
                        obj = {
                            id: followersUrl,
                            type: 'OrderedCollection',
                            first: `${followersUrl}?page=1`,
                            totalItems: row.count,
                        };
                    } else {
                        obj = {
                            id: followersUrl,
                            type: 'OrderedCollection',
                            totalItems: 0,
                            orderedItems: [],
                        };
                    }

                    return cb(null, new Collection(obj));
                }
            );
        }

        //  :TODO: actual paging...
        apDb.all(
            `SELECT obj_json
            FROM collection
            WHERE user_id = ? AND name = ?${privateQuery}
            ORDER BY timestamp;`,
            [owningUser.userId, name],
            (err, entries) => {
                if (err) {
                    return cb(err);
                }

                entries = entries || [];
                if (mapper && entries.length > 0) {
                    entries = entries.map(mapper);
                }

                const obj = {
                    id: `${followersUrl}/page=${page}`,
                    type: 'OrderedCollectionPage',
                    totalItems: entries.length,
                    orderedItems: entries,
                    partOf: followersUrl,
                };

                return cb(null, new Collection(obj));
            }
        );
    }

    static addToCollection(name, owningUser, objectId, obj, isPrivate, cb) {
        if (!isString(obj)) {
            obj = JSON.stringify(obj);
        }

        isPrivate = isPrivate ? 1 : 0;
        apDb.run(
            `INSERT OR IGNORE INTO collection (name, timestamp, user_id, obj_id, obj_json, is_private)
            VALUES (?, ?, ?, ?, ?, ?);`,
            [name, getISOTimestampString(), owningUser.userId, objectId, obj, isPrivate],
            function res(err) {
                // non-arrow for 'this' scope
                if (err) {
                    return cb(err);
                }
                return cb(err, this.lastID);
            }
        );
    }

    static removeFromCollectionById(name, owningUser, objectId, cb) {
        apDb.run(
            `DELETE FROM collection
            WHERE user_id = ? AND name = ? AND obj_id = ?;`,
            [owningUser.userId, name, objectId],
            err => {
                return cb(err);
            }
        );
    }
};