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src/flags.js

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'use strict';

const _ = require('lodash');
const winston = require('winston');
const validator = require('validator');

const db = require('./database');
const user = require('./user');
const groups = require('./groups');
const meta = require('./meta');
const notifications = require('./notifications');
const analytics = require('./analytics');
const categories = require('./categories');
const topics = require('./topics');
const posts = require('./posts');
const privileges = require('./privileges');
const plugins = require('./plugins');
const utils = require('./utils');
const batch = require('./batch');

const Flags = module.exports;

Flags._states = new Map([
    ['open', {
        label: '[[flags:state-open]]',
        class: 'danger',
    }],
    ['wip', {
        label: '[[flags:state-wip]]',
        class: 'warning',
    }],
    ['resolved', {
        label: '[[flags:state-resolved]]',
        class: 'success',
    }],
    ['rejected', {
        label: '[[flags:state-rejected]]',
        class: 'secondary',
    }],
]);

Flags.init = async function () {
    // Query plugins for custom filter strategies and merge into core filter strategies
    function prepareSets(sets, orSets, prefix, value) {
        if (!Array.isArray(value)) {
            sets.push(prefix + value);
        } else if (value.length) {
            if (value.length === 1) {
                sets.push(prefix + value[0]);
            } else {
                orSets.push(value.map(x => prefix + x));
            }
        }
    }

    const hookData = {
        filters: {
            type: function (sets, orSets, key) {
                prepareSets(sets, orSets, 'flags:byType:', key);
            },
            state: function (sets, orSets, key) {
                prepareSets(sets, orSets, 'flags:byState:', key);
            },
            reporterId: function (sets, orSets, key) {
                prepareSets(sets, orSets, 'flags:byReporter:', key);
            },
            assignee: function (sets, orSets, key) {
                prepareSets(sets, orSets, 'flags:byAssignee:', key);
            },
            targetUid: function (sets, orSets, key) {
                prepareSets(sets, orSets, 'flags:byTargetUid:', key);
            },
            cid: function (sets, orSets, key) {
                prepareSets(sets, orSets, 'flags:byCid:', key);
            },
            page: function () { /* noop */ },
            perPage: function () { /* noop */ },
            quick: function (sets, orSets, key, uid) {
                switch (key) {
                    case 'mine':
                        sets.push(`flags:byAssignee:${uid}`);
                        break;

                    case 'unresolved':
                        prepareSets(sets, orSets, 'flags:byState:', ['open', 'wip']);
                        break;
                }
            },
        },
        states: Flags._states,
        helpers: {
            prepareSets: prepareSets,
        },
    };

    try {
        ({ filters: Flags._filters } = await plugins.hooks.fire('filter:flags.getFilters', hookData));
        ({ filters: Flags._filters, states: Flags._states } = await plugins.hooks.fire('filter:flags.init', hookData));
    } catch (err) {
        winston.error(`[flags/init] Could not retrieve filters\n${err.stack}`);
        Flags._filters = {};
    }
};

Flags.get = async function (flagId) {
    const [base, notes, reports] = await Promise.all([
        db.getObject(`flag:${flagId}`),
        Flags.getNotes(flagId),
        Flags.getReports(flagId),
    ]);
    if (!base) {
        throw new Error('[[error:no-flag]]');
    }
    const flagObj = {
        state: 'open',
        assignee: null,
        ...base,
        datetimeISO: utils.toISOString(base.datetime),
        target_readable: `${base.type.charAt(0).toUpperCase() + base.type.slice(1)} ${base.targetId}`,
        target: await Flags.getTarget(base.type, base.targetId, 0),
        notes,
        reports,
    };

    const data = await plugins.hooks.fire('filter:flags.get', {
        flag: flagObj,
    });
    return data.flag;
};

Flags.getCount = async function ({ uid, filters, query }) {
    filters = filters || {};
    const flagIds = await Flags.getFlagIdsWithFilters({ filters, uid, query });
    return flagIds.length;
};

Flags.getFlagIdsWithFilters = async function ({ filters, uid, query }) {
    let sets = [];
    const orSets = [];

    // Default filter
    filters.page = filters.hasOwnProperty('page') ? Math.abs(parseInt(filters.page, 10) || 1) : 1;
    filters.perPage = filters.hasOwnProperty('perPage') ? Math.abs(parseInt(filters.perPage, 10) || 20) : 20;

    for (const type of Object.keys(filters)) {
        if (Flags._filters.hasOwnProperty(type)) {
            Flags._filters[type](sets, orSets, filters[type], uid);
        } else {
            winston.warn(`[flags/list] No flag filter type found: ${type}`);
        }
    }
    sets = (sets.length || orSets.length) ? sets : ['flags:datetime']; // No filter default

    let flagIds = [];
    if (sets.length === 1) {
        flagIds = await db.getSortedSetRevRange(sets[0], 0, -1);
    } else if (sets.length > 1) {
        flagIds = await db.getSortedSetRevIntersect({ sets: sets, start: 0, stop: -1, aggregate: 'MAX' });
    }

    if (orSets.length) {
        let _flagIds = await Promise.all(orSets.map(async orSet => await db.getSortedSetRevUnion({ sets: orSet, start: 0, stop: -1, aggregate: 'MAX' })));

        // Each individual orSet is ANDed together to construct the final list of flagIds
        _flagIds = _.intersection(..._flagIds);

        // Merge with flagIds returned by sets
        if (sets.length) {
            // If flag ids are already present, return a subset of flags that are in both sets
            flagIds = _.intersection(flagIds, _flagIds);
        } else {
            // Otherwise, return all flags returned via orSets
            flagIds = _.union(flagIds, _flagIds);
        }
    }

    const result = await plugins.hooks.fire('filter:flags.getFlagIdsWithFilters', {
        filters,
        uid,
        query,
        flagIds,
    });
    return result.flagIds;
};

Flags.list = async function (data) {
    const filters = data.filters || {};
    let flagIds = await Flags.getFlagIdsWithFilters({
        filters,
        uid: data.uid,
        query: data.query,
    });
    flagIds = await Flags.sort(flagIds, data.sort);
    const count = flagIds.length;

    // Create subset for parsing based on page number (n=20)
    const flagsPerPage = Math.abs(parseInt(filters.perPage, 10) || 1);
    const pageCount = Math.ceil(flagIds.length / flagsPerPage);
    flagIds = flagIds.slice((filters.page - 1) * flagsPerPage, filters.page * flagsPerPage);

    const reportCounts = await db.sortedSetsCard(flagIds.map(flagId => `flag:${flagId}:reports`));

    const flags = await Promise.all(flagIds.map(async (flagId, idx) => {
        let flagObj = await db.getObject(`flag:${flagId}`);
        flagObj = {
            state: 'open',
            assignee: null,
            heat: reportCounts[idx],
            ...flagObj,
        };
        flagObj.labelClass = Flags._states.get(flagObj.state).class;

        return Object.assign(flagObj, {
            target_readable: `${flagObj.type.charAt(0).toUpperCase() + flagObj.type.slice(1)} ${flagObj.targetId}`,
            datetimeISO: utils.toISOString(flagObj.datetime),
        });
    }));

    const payload = await plugins.hooks.fire('filter:flags.list', {
        flags: flags,
        page: filters.page,
        uid: data.uid,
    });

    return {
        flags: payload.flags,
        count,
        page: payload.page,
        pageCount: pageCount,
    };
};

Flags.sort = async function (flagIds, sort) {
    const filterPosts = async (flagIds) => {
        const keys = flagIds.map(id => `flag:${id}`);
        const types = await db.getObjectsFields(keys, ['type']);
        return flagIds.filter((id, idx) => types[idx].type === 'post');
    };

    switch (sort) {
        // 'newest' is not handled because that is default
        case 'oldest':
            flagIds = flagIds.reverse();
            break;

        case 'reports': {
            const keys = flagIds.map(id => `flag:${id}:reports`);
            const heat = await db.sortedSetsCard(keys);
            const mapped = heat.map((el, i) => ({
                index: i, heat: el,
            }));
            mapped.sort((a, b) => b.heat - a.heat);
            flagIds = mapped.map(obj => flagIds[obj.index]);
            break;
        }

        case 'upvotes': // fall-through
        case 'downvotes':
        case 'replies': {
            flagIds = await filterPosts(flagIds);
            const keys = flagIds.map(id => `flag:${id}`);
            const pids = (await db.getObjectsFields(keys, ['targetId'])).map(obj => obj.targetId);
            const votes = (await posts.getPostsFields(pids, [sort])).map(obj => parseInt(obj[sort], 10) || 0);
            const sortRef = flagIds.reduce((memo, cur, idx) => {
                memo[cur] = votes[idx];
                return memo;
            }, {});

            flagIds = flagIds.sort((a, b) => sortRef[b] - sortRef[a]);
        }
    }

    return flagIds;
};

Flags.validate = async function (payload) {
    const [target, reporter] = await Promise.all([
        Flags.getTarget(payload.type, payload.id, payload.uid),
        user.getUserData(payload.uid),
    ]);

    if (!target) {
        throw new Error('[[error:invalid-data]]');
    } else if (target.deleted) {
        throw new Error('[[error:post-deleted]]');
    } else if (!reporter || !reporter.userslug) {
        throw new Error('[[error:no-user]]');
    } else if (reporter.banned) {
        throw new Error('[[error:user-banned]]');
    }

    // Disallow flagging of profiles/content of privileged users
    const [targetPrivileged, reporterPrivileged] = await Promise.all([
        user.isPrivileged(target.uid),
        user.isPrivileged(reporter.uid),
    ]);
    if (targetPrivileged && !reporterPrivileged) {
        throw new Error('[[error:cant-flag-privileged]]');
    }

    if (payload.type === 'post') {
        const editable = await privileges.posts.canEdit(payload.id, payload.uid);
        if (!editable.flag && !meta.config['reputation:disabled'] && reporter.reputation < meta.config['min:rep:flag']) {
            throw new Error(`[[error:not-enough-reputation-to-flag, ${meta.config['min:rep:flag']}]]`);
        }
    } else if (payload.type === 'user') {
        if (parseInt(payload.id, 10) === parseInt(payload.uid, 10)) {
            throw new Error('[[error:cant-flag-self]]');
        }
        const editable = await privileges.users.canEdit(payload.uid, payload.id);
        if (!editable && !meta.config['reputation:disabled'] && reporter.reputation < meta.config['min:rep:flag']) {
            throw new Error(`[[error:not-enough-reputation-to-flag, ${meta.config['min:rep:flag']}]]`);
        }
    } else {
        throw new Error('[[error:invalid-data]]');
    }
};

Flags.getNotes = async function (flagId) {
    let notes = await db.getSortedSetRevRangeWithScores(`flag:${flagId}:notes`, 0, -1);
    notes = await modifyNotes(notes);
    return notes;
};

Flags.getNote = async function (flagId, datetime) {
    datetime = parseInt(datetime, 10);
    if (isNaN(datetime)) {
        throw new Error('[[error:invalid-data]]');
    }

    let notes = await db.getSortedSetRangeByScoreWithScores(`flag:${flagId}:notes`, 0, 1, datetime, datetime);
    if (!notes.length) {
        throw new Error('[[error:invalid-data]]');
    }

    notes = await modifyNotes(notes);
    return notes[0];
};

Flags.getFlagIdByTarget = async function (type, id) {
    let method;
    switch (type) {
        case 'post':
            method = posts.getPostField;
            break;

        case 'user':
            method = user.getUserField;
            break;

        default:
            throw new Error('[[error:invalid-data]]');
    }

    return await method(id, 'flagId');
};

async function modifyNotes(notes) {
    const uids = [];
    notes = notes.map((note) => {
        const noteObj = JSON.parse(note.value);
        uids.push(noteObj[0]);
        return {
            uid: noteObj[0],
            content: noteObj[1],
            datetime: note.score,
            datetimeISO: utils.toISOString(note.score),
        };
    });
    const userData = await user.getUsersFields(uids, ['username', 'userslug', 'picture']);
    return notes.map((note, idx) => {
        note.user = userData[idx];
        note.content = validator.escape(note.content);
        return note;
    });
}

Flags.deleteNote = async function (flagId, datetime) {
    datetime = parseInt(datetime, 10);
    if (isNaN(datetime)) {
        throw new Error('[[error:invalid-data]]');
    }

    const note = await db.getSortedSetRangeByScore(`flag:${flagId}:notes`, 0, 1, datetime, datetime);
    if (!note.length) {
        throw new Error('[[error:invalid-data]]');
    }

    await db.sortedSetRemove(`flag:${flagId}:notes`, note[0]);
};

Flags.create = async function (type, id, uid, reason, timestamp, forceFlag = false) {
    let doHistoryAppend = false;
    if (!timestamp) {
        timestamp = Date.now();
        doHistoryAppend = true;
    }
    const [flagExists, targetExists,, targetFlagged, targetUid, targetCid] = await Promise.all([
        // Sanity checks
        Flags.exists(type, id, uid),
        Flags.targetExists(type, id),
        Flags.canFlag(type, id, uid, forceFlag),
        Flags.targetFlagged(type, id),

        // Extra data for zset insertion
        Flags.getTargetUid(type, id),
        Flags.getTargetCid(type, id),
    ]);
    if (!forceFlag && flagExists) {
        throw new Error(`[[error:${type}-already-flagged]]`);
    } else if (!targetExists) {
        throw new Error('[[error:invalid-data]]');
    }

    // If the flag already exists, just add the report
    if (targetFlagged) {
        const flagId = await Flags.getFlagIdByTarget(type, id);
        await Promise.all([
            Flags.addReport(flagId, type, id, uid, reason, timestamp),
            Flags.update(flagId, uid, {
                state: 'open',
                report: 'added',
            }),
        ]);

        return await Flags.get(flagId);
    }

    const flagId = await db.incrObjectField('global', 'nextFlagId');
    const batched = [];

    batched.push(
        db.setObject(`flag:${flagId}`, {
            flagId: flagId,
            type: type,
            targetId: id,
            targetUid: targetUid,
            datetime: timestamp,
        }),
        Flags.addReport(flagId, type, id, uid, reason, timestamp),
        db.sortedSetAdd('flags:datetime', timestamp, flagId), // by time, the default
        db.sortedSetAdd(`flags:byType:${type}`, timestamp, flagId), // by flag type
        db.sortedSetIncrBy('flags:byTarget', 1, [type, id].join(':')), // by flag target (score is count)
        analytics.increment('flags') // some fancy analytics
    );

    if (targetUid) {
        batched.push(db.sortedSetAdd(`flags:byTargetUid:${targetUid}`, timestamp, flagId)); // by target uid
    }

    if (targetCid) {
        batched.push(db.sortedSetAdd(`flags:byCid:${targetCid}`, timestamp, flagId)); // by target cid
    }

    if (type === 'post') {
        batched.push(
            db.sortedSetAdd(`flags:byPid:${id}`, timestamp, flagId), // by target pid
            posts.setPostField(id, 'flagId', flagId)
        );

        if (targetUid && parseInt(targetUid, 10) !== parseInt(uid, 10)) {
            batched.push(user.incrementUserFlagsBy(targetUid, 1));
        }
    } else if (type === 'user') {
        batched.push(user.setUserField(id, 'flagId', flagId));
    }

    // Run all the database calls in one single batched call...
    await Promise.all(batched);

    if (doHistoryAppend) {
        await Flags.update(flagId, uid, { state: 'open' });
    }

    const flagObj = await Flags.get(flagId);

    plugins.hooks.fire('action:flags.create', { flag: flagObj });
    return flagObj;
};

Flags.purge = async function (flagIds) {
    const flagData = (await db.getObjects(flagIds.map(flagId => `flag:${flagId}`))).filter(Boolean);
    const postFlags = flagData.filter(flagObj => flagObj.type === 'post');
    const userFlags = flagData.filter(flagObj => flagObj.type === 'user');
    const assignedFlags = flagData.filter(flagObj => !!flagObj.assignee);

    const [allReports, cids] = await Promise.all([
        db.getSortedSetsMembers(flagData.map(flagObj => `flag:${flagObj.flagId}:reports`)),
        categories.getAllCidsFromSet('categories:cid'),
    ]);
    const allReporterUids = allReports.map(flagReports => flagReports.map(report => report && report.split(';')[0]));
    const removeReporters = [];
    flagData.forEach((flagObj, i) => {
        if (Array.isArray(allReporterUids[i])) {
            allReporterUids[i].forEach((uid) => {
                removeReporters.push([`flags:hash`, [flagObj.type, flagObj.targetId, uid].join(':')]);
                removeReporters.push([`flags:byReporter:${uid}`, flagObj.flagId]);
            });
        }
    });
    await Promise.all([
        db.sortedSetRemoveBulk([
            ...flagData.map(flagObj => ([`flags:byType:${flagObj.type}`, flagObj.flagId])),
            ...flagData.map(flagObj => ([`flags:byState:${flagObj.state}`, flagObj.flagId])),
            ...removeReporters,
            ...postFlags.map(flagObj => ([`flags:byPid:${flagObj.targetId}`, flagObj.flagId])),
            ...assignedFlags.map(flagObj => ([`flags:byAssignee:${flagObj.assignee}`, flagObj.flagId])),
            ...userFlags.map(flagObj => ([`flags:byTargetUid:${flagObj.targetUid}`, flagObj.flagId])),
        ]),
        db.deleteObjectFields(postFlags.map(flagObj => `post:${flagObj.targetId}`, ['flagId'])),
        db.deleteObjectFields(userFlags.map(flagObj => `user:${flagObj.targetId}`, ['flagId'])),
        db.deleteAll([
            ...flagIds.map(flagId => `flag:${flagId}`),
            ...flagIds.map(flagId => `flag:${flagId}:notes`),
            ...flagIds.map(flagId => `flag:${flagId}:reports`),
            ...flagIds.map(flagId => `flag:${flagId}:history`),
        ]),
        db.sortedSetRemove(cids.map(cid => `flags:byCid:${cid}`), flagIds),
        db.sortedSetRemove('flags:datetime', flagIds),
        db.sortedSetRemove(
            'flags:byTarget',
            flagData.map(flagObj => [flagObj.type, flagObj.targetId].join(':'))
        ),
    ]);
};

Flags.getReports = async function (flagId) {
    const payload = await db.getSortedSetRevRangeWithScores(`flag:${flagId}:reports`, 0, -1);
    const [reports, uids] = payload.reduce((memo, cur) => {
        const value = cur.value.split(';');
        memo[1].push(value.shift());
        cur.value = validator.escape(String(value.join(';')));
        memo[0].push(cur);

        return memo;
    }, [[], []]);

    await Promise.all(reports.map(async (report, idx) => {
        report.timestamp = report.score;
        report.timestampISO = new Date(report.score).toISOString();
        delete report.score;
        report.reporter = await user.getUserFields(uids[idx], ['username', 'userslug', 'picture', 'reputation']);
    }));

    return reports;
};

// Not meant to be called directly, call Flags.create() instead.
Flags.addReport = async function (flagId, type, id, uid, reason, timestamp) {
    await db.sortedSetAddBulk([
        [`flags:byReporter:${uid}`, timestamp, flagId],
        [`flag:${flagId}:reports`, timestamp, [uid, reason].join(';')],

        ['flags:hash', flagId, [type, id, uid].join(':')],
    ]);

    plugins.hooks.fire('action:flags.addReport', { flagId, type, id, uid, reason, timestamp });
};

Flags.rescindReport = async (type, id, uid) => {
    const exists = await Flags.exists(type, id, uid);
    if (!exists) {
        return true;
    }

    const flagId = await db.sortedSetScore('flags:hash', [type, id, uid].join(':'));
    const reports = await db.getSortedSetMembers(`flag:${flagId}:reports`);
    let reason;
    reports.forEach((payload) => {
        if (!reason) {
            const [payloadUid, payloadReason] = payload.split(';');
            if (parseInt(payloadUid, 10) === parseInt(uid, 10)) {
                reason = payloadReason;
            }
        }
    });

    if (!reason) {
        throw new Error('[[error:cant-locate-flag-report]]');
    }

    await db.sortedSetRemoveBulk([
        [`flags:byReporter:${uid}`, flagId],
        [`flag:${flagId}:reports`, [uid, reason].join(';')],

        ['flags:hash', [type, id, uid].join(':')],
    ]);

    // If there are no more reports, consider the flag resolved
    const reportCount = await db.sortedSetCard(`flag:${flagId}:reports`);
    if (reportCount < 1) {
        await Flags.update(flagId, uid, {
            state: 'resolved',
            report: 'rescinded',
        });
    }
};

Flags.exists = async function (type, id, uid) {
    return await db.isSortedSetMember('flags:hash', [type, id, uid].join(':'));
};

Flags.canView = async (flagId, uid) => {
    const exists = await db.isSortedSetMember('flags:datetime', flagId);
    if (!exists) {
        return false;
    }

    const [{ type, targetId }, isAdminOrGlobalMod] = await Promise.all([
        db.getObject(`flag:${flagId}`),
        user.isAdminOrGlobalMod(uid),
    ]);

    if (type === 'post') {
        const cid = await Flags.getTargetCid(type, targetId);
        const isModerator = await user.isModerator(uid, cid);

        return isAdminOrGlobalMod || isModerator;
    }

    return isAdminOrGlobalMod;
};

Flags.canFlag = async function (type, id, uid, skipLimitCheck = false) {
    const limit = meta.config['flags:limitPerTarget'];
    if (!skipLimitCheck && limit > 0) {
        const score = await db.sortedSetScore('flags:byTarget', `${type}:${id}`);
        if (score >= limit) {
            throw new Error(`[[error:${type}-flagged-too-many-times]]`);
        }
    }
    const oneday = 24 * 60 * 60 * 1000;
    const now = Date.now();
    const [flagIds, canRead, isPrivileged] = await Promise.all([
        db.getSortedSetRangeByScore(`flags:byReporter:${uid}`, 0, -1, now - oneday, '+inf'),
        privileges.posts.can('topics:read', id, uid),
        user.isPrivileged(uid),
    ]);
    const allowedFlagsPerDay = meta.config[`flags:${type}FlagsPerDay`];
    if (!isPrivileged && allowedFlagsPerDay > 0) {
        const flagData = await db.getObjects(flagIds.map(id => `flag:${id}`));
        const flagsOfType = flagData.filter(f => f && f.type === type);
        if (allowedFlagsPerDay > 0 && flagsOfType.length > allowedFlagsPerDay) {
            throw new Error(`[[error:too-many-${type}-flags-per-day, ${allowedFlagsPerDay}]]`);
        }
    }

    switch (type) {
        case 'user':
            return true;

        case 'post':
            if (!canRead) {
                throw new Error('[[error:no-privileges]]');
            }
            break;

        default:
            throw new Error('[[error:invalid-data]]');
    }
};

Flags.getTarget = async function (type, id, uid) {
    if (type === 'user') {
        const userData = await user.getUserData(id);
        return userData && userData.uid ? userData : {};
    }
    if (type === 'post') {
        let postData = await posts.getPostData(id);
        if (!postData) {
            return {};
        }
        postData = await posts.parsePost(postData);
        postData = await topics.addPostData([postData], uid);
        return postData[0];
    }
    throw new Error('[[error:invalid-data]]');
};

Flags.targetExists = async function (type, id) {
    if (type === 'post') {
        return await posts.exists(id);
    } else if (type === 'user') {
        return await user.exists(id);
    }
    throw new Error('[[error:invalid-data]]');
};

Flags.targetFlagged = async function (type, id) {
    return await db.sortedSetScore('flags:byTarget', [type, id].join(':')) >= 1;
};

Flags.getTargetUid = async function (type, id) {
    if (type === 'post') {
        return await posts.getPostField(id, 'uid');
    }
    return id;
};

Flags.getTargetCid = async function (type, id) {
    if (type === 'post') {
        return await posts.getCidByPid(id);
    }
    return null;
};

Flags.update = async function (flagId, uid, changeset) {
    const current = await db.getObjectFields(`flag:${flagId}`, ['uid', 'state', 'assignee', 'type', 'targetId']);
    if (!current.type) {
        return;
    }
    const now = changeset.datetime || Date.now();
    const notifyAssignee = async function (assigneeId) {
        if (assigneeId === '' || parseInt(uid, 10) === parseInt(assigneeId, 10)) {
            return;
        }
        const notifObj = await notifications.create({
            type: 'my-flags',
            bodyShort: `[[notifications:flag-assigned-to-you, ${flagId}]]`,
            bodyLong: '',
            path: `/flags/${flagId}`,
            nid: `flags:assign:${flagId}:uid:${assigneeId}`,
            from: uid,
        });
        await notifications.push(notifObj, [assigneeId]);
    };
    const isAssignable = async function (assigneeId) {
        let allowed = false;
        allowed = await user.isAdminOrGlobalMod(assigneeId);

        // Mods are also allowed to be assigned, if flag target is post in uid's moderated cid
        if (!allowed && current.type === 'post') {
            const cid = await posts.getCidByPid(current.targetId);
            allowed = await user.isModerator(assigneeId, cid);
        }

        return allowed;
    };

    async function rescindNotifications(match) {
        const nids = await db.getSortedSetScan({ key: 'notifications', match: `${match}*` });
        return notifications.rescind(nids);
    }

    // Retrieve existing flag data to compare for history-saving/reference purposes
    const tasks = [];
    for (const prop of Object.keys(changeset)) {
        if (current[prop] === changeset[prop]) {
            delete changeset[prop];
        } else if (prop === 'state') {
            if (!Flags._states.has(changeset[prop])) {
                delete changeset[prop];
            } else {
                tasks.push(db.sortedSetAdd(`flags:byState:${changeset[prop]}`, now, flagId));
                tasks.push(db.sortedSetRemove(`flags:byState:${current[prop]}`, flagId));
                if (changeset[prop] === 'resolved' && meta.config['flags:actionOnResolve'] === 'rescind') {
                    tasks.push(rescindNotifications(`flag:${current.type}:${current.targetId}`));
                }
                if (changeset[prop] === 'rejected' && meta.config['flags:actionOnReject'] === 'rescind') {
                    tasks.push(rescindNotifications(`flag:${current.type}:${current.targetId}`));
                }
            }
        } else if (prop === 'assignee') {
            if (changeset[prop] === '') {
                tasks.push(db.sortedSetRemove(`flags:byAssignee:${changeset[prop]}`, flagId));
            /* eslint-disable-next-line */
            } else if (!await isAssignable(parseInt(changeset[prop], 10))) {
                delete changeset[prop];
            } else {
                tasks.push(db.sortedSetAdd(`flags:byAssignee:${changeset[prop]}`, now, flagId));
                tasks.push(notifyAssignee(changeset[prop]));
            }
        }
    }

    if (!Object.keys(changeset).length) {
        return;
    }

    tasks.push(db.setObject(`flag:${flagId}`, changeset));
    tasks.push(Flags.appendHistory(flagId, uid, changeset));
    await Promise.all(tasks);

    plugins.hooks.fire('action:flags.update', { flagId: flagId, changeset: changeset, uid: uid });
};

Flags.resolveFlag = async function (type, id, uid) {
    const flagId = await Flags.getFlagIdByTarget(type, id);
    if (parseInt(flagId, 10)) {
        await Flags.update(flagId, uid, { state: 'resolved' });
    }
};

Flags.resolveUserPostFlags = async function (uid, callerUid) {
    if (meta.config['flags:autoResolveOnBan']) {
        await batch.processSortedSet(`uid:${uid}:posts`, async (pids) => {
            let postData = await posts.getPostsFields(pids, ['pid', 'flagId']);
            postData = postData.filter(p => p && p.flagId);
            for (const postObj of postData) {
                if (parseInt(postObj.flagId, 10)) {
                    // eslint-disable-next-line no-await-in-loop
                    await Flags.update(postObj.flagId, callerUid, { state: 'resolved' });
                }
            }
        }, {
            batch: 500,
        });
    }
};

Flags.getHistory = async function (flagId) {
    const uids = [];
    let history = await db.getSortedSetRevRangeWithScores(`flag:${flagId}:history`, 0, -1);
    const targetUid = await db.getObjectField(`flag:${flagId}`, 'targetUid');

    history = history.map((entry) => {
        entry.value = JSON.parse(entry.value);

        uids.push(entry.value[0]);

        // Deserialise changeset
        const changeset = entry.value[1];
        if (changeset.hasOwnProperty('state')) {
            changeset.state = changeset.state === undefined ? '' : `[[flags:state-${changeset.state}]]`;
        }
        if (changeset.hasOwnProperty('report')) {
            changeset.report = `[[flags:report-${changeset.report}]]`;
        }

        return {
            uid: entry.value[0],
            fields: changeset,
            datetime: entry.score,
            datetimeISO: utils.toISOString(entry.score),
        };
    });

    // turn assignee uids into usernames
    await Promise.all(history.map(async (entry) => {
        if (entry.fields.hasOwnProperty('assignee')) {
            entry.fields.assignee = await user.getUserField(entry.fields.assignee, 'username');
        }
    }));

    // Append ban history and username change data
    history = await mergeBanHistory(history, targetUid, uids);
    history = await mergeMuteHistory(history, targetUid, uids);
    history = await mergeUsernameEmailChanges(history, targetUid, uids);

    const userData = await user.getUsersFields(uids, ['username', 'userslug', 'picture']);
    history.forEach((event, idx) => { event.user = userData[idx]; });

    // Resort by date
    history = history.sort((a, b) => b.datetime - a.datetime);

    return history;
};

Flags.appendHistory = async function (flagId, uid, changeset) {
    const datetime = changeset.datetime || Date.now();
    delete changeset.datetime;
    const payload = JSON.stringify([uid, changeset, datetime]);
    await db.sortedSetAdd(`flag:${flagId}:history`, datetime, payload);
};

Flags.appendNote = async function (flagId, uid, note, datetime) {
    if (datetime) {
        try {
            await Flags.deleteNote(flagId, datetime);
        } catch (e) {
            // Do not throw if note doesn't exist
            if (!e.message === '[[error:invalid-data]]') {
                throw e;
            }
        }
    }
    datetime = datetime || Date.now();

    const payload = JSON.stringify([uid, note]);
    await db.sortedSetAdd(`flag:${flagId}:notes`, datetime, payload);
    await Flags.appendHistory(flagId, uid, {
        notes: null,
        datetime: datetime,
    });
};

Flags.notify = async function (flagObj, uid, notifySelf = false) {
    const [admins, globalMods] = await Promise.all([
        groups.getMembers('administrators', 0, -1),
        groups.getMembers('Global Moderators', 0, -1),
    ]);
    let uids = admins.concat(globalMods);
    let notifObj = null;

    const { displayname } = flagObj.reports[flagObj.reports.length - 1].reporter;

    if (flagObj.type === 'post') {
        const [title, cid] = await Promise.all([
            topics.getTitleByPid(flagObj.targetId),
            posts.getCidByPid(flagObj.targetId),
        ]);

        const modUids = await categories.getModeratorUids([cid]);
        const titleEscaped = utils.decodeHTMLEntities(title).replace(/%/g, '&#37;').replace(/,/g, '&#44;');

        notifObj = await notifications.create({
            type: 'new-post-flag',
            bodyShort: `[[notifications:user-flagged-post-in, ${displayname}, ${titleEscaped}]]`,
            bodyLong: await plugins.hooks.fire('filter:parse.raw', String(flagObj.description || '')),
            pid: flagObj.targetId,
            path: `/flags/${flagObj.flagId}`,
            nid: `flag:post:${flagObj.targetId}:${uid}`,
            from: uid,
            mergeId: `notifications:user-flagged-post-in|${flagObj.targetId}`,
            topicTitle: title,
        });
        uids = uids.concat(modUids[0]);
    } else if (flagObj.type === 'user') {
        const targetDisplayname = flagObj.target && flagObj.target.user ? flagObj.target.user.displayname : '[[global:guest]]';
        notifObj = await notifications.create({
            type: 'new-user-flag',
            bodyShort: `[[notifications:user-flagged-user, ${displayname}, ${targetDisplayname}]]`,
            bodyLong: await plugins.hooks.fire('filter:parse.raw', String(flagObj.description || '')),
            path: `/flags/${flagObj.flagId}`,
            nid: `flag:user:${flagObj.targetId}:${uid}`,
            from: uid,
            mergeId: `notifications:user-flagged-user|${flagObj.targetId}`,
        });
    } else {
        throw new Error('[[error:invalid-data]]');
    }

    plugins.hooks.fire('action:flags.notify', {
        flag: flagObj,
        notification: notifObj,
        from: uid,
        to: uids,
    });
    if (!notifySelf) {
        uids = uids.filter(_uid => parseInt(_uid, 10) !== parseInt(uid, 10));
    }
    await notifications.push(notifObj, uids);
};

async function mergeBanHistory(history, targetUid, uids) {
    return await mergeBanMuteHistory(history, uids, {
        set: `uid:${targetUid}:bans:timestamp`,
        label: '[[user:banned]]',
        reasonDefault: '[[user:info.banned-no-reason]]',
        expiryKey: '[[user:info.banned-expiry]]',
    });
}

async function mergeMuteHistory(history, targetUid, uids) {
    return await mergeBanMuteHistory(history, uids, {
        set: `uid:${targetUid}:mutes:timestamp`,
        label: '[[user:muted]]',
        reasonDefault: '[[user:info.muted-no-reason]]',
        expiryKey: '[[user:info.muted-expiry]]',
    });
}

async function mergeBanMuteHistory(history, uids, params) {
    let recentObjs = await db.getSortedSetRevRange(params.set, 0, 19);
    recentObjs = await db.getObjects(recentObjs);

    return history.concat(recentObjs.reduce((memo, cur) => {
        uids.push(cur.fromUid);
        memo.push({
            uid: cur.fromUid,
            meta: [
                {
                    key: params.label,
                    value: validator.escape(String(cur.reason || params.reasonDefault)),
                    labelClass: 'danger',
                },
                {
                    key: params.expiryKey,
                    value: new Date(parseInt(cur.expire, 10)).toISOString(),
                    labelClass: 'default',
                },
            ],
            datetime: parseInt(cur.timestamp, 10),
            datetimeISO: utils.toISOString(parseInt(cur.timestamp, 10)),
        });

        return memo;
    }, []));
}

async function mergeUsernameEmailChanges(history, targetUid, uids) {
    const usernameChanges = await user.getHistory(`user:${targetUid}:usernames`);
    const emailChanges = await user.getHistory(`user:${targetUid}:emails`);

    return history.concat(usernameChanges.reduce((memo, changeObj) => {
        uids.push(targetUid);
        memo.push({
            uid: targetUid,
            meta: [
                {
                    key: '[[user:change-username]]',
                    value: changeObj.value,
                    labelClass: 'primary',
                },
            ],
            datetime: changeObj.timestamp,
            datetimeISO: changeObj.timestampISO,
        });

        return memo;
    }, [])).concat(emailChanges.reduce((memo, changeObj) => {
        uids.push(targetUid);
        memo.push({
            uid: targetUid,
            meta: [
                {
                    key: '[[user:change-email]]',
                    value: changeObj.value,
                    labelClass: 'primary',
                },
            ],
            datetime: changeObj.timestamp,
            datetimeISO: changeObj.timestampISO,
        });

        return memo;
    }, []));
}

require('./promisify')(Flags);