path: root/src/server/websocket.ts

import { blue } from 'colors';
import { createServer } from 'https';
import * as _ from 'lodash';
import { networkInterfaces } from 'os';
import { Server, Socket } from 'socket.io';
import { SecureContextOptions } from 'tls';
import { ServerUtils } from '../ServerUtils';
import { serializedDoctype, serializedFieldsType } from '../fields/ObjectField';
import { logPort } from './ActionUtilities';
import { Client } from './Client';
import { DashStats } from './DashStats';
import { DocumentsCollection } from './IDatabase';
import { Diff, GestureContent, MessageStore } from './Message';
import { resolvedPorts, socketMap, timeMap, userOperations } from './SocketData';
import { initializeGuest } from './authentication/DashUserModel';
import { Database } from './database';

export namespace WebSocket {
    let CurUser: string | undefined;
    export let _socket: Socket;
    export let _disconnect: () => void;
    export const clients: { [key: string]: Client } = {};

    function processGesturePoints(socket: Socket, content: GestureContent) {
        socket.broadcast.emit('receiveGesturePoints', content);
    }

    export async function doDelete(onlyFields = true) {
        const target: string[] = [];
        onlyFields && target.push(DocumentsCollection);
        await Database.Instance.dropSchema(...target);
        initializeGuest();
    }

    function printActiveUsers() {
        socketMap.forEach((user, socket) => !socket.disconnected && console.log(user));
    }
    function barReceived(socket: Socket, userEmail: string) {
        clients[userEmail] = new Client(userEmail.toString());
        const currentdate = new Date();
        const datetime = currentdate.getDate() + '/' + (currentdate.getMonth() + 1) + '/' + currentdate.getFullYear() + ' @ ' + currentdate.getHours() + ':' + currentdate.getMinutes() + ':' + currentdate.getSeconds();
        console.log(blue(`user ${userEmail} has connected to the web socket at: ${datetime}`));
        printActiveUsers();

        timeMap[userEmail] = Date.now();
        socketMap.set(socket, userEmail + ' at ' + datetime);
        userOperations.set(userEmail, 0);
        DashStats.logUserLogin(userEmail);
    }

    function GetRefFieldLocal(id: string, callback: (result?: serializedDoctype | undefined) => void) {
        return Database.Instance.getDocument(id, callback);
    }
    function GetRefField([id, callback]: [string, (result?: serializedDoctype) => void]) {
        process.stdout.write(`+`);
        GetRefFieldLocal(id, callback);
    }

    function GetRefFields([ids, callback]: [string[], (result?: serializedDoctype[]) => void]) {
        process.stdout.write(`${ids.length}…`);
        Database.Instance.getDocuments(ids, callback);
    }

    function addToListField(socket: Socket, diff: Diff, listDoc: serializedDoctype | undefined, cb: (res: boolean) => void): void {
        const $addToSet = diff.diff.$addToSet as serializedFieldsType;
        const updatefield = Array.from(Object.keys($addToSet ?? {}))[0];
        const newListItems = $addToSet?.[updatefield]?.fields;

        if (newListItems) {
            const length = diff.diff.$addToSet?.length;
            diff.diff.$set = $addToSet; // convert add to set to a query of the current fields, and then a set of the composition of the new fields with the old ones
            delete diff.diff.$addToSet; // can't pass $set to Mongo, or it will do that insetead of $addToSet
            const listItems = listDoc?.fields?.[updatefield.replace('fields.', '')]?.fields.filter(item => item) ?? [];
            diff.diff.$set[updatefield]!.fields = [...listItems, ...newListItems]; // , ...newListItems.filter((newItem: any) => newItem === null || !curList.some((curItem: any) => curItem.fieldId ? curItem.fieldId === newItem.fieldId : curItem.heading ? curItem.heading === newItem.heading : curItem === newItem))];

            // if the client's list length is not the same as what we're writing to the server,
            // then we need to send the server's version back to the client so that they are in synch.
            // this could happen if another client made a change before the server receives the update from the first client
            const target = length !== diff.diff.$set[updatefield].fields.length ? socket : socket.broadcast;
            target === socket && console.log('Warning: SEND BACK: list modified during add update. Composite list is being returned.');
            Database.Instance.update(diff.id, diff.diff, () => cb(target.emit(MessageStore.UpdateField.Message, diff)), false);
        } else cb(false);
    }

    /**
     * findClosestIndex() is a helper function that will try to find
     * the closest index of a list that has the same value as
     * a specified argument/index pair.
     * @param list the list to search through
     * @param indexesToDelete a list of indexes that are already marked for deletion
     * so they will be ignored
     * @param value the value of the item to remove
     * @param hintIndex the index that the element was at on the client's copy of
     * the data
     * @returns the closest index with the same value or -1 if the element was not found.
     */
    function findClosestIndex(list: { fieldId: string; __type: string }[], indexesToDelete: number[], value: { fieldId: string; __type: string }, hintIndex: number) {
        let closestIndex = -1;
        for (let i = 0; i < list.length; i++) {
            if (list[i] === value && !indexesToDelete.includes(i)) {
                if (Math.abs(i - hintIndex) < Math.abs(closestIndex - hintIndex)) {
                    closestIndex = i;
                }
            }
        }
        return closestIndex;
    }

    /**
     * remFromListField() receives the items to remove and a hint
     * from the client, and attempts to make the modification to the
     * server's copy of the data. If server's copy does not match
     * the client's after removal, the server will SEND BACk
     * its version to the client.
     * @param socket the socket that the client is connected on
     * @param diff an object containing the items to remove and a hint
     * (the hint contains start index and deleteCount, the number of
     * items to delete)
     * @param curListItems the server's current copy of the data
     */
    function remFromListField(socket: Socket, diff: Diff, curListItems: serializedDoctype | undefined, cb: (res: boolean) => void): void {
        const $remFromSet = diff.diff.$remFromSet as serializedFieldsType;
        const updatefield = Array.from(Object.keys($remFromSet ?? {}))[0];
        const remListItems = $remFromSet?.[updatefield]?.fields;

        if (remListItems) {
            const hint = diff.diff.$remFromSet?.hint;
            const length = diff.diff.$remFromSet?.length;
            diff.diff.$set = $remFromSet; // convert rem from set to a query of the current fields, and then a set of the old fields minus the removed ones
            delete diff.diff.$remFromSet; // can't pass $set to Mongo, or it will do that insetead of $remFromSet
            const curList = curListItems?.fields?.[updatefield.replace('fields.', '')]?.fields.filter(f => f) ?? [];

            if (hint) {
                // indexesToRemove stores the indexes that we mark for deletion, which is later used to filter the list (delete the elements)
                const indexesToRemove: number[] = [];
                for (let i = 0; i < hint.deleteCount; i++) {
                    if (curList.length > i + hint.start && _.isEqual(curList[i + hint.start], remListItems[i])) {
                        indexesToRemove.push(i + hint.start);
                    } else {
                        const closestIndex = findClosestIndex(curList, indexesToRemove, remListItems[i], i + hint.start);
                        if (closestIndex !== -1) {
                            indexesToRemove.push(closestIndex);
                        } else {
                            console.log('Item to delete was not found');
                        }
                    }
                }
                diff.diff.$set[updatefield]!.fields = curList.filter((curItem, index) => !indexesToRemove.includes(index));
            } else {
                // if we didn't get a hint, remove all matching items from the list
                diff.diff.$set[updatefield]!.fields = curList?.filter(curItem => !remListItems.some(remItem => (remItem.fieldId ? remItem.fieldId === curItem.fieldId : remItem.heading ? remItem.heading === curItem.heading : remItem === curItem)));
            }

            // if the client's list length is not the same as what we're writing to the server,
            // then we need to send the server's version back to the client so that they are in synch.
            // this could happen if another client made a change before the server receives the update from the first client
            const target = length !== diff.diff.$set[updatefield].fields.length ? socket : socket.broadcast;
            target === socket && console.log('Warning: SEND BACK: list modified during remove update. Composite list is being returned.');
            Database.Instance.update(diff.id, diff.diff, () => cb(target.emit(MessageStore.UpdateField.Message, diff)), false);
        } else cb(false);
    }

    const pendingOps = new Map<string, { diff: Diff; socket: Socket }[]>();

    function dispatchNextOp(id: string): unknown {
        const next = pendingOps.get(id)?.shift();
        // eslint-disable-next-line @typescript-eslint/no-unused-vars
        const nextOp = (res: boolean) => dispatchNextOp(id);
        if (next) {
            const { diff, socket } = next;
            // ideally, we'd call the Database update method for all actions, but for now we handle list insertion/removal on our own
            switch (diff.diff.$addToSet ? 'add' : diff.diff.$remFromSet ? 'rem' : 'set') {
                case 'add': return GetRefFieldLocal(id, (result) => addToListField(socket, diff, result, nextOp)); // prettier-ignore
                case 'rem': return GetRefFieldLocal(id, (result) => remFromListField(socket, diff, result, nextOp)); // prettier-ignore
                default:    return Database.Instance.update(id, diff.diff, 
                                                            () => nextOp(socket.broadcast.emit(MessageStore.UpdateField.Message, diff)),
                                                            false
                                                        ); // prettier-ignore
            }
        }
        return !pendingOps.get(id)?.length && pendingOps.delete(id);
    }

    function UpdateField(socket: Socket, diff: Diff) {
        const curUser = socketMap.get(socket);
        if (curUser) {
            const currentUsername = curUser.split(' ')[0];
            userOperations.set(currentUsername, userOperations.get(currentUsername) !== undefined ? userOperations.get(currentUsername)! + 1 : 0);

            if (CurUser !== socketMap.get(socket)) {
                CurUser = socketMap.get(socket);
                console.log('Switch User: ' + CurUser);
            }
            if (pendingOps.has(diff.id)) {
                pendingOps.get(diff.id)!.push({ diff, socket });
                return true;
            }
            pendingOps.set(diff.id, [{ diff, socket }]);
            return dispatchNextOp(diff.id);
        }
        return false;
    }

    function DeleteField(socket: Socket, id: string) {
        Database.Instance.delete({ _id: id }).then(() => socket.broadcast.emit(MessageStore.DeleteField.Message, id));
    }

    function DeleteFields(socket: Socket, ids: string[]) {
        Database.Instance.delete({ _id: { $in: ids } }).then(() => socket.broadcast.emit(MessageStore.DeleteFields.Message, ids));
    }

    function CreateDocField(newValue: serializedDoctype) {
        Database.Instance.insert(newValue);
    }

    export async function initialize(isRelease: boolean, credentials: SecureContextOptions) {
        let io: Server;
        if (isRelease) {
            const { socketPort } = process.env;
            if (socketPort) {
                resolvedPorts.socket = Number(socketPort);
            }
            const httpsServer = createServer(credentials);
            io = new Server(httpsServer, {});
            httpsServer.listen(resolvedPorts.socket);
        } else {
            io = new Server();
            io.listen(resolvedPorts.socket);
        }
        logPort('websocket', resolvedPorts.socket);

        io.on('connection', socket => {
            _socket = socket;
            socket.use((_packet, next) => {
                const userEmail = socketMap.get(socket);
                if (userEmail) {
                    timeMap[userEmail] = Date.now();
                }
                next();
            });

            socket.emit(MessageStore.UpdateStats.Message, DashStats.getUpdatedStatsBundle());

            socket.on('message', (message, room) => {
                console.log('Client said: ', message);
                socket.in(room).emit('message', message);
            });

            socket.on('ipaddr', () =>
                networkInterfaces().keys?.forEach(dev => {
                    if (dev.family === 'IPv4' && dev.address !== '127.0.0.1') {
                        socket.emit('ipaddr', dev.address);
                    }
                })
            );

            socket.on('bye', () => console.log('received bye'));

            socket.on('disconnect', () => {
                const currentUser = socketMap.get(socket);
                if (currentUser !== undefined) {
                    const currentUsername = currentUser.split(' ')[0];
                    DashStats.logUserLogout(currentUsername);
                    delete timeMap[currentUsername];
                }
            });

            ServerUtils.Emit(socket, MessageStore.Foo, 'handshooken');

            ServerUtils.AddServerHandler(socket, MessageStore.Bar, guid => barReceived(socket, guid));
            if (isRelease) {
                ServerUtils.AddServerHandler(socket, MessageStore.DeleteAll, () => doDelete(false));
            }

            ServerUtils.AddServerHandler(socket, MessageStore.CreateDocField, CreateDocField);
            ServerUtils.AddServerHandler(socket, MessageStore.UpdateField, diff => UpdateField(socket, diff));
            ServerUtils.AddServerHandler(socket, MessageStore.DeleteField, id => DeleteField(socket, id));
            ServerUtils.AddServerHandler(socket, MessageStore.DeleteFields, ids => DeleteFields(socket, ids));
            ServerUtils.AddServerHandler(socket, MessageStore.GesturePoints, content => processGesturePoints(socket, content));
            ServerUtils.AddServerHandlerCallback(socket, MessageStore.GetRefField, GetRefField);
            ServerUtils.AddServerHandlerCallback(socket, MessageStore.GetRefFields, GetRefFields);

            /**
             * Whenever we receive the go-ahead, invoke the import script and pass in
             * as an emitter and a terminator the functions that simply broadcast a result
             * or indicate termination to the client via the web socket
             */

            _disconnect = () => {
                socket.broadcast.emit('connection_terminated', Date.now());
                socket.disconnect(true);
            };
        });

        setInterval(() => {
            // Utils.Emit(socket, MessageStore.UpdateStats, DashStats.getUpdatedStatsBundle());

            io.emit(MessageStore.UpdateStats.Message, DashStats.getUpdatedStatsBundle());
        }, DashStats.SAMPLING_INTERVAL);
    }
}