desk2/server/recv.js

import * as des from './deserializer';
import * as send from './send';
import * as math from './math';
import * as storage from './storage';
import * as config from './config';

import { SESSION, MESSAGE, EVENT } from './enums';
import { sessions, desks, queries } from './storage';

// Session ACKed events up to SN
function recv_ack(d, session) {
    const sn = des.u32(d);

    session.state = SESSION.READY;
    session.sn = sn;

    if (config.DEBUG_PRINT) console.log(`ack ${sn} in`);
}

async function recv_syn(d, session) {
    const lsn = des.u32(d);
    const count = des.u32(d);

    if (config.DEBUG_PRINT) console.log(`syn ${lsn} in, total size = ${d.size}`);

    const we_expect = lsn - session.lsn;
    const first = count - we_expect;
    const events = [];

    if (config.DEBUG_PRINT) console.log(`we expect ${we_expect}, count ${count}`);

    for (let i = 0; i < count; ++i) {
        const event = des.event(d);
        if (i >= first) {
            event.desk_id = session.desk_id;
            event.user_id = session.user_id;
            handle_event(session, event);
            events.push(event);
        }
    }

    desks[session.desk_id].sn += we_expect;
    desks[session.desk_id].events.push(...events);
    session.lsn = lsn;

    storage.queries.update_desk_sn.run({
        '$id': session.desk_id,
        '$sn': desks[session.desk_id].sn
    });

    storage.queries.update_session_lsn.run({
        '$id': session.id,
        '$lsn': lsn
    });

    send.send_ack(session.ws, lsn);
    send.sync_desk(session.desk_id);
}

function recv_fire(d, session) {
    const event = des.event(d);

    event.user_id = session.user_id;

    switch (event.type) {
        case EVENT.SET_COLOR: {
            session.color = event.color;
            
            storage.queries.update_session_color.run({
                '$id': session.id,
                '$color': event.color
            });

            break;
        }

        case EVENT.SET_WIDTH: {
            session.width = event.width;

            storage.queries.update_session_width.run({
                '$id': session.id,
                'width': event.width
            });

            break;
        }
    }

    for (const sid in sessions) {
        const other = sessions[sid];
        
        if (other.id === session.id) {
            continue;
        }

        if (other.state !== SESSION.READY) {
            continue;
        }

        if (other.desk_id != session.desk_id) {
            continue;
        }

        send.send_fire(other.ws, event);
    }
}

function handle_event(session, event) {
    switch (event.type) {
        case EVENT.STROKE: {
            event.stroke_id = math.fast_random32();
            
            storage.queries.insert_stroke.run({
                '$id': event.stroke_id,
                '$width': event.width, 
                '$color': event.color,
                '$points': event.points
            });

            storage.queries.insert_event.run({
                '$type': event.type,
                '$desk_id': session.desk_id, 
                '$session_id': session.id, 
                '$stroke_id': event.stroke_id, 
                '$image_id': 0, 
                '$x': 0, 
                '$y': 0,
            });

            break;
        }

        case EVENT.ERASER:
        case EVENT.IMAGE:
        case EVENT.IMAGE_MOVE:
        case EVENT.UNDO: {
            storage.queries.insert_event.run({
                '$type': event.type,
                '$desk_id': session.desk_id, 
                '$session_id': session.id, 
                '$stroke_id': event.stroke_id || 0,
                '$image_id': event.image_id || 0, 
                '$x': event.x || 0, 
                '$y': event.y || 0,
            });

            break;      
        }

        default: {
            console.error('fuck');
            console.trace();
            process.exit(1);
        }
    }
}

export async function handle_message(ws, d) {
    if (!(ws.data.session_id in sessions)) {
        return;
    }

    const session = sessions[ws.data.session_id];
    const desk_id = session.desk_id;
    const message_type = des.u8(d);

    switch (message_type) {
        case MESSAGE.FIRE: {
            recv_fire(d, session);
            break;
        }

        case MESSAGE.SYN: {
            recv_syn(d, session);
            break;
        }

        case MESSAGE.ACK: {
            recv_ack(d, session);
            break;
        }

        default: {
            console.error('fuck');
            console.trace();
            process.exit(1);
        }
    }
}