notif.n.js

//?addrs=<$addr,>&msg=<$msg> // send message to addresses
//output: {msgId,addrs:[$addr,],msg,date:$ms}
//?addrs=<$addr,>&msgAfter=<$msgId> // get messages for addresses after msgId
//output: [{msgId,addrs:[$addr,],msg,date:$ms},]

const PORT = 4697
const http = require( 'http' )
const url = require( 'url' )
const fs = require( 'fs' )

let msgId = 0
let subId = 0
let msgs = {} // {$msgId:{addrs:[$addr,],msg,date:$ms},}
let subs = {} // {$subId:{addrs:[$addr,],msgAfter,date:$ms,res},}
let addr_subs = {} // {$addr:{$subId:$msgAfter,},}
let addr_msgs = {} // {$addr:{$msgId:$date,},,lastMsgId}
let mylog = s => console.log( new Date().toLocaleString( 'sv' ) + " " + s )

let logFile = {}
let webserver = http.createServer( function( req, res ){
    res.writeHead( 200, { "Content-Type" : "text/html" } )
    let q = url.parse( req.url, true ).query
    if ( ! q.addrs || ! /^[a-z0-9_\-]{1,12}(,[a-z0-9_\-]{1,12})*$/.test( q.addrs ) )
        q.addrs = ""
    if ( q.msg )
        q.msg = q.msg.replace( /[^!-~\s\t\r\n]/g, "" )
    if ( q.msgAfter )
        q.msgAfter = q.msgAfter | 0
    mylog( `Query param: ${ JSON.stringify( q ) }.` )
    let date = Date.now()
    let addrs = q.addrs.split( ',' )
    if ( q.addrs && q.msg ){
        msgId++
        msgs[ msgId ] = { addrs: addrs, msg: q.msg, date: date }
        mylog( `New message ${msgId} saved.` )
        let out = { msgId: msgId, addrs: addrs, msg: q.msg, date: date }
        addrs.forEach( ( addr ) => {
            if ( addr_subs[addr] ){
                for ( const [ subId, msgAfter ] of Object.entries( addr_subs[addr] ) ){
                    if ( msgAfter < msgId ){
                        mylog( `Serve message ${msgId} to subscriber ${subId}.` )
                        let sub = subs[subId]
                        let out = [ { msgId: msgId, addrs: addrs, msg: q.msg, date: date } ]
                        sub.res.write( JSON.stringify( out ) )
                        sub.res.end()
                        mylog( `Subscriber ${subId} unsubscribe.` )
                        sub.addrs.forEach( ( addr )=>{
                            delete addr_subs[addr][subId]
                        } )
                        delete subs[subId]
                    }
                }
            }
            addr_msgs[addr] = addr_msgs[addr] || {}
            addr_msgs[addr][ msgId ] = date
            addr_msgs[addr].lastMsgId = msgId
        } )
        res.write( JSON.stringify( out ) )
        res.end()

        let ymd = new Date( date ).toLocaleString( 'sv' ).slice( 0, 10 )
        if ( logFile.ymd != ymd ){
            if ( logFile.stream )
                logFile.stream.end()
            logFile.stream = fs.createWriteStream( `${ymd}.txt`, { flags: 'a' } )
        }
        logFile.stream.write( JSON.stringify( { msgId: msgId, addrs: addrs, msg: q.msg, date: date } ) + "\n" )
    } else if ( q.addrs && q.msgAfter ){
        let out = []
        mylog( `New client` )
        addrs.forEach( ( addr ) => {
            if ( addr_msgs[addr] && addr_msgs[addr].lastMsgId > + q.msgAfter ){
                for ( let msgId in addr_msgs[addr] ){
                    if ( + msgId > + q.msgAfter ){
                        mylog( `Serve message ${msgId} to client.` )
                        let msg = msgs[ msgId ]
                        out.push( { msgId: msgId, addrs:msg.addrs, msg: msg.msg, date: msg.date } )
                    }
                }
            }
        } )
        if ( out.length ){
            res.write( JSON.stringify( out ) )
            res.end()
        } else {
            subId++
            subs[ subId ] = { addrs: addrs, msgAfter: + q.msgAfter, date:date, res: res }
            mylog( `Saved as new subscriber ${subId}.` )
            addrs.forEach( ( addr ) => {
                addr_subs[addr] = addr_subs[addr] || {}
                addr_subs[addr][subId] = + q.msgAfter
            } )
        }
    } else {
        res.write( JSON.stringify( { error: "wtf are you doing?" } ) )
        res.end()
    }
} ).listen( PORT, 'localhost' ).on( 'connection', function( socket ){
    socket.setTimeout( 600_000 );
} )

let cleanups = () => {
    let oldest = Date.now() + 240_000 // 4 = 5 - 1 minutes in ms = 240_000
    mylog( `Iteration tick` )
    let old = Date.now() - 2_629_746_000 // 1 month in ms = 2_629_746_000
    let found = false
    for ( const [ msgId, msg ] of Object.entries( msgs ) ){ // Remove old mesages
        if ( msg.date < old ){
            found = true
            mylog( `Cleanup: Remove message ${msgId}.` )
            delete msgs[ msgId ]
        } else {
            oldest = Math.min( oldest, msg.date + 2_629_746_000 )
            break
        }
    }
    if ( found ) for ( const [ addr, msg ] of Object.entries( addr_msgs ) ){ // Remove old mesages
        for ( const [ msgId, date ] of Object.entries( msg ) ){
            if ( + msgId && date < old ){
                mylog( `Cleanup: Remove message ${msgId} address ${addr}.` )
                delete addr_msgs[addr][msgId]
            } else if ( + msgId )
                oldest = Math.min( oldest, date + 2_629_746_000 )
        }
    }
    old = Date.now() - 300_000 // 5 minutes in ms = 300_000
    for ( const [ subId, sub ] of Object.entries( subs ) ){ // Serve old subscribers closing them
        if ( sub.date < old ){
            mylog( `Cleanup: Close subscriber ${subId}.` )
            sub.res.write( "[]" )
            sub.res.end()
            sub.addrs.forEach( ( addr ) => {
                delete addr_subs[addr][subId]
            } )
            delete subs[ subId ]
        } else {
            oldest = Math.min( oldest, sub.date + 300_000 )
            break
        }
    }
    oldest = Math.max( oldest - Date.now(), 60_000 ) // 1 minute in ms = 60_000
    mylog( `Cleanup: Sleep ${oldest} ms.` )
    setTimeout( cleanups, oldest )
}
cleanups()