#!/usr/bin/nodejs
// "Stupid" gossip algorithm simulation tool

function test_simple(options)
{
    options.total ||= 100;
    options.gossip ||= 4;
    options.msgcap ||= 5;
    options.update ||= 0;
    options.initial ||= 5;
    let messages_sent = 0;
    let tick = 1;
    const known = {};
    const lists = {};
    const listsv2 = {};
    for (let i = 1; i <= options.total; i++)
    {
        known[i] = {};
        lists[i] = [];
        for (let j = 1; j <= (options.update ? options.total : options.initial); j++)
        {
            known[i][j] = 1; // meta version 1
            lists[i].push(j);
        }
        listsv2[i] = [];
    }
    let cmp_lists;
    let cmp_n;
    if (options.update)
    {
        // We want to update <options.update> nodes metadata to version 2
        for (let i = 1; i <= options.update; i++)
        {
            known[i][i] = 2;
            listsv2[i].push(i);
        }
        cmp_lists = listsv2;
        cmp_n = options.update;
    }
    else
    {
        // We want <options.total-options.initial> to join <options.initial>
        for (let i = 1; i <= options.initial; i++)
        {
            if (!known[i][i])
            {
                known[i][i] = 1;
                lists[i].push(i);
            }
            for (let alive = options.initial+1; alive <= options.total; alive++)
            {
                if (!known[i][alive])
                {
                    known[i][alive] = true;
                    lists[i].push(alive);
                }
            }
        }
        cmp_lists = lists;
        cmp_n = options.total;
    }
    let in_sync = 0;
    for (let i = 1; i <= options.total; i++)
    {
        if (cmp_lists[i].length == cmp_n)
        {
            in_sync++;
        }
    }
    let avg_known = 0;
    while (in_sync < options.total)
    {
        console.log('tick '+tick+': '+in_sync+' in sync, avg '+avg_known);
        for (let i = 1; i <= options.total; i++)
        {
            const known_i = lists[i];
            const send_to = [];
            for (let j = 0; j < options.gossip; j++)
            {
                send_to.push(known_i[0|(Math.random()*known_i.length)]);
            }
            const send_what = [];
            for (let j = 0; j < options.msgcap; j++)
            {
                // FIXME: Exclude duplicates, exclude <send_to>
                send_what.push(known_i[0|(Math.random()*known_i.length)]);
            }
            for (const alive of send_what)
            {
                for (const to of send_to)
                {
                    if (!known[to][alive] || known[i][alive] > known[to][alive])
                    {
                        known[to][alive] = known[i][alive];
                        cmp_lists[to].push(alive);
                        if (cmp_lists[to].length == cmp_n)
                        {
                            console.log('node '+to+': tick '+tick);
                            in_sync++;
                        }
                    }
                }
            }
            messages_sent += send_what.length*send_to.length;
        }
        avg_known = 0;
        for (let i = 1; i <= options.total; i++)
        {
            avg_known += cmp_lists[i].length;
        }
        avg_known /= options.total;
        tick++;
    }
    console.log('tick '+tick+': '+in_sync+' in sync, avg '+avg_known);
    console.log(messages_sent+' messages sent');
}

const options = {};

for (let i = 2; i < process.argv.length; i++)
{
    if (process.argv[i] === '-h' || process.argv[i] === '--help')
    {
        console.error('USAGE: '+process.argv[0]+' '+process.argv[1]+` [OPTIONS]

--gossip 4      how many nodes to gossip with every tick
--msgcap 5      how many nodes to gossip about every tick
--total 1000    total nodes
--update 0      total nodes to update if testing update. if 0 then test joining
--initial 5     initial nodes in sync to test joining (when --update is 0)`);
        process.exit();
    }
    else if (process.argv[i].substr(0, 2) == '--')
    {
        options[process.argv[i].substr(2)] = 0|process.argv[i+1];
        i++;
    }
}

test_simple(options);