rangevote/rangevote.js

var express = require('express')
var bodyParser = require('body-parser')
var fs=require('fs')

var app = express()

var Candidates=[ "Chris Christie", "Ron DeSantis", "Nikki Haley", "Mike Pence",
		 "Vivek Ramaswamy", "Tim Scott", "Donald Trump" ];

function CanId(c)
{
    let w=c.split(" ");
    let lastname=w[w.length-1].toLowerCase();
    let id=lastname.split("-");
    let rval=id[id.length-1];
    return(rval);
}



// Set up data structures for Range Votes and Plur Votes
var RangeVotes=new Map();
var RangePower=new Map();
var RangeResult=new Map();
var PlurVotes=new Map();
var PlurResult=new Map();
var PlurCount=0;
for (let c of Candidates)
{
    let k=CanId(c);
    let v=RangePower.get(k);
    if (typeof(v)!='number' || v==NaN || v==Infinity) RangePower.set(k,0);
    v=RangeResult.get(k);
    if (typeof(v)!='number' || v==NaN || v==Infinity) RangeResult.set(k,0);
    v=PlurResult.get(k);
    if (typeof(v)!='number' || v==NaN || v==Infinity) PlurResult.set(k,0);
}



// Construct the static page for range voting
var RangeHTML="";
for (let c of Candidates)
{
    RangeHTML=RangeHTML+'      <tr>'+
	'          <td>'+c+'</td><td><input type="range" min="-1" max="100" value="-1" id="i-'+CanId(c)+'" name="n-'+CanId(c)+'" /></td><td><span id="o-'+CanId(c)+'">No Opinion</span></td></tr>\n';
}
var TemplateHTML=fs.readFileSync("rangevote.html").toString();
var TemplateSearch="<!-- INJECT0 -->";
var TemplateIndex=TemplateHTML.indexOf(TemplateSearch);
RangeHTML=TemplateHTML.substr(0,TemplateIndex)+RangeHTML+TemplateHTML.substr(TemplateIndex+TemplateSearch.length,1000000);

// Construct the static page for Plurality Voting
var PlurHTML="";
for (let c of Candidates)
{
    PlurHTML=PlurHTML+'      <tr>'+
	'          <td><input type="radio" value="v-'+CanId(c)+'" name="pick" /></td><td>'+c+'</td></tr>\n';
}
TemplateHTML=fs.readFileSync("plurvote.html").toString();
TemplateSearch="<!-- INJECT0 -->";
TemplateIndex=TemplateHTML.indexOf(TemplateSearch);
PlurHTML=TemplateHTML.substr(0,TemplateIndex)+PlurHTML+TemplateHTML.substr(TemplateIndex+TemplateSearch.length,1000000);


// create application/json parser
var jsonParser = bodyParser.json()

// create application/x-www-form-urlencoded parser
var urlencodedParser = bodyParser.urlencoded({ extended: false })

app.get('/', (req, res) => {
    res.send(RangeHTML);
//    res.send(PlurHTML);
})

function lerp(a,b,c,d,e)
{
    if (a<b) a=b;
    if (a>c) a=c;
    let rval=d+(a-b)*(e-d)/(c-b);
    return(rval);
}

function PlurVote(ip,NewChoice)
{
    let OldChoice=PlurResult.get(ip);
    if (typeof(OldChoice)=='string') { PlurResult.set(OldChoice,PlurResult.get(OldChoice)-1); PlurCount=PlurCount-1; }
    if (!NewChoice) return;
    NewChoice=CanId(NewChoice);
    if (typeof(NewChoice)=='string') { PlurResult.set(NewChoice,PlurResult.get(NewChoice)+1); PlurCount=PlurCount+1; }
}


function AddToRangeResult(vote,mult=1)
{
    for (let[key,val] of vote) if (key) if (val>=0)
    {
	RangeResult.set(key,RangeResult.get(key)+val*mult);
	RangePower.set(key,RangePower.get(key)+mult);
    }
}


function RangeVote(ip,entries)
{
    let r0=null,r1=null;
    for (let [key,val] of entries) if (typeof(key)=="string" && val>=0)
    {
        if (r0==null) { r0=val; r1=val; }
	r0=Math.min(r0,val);
	r1=Math.max(r1,val);
    }
    if (r1<=r0) return;
    let NewVote=new Map()
    for (let [key,val] of entries) if (typeof(key)=="string")
    {
	let id=CanId(key);
	let norm=Math.round(lerp(val,r0,r1,0,100));
	if (val>=0) NewVote.set(id,norm);
    }
    let OldVote=RangeVotes.get(ip);
//    if (OldVote) AddToRangeResult(OldVote,-1);
    RangeVotes.set(ip,NewVote);
    AddToRangeResult(NewVote,1);
}


// POST /login gets urlencoded bodies
app.post('/range_vote', urlencodedParser, function (req, res) {
    RangeVote(req.socket.remoteAddress,Object.entries(req.body));
    let str="Results:<br>";
    for (let c of Candidates)
    {
	let key=CanId(c);
	if (RangePower.get(key)>0) str=str+c+': '+Math.round(RangeResult.get(key)/RangePower.get(key))+'<br>';
    }
    res.send(str);
})

app.post('/plur_vote', urlencodedParser, function (req, res) {
    PlurVote(req.socket.remoteAddress,req.body.pick);
    let str="Results:<br>";
    for (let c of Candidates)
    {
	let key=CanId(c);
	if (PlurResult.get(key)>0) str=str+c+': '+Math.round(100.0*PlurResult.get(key)/PlurCount)+'%<br>';
    }
    res.send(str);
})


app.listen(3000,function(req,res) { console.log("Listening for connections"); })