const index = require('./index.js');
const fs=require("fs");
let uptimeObject={};
if(fs.existsSync("./uptime.json")){
    try{
        uptimeObject=JSON.parse(fs.readFileSync('./uptime.json', 'utf8'));
    }catch{
        uptimeObject={};
    }
}

async function observe(instances){
    const active=new Set();
    async function resolveinstance(instance){
        calcStats(instance);
        let api;
        if(instance.urls){
            api=instance.urls.api;
        }else if(instance.url){
            const urls=await index.getapiurls(instance.url);
            if(urls){
                api=urls.api;
            }
        }
        if(!api||api===""){

            setSatus(instance,false);
            console.warn(instance.name+" does not resolve api URL");
            setTimeout(_=>{resolveinstance(instance)},1000*60*30,);
            return
        }
        active.add(instance.name);
        api+=api.endsWith("/")?"":"/"
        function check(){
            fetch(api+"ping").then(_=>{
                setSatus(instance,_.ok);
            })
        }
        setTimeout(
            _=>{
                check();
                setInterval(_=>{
                    check();
                },1000*60*30)
            },Math.random()*1000*60*10
        )
    }
    const promlist=[];
    for(const instance of instances){
        promlist.push(resolveinstance(instance));
    }
    await Promise.allSettled(promlist);
    for(const key of Object.keys(uptimeObject)){
        if(!active.has(key)){
            setSatus(key,false);
        }
    }
}
function calcStats(instance){
    let obj=uptimeObject[instance.name];
    if(!obj) return;
    const day=Date.now()-1000*60*60*24;
    const week=Date.now()-1000*60*60*24*7;
    let alltime=-1;
    let totalTimePassed=0;
    let laststamp=0;
    let daytime=-1;
    let weektime=-1;
    let online=false;
    for(const thing of obj){
        const stamp=thing.time;
        if(alltime===-1){
            laststamp=stamp;
            alltime=0;
        }
        const timepassed=stamp-laststamp;
        totalTimePassed+=timepassed;
        alltime+=online*timepassed;
        if(stamp>week){
            if(weektime===-1){
                weektime=online*(stamp-week);
            }else{
                weektime+=online*timepassed;
            }
            if(stamp>day){
                if(daytime===-1){
                    daytime=online*(stamp-day);
                }else{
                    daytime+=online*timepassed;
                }
            }
        }
        online=thing.online;
    }
    instance.online=online;
    const timepassed=Date.now()-laststamp;
    totalTimePassed+=timepassed;
    daytime+=online*timepassed;
    weektime+=online*timepassed;
    alltime+=online*timepassed;
    alltime/=totalTimePassed;
    if(timepassed>1000*60*60*24){
        daytime/=1000*60*60*24;
        if(timepassed>1000*60*60*24*7){
            weektime/=1000*60*60*24*7;
        }else{
            weektime=alltime;
        }
    }else{
        weektime=alltime
        daytime=alltime;
    }
    instance.uptime={daytime,weektime,alltime}
}
/**
 * @param {string} name
 * @param {boolean} status
 */
function setSatus(instance,status){
    const name=instance.name;
    let obj=uptimeObject[name];
    let needSetting=false;
    if(!obj){
        obj=[];
        uptimeObject[name]=obj;
        needSetting=true;
    }else{
        if(obj[obj.length-1].online!==status){
            needSetting=true;
        }
    }
    if(needSetting){
        obj.push({time:Date.now(),online:status});
        updatejson();
    }
    calcStats(instance);
}
function updatejson(){
    fs.writeFile('./uptime.json',JSON.stringify(uptimeObject),_=>{});
}
exports.observe=observe;
exports.uptime=uptimeObject;