const spawn=require('child_process').spawn
const crypto=require('crypto')
const promisify=require('util').promisify
const fs=require('fs')
const path=require('path')

const request=require('request')

const express=require('express')
const multer=require('multer')
const maxmind=require('maxmind')

const countryLookup=maxmind.openSync('GeoLite2-Country.mmdb')
const app=express()
let packageListHash=null

function GetRequestIP(req) {
    return req.headers['x-forwarded-for'] || 
    req.connection.remoteAddress || 
    req.socket.remoteAddress || 
    req.connection.socket.remoteAddress || ''
}

function GetIPCountry(ip) {
    let x=countryLookup.get(ip)
    if(x) return x.country.iso_code
    else return null
}

app.get("/gateway",async (req,res)=>{
    let ip=GetRequestIP(req)
    let country=GetIPCountry(ip)
    console.log(`Client IP: ${ip} Country: ${country}`)
    res.end(country)
})

app.get("/listver",(req,res)=>{
    res.writeHead(200,'OK')
    res.end(packageListHash)
})

app.use("/list",express.static("tmp"))

function GetFileHash(filepath) {
    return new Promise((resolve)=>{
        let hash=crypto.createHash('sha256')
        let input=fs.createReadStream(filepath)
        input.on('data',(data)=>{
            hash.update(data)
        })
        input.on('end',()=>{
            return resolve(hash.digest('hex'))
        })
    })
}

function UpdatePackageList() {
    return new Promise((resolve,reject)=>{
        request('http://kiritow.com:3000/gpm/list/raw/master/programs.info',(err,res,body)=>{
            if(err) return reject(err)
            if(!res || res.statusCode!=200 ) return reject("Invalid response.")
            fs.writeFile(path.join('tmp','programs.info.tmp'),body,(err)=>{
                if(err) return reject(err)
                GetFileHash(path.join('tmp','programs.info.tmp')).then((hash)=>{
                    fs.rename(path.join('tmp','programs.info.tmp'),path.join('tmp',hash),(err)=>{
                        if(err) return reject(err)
                        packageListHash=hash
                        return resolve()
                    })
                }).catch((err)=>{
                    return reject(err)
                })
            })
        })
    })
}

async function ClearTmp() {
    let files=await promisify(fs.readdir)('tmp')
    let parr=new Array
    files.forEach((name)=>{
        parr.push(promisify(fs.unlink)(path.join('tmp',name)))
    })
    await Promise.all(parr)
    return parr.length
}

async function main() {
    let _tmBefore=new Date()
    console.log("[Init] Grab Server Starting...")
    console.log("[Init] Checking directories...")
    fs.mkdirSync("tmp",{recursive:true})
    console.log("[Init] Cleaning tmp...")
    let count=await ClearTmp()
    console.log(`${count} files removed.`)
    console.log("[Init] Initializing package list...")
    UpdatePackageList()

    console.log("[Working] Starting web server...")
    app.listen(7887)
    console.log(`[Done] Server started in ${(new Date()-_tmBefore)/1000}s`)
}

main()