package proxy

import (
	"context"
	"math/rand"
	"net"
	"runtime"
	"sync"
	"time"

	"github.com/Neur0toxine/wa-profile-api/internal/log"
	"github.com/gocolly/colly"
)

const proxiesSource = "https://free-proxy-list.net"

type RandomListProvider struct {
	r       *rand.Rand
	proxies []string
	ctx     context.Context
	cancel  func()
	lock    sync.RWMutex
}

func NewRandomListProvider() Provider {
	ctx, cancel := context.WithCancel(context.Background())
	pr := &RandomListProvider{
		r:      rand.New(rand.NewSource(time.Now().UnixNano())),
		ctx:    ctx,
		cancel: cancel,
	}
	go pr.refreshRegular()
	runtime.SetFinalizer(pr, randomListProviderDestructor)
	return pr
}

func randomListProviderDestructor(pr *RandomListProvider) {
	pr.cancel()
}

func (pr *RandomListProvider) Provide() string {
	defer pr.lock.RUnlock()
	pr.lock.RLock()
	if len(pr.proxies) == 0 {
		log.Debug("empty proxy list, waiting for 0.5s to populate...")
		time.Sleep(time.Millisecond * 500)
		if len(pr.proxies) == 0 {
			log.Debug("no proxies found, direct will be used.")
			return ""
		}
	}

	proxyAddress := pr.proxies[pr.r.Intn(len(pr.proxies)-1)]
	log.Debug("providing proxy", proxyAddress)
	return proxyAddress
}

func (pr *RandomListProvider) Bad(addr string) {
	defer pr.lock.Unlock()
	pr.lock.Lock()
	for i, val := range pr.proxies {
		if val == addr {
			pr.proxies[i] = pr.proxies[len(pr.proxies)-1]
			pr.proxies = pr.proxies[:len(pr.proxies)-1]
			break
		}
	}
}

func (pr *RandomListProvider) refreshRegular() {
	for {
		select {
		case <-pr.ctx.Done():
			return
		default:
			pr.refresh()
			time.Sleep(time.Hour)
		}
	}
}

func (pr *RandomListProvider) refresh() {
	log.Debug("preparing to download fresh proxies")
	defer pr.lock.Unlock()
	pr.lock.Lock()

	proxies := pr.loadProxies()
	if len(proxies) > 0 {
		pr.proxies = proxies
	}

	log.Debug("downloaded", len(proxies), "proxies")
}

func (pr *RandomListProvider) loadProxies() []string {
	proxies := []string{}
	c := colly.NewCollector(colly.AllowURLRevisit())
	c.OnRequest(func(r *colly.Request) {
		r.Headers.Set("User-Agent", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36")
		log.Debug("proxy crawler: visiting", r.URL)
	})
	c.OnHTML("div.table-responsive.fpl-list > table > tbody", func(tbody *colly.HTMLElement) {
		tbody.ForEach("tr", func(_ int, el *colly.HTMLElement) {
			host, port := el.ChildText("td:nth-child(1)"), el.ChildText("td:nth-child(2)")
			if port == "80" || port == "8080" {
				proxies = append(proxies, "http://"+net.JoinHostPort(host, port))
			}
		})
	})
	c.Visit(proxiesSource)
	return proxies
}