package torr

import (
	"log"
	"net"
	"strconv"
	"sync"

	"github.com/anacrolix/torrent"
	"github.com/anacrolix/torrent/metainfo"

	"server/settings"
	"server/torr/storage/torrstor"
	"server/torr/utils"
	"server/version"
)

type BTServer struct {
	config *torrent.ClientConfig
	client *torrent.Client

	storage *torrstor.Storage

	torrents map[metainfo.Hash]*Torrent

	mu sync.Mutex
}

func NewBTS() *BTServer {
	bts := new(BTServer)
	bts.torrents = make(map[metainfo.Hash]*Torrent)
	return bts
}

func (bt *BTServer) Connect() error {
	bt.mu.Lock()
	defer bt.mu.Unlock()
	var err error
	bt.configure()
	bt.client, err = torrent.NewClient(bt.config)
	bt.torrents = make(map[metainfo.Hash]*Torrent)
	InitApiHelper(bt)
	return err
}

func (bt *BTServer) Disconnect() {
	bt.mu.Lock()
	defer bt.mu.Unlock()
	if bt.client != nil {
		bt.client.Close()
		bt.client = nil
		utils.FreeOSMemGC()
	}
}

func (bt *BTServer) configure() {
	blocklist, _ := utils.ReadBlockedIP()
	bt.config = torrent.NewDefaultClientConfig()

	bt.storage = torrstor.NewStorage(settings.BTsets.CacheSize)
	bt.config.DefaultStorage = bt.storage

	userAgent := "qBittorrent/4.3.9"
	peerID := "-qB4390-"
	upnpID := "TorrServer/" + version.Version
	cliVers := userAgent

	//	bt.config.AcceptPeerConnections = false
	//	bt.config.AlwaysWantConns = true
	bt.config.Debug = settings.BTsets.EnableDebug
	bt.config.DisableIPv6 = settings.BTsets.EnableIPv6 == false
	bt.config.DisableTCP = settings.BTsets.DisableTCP
	bt.config.DisableUTP = settings.BTsets.DisableUTP
	//	https://github.com/anacrolix/torrent/issues/703
	bt.config.DisableWebtorrent = true
	bt.config.NoDefaultPortForwarding = settings.BTsets.DisableUPNP
	bt.config.NoDHT = settings.BTsets.DisableDHT
	bt.config.DisablePEX = settings.BTsets.DisablePEX
	bt.config.NoUpload = settings.BTsets.DisableUpload
	bt.config.IPBlocklist = blocklist
	bt.config.Bep20 = peerID
	bt.config.PeerID = utils.PeerIDRandom(peerID)
	bt.config.UpnpID = upnpID
	bt.config.HTTPUserAgent = userAgent
	bt.config.ExtendedHandshakeClientVersion = cliVers
	bt.config.EstablishedConnsPerTorrent = settings.BTsets.ConnectionsLimit
	bt.config.TotalHalfOpenConns = 500
	// Encryption/Obfuscation
	bt.config.HeaderObfuscationPolicy = torrent.HeaderObfuscationPolicy{
		RequirePreferred: settings.BTsets.ForceEncrypt,
		Preferred:        true,
	}
	if settings.BTsets.DownloadRateLimit > 0 {
		bt.config.DownloadRateLimiter = utils.Limit(settings.BTsets.DownloadRateLimit * 1024)
	}
	if settings.BTsets.UploadRateLimit > 0 {
		bt.config.UploadRateLimiter = utils.Limit(settings.BTsets.UploadRateLimit * 1024)
	}
	if settings.BTsets.PeersListenPort > 0 {
		log.Println("Set listen port", settings.BTsets.PeersListenPort)
		bt.config.ListenPort = settings.BTsets.PeersListenPort
	} else {
		upnpport := 32000
		for {
			log.Println("Check upnp port", upnpport)
			l, err := net.Listen("tcp", ":"+strconv.Itoa(upnpport))
			if l != nil {
				l.Close()
			}
			if err == nil {
				break
			}
			upnpport++
		}
		log.Println("Set upnp port", upnpport)
		bt.config.ListenPort = upnpport
	}

	log.Println("Client config:", settings.BTsets)

	// set public IPv4
	if settings.PubIPv4 != "" {
		ip4 := net.ParseIP(settings.PubIPv4)
		if ip4.To4 != nil {
			bt.config.PublicIp4 = ip4
		}
	}
	if bt.config.PublicIp4 == nil {
			bt.config.PublicIp4 = getPublicIp4()
	}
	if bt.config.PublicIp4 != nil {
		log.Println("PublicIp4:", bt.config.PublicIp4)
	}

	// set public IPv6
	if settings.PubIPv6 != "" {
		ip6 := net.ParseIP(settings.PubIPv6)
		if ip6.To4 == nil && ip6.To16 != nil {
			bt.config.PublicIp6 = ip6
		}
	}
	if bt.config.PublicIp6 == nil {
			bt.config.PublicIp6 = getPublicIp6()
	}
	if bt.config.PublicIp6 != nil {
		log.Println("PublicIp6:", bt.config.PublicIp6)
	}
}

func (bt *BTServer) GetTorrent(hash torrent.InfoHash) *Torrent {
	if torr, ok := bt.torrents[hash]; ok {
		return torr
	}
	return nil
}

func (bt *BTServer) ListTorrents() map[metainfo.Hash]*Torrent {
	list := make(map[metainfo.Hash]*Torrent)
	for k, v := range bt.torrents {
		list[k] = v
	}
	return list
}

func (bt *BTServer) RemoveTorrent(hash torrent.InfoHash) {
	if torr, ok := bt.torrents[hash]; ok {
		torr.Close()
	}
}

func getPublicIp4() net.IP {
	ifaces, err := net.Interfaces()
	if err != nil {
		log.Println("Error get public IPv4")
		return nil
	}
	for _, i := range ifaces {
		addrs, _ := i.Addrs()
		if i.Flags&net.FlagUp == net.FlagUp {
			for _, addr := range addrs {
				var ip net.IP
				switch v := addr.(type) {
				case *net.IPNet:
					ip = v.IP
				case *net.IPAddr:
					ip = v.IP
				}
				if !ip.IsLoopback() && !ip.IsPrivate() && ip.To4 != nil && ip.To16 == nil {
					return ip
				}
			}
		}
	}
	return nil
}

func getPublicIp6() net.IP {
	ifaces, err := net.Interfaces()
	if err != nil {
		log.Println("Error get public IPv6")
		return nil
	}
	for _, i := range ifaces {
		addrs, _ := i.Addrs()
		if i.Flags&net.FlagUp == net.FlagUp {
			for _, addr := range addrs {
				var ip net.IP
				switch v := addr.(type) {
				case *net.IPNet:
					ip = v.IP
				case *net.IPAddr:
					ip = v.IP
				}
				if !ip.IsLoopback() && !ip.IsPrivate() && ip.To4 == nil && ip.To16 != nil {
					return ip
				}
			}
		}
	}
	return nil
}