package job

import (
	"bufio"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"os"
	"regexp"
	"sort"
	"time"

	"github.com/mhsanaei/3x-ui/v2/database"
	"github.com/mhsanaei/3x-ui/v2/database/model"
	"github.com/mhsanaei/3x-ui/v2/logger"
	"github.com/mhsanaei/3x-ui/v2/web/service"
	"github.com/mhsanaei/3x-ui/v2/xray"
)

// IPWithTimestamp tracks an IP address with its last seen timestamp
type IPWithTimestamp struct {
	IP        string `json:"ip"`
	Timestamp int64  `json:"timestamp"`
}

// CheckClientIpJob monitors client IP addresses from access logs and manages IP blocking based on configured limits.
type CheckClientIpJob struct {
	lastClear       int64
	tempBansByEmail map[string]int64
	inboundService  service.InboundService
	xrayService     *service.XrayService
}

var job *CheckClientIpJob

const (
	ipLimitWindowDuration = 3 * time.Minute
	ipLimitBanDuration    = 3 * time.Minute
)

// NewCheckClientIpJob creates a new client IP monitoring job instance.
func NewCheckClientIpJob(xrayService *service.XrayService) *CheckClientIpJob {
	job = &CheckClientIpJob{
		tempBansByEmail: map[string]int64{},
		xrayService:     xrayService,
	}
	return job
}

func (j *CheckClientIpJob) Run() {
	if j.lastClear == 0 {
		j.lastClear = time.Now().Unix()
	}

	shouldClearAccessLog := false
	iplimitActive := j.hasLimitIp()
	isAccessLogAvailable := j.checkAccessLogAvailable(iplimitActive)

	j.restoreExpiredClientAccess()

	if isAccessLogAvailable {
		if iplimitActive {
			shouldClearAccessLog = j.processLogFile()
		}
	}

	if shouldClearAccessLog || (isAccessLogAvailable && time.Now().Unix()-j.lastClear > 3600) {
		j.clearAccessLog()
	}
}

func (j *CheckClientIpJob) clearAccessLog() {
	logAccessP, err := os.OpenFile(xray.GetAccessPersistentLogPath(), os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o644)
	j.checkError(err)
	defer logAccessP.Close()

	accessLogPath, err := xray.GetAccessLogPath()
	j.checkError(err)

	file, err := os.Open(accessLogPath)
	j.checkError(err)
	defer file.Close()

	_, err = io.Copy(logAccessP, file)
	j.checkError(err)

	err = os.Truncate(accessLogPath, 0)
	j.checkError(err)

	j.lastClear = time.Now().Unix()
}

func (j *CheckClientIpJob) hasLimitIp() bool {
	db := database.GetDB()
	var inbounds []*model.Inbound

	err := db.Model(model.Inbound{}).Find(&inbounds).Error
	if err != nil {
		return false
	}

	for _, inbound := range inbounds {
		if inbound.Settings == "" {
			continue
		}

		settings := map[string][]model.Client{}
		json.Unmarshal([]byte(inbound.Settings), &settings)
		clients := settings["clients"]

		for _, client := range clients {
			limitIp := client.LimitIP
			if limitIp > 0 {
				return true
			}
		}
	}

	return false
}

func (j *CheckClientIpJob) processLogFile() bool {

	ipRegex := regexp.MustCompile(`from (?:tcp:|udp:)?\[?([0-9a-fA-F\.:]+)\]?:\d+ accepted`)
	emailRegex := regexp.MustCompile(`email: (.+)$`)
	timestampRegex := regexp.MustCompile(`^(\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2})`)

	accessLogPath, _ := xray.GetAccessLogPath()
	file, _ := os.Open(accessLogPath)
	defer file.Close()

	// Track IPs with their last seen timestamp
	inboundClientIps := make(map[string]map[string]int64, 100)

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()

		ipMatches := ipRegex.FindStringSubmatch(line)
		if len(ipMatches) < 2 {
			continue
		}

		ip := ipMatches[1]

		if ip == "127.0.0.1" || ip == "::1" {
			continue
		}

		emailMatches := emailRegex.FindStringSubmatch(line)
		if len(emailMatches) < 2 {
			continue
		}
		email := emailMatches[1]

		// Extract timestamp from log line
		var timestamp int64
		timestampMatches := timestampRegex.FindStringSubmatch(line)
		if len(timestampMatches) >= 2 {
			t, err := time.Parse("2006/01/02 15:04:05", timestampMatches[1])
			if err == nil {
				timestamp = t.Unix()
			} else {
				timestamp = time.Now().Unix()
			}
		} else {
			timestamp = time.Now().Unix()
		}

		if _, exists := inboundClientIps[email]; !exists {
			inboundClientIps[email] = make(map[string]int64)
		}
		// Update timestamp - keep the latest
		if existingTime, ok := inboundClientIps[email][ip]; !ok || timestamp > existingTime {
			inboundClientIps[email][ip] = timestamp
		}
	}

	shouldCleanLog := false
	for email, ipTimestamps := range inboundClientIps {

		// Convert to IPWithTimestamp slice
		ipsWithTime := make([]IPWithTimestamp, 0, len(ipTimestamps))
		for ip, timestamp := range ipTimestamps {
			ipsWithTime = append(ipsWithTime, IPWithTimestamp{IP: ip, Timestamp: timestamp})
		}

		clientIpsRecord, err := j.getInboundClientIps(email)
		if err != nil {
			j.addInboundClientIps(email, ipsWithTime)
			continue
		}

		shouldCleanLog = j.updateInboundClientIps(clientIpsRecord, email, ipsWithTime) || shouldCleanLog
	}

	return shouldCleanLog
}

func (j *CheckClientIpJob) checkAccessLogAvailable(iplimitActive bool) bool {
	accessLogPath, err := xray.GetAccessLogPath()
	if err != nil {
		return false
	}

	if accessLogPath == "none" || accessLogPath == "" {
		if iplimitActive {
			logger.Warning("[LimitIP] Access log path is not set, Please configure the access log path in Xray configs.")
		}
		return false
	}

	return true
}

func (j *CheckClientIpJob) checkError(e error) {
	if e != nil {
		logger.Warning("client ip job err:", e)
	}
}

func (j *CheckClientIpJob) getInboundClientIps(clientEmail string) (*model.InboundClientIps, error) {
	db := database.GetDB()
	InboundClientIps := &model.InboundClientIps{}
	err := db.Model(model.InboundClientIps{}).Where("client_email = ?", clientEmail).First(InboundClientIps).Error
	if err != nil {
		return nil, err
	}
	return InboundClientIps, nil
}

func (j *CheckClientIpJob) addInboundClientIps(clientEmail string, ipsWithTime []IPWithTimestamp) error {
	inboundClientIps := &model.InboundClientIps{}
	jsonIps, err := json.Marshal(ipsWithTime)
	j.checkError(err)

	inboundClientIps.ClientEmail = clientEmail
	inboundClientIps.Ips = string(jsonIps)

	db := database.GetDB()
	tx := db.Begin()

	defer func() {
		if err == nil {
			tx.Commit()
		} else {
			tx.Rollback()
		}
	}()

	err = tx.Save(inboundClientIps).Error
	if err != nil {
		return err
	}
	return nil
}

func (j *CheckClientIpJob) updateInboundClientIps(inboundClientIps *model.InboundClientIps, clientEmail string, newIpsWithTime []IPWithTimestamp) bool {
	// Get the inbound configuration
	inbound, err := j.getInboundByEmail(clientEmail)
	if err != nil {
		logger.Errorf("failed to fetch inbound settings for email %s: %s", clientEmail, err)
		return false
	}

	if inbound.Settings == "" {
		logger.Debug("wrong data:", inbound)
		return false
	}

	settings := map[string][]model.Client{}
	json.Unmarshal([]byte(inbound.Settings), &settings)
	clients := settings["clients"]

	// Find the client's IP limit
	var limitIp int
	var clientFound bool
	for _, client := range clients {
		if client.Email == clientEmail {
			limitIp = client.LimitIP
			clientFound = true
			break
		}
	}

	if !clientFound || limitIp <= 0 || !inbound.Enable {
		// No limit or inbound disabled, just update and return
		jsonIps, _ := json.Marshal(newIpsWithTime)
		inboundClientIps.Ips = string(jsonIps)
		db := database.GetDB()
		db.Save(inboundClientIps)
		return false
	}

	// Parse old IPs from database
	var oldIpsWithTime []IPWithTimestamp
	if inboundClientIps.Ips != "" {
		json.Unmarshal([]byte(inboundClientIps.Ips), &oldIpsWithTime)
	}

	// Merge old and new IPs, keeping the latest timestamp for each IP
	ipMap := make(map[string]int64)
	for _, ipTime := range oldIpsWithTime {
		ipMap[ipTime.IP] = ipTime.Timestamp
	}
	for _, ipTime := range newIpsWithTime {
		if existingTime, ok := ipMap[ipTime.IP]; !ok || ipTime.Timestamp > existingTime {
			ipMap[ipTime.IP] = ipTime.Timestamp
		}
	}

	// Convert back to slice and sort by timestamp (oldest first)
	// This ensures we always protect the original/current connections and ban new excess ones.
	allIps := make([]IPWithTimestamp, 0, len(ipMap))
	for ip, timestamp := range ipMap {
		allIps = append(allIps, IPWithTimestamp{IP: ip, Timestamp: timestamp})
	}
	sort.Slice(allIps, func(i, j int) bool {
		return allIps[i].Timestamp < allIps[j].Timestamp // Ascending order (oldest first)
	})

	shouldCleanLog := false

	// Open log file
	logIpFile, err := os.OpenFile(xray.GetIPLimitLogPath(), os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
	if err != nil {
		logger.Errorf("failed to open IP limit log file: %s", err)
		return false
	}
	defer logIpFile.Close()
	log.SetOutput(logIpFile)
	log.SetFlags(log.LstdFlags)

	recentIps := j.filterRecentIPs(allIps, time.Now().Add(-ipLimitWindowDuration).Unix())

	jsonIps, _ := json.Marshal(recentIps)
	inboundClientIps.Ips = string(jsonIps)

	// Check if the recent 3-minute window exceeds the limit.
	if len(recentIps) > limitIp {
		shouldCleanLog = true
		for _, ipTime := range recentIps {
			log.Printf("[LIMIT_IP] Email = %s || Recent IP = %s || Timestamp = %d", clientEmail, ipTime.IP, ipTime.Timestamp)
		}

		if err := j.disableClientTemporarily(clientEmail, ipLimitBanDuration); err != nil {
			logger.Warningf("[LIMIT_IP] Failed to temporarily disable client %s: %v", clientEmail, err)
		} else {
			logger.Infof("[LIMIT_IP] Client %s: observed %d IPs in the last 3 minutes (limit=%d), temporarily disabled for 3 minutes", clientEmail, len(recentIps), limitIp)
		}
	}

	db := database.GetDB()
	err = db.Save(inboundClientIps).Error
	if err != nil {
		logger.Error("failed to save inboundClientIps:", err)
		return false
	}

	return shouldCleanLog
}

func (j *CheckClientIpJob) getInboundByEmail(clientEmail string) (*model.Inbound, error) {
	db := database.GetDB()
	inbound := &model.Inbound{}

	err := db.Model(&model.Inbound{}).Where("settings LIKE ?", "%"+clientEmail+"%").First(inbound).Error
	if err != nil {
		return nil, err
	}

	return inbound, nil
}

func (j *CheckClientIpJob) disableClientTemporarily(clientEmail string, duration time.Duration) error {
	now := time.Now().Unix()
	if until, ok := j.tempBansByEmail[clientEmail]; ok && until > now {
		return nil
	}

	changed, needRestart, err := j.inboundService.SetClientEnableByEmail(clientEmail, false)
	if err != nil {
		return err
	}
	if needRestart && j.xrayService != nil {
		j.xrayService.SetToNeedRestart()
	}
	if !changed {
		return fmt.Errorf("client %s was not disabled", clientEmail)
	}

	j.tempBansByEmail[clientEmail] = time.Now().Add(duration).Unix()
	return nil
}

func (j *CheckClientIpJob) restoreExpiredClientAccess() {
	now := time.Now().Unix()
	for clientEmail, until := range j.tempBansByEmail {
		if until > now {
			continue
		}

		changed, needRestart, err := j.inboundService.SetClientEnableByEmail(clientEmail, true)
		if err != nil {
			logger.Warningf("[LIMIT_IP] Failed to restore client %s after temporary disable: %v", clientEmail, err)
			continue
		}
		if needRestart && j.xrayService != nil {
			j.xrayService.SetToNeedRestart()
		}

		delete(j.tempBansByEmail, clientEmail)
		if changed {
			logger.Infof("[LIMIT_IP] Client %s: temporary 3-minute disable expired, access restored", clientEmail)
		}
	}
}

func (j *CheckClientIpJob) filterRecentIPs(ips []IPWithTimestamp, minTimestamp int64) []IPWithTimestamp {
	recent := make([]IPWithTimestamp, 0, len(ips))
	for _, ipTime := range ips {
		if ipTime.Timestamp >= minTimestamp {
			recent = append(recent, ipTime)
		}
	}
	return recent
}