package tools

import (
	"bufio"
	"context"
	"fmt"
	"net"
	"os/exec"
	"regexp"
	"strconv"
	"strings"
	"time"
)

var (
	validHostRegex   = regexp.MustCompile(`^[a-zA-Z0-9.:_-]+$`)
	pingReplyRegex   = regexp.MustCompile(`(\d+)\s+bytes from\s+([^:]+):\s+icmp_seq=(\d+)\s+ttl=(\d+)\s+time=([\d.]+)\s+ms`)
	pingTimeoutRegex = regexp.MustCompile(`(?:no answer yet for icmp_seq=|Request timeout for icmp_seq\s+)(\d+)`)
	pingUnreachRegex = regexp.MustCompile(`From\s+([^\s:]+)\s+icmp_seq=(\d+)\s+(.*)`)
	pingStatRegex    = regexp.MustCompile(`(\d+)\s+packets transmitted,\s+(\d+)\s+(?:packets\s+)?received,\s+([\d.]+)%\s+packet loss`)
	pingRttRegex     = regexp.MustCompile(`rtt min/avg/max/mdev = ([\d.]+)/([\d.]+)/([\d.]+)/([\d.]+)\s+ms`)
	mtrHopRegex      = regexp.MustCompile(`^\s*(\d+)\.\|--\s+(\S+)\s+([\d.]+)%?\s+(\d+)\s+([\d.]+)\s+([\d.]+)\s+([\d.]+)\s+([\d.]+)\s+([\d.]+)`)
)

type Manager struct{}

func NewManager() *Manager {
	return &Manager{}
}

func sanitizeTarget(target string) (string, error) {
	t := strings.TrimSpace(target)
	if t == "" {
		return "", fmt.Errorf("target host or IP is required")
	}
	if len(t) > 255 || !validHostRegex.MatchString(t) {
		return "", fmt.Errorf("invalid target host format")
	}
	return t, nil
}

// RunPing executes ICMP ping with custom parameters
func (m *Manager) RunPing(ctx context.Context, req PingRequest) (*PingResponse, error) {
	target, err := sanitizeTarget(req.Target)
	if err != nil {
		return nil, err
	}

	count := req.Count
	if count <= 0 {
		count = 4
	}
	if count > 30 {
		count = 30
	}

	size := req.Size
	if size <= 0 {
		size = 56
	}
	if size > 65500 {
		size = 65500
	}

	timeout := req.Timeout
	if timeout <= 0 {
		timeout = 5
	}
	if timeout > 30 {
		timeout = 30
	}

	args := []string{
		"-c", strconv.Itoa(count),
		"-s", strconv.Itoa(size),
		"-W", strconv.Itoa(timeout),
	}

	if req.Interface != "" && validHostRegex.MatchString(req.Interface) {
		args = append(args, "-I", req.Interface)
	}

	if req.DoNotFrag {
		args = append(args, "-M", "do")
	}

	args = append(args, target)

	cmd := exec.CommandContext(ctx, "ping", args...)
	outBytes, _ := cmd.CombinedOutput()
	outStr := string(outBytes)

	resp := &PingResponse{
		Target:      target,
		PacketsSent: count,
		Replies:     []PingReply{},
		RawOutput:   outStr,
		Status:      "timeout",
	}

	// Parse individual ping replies
	matches := pingReplyRegex.FindAllStringSubmatch(outStr, -1)
	for _, match := range matches {
		if len(match) >= 6 {
			bytes, _ := strconv.Atoi(match[1])
			from := match[2]
			seq, _ := strconv.Atoi(match[3])
			ttl, _ := strconv.Atoi(match[4])
			timeMs, _ := strconv.ParseFloat(match[5], 64)

			resp.Replies = append(resp.Replies, PingReply{
				Seq:    seq,
				Bytes:  bytes,
				From:   from,
				TTL:    ttl,
				TimeMs: timeMs,
			})
		}
	}

	// Parse overall stats
	if statMatch := pingStatRegex.FindStringSubmatch(outStr); len(statMatch) >= 4 {
		resp.PacketsSent, _ = strconv.Atoi(statMatch[1])
		resp.PacketsRecv, _ = strconv.Atoi(statMatch[2])
		resp.PacketLossPct, _ = strconv.ParseFloat(statMatch[3], 64)
	}

	// Parse RTT min/avg/max/mdev
	if rttMatch := pingRttRegex.FindStringSubmatch(outStr); len(rttMatch) >= 5 {
		resp.MinRTT, _ = strconv.ParseFloat(rttMatch[1], 64)
		resp.AvgRTT, _ = strconv.ParseFloat(rttMatch[2], 64)
		resp.MaxRTT, _ = strconv.ParseFloat(rttMatch[3], 64)
		resp.MdevRTT, _ = strconv.ParseFloat(rttMatch[4], 64)
	}

	if resp.PacketsRecv == resp.PacketsSent && resp.PacketsSent > 0 {
		resp.Status = "ok"
	} else if resp.PacketsRecv > 0 {
		resp.Status = "partial"
	} else {
		resp.Status = "timeout"
	}

	return resp, nil
}

// StreamPing executes ICMP ping and streams real-time events line-by-line
func (m *Manager) StreamPing(ctx context.Context, req PingRequest, onEvent func(PingStreamEvent)) error {
	target, err := sanitizeTarget(req.Target)
	if err != nil {
		return err
	}

	size := req.Size
	if size <= 0 {
		size = 56
	}
	if size > 65500 {
		size = 65500
	}

	timeout := req.Timeout
	if timeout <= 0 {
		timeout = 3
	}
	if timeout > 30 {
		timeout = 30
	}

	args := []string{
		"-O", // report outstanding replies/timeouts in real time
		"-s", strconv.Itoa(size),
		"-W", strconv.Itoa(timeout),
	}

	if req.Count > 0 {
		args = append(args, "-c", strconv.Itoa(req.Count))
	}

	if req.Interface != "" && validHostRegex.MatchString(req.Interface) {
		args = append(args, "-I", req.Interface)
	}

	if req.DoNotFrag {
		args = append(args, "-M", "do")
	}

	args = append(args, target)

	cmd := exec.CommandContext(ctx, "ping", args...)
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return err
	}
	cmd.Stderr = cmd.Stdout

	if err := cmd.Start(); err != nil {
		return err
	}

	packetsSent := 0
	packetsRecv := 0
	var minRTT, maxRTT, sumRTT float64

	scanner := bufio.NewScanner(stdout)
	for scanner.Scan() {
		line := scanner.Text()
		trimmed := strings.TrimSpace(line)
		if trimmed == "" {
			continue
		}

		if strings.HasPrefix(trimmed, "PING ") {
			onEvent(PingStreamEvent{
				Type: "header",
				Raw:  line,
			})
			continue
		}

		// Match reply
		if match := pingReplyRegex.FindStringSubmatch(trimmed); len(match) >= 6 {
			bytes, _ := strconv.Atoi(match[1])
			from := match[2]
			seq, _ := strconv.Atoi(match[3])
			ttl, _ := strconv.Atoi(match[4])
			timeMs, _ := strconv.ParseFloat(match[5], 64)

			packetsSent++
			packetsRecv++
			sumRTT += timeMs
			if packetsRecv == 1 || timeMs < minRTT {
				minRTT = timeMs
			}
			if timeMs > maxRTT {
				maxRTT = timeMs
			}
			avgRTT := sumRTT / float64(packetsRecv)
			lossPct := float64(packetsSent-packetsRecv) * 100.0 / float64(packetsSent)

			onEvent(PingStreamEvent{
				Type:          "reply",
				Seq:           seq,
				Bytes:         bytes,
				From:          from,
				TTL:           ttl,
				TimeMs:        timeMs,
				PacketsSent:   packetsSent,
				PacketsRecv:   packetsRecv,
				PacketLossPct: lossPct,
				MinRTT:        minRTT,
				AvgRTT:        avgRTT,
				MaxRTT:        maxRTT,
				Raw:           line,
			})
			continue
		}

		// Match timeout (no answer yet for icmp_seq=X)
		if match := pingTimeoutRegex.FindStringSubmatch(trimmed); len(match) >= 2 {
			seq, _ := strconv.Atoi(match[1])
			packetsSent++
			lossPct := float64(packetsSent-packetsRecv) * 100.0 / float64(packetsSent)
			avgRTT := 0.0
			if packetsRecv > 0 {
				avgRTT = sumRTT / float64(packetsRecv)
			}

			onEvent(PingStreamEvent{
				Type:          "timeout",
				Seq:           seq,
				PacketsSent:   packetsSent,
				PacketsRecv:   packetsRecv,
				PacketLossPct: lossPct,
				MinRTT:        minRTT,
				AvgRTT:        avgRTT,
				MaxRTT:        maxRTT,
				Message:       "Request timed out",
				Raw:           line,
			})
			continue
		}

		// Match ICMP unreach error
		if match := pingUnreachRegex.FindStringSubmatch(trimmed); len(match) >= 4 {
			from := match[1]
			seq, _ := strconv.Atoi(match[2])
			msg := match[3]
			packetsSent++
			lossPct := float64(packetsSent-packetsRecv) * 100.0 / float64(packetsSent)
			avgRTT := 0.0
			if packetsRecv > 0 {
				avgRTT = sumRTT / float64(packetsRecv)
			}

			onEvent(PingStreamEvent{
				Type:          "unreach",
				Seq:           seq,
				From:          from,
				PacketsSent:   packetsSent,
				PacketsRecv:   packetsRecv,
				PacketLossPct: lossPct,
				MinRTT:        minRTT,
				AvgRTT:        avgRTT,
				MaxRTT:        maxRTT,
				Message:       msg,
				Raw:           line,
			})
			continue
		}

		// Match overall stats summary
		if match := pingStatRegex.FindStringSubmatch(trimmed); len(match) >= 4 {
			sSent, _ := strconv.Atoi(match[1])
			sRecv, _ := strconv.Atoi(match[2])
			sLoss, _ := strconv.ParseFloat(match[3], 64)
			packetsSent = sSent
			packetsRecv = sRecv

			avgRTT := 0.0
			if packetsRecv > 0 {
				avgRTT = sumRTT / float64(packetsRecv)
			}

			onEvent(PingStreamEvent{
				Type:          "stats",
				PacketsSent:   packetsSent,
				PacketsRecv:   packetsRecv,
				PacketLossPct: sLoss,
				MinRTT:        minRTT,
				AvgRTT:        avgRTT,
				MaxRTT:        maxRTT,
				Raw:           line,
			})
			continue
		}

		// Match RTT min/avg/max/mdev
		if match := pingRttRegex.FindStringSubmatch(trimmed); len(match) >= 5 {
			sMin, _ := strconv.ParseFloat(match[1], 64)
			sAvg, _ := strconv.ParseFloat(match[2], 64)
			sMax, _ := strconv.ParseFloat(match[3], 64)
			sMdev, _ := strconv.ParseFloat(match[4], 64)

			lossPct := 0.0
			if packetsSent > 0 {
				lossPct = float64(packetsSent-packetsRecv) * 100.0 / float64(packetsSent)
			}

			onEvent(PingStreamEvent{
				Type:          "stats",
				PacketsSent:   packetsSent,
				PacketsRecv:   packetsRecv,
				PacketLossPct: lossPct,
				MinRTT:        sMin,
				AvgRTT:        sAvg,
				MaxRTT:        sMax,
				MdevRTT:       sMdev,
				Raw:           line,
			})
			continue
		}

		// Generic line
		onEvent(PingStreamEvent{
			Type: "raw",
			Raw:  line,
		})
	}

	_ = cmd.Wait()

	lossPct := 0.0
	if packetsSent > 0 {
		lossPct = float64(packetsSent-packetsRecv) * 100.0 / float64(packetsSent)
	}
	avgRTT := 0.0
	if packetsRecv > 0 {
		avgRTT = sumRTT / float64(packetsRecv)
	}

	onEvent(PingStreamEvent{
		Type:          "done",
		PacketsSent:   packetsSent,
		PacketsRecv:   packetsRecv,
		PacketLossPct: lossPct,
		MinRTT:        minRTT,
		AvgRTT:        avgRTT,
		MaxRTT:        maxRTT,
		Raw:           "Ping finished",
	})

	return nil
}

// RunTraceroute traces the route to a target
func (m *Manager) RunTraceroute(ctx context.Context, req TracerouteRequest) (*TracerouteResponse, error) {
	target, err := sanitizeTarget(req.Target)
	if err != nil {
		return nil, err
	}

	maxHops := req.MaxHops
	if maxHops <= 0 {
		maxHops = 15
	}
	if maxHops > 30 {
		maxHops = 30
	}

	args := []string{
		"-m", strconv.Itoa(maxHops),
		"-q", "2",
		"-w", "1",
	}

	if !req.Resolve {
		args = append(args, "-n")
	}

	if req.Protocol == "icmp" {
		args = append(args, "-I")
	}

	if req.Interface != "" && validHostRegex.MatchString(req.Interface) {
		args = append(args, "-i", req.Interface)
	}

	args = append(args, target)

	cmd := exec.CommandContext(ctx, "traceroute", args...)
	outBytes, _ := cmd.CombinedOutput()
	outStr := string(outBytes)

	resp := &TracerouteResponse{
		Target:    target,
		Hops:      []TracerouteHop{},
		RawOutput: outStr,
	}

	lines := strings.Split(outStr, "\n")
	for i, line := range lines {
		if i == 0 {
			continue // skip header line
		}
		trimmed := strings.TrimSpace(line)
		if trimmed == "" {
			continue
		}

		fields := strings.Fields(trimmed)
		if len(fields) < 2 {
			continue
		}

		hopNum, err := strconv.Atoi(fields[0])
		if err != nil {
			continue
		}

		if fields[1] == "*" {
			resp.Hops = append(resp.Hops, TracerouteHop{
				Hop:     hopNum,
				Host:    "*",
				IP:      "*",
				TimesMs: []string{"*"},
				Status:  "timeout",
			})
		} else {
			hostOrIP := fields[1]
			ip := hostOrIP
			if len(fields) >= 3 && strings.HasPrefix(fields[2], "(") && strings.HasSuffix(fields[2], ")") {
				ip = strings.Trim(fields[2], "()")
			}
			times := make([]string, 0)
			for _, f := range fields[2:] {
				if f != "ms" && !strings.HasPrefix(f, "(") {
					times = append(times, f)
				}
			}

			resp.Hops = append(resp.Hops, TracerouteHop{
				Hop:     hopNum,
				Host:    hostOrIP,
				IP:      ip,
				TimesMs: times,
				Status:  "ok",
			})
		}
	}

	return resp, nil
}

// StreamTraceroute executes traceroute and streams hop events line-by-line
func (m *Manager) StreamTraceroute(ctx context.Context, req TracerouteRequest, onEvent func(TracerouteStreamEvent)) error {
	target, err := sanitizeTarget(req.Target)
	if err != nil {
		return err
	}

	maxHops := req.MaxHops
	if maxHops <= 0 {
		maxHops = 15
	}
	if maxHops > 30 {
		maxHops = 30
	}

	args := []string{
		"-m", strconv.Itoa(maxHops),
		"-q", "2",
		"-w", "1",
	}

	if !req.Resolve {
		args = append(args, "-n")
	}

	if req.Protocol == "icmp" {
		args = append(args, "-I")
	}

	if req.Interface != "" && validHostRegex.MatchString(req.Interface) {
		args = append(args, "-i", req.Interface)
	}

	args = append(args, target)

	cmd := exec.CommandContext(ctx, "traceroute", args...)
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return err
	}
	cmd.Stderr = cmd.Stdout

	if err := cmd.Start(); err != nil {
		return err
	}

	hopsCount := 0
	scanner := bufio.NewScanner(stdout)
	isHeader := true

	for scanner.Scan() {
		line := scanner.Text()
		trimmed := strings.TrimSpace(line)
		if trimmed == "" {
			continue
		}

		if isHeader {
			isHeader = false
			onEvent(TracerouteStreamEvent{
				Type: "header",
				Raw:  line,
			})
			continue
		}

		fields := strings.Fields(trimmed)
		if len(fields) < 2 {
			continue
		}

		hopNum, err := strconv.Atoi(fields[0])
		if err != nil {
			continue
		}

		hopsCount++
		var hop TracerouteHop
		if fields[1] == "*" {
			hop = TracerouteHop{
				Hop:     hopNum,
				Host:    "*",
				IP:      "*",
				TimesMs: []string{"*"},
				Status:  "timeout",
			}
		} else {
			hostOrIP := fields[1]
			ip := hostOrIP
			if len(fields) >= 3 && strings.HasPrefix(fields[2], "(") && strings.HasSuffix(fields[2], ")") {
				ip = strings.Trim(fields[2], "()")
			}
			times := make([]string, 0)
			for _, f := range fields[2:] {
				if f != "ms" && !strings.HasPrefix(f, "(") {
					times = append(times, f)
				}
			}
			hop = TracerouteHop{
				Hop:     hopNum,
				Host:    hostOrIP,
				IP:      ip,
				TimesMs: times,
				Status:  "ok",
			}
		}

		onEvent(TracerouteStreamEvent{
			Type:      "hop",
			Hop:       &hop,
			HopsCount: hopsCount,
			Raw:       line,
		})
	}

	_ = cmd.Wait()

	onEvent(TracerouteStreamEvent{
		Type:      "done",
		HopsCount: hopsCount,
		Raw:       "Traceroute finished",
	})

	return nil
}

// RunDNSLookup performs DNS resolution via dig
func (m *Manager) RunDNSLookup(ctx context.Context, req DNSRequest) (*DNSResponse, error) {
	domain, err := sanitizeTarget(req.Domain)
	if err != nil {
		return nil, err
	}

	qType := strings.ToUpper(strings.TrimSpace(req.Type))
	if qType == "" {
		qType = "A"
	}

	args := []string{
		"+noall", "+answer", "+stats",
		domain,
		qType,
	}

	if req.Server != "" {
		srv, sErr := sanitizeTarget(req.Server)
		if sErr == nil {
			args = append(args, "@"+srv)
		}
	}

	cmd := exec.CommandContext(ctx, "dig", args...)
	outBytes, _ := cmd.CombinedOutput()
	outStr := string(outBytes)

	resp := &DNSResponse{
		Domain:    domain,
		Type:      qType,
		Server:    req.Server,
		Records:   []DNSRecord{},
		RawOutput: outStr,
	}

	lines := strings.Split(outStr, "\n")
	for _, line := range lines {
		l := strings.TrimSpace(line)
		if l == "" {
			continue
		}
		if strings.HasPrefix(l, ";; Query time:") {
			parts := strings.Fields(l)
			if len(parts) >= 4 {
				resp.QueryTimeMs, _ = strconv.Atoi(parts[2])
			}
			continue
		}
		if strings.HasPrefix(l, ";; SERVER:") {
			parts := strings.Fields(l)
			if len(parts) >= 3 {
				resp.Server = parts[2]
			}
			continue
		}
		if strings.HasPrefix(l, ";") {
			continue
		}

		fields := strings.Fields(l)
		if len(fields) >= 5 {
			ttl, _ := strconv.Atoi(fields[1])
			resp.Records = append(resp.Records, DNSRecord{
				Name:  fields[0],
				TTL:   ttl,
				Class: fields[2],
				Type:  fields[3],
				Value: strings.Join(fields[4:], " "),
			})
		}
	}

	return resp, nil
}

// RunPortProbe tests TCP port connectivity and measures latency
func (m *Manager) RunPortProbe(ctx context.Context, req PortProbeRequest) (*PortProbeResponse, error) {
	target, err := sanitizeTarget(req.Target)
	if err != nil {
		return nil, err
	}

	if req.Port <= 0 || req.Port > 65535 {
		return nil, fmt.Errorf("invalid port number: must be between 1 and 65535")
	}

	timeoutSec := req.Timeout
	if timeoutSec <= 0 {
		timeoutSec = 3
	}
	if timeoutSec > 10 {
		timeoutSec = 10
	}

	serviceMap := map[int]string{
		21: "FTP", 22: "SSH", 23: "Telnet", 25: "SMTP", 53: "DNS",
		80: "HTTP", 110: "POP3", 143: "IMAP", 179: "BGP", 443: "HTTPS",
		587: "Submission", 993: "IMAPS", 995: "POP3S", 1194: "OpenVPN",
		3389: "RDP", 5060: "SIP", 8080: "HTTP-Alt", 8291: "Winbox (MikroTik)",
		8443: "HTTPS-Alt", 8006: "Proxmox VE",
	}

	addr := net.JoinHostPort(target, strconv.Itoa(req.Port))
	start := time.Now()

	d := net.Dialer{Timeout: time.Duration(timeoutSec) * time.Second}
	conn, dialErr := d.DialContext(ctx, "tcp", addr)
	elapsed := float64(time.Since(start).Microseconds()) / 1000.0

	resp := &PortProbeResponse{
		Target:    target,
		Port:      req.Port,
		LatencyMs: elapsed,
		Service:   serviceMap[req.Port],
	}

	if dialErr != nil {
		resp.Open = false
		resp.Error = dialErr.Error()
		resp.RawOutput = fmt.Sprintf("Failed to connect to %s: %v", addr, dialErr)
	} else {
		_ = conn.Close()
		resp.Open = true
		resp.RawOutput = fmt.Sprintf("Successfully connected to %s (%s) in %.2f ms (TCP handshake OK)", addr, resp.Service, elapsed)
	}

	return resp, nil
}

// RunMTR executes MTR (My Traceroute) report
func (m *Manager) RunMTR(ctx context.Context, req MTRRequest) (*MTRResponse, error) {
	target, err := sanitizeTarget(req.Target)
	if err != nil {
		return nil, err
	}

	count := req.Count
	if count <= 0 {
		count = 3
	}
	if count > 10 {
		count = 10
	}

	cmd := exec.CommandContext(ctx, "mtr", "-n", "-r", "-c", strconv.Itoa(count), target)
	outBytes, _ := cmd.CombinedOutput()
	outStr := string(outBytes)

	resp := &MTRResponse{
		Target:    target,
		Hops:      []MTRHop{},
		RawOutput: outStr,
	}

	lines := strings.Split(outStr, "\n")
	for _, line := range lines {
		matches := mtrHopRegex.FindStringSubmatch(line)
		if len(matches) >= 10 {
			hopNum, _ := strconv.Atoi(matches[1])
			host := matches[2]
			loss, _ := strconv.ParseFloat(matches[3], 64)
			sent, _ := strconv.Atoi(matches[4])
			last, _ := strconv.ParseFloat(matches[5], 64)
			avg, _ := strconv.ParseFloat(matches[6], 64)
			best, _ := strconv.ParseFloat(matches[7], 64)
			wrst, _ := strconv.ParseFloat(matches[8], 64)
			stdev, _ := strconv.ParseFloat(matches[9], 64)

			resp.Hops = append(resp.Hops, MTRHop{
				Hop:     hopNum,
				Host:    host,
				LossPct: loss,
				Sent:    sent,
				LastMs:  last,
				AvgMs:   avg,
				BestMs:  best,
				WrstMs:  wrst,
				StDevMs: stdev,
			})
		}
	}

	return resp, nil
}