package dhcp

import (
	"bufio"
	"os"
	"os/exec"
	"regexp"
	"strings"

	"github.com/nemunaire/repeater/internal/models"
)

// parseDHCPLeases reads and parses DHCP lease file
func parseDHCPLeases(path string) ([]models.DHCPLease, error) {
	var leases []models.DHCPLease

	file, err := os.Open(path)
	if err != nil {
		return leases, err
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	var currentLease models.DHCPLease

	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		fields := strings.Fields(line)

		switch {
		case strings.HasPrefix(line, "lease "):
			if len(fields) < 2 {
				continue
			}
			currentLease = models.DHCPLease{IP: fields[1]}
		case strings.Contains(line, "hardware ethernet"):
			if len(fields) < 3 {
				continue
			}
			currentLease.MAC = strings.TrimSuffix(fields[2], ";")
		case strings.Contains(line, "client-hostname"):
			if len(fields) < 2 {
				continue
			}
			currentLease.Hostname = strings.Trim(fields[1], `";`)
		case line == "}":
			if currentLease.IP != "" && currentLease.MAC != "" {
				leases = append(leases, currentLease)
			}
			currentLease = models.DHCPLease{}
		}
	}

	return leases, nil
}

// getARPInfo retrieves ARP table information using arp command
// Returns a map of IP -> MAC address
func getARPInfo() (map[string]string, error) {
	arpInfo := make(map[string]string)

	cmd := exec.Command("arp", "-a")
	output, err := cmd.Output()
	if err != nil {
		return arpInfo, err
	}

	lines := strings.Split(string(output), "\n")
	for _, line := range lines {
		if matches := regexp.MustCompile(`\(([^)]+)\) at ([0-9a-fA-F:]{17})`).FindStringSubmatch(line); len(matches) > 2 {
			ip := matches[1]
			mac := matches[2]
			arpInfo[ip] = mac
		}
	}

	return arpInfo, nil
}