package main

import (
	"fmt"
	"sort"
	"strings"
)

// Host is one static host entry: hostname, IP, optional MAC, free-text comment.
type Host struct {
	Name    string
	IP      string
	MAC     string // "" if not set
	Comment string
}

const hostHeader = "# ipadm host database - managed with `ipadm`, do not edit while ipadm is running\n" +
	"# name\tip\tmac\tcomment\n"

// One line per host, tab-separated: name\tip\tmac\tcomment
// MAC is stored as "-" when empty.
func parseHostLine(line string) (Host, error) {
	parts := strings.SplitN(line, "\t", 4)
	if len(parts) < 3 {
		return Host{}, fmt.Errorf("invalid line (expected at least 3 tab-separated fields): %q", line)
	}
	mac := parts[2]
	if mac == "-" {
		mac = ""
	}
	comment := ""
	if len(parts) == 4 {
		comment = parts[3]
	}
	return Host{Name: parts[0], IP: parts[1], MAC: mac, Comment: comment}, nil
}

func formatHostLine(h Host) string {
	mac := h.MAC
	if mac == "" {
		mac = "-"
	}
	return fmt.Sprintf("%s\t%s\t%s\t%s", h.Name, h.IP, mac, h.Comment)
}

func openHostStore(path string) (*LineStore[Host], error) {
	return openLineStore(path, hostHeader, parseHostLine, formatHostLine)
}

func sortHosts(hosts []Host) {
	sort.Slice(hosts, func(i, j int) bool {
		return strings.ToLower(hosts[i].Name) < strings.ToLower(hosts[j].Name)
	})
}

func findHost(hosts []Host, name string) int {
	for i, h := range hosts {
		if strings.EqualFold(h.Name, name) {
			return i
		}
	}
	return -1
}

func findByIP(hosts []Host, ip string, exceptIdx int) int {
	for i, h := range hosts {
		if i != exceptIdx && h.IP == ip {
			return i
		}
	}
	return -1
}

func findByMAC(hosts []Host, mac string, exceptIdx int) int {
	if mac == "" {
		return -1
	}
	for i, h := range hosts {
		if i != exceptIdx && h.MAC != "" && strings.EqualFold(h.MAC, mac) {
			return i
		}
	}
	return -1
}