package main

import (
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"net/url"
	"os"
	"strings"
)

const (
	baseURL = "https://dynamicdns.park-your-domain.com/update?"
)

type DomainTuple struct {
	Domain   string
	Password string
}

func Config(path string) ([]DomainTuple, error) {
	conf, err := ioutil.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read conf: %w", err)
	}
	tuples := []DomainTuple{}
	for _, line := range strings.Split(string(conf), "\n") {
		line := strings.TrimSpace(line)
		if !strings.Contains(line, "=") {
			continue
		}
		parts := strings.SplitN(line, "=", 2)
		if len(parts) != 2 {
			continue
		}
		tuples = append(tuples, DomainTuple{
			Domain:   parts[0],
			Password: parts[1],
		})
	}
	return tuples, nil
}

func fatal(name string, err error) {
	if err != nil {
		fmt.Fprintln(os.Stderr, name, err.Error())
		os.Exit(1)
	}
}

func main() {
	cfgPath := flag.String("config", "nc.conf", "config file path")
	flag.Parse()

	ip, err := IP()
	fatal("ip", err)
	cfg, err := Config(*cfgPath)
	fatal("config", err)
	for _, cfgEntry := range cfg {
		fmt.Println(cfgEntry.Domain)
		err = Set(ip, cfgEntry.Domain, cfgEntry.Password, "*")
		fatal(cfgEntry.Domain, err)
		err = Set(ip, cfgEntry.Domain, cfgEntry.Password, "@")
		fatal(cfgEntry.Domain, err)
	}
}

func IP() (string, error) {
	resp, err := http.Get("https://ipv4.icanhazip.com")
	if err != nil {
		return "", fmt.Errorf("get ip: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", fmt.Errorf("read body: %w", err)
	}

	return string(body), nil
}

func Set(ip, domain, password, host string) error {
	params := url.Values{}
	params.Add("host", host)
	params.Add("domain", domain)
	params.Add("password", password)
	params.Add("ip", ip)

	resp, err := http.Get(fmt.Sprintf("%s%s", baseURL, params.Encode()))
	if err != nil {
		return fmt.Errorf("request: %w", err)
	}
	defer resp.Body.Close()

	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("read body: %w", err)
	}

	if resp.StatusCode != http.StatusOK {
		fmt.Fprintf(os.Stderr, "got status [%d]: %s\n", resp.StatusCode, string(data))
	}
	return nil
}