// Package hosts provides a simple way to parse hostnames and ports.
// Supported formats are:
//   - https://example.com:8080
//   - https://example.com
//   - tls://example.com:8080
//   - tls://example.com
//   - example.com:8080
//   - example.com
//
// Hosts parsed here are expected to be TLS hosts, and the port defaults to 443.
package hosts

import (
	"errors"
	"fmt"
	"net"
	"net/url"
	"strconv"
	"strings"
)

const defaultHTTPSPort = 443

type Target struct {
	Host string
	Port int
}

func (t *Target) String() string {
	return fmt.Sprintf("%s:%d", t.Host, t.Port)
}

func parseURL(host string) (string, int, error) {
	url, err := url.Parse(host)
	if err != nil {
		return "", 0, fmt.Errorf("certlib/hosts: invalid host: %s", host)
	}

	switch strings.ToLower(url.Scheme) {
	case "https":
	// OK
	case "tls":
	// OK
	default:
		return "", 0, errors.New("certlib/hosts: only https scheme supported")
	}

	if url.Port() == "" {
		return url.Hostname(), defaultHTTPSPort, nil
	}

	portInt, err2 := strconv.ParseInt(url.Port(), 10, 16)
	if err2 != nil {
		return "", 0, fmt.Errorf("certlib/hosts: invalid port: %s", url.Port())
	}

	return url.Hostname(), int(portInt), nil
}

func parseHostPort(host string) (string, int, error) {
	shost, sport, err := net.SplitHostPort(host)
	if err == nil {
		portInt, err2 := strconv.ParseInt(sport, 10, 16)
		if err2 != nil {
			return "", 0, fmt.Errorf("certlib/hosts: invalid port: %s", sport)
		}

		return shost, int(portInt), nil
	}

	return host, defaultHTTPSPort, nil
}

func ParseHost(host string) (*Target, error) {
	uhost, port, err := parseURL(host)
	if err == nil {
		return &Target{Host: uhost, Port: port}, nil
	}

	shost, port, err := parseHostPort(host)
	if err == nil {
		return &Target{Host: shost, Port: port}, nil
	}

	return nil, fmt.Errorf("certlib/hosts: invalid host: %s", host)
}

func ParseHosts(hosts ...string) ([]*Target, error) {
	targets := make([]*Target, 0, len(hosts))
	for _, host := range hosts {
		target, err := ParseHost(host)
		if err != nil {
			return nil, err
		}
		targets = append(targets, target)
	}

	return targets, nil
}