package link

import (

"net/url"

"strings"

"github.com/pkg/errors"

)

type twitter struct{}

// Twitter service.

var Twitter = &twitter{}

func (s *twitter) ID() string {

return "twitter"

}

func (s *twitter) NormalizeURLString(name string, urs string) (string, error) {

return basicURLString(strings.ToLower(urs))

}

func (s *twitter) ValidateURLString(name string, urs string) (string, error) {

u, err := url.Parse(urs)

if err != nil {

return "", err

}

if u.Scheme != "https" {

return "", errors.Errorf("invalid scheme for url %s", u)

}

switch u.Host {

case "twitter.com", "mobile.twitter.com":

// OK

default:

return "", errors.Errorf("invalid host for url %s", u)

}

path := u.Path

path = strings.TrimPrefix(path, "/")

paths := strings.Split(path, "/")

if len(paths) != 3 {

return "", errors.Errorf("path invalid %s for url %s", paths, u)

}

if paths[0] != name {

return "", errors.Errorf("path invalid (name mismatch) for url %s", u)

}

// Use mobile twitter url.

return "https://mobile.twitter.com/" + path, nil

}

func (s *twitter) NormalizeName(name string) string {

name = strings.ToLower(name)

if len(name) > 0 && name[0] == '@' {

name = name[1:]

}

return name

}

func (s *twitter) ValidateName(name string) error {

ok := isAlphaNumericWithUnderscore(name)

if !ok {

return errors.Errorf("name has an invalid character")

}

if len(name) > 15 {

return errors.Errorf("twitter name is too long, it must be less than 16 characters")

}

return nil

}

func (s *twitter) CheckContent(name string, b []byte) ([]byte, error) {

return b, nil

}