1package emoji
 2
 3import (
 4	"fmt"
 5	"html"
 6	"strings"
 7)
 8
 9// Base attributes
10const (
11	unicodeFlagBaseIndex = 127397
12)
13
14// Skin tone colors
15const (
16	Default     Tone = ""
17	Light       Tone = "\U0001F3FB"
18	MediumLight Tone = "\U0001F3FC"
19	Medium      Tone = "\U0001F3FD"
20	MediumDark  Tone = "\U0001F3FE"
21	Dark        Tone = "\U0001F3FF"
22)
23
24// Emoji defines an emoji object.
25type Emoji string
26
27func (e Emoji) String() string {
28	return string(e)
29}
30
31// EmojiWithTone defines an emoji object that has skin tone options.
32type EmojiWithTone Emoji
33
34func (e EmojiWithTone) String() string {
35	return strings.ReplaceAll(string(e), "@", string(Default))
36}
37
38// Tone returns an emoji object with given skin tone.
39func (e EmojiWithTone) Tone(tones ...Tone) EmojiWithTone {
40	str := string(e)
41	for _, tone := range tones {
42		str = strings.Replace(str, "@", string(tone), 1)
43	}
44
45	if strings.Count(str, "@") > 0 {
46		lastTone := tones[len(tones)-1]
47		str = strings.ReplaceAll(str, "@", string(lastTone))
48	}
49
50	return EmojiWithTone(str)
51}
52
53// Tone defines skin tone options for emojis.
54type Tone string
55
56func (t Tone) String() string {
57	return string(t)
58}
59
60// CountryFlag returns a country flag emoji from given country code.
61// Full list of country codes: https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
62func CountryFlag(code string) (Emoji, error) {
63	if len(code) != 2 {
64		return "", fmt.Errorf("not valid country code: %q", code)
65	}
66
67	code = strings.ToUpper(code)
68	flag := countryCodeLetter(code[0]) + countryCodeLetter(code[1])
69
70	return Emoji(flag), nil
71}
72
73// countryCodeLetter shifts given letter byte as unicodeFlagBaseIndex and changes encoding
74func countryCodeLetter(l byte) string {
75	return html.UnescapeString(fmt.Sprintf("&#%v;", unicodeFlagBaseIndex+int(l)))
76}