1package emoji
  2
  3import (
  4	"fmt"
  5	"strings"
  6)
  7
  8// Base attributes
  9const (
 10	TonePlaceholder = "@"
 11	flagBaseIndex   = '\U0001F1E6' - 'a'
 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 with no skin variations.
 25type Emoji string
 26
 27// String returns string representation of the simple emoji.
 28func (e Emoji) String() string {
 29	return string(e)
 30}
 31
 32// EmojiWithTone defines an emoji object that has skin tone options.
 33type EmojiWithTone struct {
 34	oneTonedCode string
 35	twoTonedCode string
 36	defaultTone  Tone
 37}
 38
 39// newEmojiWithTone constructs a new emoji object that has skin tone options.
 40func newEmojiWithTone(codes ...string) EmojiWithTone {
 41	if len(codes) == 0 {
 42		return EmojiWithTone{}
 43	}
 44
 45	one := codes[0]
 46	two := codes[0]
 47
 48	if len(codes) > 1 {
 49		two = codes[1]
 50	}
 51
 52	return EmojiWithTone{
 53		oneTonedCode: one,
 54		twoTonedCode: two,
 55	}
 56}
 57
 58// withDefaultTone sets default tone for an emoji and returns it.
 59func (e EmojiWithTone) withDefaultTone(tone string) EmojiWithTone {
 60	e.defaultTone = Tone(tone)
 61
 62	return e
 63}
 64
 65// String returns string representation of the emoji with default skin tone.
 66func (e EmojiWithTone) String() string {
 67	return strings.ReplaceAll(e.oneTonedCode, TonePlaceholder, e.defaultTone.String())
 68}
 69
 70// Tone returns string representation of the emoji with given skin tone.
 71func (e EmojiWithTone) Tone(tones ...Tone) string {
 72	// if no tone given, return with default skin tone
 73	if len(tones) == 0 {
 74		return e.String()
 75	}
 76
 77	str := e.twoTonedCode
 78	replaceCount := 1
 79
 80	// if one tone given or emoji doesn't have twoTonedCode, use oneTonedCode
 81	// Also, replace all with one tone
 82	if len(tones) == 1 {
 83		str = e.oneTonedCode
 84		replaceCount = -1
 85	}
 86
 87	// replace tone one by one
 88	for _, t := range tones {
 89		// use emoji's default tone
 90		if t == Default {
 91			t = e.defaultTone
 92		}
 93
 94		str = strings.Replace(str, TonePlaceholder, t.String(), replaceCount)
 95	}
 96
 97	return str
 98}
 99
100// Tone defines skin tone options for emojis.
101type Tone string
102
103// String returns string representation of the skin tone.
104func (t Tone) String() string {
105	return string(t)
106}
107
108// CountryFlag returns a country flag emoji from given country code.
109// Full list of country codes: https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
110func CountryFlag(code string) (Emoji, error) {
111	if len(code) != 2 {
112		return "", fmt.Errorf("not valid country code: %q", code)
113	}
114
115	code = strings.ToLower(code)
116	flag := countryCodeLetter(code[0]) + countryCodeLetter(code[1])
117
118	return Emoji(flag), nil
119}
120
121// countryCodeLetter shifts given letter byte as flagBaseIndex.
122func countryCodeLetter(l byte) string {
123	return string(rune(l) + flagBaseIndex)
124}