1package emoji
  2
  3import (
  4	"fmt"
  5	"regexp"
  6	"strings"
  7	"unicode"
  8)
  9
 10var (
 11	flagRegex = regexp.MustCompile(`^:flag-([a-zA-Z]{2}):$`)
 12)
 13
 14// Parse replaces emoji aliases (:pizza:) with unicode representation.
 15func Parse(input string) string {
 16	var matched strings.Builder
 17	var output strings.Builder
 18
 19	for _, r := range input {
 20		// when it's not `:`, it might be inner or outer of the emoji alias
 21		if r != ':' {
 22			// if matched is empty, it's the outer of the emoji alias
 23			if matched.Len() == 0 {
 24				output.WriteRune(r)
 25				continue
 26			}
 27
 28			matched.WriteRune(r)
 29
 30			// if it's space, the alias's not valid.
 31			// reset matched for breaking the emoji alias
 32			if unicode.IsSpace(r) {
 33				output.WriteString(matched.String())
 34				matched.Reset()
 35			}
 36			continue
 37		}
 38
 39		// r is `:` now
 40		// if matched is empty, it's the beginning of the emoji alias
 41		if matched.Len() == 0 {
 42			matched.WriteRune(r)
 43			continue
 44		}
 45
 46		// it's the end of the emoji alias
 47		match := matched.String()
 48		alias := match + ":"
 49
 50		// check for emoji alias
 51		if code, ok := emojiMap[alias]; ok {
 52			output.WriteString(code)
 53			matched.Reset()
 54			continue
 55		}
 56
 57		// check for `flag-[CODE]` emoji
 58		if flag := checkFlag(alias); len(flag) > 0 {
 59			output.WriteString(flag)
 60			matched.Reset()
 61			continue
 62		}
 63
 64		// not found any emoji
 65		output.WriteString(match)
 66		// it might be the beginning of the another emoji alias
 67		matched.Reset()
 68		matched.WriteRune(r)
 69
 70	}
 71
 72	// if matched not empty, add it to output
 73	if matched.Len() != 0 {
 74		output.WriteString(matched.String())
 75		matched.Reset()
 76	}
 77
 78	return output.String()
 79}
 80
 81// checkFlag finds flag emoji for `flag-[CODE]` pattern
 82func checkFlag(alias string) string {
 83	if matches := flagRegex.FindStringSubmatch(alias); len(matches) == 2 {
 84		flag, _ := CountryFlag(matches[1])
 85
 86		return flag.String()
 87	}
 88
 89	return ""
 90}
 91
 92// Map returns the emojis map.
 93// Key is the alias of the emoji.
 94// Value is the code of the emoji.
 95func Map() map[string]string {
 96	return emojiMap
 97}
 98
 99// AppendAlias adds new emoji pair to the emojis map.
100func AppendAlias(alias, code string) error {
101	if c, ok := emojiMap[alias]; ok {
102		return fmt.Errorf("emoji already exist: %q => %+q", alias, c)
103	}
104
105	for _, r := range alias {
106		if unicode.IsSpace(r) {
107			return fmt.Errorf("emoji alias is not valid: %q", alias)
108		}
109	}
110
111	emojiMap[alias] = code
112
113	return nil
114}
115
116// Exist checks existence of the emoji by alias.
117func Exist(alias string) bool {
118	_, ok := emojiMap[alias]
119
120	return ok
121}
122
123// Find returns the emoji code by alias.
124func Find(alias string) (string, bool) {
125	code, ok := emojiMap[alias]
126	if !ok {
127		return "", false
128	}
129
130	return code, true
131}