1// Copyright 2016 The Hugo Authors. All rights reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14package helpers
15
16import (
17	"bytes"
18	"sync"
19
20	"github.com/kyokomi/emoji/v2"
21)
22
23var (
24	emojiInit sync.Once
25
26	emojis = make(map[string][]byte)
27
28	emojiDelim     = []byte(":")
29	emojiWordDelim = []byte(" ")
30	emojiMaxSize   int
31)
32
33// Emoji returns the emojy given a key, e.g. ":smile:", nil if not found.
34func Emoji(key string) []byte {
35	emojiInit.Do(initEmoji)
36	return emojis[key]
37}
38
39// Emojify "emojifies" the input source.
40// Note that the input byte slice will be modified if needed.
41// See http://www.emoji-cheat-sheet.com/
42func Emojify(source []byte) []byte {
43	emojiInit.Do(initEmoji)
44
45	start := 0
46	k := bytes.Index(source[start:], emojiDelim)
47
48	for k != -1 {
49
50		j := start + k
51
52		upper := j + emojiMaxSize
53
54		if upper > len(source) {
55			upper = len(source)
56		}
57
58		endEmoji := bytes.Index(source[j+1:upper], emojiDelim)
59		nextWordDelim := bytes.Index(source[j:upper], emojiWordDelim)
60
61		if endEmoji < 0 {
62			start++
63		} else if endEmoji == 0 || (nextWordDelim != -1 && nextWordDelim < endEmoji) {
64			start += endEmoji + 1
65		} else {
66			endKey := endEmoji + j + 2
67			emojiKey := source[j:endKey]
68
69			if emoji, ok := emojis[string(emojiKey)]; ok {
70				source = append(source[:j], append(emoji, source[endKey:]...)...)
71			}
72
73			start += endEmoji
74		}
75
76		if start >= len(source) {
77			break
78		}
79
80		k = bytes.Index(source[start:], emojiDelim)
81	}
82
83	return source
84}
85
86func initEmoji() {
87	emojiMap := emoji.CodeMap()
88
89	for k, v := range emojiMap {
90		emojis[k] = []byte(v)
91
92		if len(k) > emojiMaxSize {
93			emojiMaxSize = len(k)
94		}
95	}
96}
97