forked from tinode/chat
/
drafty.go
190 lines (166 loc) · 4.2 KB
/
drafty.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
// Package drafty contains utilities for conversion from Drafty to plain text.
package drafty
import (
"errors"
"sort"
"strings"
"unicode/utf8"
)
var errUnrecognizedContent = errors.New("content unrecognized")
var errInvalidContent = errors.New("invalid format")
type span struct {
tp string
at int
end int
key int
data map[string]interface{}
}
type spanfmt struct {
dec string
isVoid bool
}
var tags = map[string]spanfmt{
"ST": {"*", false},
"EM": {"_", false},
"DL": {"~", false},
"CO": {"", false},
"BR": {"\n", true},
"LN": {"", false},
"MN": {"", false},
"HT": {"", false},
"IM": {"", true},
"EX": {"", true},
}
// ToPlainText converts message payload from Drafy format to string.
// If content is plain string, then it's returned unchanged. If content is not recognized
// as either Drafy (as a map[string]interface{}) or as a string, an error is returned.
func ToPlainText(content interface{}) (string, error) {
if content == nil {
return "", nil
}
var drafty map[string]interface{}
switch data := content.(type) {
case string:
return data, nil
case map[string]interface{}:
drafty = data
default:
return "", errUnrecognizedContent
}
txt, txtOK := drafty["txt"].(string)
fmt, fmtOK := drafty["fmt"].([]interface{})
ent, entOK := drafty["ent"].([]interface{})
// At least one must be set.
if !txtOK && !fmtOK && !entOK {
return "", errUnrecognizedContent
}
if fmt == nil {
if txtOK {
return txt, nil
}
return "", errUnrecognizedContent
}
textLen := utf8.RuneCountInString(txt)
var spans []*span
for i := range fmt {
s := span{}
f, _ := fmt[i].(map[string]interface{})
if f == nil {
continue
}
s.tp, _ = f["tp"].(string)
tmp, _ := f["at"].(float64)
s.at = int(tmp)
tmp, _ = f["len"].(float64)
s.end = s.at + int(tmp)
if s.end > textLen || s.end < s.at {
return "", errInvalidContent
}
tmp, _ = f["key"].(float64)
s.key = int(tmp)
// Denormalize entities into spans.
if s.tp == "" && entOK {
if s.key < 0 || s.key >= len(ent) {
return "", errInvalidContent
}
e, _ := ent[s.key].(map[string]interface{})
if e == nil {
continue
}
s.data, _ = e["data"].(map[string]interface{})
s.tp, _ = e["tp"].(string)
}
if s.tp == "" && s.at == 0 && s.end == 0 && s.key == 0 {
return "", errUnrecognizedContent
}
spans = append(spans, &s)
}
// Sort spans first by start index (asc) then by length (desc).
sort.Slice(spans, func(i, j int) bool {
if spans[i].at == spans[j].at {
// longer one comes first
return spans[i].end > spans[j].end
}
return spans[i].at < spans[j].at
})
return forEach([]rune(txt), 0, textLen, spans), nil
}
func forEach(line []rune, start, end int, spans []*span) string {
// Process ranges calling formatter for each range.
var result []string
for i := 0; i < len(spans); i++ {
sp := spans[i]
if sp.at < 0 {
// Attachment
result = append(result, formatter(sp.tp, sp.data, ""))
continue
}
// Add un-styled range before the styled span starts.
if start < sp.at {
result = append(result, formatter("", nil, string(line[start:sp.at])))
start = sp.at
}
// Get all spans which are within current span.
var subspans []*span
for si := i + 1; si < len(spans) && spans[si].at < sp.end; si++ {
subspans = append(subspans, spans[si])
i = si
}
tag := tags[sp.tp]
if tag.isVoid {
result = append(result, formatter(sp.tp, sp.data, ""))
} else {
result = append(result, formatter(sp.tp, sp.data, forEach(line, start, sp.end, subspans)))
}
start = sp.end
}
// Add the last unformatted range.
if start < end {
result = append(result, formatter("", nil, string(line[start:end])))
}
return strings.Join(result, "")
}
func formatter(tp string, data map[string]interface{}, value string) string {
switch tp {
case "ST", "EM", "DL", "CO":
return tags[tp].dec + value + tags[tp].dec
case "LN":
url := data["url"].(string)
if url != value {
return "[" + value + "](" + url + ")"
}
return value
case "MN", "HT":
return value
case "BR":
return "\n"
case "IM":
name, _ := data["name"].(string)
return "[IMAGE '" + name + "']"
case "EX":
name, _ := data["name"].(string)
return "[FILE '" + name + "']"
default:
return value
}
}