💾 Archived View for anachronauts.club › cgi-bin › repos › cgi › gmikit.git › tree › trunk › html.go captured on 2021-12-05 at 23:47:19. Gemini links have been rewritten to link to archived content
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1 package gmikit
2
3 import (
4 "fmt"
5 "html/template"
6 "io"
7 "net/url"
8 )
9
10 type UrlRewriter func(*url.URL) (*url.URL, string, error)
11
12 type element int
13
14 const (
15 Clear element = iota
16 Pre
17 AltPre
18 Quoting
19 Para
20 List
21 )
22
23 type HtmlWriter struct {
24 w io.Writer
25 Rewriter UrlRewriter
26 elem element
27 }
28
29 func NewHtmlWriter(w io.Writer, rewriter UrlRewriter) *HtmlWriter {
30 return &HtmlWriter{
31 w: w,
32 Rewriter: rewriter,
33 elem: Clear,
34 }
35 }
36
37 func (h *HtmlWriter) Write(p []byte) (n int, err error) {
38 return h.w.Write(p)
39 }
40
41 func (h *HtmlWriter) Clear() error {
42 var err error
43 switch h.elem {
44 case Pre:
45 _, err = fmt.Fprintf(h.w, "</pre>\n")
46 case AltPre:
47 _, err = fmt.Fprintf(h.w, "</pre>\n</div>\n")
48 case Quoting:
49 _, err = fmt.Fprintf(h.w, "</blockquote>\n")
50 case Para:
51 _, err = fmt.Fprintf(h.w, "</p>\n")
52 case List:
53 _, err = fmt.Fprint(h.w, "</ul>\n")
54 }
55 if err != nil {
56 return err
57 }
58 h.elem = Clear
59 return nil
60 }
61
62 func (h *HtmlWriter) Begin() error { return nil }
63
64 func (h *HtmlWriter) End() error {
65 return h.Clear()
66 }
67
68 func (h *HtmlWriter) Text(text string) error {
69 if h.elem != Para {
70 err := h.Clear()
71 if err != nil {
72 return err
73 }
74
75 if _, err := fmt.Fprintf(h.w, "<p>"); err != nil {
76 return err
77 }
78
79 h.elem = Para
80 }
81
82 _, err := fmt.Fprintf(h.w, "%s\n", template.HTMLEscapeString(text))
83 return err
84 }
85
86 var anchor = template.Must(
87 template.New("anchor").Parse(
88 "<a href=\"{{.Href}}\"" +
89 "{{ if .Class }} class=\"{{.Class}}\" {{- end }}>" +
90 "{{.Text}}</a><br/>\n"))
91
92 func (h *HtmlWriter) Link(target *url.URL, friendlyName string) error {
93 err := h.Clear()
94 if err != nil {
95 return err
96 }
97
98 class := target.Scheme
99 if h.Rewriter != nil {
100 target, class, err = h.Rewriter(target)
101 if err != nil {
102 return err
103 }
104 }
105
106 if friendlyName == "" {
107 friendlyName = target.String()
108 }
109
110 return anchor.Execute(h.w, struct {
111 Href *url.URL
112 Class string
113 Text string
114 }{
115 Href: target,
116 Class: class,
117 Text: friendlyName,
118 })
119 }
120
121 var altPre = template.Must(
122 template.New("altPre").
123 Parse(`<div aria-label="{{.}}">
124 <pre aria-hidden="true" alt="{{.}}">
125 `))
126
127 func (h *HtmlWriter) PreformattingToggle(altText string) error {
128 elem := h.elem
129 err := h.Clear()
130 if err != nil {
131 return err
132 }
133
134 if elem == Pre || elem == AltPre {
135 return nil
136 }
137
138 if altText == "" {
139 h.elem = Pre
140 _, err := fmt.Fprint(h.w, "<pre>\n")
141 return err
142 } else {
143 h.elem = AltPre
144 return altPre.Execute(h.w, altText)
145 }
146 }
147
148 func (h *HtmlWriter) PreformattedText(text string) error {
149 _, err := fmt.Fprintf(h.w, "%s\n", template.HTMLEscapeString(text))
150 return err
151 }
152
153 var h1 = template.Must(
154 template.New("h1").
155 Parse("<h1>{{.}}</h1>\n"))
156
157 func (h *HtmlWriter) Heading1(text string) error {
158 err := h.Clear()
159 if err != nil {
160 return err
161 }
162
163 return h1.Execute(h.w, text)
164 }
165
166 var h2 = template.Must(
167 template.New("h2").
168 Parse("<h2>{{.}}</h2>\n"))
169
170 func (h *HtmlWriter) Heading2(text string) error {
171 err := h.Clear()
172 if err != nil {
173 return err
174 }
175
176 return h2.Execute(h.w, text)
177 }
178
179 var h3 = template.Must(
180 template.New("h3").
181 Parse("<h3>{{.}}</h3>\n"))
182
183 func (h *HtmlWriter) Heading3(text string) error {
184 err := h.Clear()
185 if err != nil {
186 return err
187 }
188
189 return h3.Execute(h.w, text)
190 }
191
192 var li = template.Must(
193 template.New("li").
194 Parse("<li>{{.}}</li>\n"))
195
196 func (h *HtmlWriter) UnorderedListItem(text string) error {
197 if h.elem != List {
198 err := h.Clear()
199 if err != nil {
200 return err
201 }
202
203 if _, err := fmt.Fprintf(h.w, "<ul>\n"); err != nil {
204 return err
205 }
206 h.elem = List
207 }
208
209 return li.Execute(h.w, text)
210 }
211
212 func (h *HtmlWriter) Quote(text string) error {
213 if h.elem != Quoting {
214 err := h.Clear()
215 if err != nil {
216 return err
217 }
218
219 if _, err := fmt.Fprintf(h.w, "<blockquote>"); err != nil {
220 return err
221 }
222 h.elem = Quoting
223 }
224
225 _, err := fmt.Fprintf(h.w, "%s\n", template.HTMLEscapeString(text))
226 return err
227 }
228
229 func GmiToHtml(r io.Reader, w io.Writer) error {
230 return ParseLines(r, NewHtmlWriter(w, nil))
231 }