294 lines
7.5 KiB
Go
294 lines
7.5 KiB
Go
package kaku
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import (
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"html"
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"html/template"
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"strconv"
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"strings"
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)
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func (document *Document) Render() template.HTML {
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var b strings.Builder
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render(&b, document.Children)
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return template.HTML(b.String())
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}
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// Loops over nodes of the document's children to detect node types and render them in HTML
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func render(b *strings.Builder, nodes []Node) {
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for _, n := range nodes {
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switch v := n.(type) {
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case *Heading:
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id := toKebabCase(plainText(v.Children))
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tagName := "h" + strconv.Itoa(v.Level)
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b.WriteString("<")
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b.WriteString(tagName)
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b.WriteString(` id="`)
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b.WriteString(id)
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b.WriteString(`">`)
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render(b, v.Children)
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b.WriteString(`<a href="#`)
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b.WriteString(id)
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b.WriteString(`" aria-label="`)
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b.WriteString(html.EscapeString(plainText(v.Children)))
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b.WriteString(` permalink" class="heading-anchor" title="Link to this heading">#</a></`)
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b.WriteString(tagName)
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b.WriteString(">")
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case *Paragraph:
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wrap(b, "p", v.Children)
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case *Bold:
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wrap(b, "strong", v.Children)
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case *Em:
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wrap(b, "em", v.Children)
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case *Strike:
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wrap(b, "del", v.Children)
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case *Code:
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b.WriteString("<code>")
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b.WriteString(html.EscapeString(v.Value))
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b.WriteString("</code>")
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case *Text:
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b.WriteString(html.EscapeString(v.Value))
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case *HR:
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b.WriteString("<hr>")
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case *CodeBlock:
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b.WriteString("<pre><code")
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if v.Language != "" {
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b.WriteString(` class="language-`)
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b.WriteString(html.EscapeString(v.Language))
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b.WriteString(`"`)
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}
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b.WriteString(">")
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b.WriteString(html.EscapeString(v.Content))
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b.WriteString("</code></pre>")
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case *List:
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b.WriteString("<")
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b.WriteString(v.Kind)
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b.WriteString(">")
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for _, item := range v.Items {
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b.WriteString("<li>")
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render(b, item.Children)
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b.WriteString("</li>")
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}
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b.WriteString("</")
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b.WriteString(v.Kind)
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b.WriteString(">")
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case *DefList:
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b.WriteString("<dl>")
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for _, item := range v.Items {
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b.WriteString("<dt>")
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render(b, item.Term)
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b.WriteString("</dt><dd>")
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render(b, item.Definition)
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b.WriteString("</dd>")
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}
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b.WriteString("</dl>")
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case *Quote:
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b.WriteString("<figure>")
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if v.Link != "" {
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b.WriteString(`<blockquote cite="`)
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b.WriteString(html.EscapeString(safeUrl(v.Link)))
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b.WriteString(`">`)
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} else {
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b.WriteString("<blockquote>")
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}
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render(b, v.Text)
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b.WriteString("</blockquote>")
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if v.Author != "" || v.Source != "" {
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b.WriteString("<figcaption>—")
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b.WriteString(html.EscapeString(v.Author))
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if v.Source != "" {
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b.WriteString(", ")
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if v.Link != "" {
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b.WriteString(`<a href="`)
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b.WriteString(html.EscapeString(safeUrl(v.Link)))
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b.WriteString(`">`)
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b.WriteString(html.EscapeString(v.Source))
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b.WriteString("</a>")
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} else {
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b.WriteString(html.EscapeString(v.Source))
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}
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}
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b.WriteString("</figcaption>")
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}
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b.WriteString("</figure>")
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case *Link:
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b.WriteString(`<a href="`)
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b.WriteString(html.EscapeString(safeUrl(v.URL)))
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b.WriteString(`"`)
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if v.Label != "" {
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b.WriteString(` aria-label="`)
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b.WriteString(html.EscapeString(v.Label))
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b.WriteString(`"`)
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}
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if v.Title != "" {
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b.WriteString(` title="`)
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b.WriteString(html.EscapeString(v.Title))
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b.WriteString(`"`)
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}
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b.WriteString(">")
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render(b, v.Text)
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b.WriteString("</a>")
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case *Image:
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url := imageURL(v.URL)
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b.WriteString("<figure>")
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b.WriteString(`<img src="`)
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b.WriteString(html.EscapeString(safeUrl(url)))
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b.WriteString(`" alt="`)
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b.WriteString(html.EscapeString(safeUrl(v.Alt)))
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b.WriteString(`">`)
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b.WriteString("<figcaption>")
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if len(v.Caption) > 0 {
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render(b, v.Caption)
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b.WriteString(` | `)
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}
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b.WriteString(`<small><a href="/uploaded/`)
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b.WriteString(html.EscapeString(safeUrl(v.URL)))
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b.WriteString(`">Full size</a></small>`)
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b.WriteString("</figcaption>")
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b.WriteString("</figure>")
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case *Video:
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b.WriteString("<figure>")
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tag := `<video controls="" preload="metadata" src="/uploaded/`
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if v.Autoplay {
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tag = `<video autoplay="true" playsinline="true" loop="true" muted="true" preload="metadata" src="/uploaded/`
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}
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b.WriteString(tag)
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b.WriteString(html.EscapeString(safeUrl(v.URL)))
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b.WriteString(`" type="video/mp4"></video>`)
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if len(v.Caption) > 0 {
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b.WriteString("<figcaption>")
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render(b, v.Caption)
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b.WriteString("</figcaption>")
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}
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b.WriteString("</figure>")
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case *Audio:
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b.WriteString(`<audio controls="" preload="metadata" src="/uploaded/`)
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b.WriteString(html.EscapeString(safeUrl(v.URL)))
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b.WriteString(`" type="audio/mpeg"></audio>`)
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case *Aside:
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b.WriteString("<aside><p>Side note</p>")
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render(b, v.Children)
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b.WriteString("</aside>")
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case *Details:
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b.WriteString("<details><summary>")
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render(b, v.Summary)
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b.WriteString("</summary>")
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render(b, v.Content)
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b.WriteString("</details>")
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case *TodoList:
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b.WriteString("<ul>")
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for _, item := range v.Items {
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label := ""
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switch item.State {
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case ' ':
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label = "Opened task"
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case '@':
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label = "Ongoing task"
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case '~':
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label = "Paused or abandonned task"
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case 'x':
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label = "Completed task"
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}
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b.WriteString(`<li><code aria-hidden="true">[`)
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b.WriteByte(item.State)
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b.WriteString(`]</code><span class="visually-hidden">`)
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b.WriteString(label)
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b.WriteString("</span> ")
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render(b, item.Children)
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b.WriteString("</li>")
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}
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b.WriteString("</ul>")
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case *RawHTML:
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b.WriteString(v.Content)
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}
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}
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}
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// Wraps each node from render into its html tag, then calls render again for possible nested tags
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func wrap(b *strings.Builder, tag string, children []Node) {
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b.WriteString("<")
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b.WriteString(tag)
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b.WriteString(">")
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render(b, children)
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b.WriteString("</")
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b.WriteString(tag)
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b.WriteString(">")
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}
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// Sanitizes urls for href and src attributes
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func safeUrl(url string) string {
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trimmed := strings.TrimSpace(url)
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scheme, _, found := strings.Cut(trimmed, ":")
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if !found {
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return trimmed
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}
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switch strings.ToLower(scheme) {
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case "javascript", "data", "vbscript", "file":
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return ""
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default:
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return trimmed
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}
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}
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// Flattens inline nodes down to their visible text, ignoring markup like Bold/Em/Strike/Code. Used to create IDs or Aria Label text
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func plainText(nodes []Node) string {
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var b strings.Builder
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for _, n := range nodes {
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switch v := n.(type) {
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case *Text:
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b.WriteString(v.Value)
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case *Code:
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b.WriteString(v.Value)
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case *Bold:
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b.WriteString(plainText(v.Children))
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case *Em:
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b.WriteString(plainText(v.Children))
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case *Strike:
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b.WriteString(plainText(v.Children))
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case *Link:
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b.WriteString(plainText(v.Text))
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}
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}
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return b.String()
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}
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// Converts text into a lowercase hyphen-separated slug
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func toKebabCase(text string) string {
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var b strings.Builder
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lastWasHyphen := true // avoid a leading hyphen
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for _, r := range strings.ToLower(text) {
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if r >= 'a' && r <= 'z' || r >= '0' && r <= '9' {
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b.WriteRune(r)
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lastWasHyphen = false
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continue
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}
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if !lastWasHyphen {
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b.WriteByte('-')
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lastWasHyphen = true
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}
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}
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return strings.TrimRight(b.String(), "-")
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}
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// Allows prefixing local/relative image paths and normalizes ".jpeg" extension to ".jpg"
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// Disabled in this version
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func imageURL(url string) string {
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if strings.HasPrefix(url, "http://") || strings.HasPrefix(url, "https://") {
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return url
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}
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if strings.HasSuffix(url, ".jpeg") {
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url = strings.TrimSuffix(url, ".jpeg") + ".jpg"
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}
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return "/processed/" + url
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}
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