kiln/render.go

package main

import (
	"bytes"
	"fmt"
	"html"
	"io"

	"git.sr.ht/~adnano/gmi"
)

// GeminiToHTML reads Gemini from the provided reader and returns an HTML string.
func GeminiToHTML(r io.Reader) []byte {
	var b bytes.Buffer
	var pre bool
	var list bool

	b.WriteString("<link rel='stylesheet' href='/style.css'>\n")

	text := gmi.Parse(r)
	for _, l := range text {
		if _, ok := l.(gmi.LineListItem); ok {
			if !list {
				list = true
				b.WriteString("<ul>\n")
			}
		} else if list {
			list = false
			b.WriteString("</ul>\n")
		}

		switch l.(type) {
		case gmi.LineLink:
			link := l.(gmi.LineLink)
			url := html.EscapeString(link.URL)
			name := html.EscapeString(link.Name)
			if name == "" {
				name = url
			}
			fmt.Fprintf(&b, "<p><a href='%s'>%s</a></p>", url, name)
		case gmi.LinePreformattingToggle:
			pre = !pre
			if pre {
				b.WriteString("<pre>\n")
			} else {
				b.WriteString("</pre>\n")
			}
		case gmi.LinePreformattedText:
			text := string(l.(gmi.LinePreformattedText))
			fmt.Fprintf(&b, "%s\n", html.EscapeString(text))
		case gmi.LineHeading1:
			text := string(l.(gmi.LineHeading1))
			fmt.Fprintf(&b, "<h1>%s</h1>\n", html.EscapeString(text))
		case gmi.LineHeading2:
			text := string(l.(gmi.LineHeading2))
			fmt.Fprintf(&b, "<h2>%s</h2>\n", html.EscapeString(text))
		case gmi.LineHeading3:
			text := string(l.(gmi.LineHeading3))
			fmt.Fprintf(&b, "<h3>%s</h3>\n", html.EscapeString(text))
		case gmi.LineListItem:
			text := string(l.(gmi.LineListItem))
			fmt.Fprintf(&b, "<li>%s</li>\n", html.EscapeString(text))
		case gmi.LineQuote:
			text := string(l.(gmi.LineQuote))
			fmt.Fprintf(&b, "<blockquote>%s</blockquote>\n", html.EscapeString(text))
		case gmi.LineText:
			text := string(l.(gmi.LineText))
			fmt.Fprintf(&b, "<p>%s</p>\n", html.EscapeString(text))
		}
	}
	return b.Bytes()
}