77 lines
2.3 KiB
Go
77 lines
2.3 KiB
Go
// This file is part of gmnhg.
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// gmnhg is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// gmnhg is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with gmnhg. If not, see <https://www.gnu.org/licenses/>.
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// Package gemini provides functions to convert Markdown files to
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// Gemtext. It supports the use of YAML front matter in Markdown.
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package gemini
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import (
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"bytes"
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"fmt"
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"time"
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"git.tdem.in/tdemin/gmnhg/internal/gemini"
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"github.com/gomarkdown/markdown"
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"github.com/gomarkdown/markdown/parser"
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"gopkg.in/yaml.v2"
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)
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// hugoMetadata implements gemini.Metadata, providing the bare minimum
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// of possible post props.
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type hugoMetadata struct {
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PostTitle string `yaml:"title"`
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PostDate time.Time `yaml:"date"`
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}
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func (h hugoMetadata) Title() string {
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return h.PostTitle
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}
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func (h hugoMetadata) Date() time.Time {
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return h.PostDate
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}
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var yamlDelimiter = []byte("---\n")
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// RenderMarkdown converts Markdown text to text/gemini using
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// gomarkdown, appending Hugo YAML front matter data if any is present
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// to the post header.
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func RenderMarkdown(md []byte) (geminiText []byte, err error) {
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var metadata hugoMetadata
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if len(md) > len(yamlDelimiter)*2 {
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// only allow front matter at file start
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if bytes.Index(md, yamlDelimiter) != 0 {
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goto parse
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}
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blockEnd := bytes.Index(md[len(yamlDelimiter):], yamlDelimiter)
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if blockEnd == -1 {
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goto parse
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}
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yamlContent := md[len(yamlDelimiter) : blockEnd+len(yamlDelimiter)]
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if err := yaml.Unmarshal(yamlContent, &metadata); err != nil {
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return nil, fmt.Errorf("invalid front matter: %w", err)
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}
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md = md[blockEnd+len(yamlDelimiter)*2:]
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}
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parse:
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ast := markdown.Parse(md, parser.NewWithExtensions(parser.CommonExtensions))
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var geminiContent []byte
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if metadata.PostTitle != "" {
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geminiContent = markdown.Render(ast, gemini.NewRendererWithMetadata(metadata))
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} else {
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geminiContent = markdown.Render(ast, gemini.NewRenderer())
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}
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return geminiContent, nil
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}
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