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package blog
import (
"bytes"
"errors"
"fmt"
"html/template"
"io"
"io/fs"
"net/url"
"os"
"path/filepath"
"sort"
"strings"
"time"
"github.com/bmatcuk/doublestar/v4"
"github.com/pelletier/go-toml/v2"
"gopkg.in/yaml.v3"
)
// Blog is a collection of [Article]
type Blog struct {
indexTemplate *template.Template
articleTemplate *template.Template
Articles []Article
Author Author
}
// Article is a blog post/article
type Article struct {
Filename string
Content template.HTML
ArticleMeta
}
// ArticleMeta is the metadata of an [Article]
type ArticleMeta struct {
Title string
Subtitle string
Summary string
Time time.Time
Author Author
Tags []string
Category string
}
// Author is an author of a blog/post
type Author struct {
Name string
Job string
Email string
Links []Link
}
// Link is a link name and URL
type Link struct {
Name string
URL LinkURL
}
// LinkURL is a URL
type LinkURL url.URL
func (l *LinkURL) UnmarshalText(data []byte) error {
u, err := url.Parse(string(data))
if err != nil {
return err
}
*l = LinkURL(*u)
return nil
}
// NewBlog constructs a new blog from articles in articleDir and templates in templateDir
func NewBlog(articleDir, templateDir string, author Author) (*Blog, error) {
tmpl, err := parseTemplates(os.DirFS(templateDir))
if err != nil {
return nil, fmt.Errorf("could not parse templates in %q: %w", templateDir, err)
}
indexTmpl := tmpl.Lookup("index.tmpl")
if indexTmpl == nil {
indexTmpl = tmpl.Lookup("index")
if indexTmpl == nil {
return nil, errors.New("`index` template is required but was not found")
}
}
articleTmpl := tmpl.Lookup("article.tmpl")
if articleTmpl == nil {
articleTmpl = tmpl.Lookup("article")
if articleTmpl == nil {
return nil, errors.New("`article` template is required but was not found")
}
}
articles, err := parseArticles(os.DirFS(articleDir))
if err != nil {
return nil, fmt.Errorf("could not parse articles in %q: %w", articleDir, err)
}
return &Blog{
indexTemplate: indexTmpl,
articleTemplate: articleTmpl,
Articles: articles,
Author: author,
}, nil
}
// Index renders the blog index to w
func (b *Blog) Index(w io.Writer) error {
return b.indexTemplate.Execute(w, map[string]any{
"articles": b.Articles,
"author": b.Author,
})
}
// Article renders an article to w
func (b *Blog) Article(w io.Writer, a Article) error {
return b.articleTemplate.Execute(w, map[string]any{
"article": a,
"author": b.Author,
})
}
func parseTemplates(fs fs.FS) (*template.Template, error) {
matches, err := doublestar.Glob(fs, "**/*.{tmpl,gohtml}")
if err != nil {
return nil, fmt.Errorf("could not glob templates: %w", err)
}
tmpl, err := template.New("").ParseFS(fs, matches...)
if err != nil {
return nil, fmt.Errorf("could not parse templates: %w", err)
}
return tmpl, nil
}
func parseArticles(fs fs.FS) ([]Article, error) {
matches, err := doublestar.Glob(fs, "**/*.md")
if err != nil {
return nil, fmt.Errorf("could not glob articles: %w", err)
}
articles := make([]Article, 0, len(matches))
for _, match := range matches {
if err := func() error {
fi, err := fs.Open(match)
if err != nil {
return err
}
defer fi.Close()
content, err := io.ReadAll(fi)
if err != nil {
return err
}
article, err := parseArticle(string(content))
if err != nil {
return err
}
article.Filename = strings.TrimSuffix(filepath.Base(match), filepath.Ext(match))
articles = append(articles, article)
return nil
}(); err != nil {
return nil, err
}
}
sort.SliceStable(articles, func(i, j int) bool {
return articles[i].Time.After(articles[j].Time)
})
return articles, nil
}
func parseArticle(content string) (Article, error) {
lines := strings.Split(content, "\n")
start, end := -1, -1
var isSep func(string) bool
var decoder func([]byte, any) error
for idx, line := range lines {
if strings.TrimSpace(line) == "" {
continue
}
if isSep != nil && isSep(line) {
end = idx
break
}
if isTOMLSeparator(line) {
start = idx
isSep = isTOMLSeparator
decoder = toml.Unmarshal
continue
}
if isYAMLSeparator(line) {
start = idx
isSep = isYAMLSeparator
decoder = yaml.Unmarshal
continue
}
}
var meta ArticleMeta
body := content
if start != -1 && end != -1 {
body = strings.Join(lines[end+1:], "\n")
if err := decoder([]byte(strings.Join(lines[start+1:end], "\n")), &meta); err != nil {
return Article{}, fmt.Errorf("could not parse frontmatter: %w", err)
}
}
var buf bytes.Buffer
err := Markdown.Convert([]byte(body), &buf)
if err != nil {
return Article{}, fmt.Errorf("could not convert article: %w", err)
}
return Article{
Content: template.HTML(buf.String()),
ArticleMeta: meta,
}, nil
}
func isTOMLSeparator(line string) bool {
for _, char := range line {
if char != '+' {
return false
}
}
return true
}
func isYAMLSeparator(line string) bool {
for _, char := range line {
if char != '-' {
return false
}
}
return true
}
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