1 files changed, 129 insertions, 0 deletions
diff --git a/atom.go b/atom.go
new file mode 100644
index 0000000..d905348
--- /dev/null
+++ b/atom.go
@@ -0,0 +1,129 @@
+// Atom feed synthesizer
+// Copyright (C) 2022  Nguyễn Gia Phong
+//
+// This file is part of Phylactery.
+//
+// Phylactery is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Phylactery is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with Phylactery.  If not, see <https://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"archive/zip"
+	"encoding/xml"
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Type Img represents an XHTML img tag.
+type Img struct {
+	Src string `xml:"src,attr"`
+	Alt string `xml:"alt,attr"`
+}
+
+// Type Div represents an XHTML div tag.
+type Div struct {
+	NS  string `xml:"xmlns,attr"`
+	Img []Img  `xml:"img"`
+}
+
+// Type AtomLink represents an atom:link element.
+type AtomLink struct {
+	Rel  string `xml:"rel,attr"`
+	Href string `xml:"href,attr"`
+}
+
+// Type AtomContent represents an atom:content element.
+type AtomContent struct {
+	Type string `xml:"type,attr"`
+	Div  Div    `xml:"div"`
+}
+
+// Type AtomEntry represents an Atom Entry Document.
+type AtomEntry struct {
+	Title   string      `xml:"title"`
+	ID      string      `xml:"id"`
+	Link    []AtomLink  `xml:"link"`
+	Updated time.Time   `xml:"updated"`
+	Content AtomContent `xml:"content"`
+}
+
+// Type AtomFeed represents an Atom Feed Document.
+type AtomFeed struct {
+	XMLName xml.Name    `xml:"http://www.w3.org/2005/Atom feed"`
+	Title   string      `xml:"title"`
+	ID      string      `xml:"id"`
+	Link    []AtomLink  `xml:"link"`
+	Updated time.Time   `xml:"updated"`
+	Author  string      `xml:"author>name"`
+	Entry   []AtomEntry `xml:"entry"`
+}
+
+// Function synthesizeAtom generates an Atom feed for given directory.
+func synthesizeAtom(r *http.Request, dir string, updated time.Time) AtomFeed {
+	baseURL := "http://" + r.Host
+	if r.TLS != nil {
+		baseURL = "https" + baseURL[4:]
+	}
+	var entries []AtomEntry
+	filepath.WalkDir(dir, func(p string, d os.DirEntry, err error) error {
+		if err != nil || d.IsDir() {
+			return nil
+		}
+		name := strings.TrimPrefix(p, dir)[1:]
+		u := escape(baseURL + path.Join(r.URL.Path, name))
+		var images []Img
+		cbz, err := zip.OpenReader(p)
+		if err != nil {
+			return nil
+		}
+		defer cbz.Close()
+		for i, f := range cbz.File {
+			if isImageFile(f) {
+				continue
+			}
+			images = append(images,
+				Img{u + "?entry=" + strconv.Itoa(i), f.Name})
+		}
+
+		info, _ := d.Info()
+		entries = append(entries, AtomEntry{
+			Title:   name,
+			ID:      name,
+			Link:    []AtomLink{{"alternate", u}},
+			Updated: info.ModTime(),
+			Content: AtomContent{
+				"xhtml",
+				Div{"http://www.w3.org/1999/xhtml", images},
+			},
+		})
+		return nil
+	})
+
+	id := escape(baseURL + r.URL.Path)
+	return AtomFeed{
+		Title: r.URL.Path[1 : len(r.URL.Path)-1],
+		ID:    id,
+		Link: []AtomLink{
+			{"alternate", id},
+			{"self", id + "?feed=atom"},
+		},
+		Updated: updated,
+		Entry:   entries,
+	}
+}