feat(backend): cover extraction for cbz and epub (opf cover-image/meta)

2026-09-05 00:23:02 +08:00
parent 589cb210bb
commit b02ca67d16
2 changed files with 200 additions and 0 deletions
@@ -0,0 +1,75 @@
+package bookfile
+
+import (
+	"archive/zip"
+	"bytes"
+	"testing"
+)
+
+func TestCBZCoverIsFirstPage(t *testing.T) {
+	buf := &bytes.Buffer{}
+	zw := zip.NewWriter(buf)
+	w, _ := zw.Create("02.jpg")
+	w.Write([]byte("second"))
+	w, _ = zw.Create("01.jpg")
+	w.Write([]byte("first"))
+	zw.Close()
+	r := bytes.NewReader(buf.Bytes())
+	img, ext, err := CBZCover(r, int64(r.Len()))
+	if err != nil || string(img) != "first" || ext != ".jpg" {
+		t.Fatalf("%q %q %v", img, ext, err)
+	}
+}
+
+func zipEntries(t *testing.T, kv map[string]string) *bytes.Reader {
+	t.Helper()
+	buf := &bytes.Buffer{}
+	zw := zip.NewWriter(buf)
+	for name, data := range kv {
+		w, _ := zw.Create(name)
+		w.Write([]byte(data))
+	}
+	zw.Close()
+	return bytes.NewReader(buf.Bytes())
+}
+
+const containerXML = `<?xml version="1.0"?><container><rootfiles><rootfile full-path="OEBPS/content.opf"/></rootfiles></container>`
+
+func opf(manifest, spine string) string {
+	return `<?xml version="1.0"?><package xmlns="http://www.idpf.org/2007/opf"><metadata>` +
+		spine + `</metadata><manifest>` + manifest + `</manifest></package>`
+}
+
+func TestEPUBCoverProperties(t *testing.T) {
+	r := zipEntries(t, map[string]string{
+		"META-INF/container.xml":  containerXML,
+		"OEBPS/content.opf":       opf(`<item id="c" href="img/cover%20one.png" properties="cover-image" media-type="image/png"/><item id="t" href="t.xhtml" media-type="application/xhtml+xml"/>`, ""),
+		"OEBPS/img/cover one.png": "PNGDATA",
+	})
+	img, ext, err := EPUBCover(r, int64(r.Len()))
+	if err != nil || string(img) != "PNGDATA" || ext != ".png" {
+		t.Fatalf("%q %q %v", img, ext, err)
+	}
+}
+
+func TestEPUBCoverMetaID(t *testing.T) {
+	r := zipEntries(t, map[string]string{
+		"META-INF/container.xml": containerXML,
+		"OEBPS/content.opf":      opf(`<item id="cv" href="art.jpg" media-type="image/jpeg"/><item id="t" href="t.xhtml" media-type="application/xhtml+xml"/>`, `<meta name="cover" content="cv"/>`),
+		"OEBPS/art.jpg":          "JPGDATA",
+	})
+	img, _, err := EPUBCover(r, int64(r.Len()))
+	if err != nil || string(img) != "JPGDATA" {
+		t.Fatalf("%q %v", img, err)
+	}
+}
+
+func TestEPUBNoCover(t *testing.T) {
+	r := zipEntries(t, map[string]string{
+		"META-INF/container.xml": containerXML,
+		"OEBPS/content.opf":      opf(`<item id="t" href="t.xhtml" media-type="application/xhtml+xml"/>`, ""),
+	})
+	if _, _, err := EPUBCover(r, int64(r.Len())); err == nil {
+		t.Fatal("want no-cover error")
+	}
+}