add part information in title and series meta

internal/epub/core.go

@@ -166,9 +166,20 @@ func (e *ePub) Write() error {
 		}
 		defer wz.Close()
 
+		title := e.Title
+		if totalParts > 1 {
+			title = fmt.Sprintf("%s [%d/%d]", title, i+1, totalParts)
+		}
 		content := []zipContent{
 			{"META-INF/container.xml", containerTmpl},
-			{"OEBPS/content.opf", e.render(contentTmpl, map[string]any{"Info": e, "Cover": part.Cover, "Images": part.Images})},
+			{"OEBPS/content.opf", e.render(contentTmpl, map[string]any{
+				"Info":   e,
+				"Cover":  part.Cover,
+				"Images": part.Images,
+				"Title":  title,
+				"Part":   i + 1,
+				"Total":  totalParts,
+			})},
 			{"OEBPS/toc.ncx", e.render(tocTmpl, map[string]any{"Info": e})},
 			{"OEBPS/nav.xhtml", e.render(navTmpl, map[string]any{"Info": e})},
 			{"OEBPS/Text/style.css", styleTmpl},

internal/epub/templates/content.opf.tmpl

@@ -2,7 +2,7 @@
 <package version="3.0" unique-identifier="BookID" xmlns="http://www.idpf.org/2007/opf">
 {{ $info := .Info }}
   <metadata xmlns:opf="http://www.idpf.org/2007/opf" xmlns:dc="http://purl.org/dc/elements/1.1/">
-    <dc:title>{{ $info.Title }}</dc:title>
+    <dc:title>{{ .Title }}</dc:title>
     <dc:language>en-US</dc:language>
     <dc:identifier id="BookID">urn:uuid:{{ $info.UID }}</dc:identifier>
     <dc:contributor id="contributor">{{ $info.Publisher }}</dc:contributor>
@@ -18,6 +18,10 @@
     <meta name="orientation-lock" content="portrait"/>
 {{ if eq $info.AddPanelView true }}
     <meta name="region-mag" content="true"/>
+{{ end }}
+{{ if gt .Total 1 }}
+    <meta name="calibre:series" content="{{ $info.Title }}"/>
+    <meta name="calibre:series_index" content="{{ .Part }}"/>
 {{ end }}
   </metadata>
   <manifest>