resources/page: Allow section and taxonomy pages to have a permalink configuration

Allows using permalink configuration for sections (branch bundles) and
also for taxonomy pages. Extends the current permalink configuration to
be able to specified per page kind while also staying backward compatible:
all permalink patterns not dedicated to a certain kind, get automatically
added for both normal pages and term pages.

Fixes #8523

9 files changed, 133 insertions, 36 deletions

diff --git a/config/allconfig/allconfig.go b/config/allconfig/allconfig.go
index 9079e2ce3..2dc409be7 100644
--- a/config/allconfig/allconfig.go
+++ b/config/allconfig/allconfig.go
@@ -150,7 +150,7 @@ type Config struct {
 	Minify minifiers.MinifyConfig `mapstructure:"-"`
 
 	// Permalink configuration.
-	Permalinks map[string]string `mapstructure:"-"`
+	Permalinks map[string]map[string]string `mapstructure:"-"`
 
 	// Taxonomy configuration.
 	Taxonomies map[string]string `mapstructure:"-"`
diff --git a/config/allconfig/alldecoders.go b/config/allconfig/alldecoders.go
index 1c8573f3d..4d9ef4f85 100644
--- a/config/allconfig/alldecoders.go
+++ b/config/allconfig/alldecoders.go
@@ -206,7 +206,48 @@ var allDecoderSetups = map[string]decodeWeight{
 	"permalinks": {
 		key: "permalinks",
 		decode: func(d decodeWeight, p decodeConfig) error {
-			p.c.Permalinks = maps.CleanConfigStringMapString(p.p.GetStringMapString(d.key))
+			p.c.Permalinks = make(map[string]map[string]string)
+
+			p.c.Permalinks["page"] = make(map[string]string)
+			p.c.Permalinks["section"] = make(map[string]string)
+			p.c.Permalinks["taxonomy"] = make(map[string]string)
+			p.c.Permalinks["term"] = make(map[string]string)
+
+			config := maps.CleanConfigStringMap(p.p.GetStringMap(d.key))
+			for k, v := range config {
+				switch v := v.(type) {
+				case string:
+					// [permalinks]
+					//   key = '...'
+
+					// To sucessfully be backward compatible, "default" patterns need to be set for both page and term
+					p.c.Permalinks["page"][k] = v;
+					p.c.Permalinks["term"][k] = v;
+				
+				case maps.Params:
+					// [permalinks.key]
+					//   xyz = ???
+
+					if (k == "page") || (k == "section") || (k == "taxonomy") || (k == "term") {
+						// TODO: warn if we overwrite an already set value
+						for k2, v2 := range v {
+							switch v2 := v2.(type) {
+							case string:
+								p.c.Permalinks[k][k2] = v2
+							
+							default:
+								return fmt.Errorf("permalinks configuration invalid: unknown value %q for key %q for kind %q", v2, k2, k)
+							}
+						}
+					} else {
+						return fmt.Errorf("permalinks configuration only allows per-kind configuration 'page', 'section', 'taxonomy' and 'term'; unknown kind: %q", k)
+					}
+
+				default:
+					return fmt.Errorf("permalinks configuration invalid: unknown value %q for key %q", v, k)
+				}
+			}
+
 			return nil
 		},
 	},
diff --git a/hugofs/files/classifier.go b/hugofs/files/classifier.go
index 09b239c21..5690795ed 100644
--- a/hugofs/files/classifier.go
+++ b/hugofs/files/classifier.go
@@ -93,6 +93,7 @@ const (
 	ContentClassBranch  ContentClass = "branch"
 	ContentClassFile    ContentClass = "zfile" // Sort below
 	ContentClassContent ContentClass = "zcontent"
+	ContentClassZero    ContentClass = "zero"  // Special value for zeroFile
 )
 
 func (c ContentClass) IsBundle() bool {
diff --git a/hugolib/page__paths.go b/hugolib/page__paths.go
index 72eac3182..f98531c10 100644
--- a/hugolib/page__paths.go
+++ b/hugolib/page__paths.go
@@ -18,6 +18,7 @@ import (
 	"strings"
 
 	"github.com/gohugoio/hugo/helpers"
+	"github.com/gohugoio/hugo/hugofs/files"
 
 	"github.com/gohugoio/hugo/resources/page"
 )
@@ -108,14 +109,16 @@ func createTargetPathDescriptor(s *Site, p page.Page, pm *pageMeta) (page.Target
 	)
 
 	d := s.Deps
+	classifier := files.ContentClassZero
 
 	if !p.File().IsZero() {
 		dir = p.File().Dir()
 		baseName = p.File().TranslationBaseName()
 		contentBaseName = p.File().ContentBaseName()
+		classifier = p.File().Classifier()
 	}
 
-	if baseName != contentBaseName {
+	if classifier == files.ContentClassLeaf {
 		// See https://github.com/gohugoio/hugo/issues/4870
 		// A leaf bundle
 		dir = strings.TrimSuffix(dir, contentBaseName+helpers.FilePathSeparator)
@@ -143,22 +146,26 @@ func createTargetPathDescriptor(s *Site, p page.Page, pm *pageMeta) (page.Target
 	desc.PrefixFilePath = s.getLanguageTargetPathLang(alwaysInSubDir)
 	desc.PrefixLink = s.getLanguagePermalinkLang(alwaysInSubDir)
 
-	// Expand only page.KindPage and page.KindTaxonomy; don't expand other Kinds of Pages
-	// like page.KindSection or page.KindTaxonomyTerm because they are "shallower" and
-	// the permalink configuration values are likely to be redundant, e.g.
-	// naively expanding /category/:slug/ would give /category/categories/ for
-	// the "categories" page.KindTaxonomyTerm.
-	if p.Kind() == page.KindPage || p.Kind() == page.KindTerm {
-		opath, err := d.ResourceSpec.Permalinks.Expand(p.Section(), p)
-		if err != nil {
-			return desc, err
-		}
+	opath, err := d.ResourceSpec.Permalinks.Expand(p.Section(), p)
+	if err != nil {
+		return desc, err
+	}
 
-		if opath != "" {
-			opath, _ = url.QueryUnescape(opath)
-			desc.ExpandedPermalink = opath
+	if opath != "" {
+		opath, _ = url.QueryUnescape(opath)
+		if strings.HasSuffix(opath, "//") {
+			// When rewriting the _index of the section the permalink config is applied to,
+			// we get douple slashes at the end sometimes; clear them up here
+			opath = strings.TrimSuffix(opath, "/")
 		}
 
+		desc.ExpandedPermalink = opath
+
+		if !p.File().IsZero() {
+			s.Log.Debugf("Set expanded permalink path for %s %s to %#v", p.Kind(), p.File().Path(), opath)
+		} else {
+			s.Log.Debugf("Set expanded permalink path for %s in %v to %#v", p.Kind(), desc.Sections, opath)
+		}
 	}
 
 	return desc, nil
diff --git a/resources/page/page_generate/generate_page_wrappers.go b/resources/page/page_generate/generate_page_wrappers.go
index f4b40f717..c034bc002 100644
--- a/resources/page/page_generate/generate_page_wrappers.go
+++ b/resources/page/page_generate/generate_page_wrappers.go
@@ -221,7 +221,7 @@ func generateFileIsZeroWrappers(c *codegen.Inspector) error {
 	methods := c.MethodsFromTypes([]reflect.Type{reflect.TypeOf((*source.File)(nil)).Elem()}, nil)
 
 	for _, m := range methods {
-		if m.Name == "IsZero" {
+		if m.Name == "IsZero" || m.Name == "Classifier" {
 			continue
 		}
 		fmt.Fprint(&buff, m.DeclarationNamed("zeroFile"))
@@ -255,6 +255,11 @@ func (zeroFile) IsZero() bool {
 	return true
 }
 
+func (z zeroFile) Classifier() files.ContentClass {
+	z.log.Warnln(".File.Classifier on zero object. Wrap it in if or with: {{ with .File }}{{ .Classifier }}{{ end }}")
+	return files.ContentClassZero
+}
+
 %s
 
 `, header, importsString(pkgImports), buff.String())
diff --git a/resources/page/permalinks.go b/resources/page/permalinks.go
index 3dfc36937..ab418a20b 100644
--- a/resources/page/permalinks.go
+++ b/resources/page/permalinks.go
@@ -26,6 +26,7 @@ import (
 	"errors"
 
 	"github.com/gohugoio/hugo/helpers"
+
 )
 
 // PermalinkExpander holds permalin mappings per section.
@@ -35,7 +36,7 @@ type PermalinkExpander struct {
 	// to be used to replace that tag.
 	knownPermalinkAttributes map[string]pageToPermaAttribute
 
-	expanders map[string]func(Page) (string, error)
+	expanders map[string]map[string]func(Page) (string, error)
 
 	urlize func(uri string) string
 }
@@ -68,7 +69,7 @@ func (p PermalinkExpander) callback(attr string) (pageToPermaAttribute, bool) {
 
 // NewPermalinkExpander creates a new PermalinkExpander configured by the given
 // urlize func.
-func NewPermalinkExpander(urlize func(uri string) string, patterns map[string]string) (PermalinkExpander, error) {
+func NewPermalinkExpander(urlize func(uri string) string, patterns map[string]map[string]string) (PermalinkExpander, error) {
 	p := PermalinkExpander{urlize: urlize}
 
 	p.knownPermalinkAttributes = map[string]pageToPermaAttribute{
@@ -87,12 +88,15 @@ func NewPermalinkExpander(urlize func(uri string) string, patterns map[string]st
 		"filename":       p.pageToPermalinkFilename,
 	}
 
-	e, err := p.parse(patterns)
-	if err != nil {
-		return p, err
-	}
+	p.expanders = make(map[string]map[string]func(Page) (string, error))
 
-	p.expanders = e
+	for kind, patterns := range patterns {
+		e, err := p.parse(patterns)
+		if err != nil {
+			return p, err
+		}
+		p.expanders[kind] = e
+	}
 
 	return p, nil
 }
@@ -100,7 +104,13 @@ func NewPermalinkExpander(urlize func(uri string) string, patterns map[string]st
 // Expand expands the path in p according to the rules defined for the given key.
 // If no rules are found for the given key, an empty string is returned.
 func (l PermalinkExpander) Expand(key string, p Page) (string, error) {
-	expand, found := l.expanders[key]
+	expanders, found := l.expanders[p.Kind()]
+
+	if !found {
+		return "", nil
+	}
+
+	expand, found := expanders[key]
 
 	if !found {
 		return "", nil
@@ -242,6 +252,10 @@ func (l PermalinkExpander) pageToPermalinkDate(p Page, dateField string) (string
 
 // pageToPermalinkTitle returns the URL-safe form of the title
 func (l PermalinkExpander) pageToPermalinkTitle(p Page, _ string) (string, error) {
+	if p.File().TranslationBaseName() == "_index" {
+		return "", nil
+	}
+
 	return l.urlize(p.Title()), nil
 }
 
@@ -252,6 +266,8 @@ func (l PermalinkExpander) pageToPermalinkFilename(p Page, _ string) (string, er
 		// Page bundles; the directory name will hopefully have a better name.
 		dir := strings.TrimSuffix(p.File().Dir(), helpers.FilePathSeparator)
 		_, name = filepath.Split(dir)
+	} else if name == "_index" {
+		return "", nil
 	}
 
 	return l.urlize(name), nil
diff --git a/resources/page/permalinks_test.go b/resources/page/permalinks_test.go
index b9c0ca9cb..24eb27f5b 100644
--- a/resources/page/permalinks_test.go
+++ b/resources/page/permalinks_test.go
@@ -69,6 +69,7 @@ func TestPermalinkExpansion(t *testing.T) {
 	page.date = d
 	page.section = "blue"
 	page.slug = "The Slug"
+	page.kind = "page"
 
 	for _, item := range testdataPermalinks {
 		if !item.valid {
@@ -79,8 +80,10 @@ func TestPermalinkExpansion(t *testing.T) {
 		name := specNameCleaner.ReplaceAllString(item.spec, "")
 
 		c.Run(name, func(c *qt.C) {
-			patterns := map[string]string{
-				"posts": item.spec,
+			patterns := map[string]map[string]string{
+				"page": {
+					"posts": item.spec,
+				},
 			}
 			expander, err := NewPermalinkExpander(urlize, patterns)
 			c.Assert(err, qt.IsNil)
@@ -103,14 +106,18 @@ func TestPermalinkExpansionMultiSection(t *testing.T) {
 	page.date = d
 	page.section = "blue"
 	page.slug = "The Slug"
+	page.kind = "page"
 
 	page_slug_fallback := newTestPageWithFile("/page-filename/index.md")
 	page_slug_fallback.title = "Page Title"
-
-	permalinksConfig := map[string]string{
-		"posts":   "/:slug",
-		"blog":    "/:section/:year",
-		"recipes": "/:slugorfilename",
+	page_slug_fallback.kind = "page"
+
+	permalinksConfig := map[string]map[string]string{
+		"page": {
+			"posts":   "/:slug",
+			"blog":    "/:section/:year",
+			"recipes": "/:slugorfilename",
+		},
 	}
 	expander, err := NewPermalinkExpander(urlize, permalinksConfig)
 	c.Assert(err, qt.IsNil)
@@ -137,8 +144,10 @@ func TestPermalinkExpansionConcurrent(t *testing.T) {
 
 	c := qt.New(t)
 
-	permalinksConfig := map[string]string{
-		"posts": "/:slug/",
+	permalinksConfig := map[string]map[string]string{
+		"page": {
+			"posts": "/:slug/",
+		},
 	}
 
 	expander, err := NewPermalinkExpander(urlize, permalinksConfig)
@@ -151,6 +160,7 @@ func TestPermalinkExpansionConcurrent(t *testing.T) {
 		go func(i int) {
 			defer wg.Done()
 			page := newTestPage()
+			page.kind = "page"
 			for j := 1; j < 20; j++ {
 				page.slug = fmt.Sprintf("slug%d", i+j)
 				expanded, err := expander.Expand("posts", page)
@@ -209,9 +219,12 @@ func BenchmarkPermalinkExpand(b *testing.B) {
 	page.title = "Hugo Rocks"
 	d, _ := time.Parse("2006-01-02", "2019-02-28")
 	page.date = d
+	page.kind = "page"
 
-	permalinksConfig := map[string]string{
-		"posts": "/:year-:month-:title",
+	permalinksConfig := map[string]map[string]string{
+		"page": {
+			"posts": "/:year-:month-:title",
+		},
 	}
 	expander, err := NewPermalinkExpander(urlize, permalinksConfig)
 	if err != nil {
diff --git a/resources/page/zero_file.autogen.go b/resources/page/zero_file.autogen.go
index 72d98998e..979f92a0f 100644
--- a/resources/page/zero_file.autogen.go
+++ b/resources/page/zero_file.autogen.go
@@ -18,6 +18,7 @@ package page
 import (
 	"github.com/gohugoio/hugo/common/loggers"
 	"github.com/gohugoio/hugo/hugofs"
+	"github.com/gohugoio/hugo/hugofs/files"
 	"github.com/gohugoio/hugo/source"
 )
 
@@ -34,6 +35,11 @@ func (zeroFile) IsZero() bool {
 	return true
 }
 
+func (z zeroFile) Classifier() files.ContentClass {
+	z.log.Warnln(".File.Classifier on zero object. Wrap it in if or with: {{ with .File }}{{ .Classifier }}{{ end }}")
+	return files.ContentClassZero
+}
+
 func (z zeroFile) Path() (o0 string) {
 	z.log.Warnln(".File.Path on zero object. Wrap it in if or with: {{ with .File }}{{ .Path }}{{ end }}")
 	return
diff --git a/source/fileInfo.go b/source/fileInfo.go
index c58a0c3b9..03bb1b16c 100644
--- a/source/fileInfo.go
+++ b/source/fileInfo.go
@@ -92,6 +92,9 @@ type FileWithoutOverlap interface {
 	// if file is a leaf bundle.
 	ContentBaseName() string
 
+	// Classifier is the ContentClass of the file
+	Classifier() files.ContentClass
+
 	// UniqueID is the MD5 hash of the file's path and is for most practical applications,
 	// Hugo content files being one of them, considered to be unique.
 	UniqueID() string
@@ -170,6 +173,11 @@ func (fi *FileInfo) ContentBaseName() string {
 	return fi.contentBaseName
 }
 
+// Classifier is the ContentClass of the file
+func (fi *FileInfo) Classifier() files.ContentClass {
+	return fi.classifier;
+}
+
 // Section returns a file's section.
 func (fi *FileInfo) Section() string {
 	fi.init()