Misc permalinks adjustments

* Move config loading to the page package
* Fix a lower bound panic for the `:sections` slice syntax.
* Always return the `:title`
* Add some permalinks integration tests
* Also see issues below

Fixes #9448
Fixes #11184
See #8523

4 files changed, 297 insertions, 34 deletions

diff --git a/resources/page/permalinks.go b/resources/page/permalinks.go
index ab418a20b..3b12e1154 100644
--- a/resources/page/permalinks.go
+++ b/resources/page/permalinks.go
@@ -25,8 +25,8 @@ import (
 
 	"errors"
 
+	"github.com/gohugoio/hugo/common/maps"
 	"github.com/gohugoio/hugo/helpers"
-
 )
 
 // PermalinkExpander holds permalin mappings per section.
@@ -252,16 +252,12 @@ 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
 }
 
 // pageToPermalinkFilename returns the URL-safe form of the filename
 func (l PermalinkExpander) pageToPermalinkFilename(p Page, _ string) (string, error) {
-	name := p.File().TranslationBaseName()
+	name := l.translationBaseName(p)
 	if name == "index" {
 		// Page bundles; the directory name will hopefully have a better name.
 		dir := strings.TrimSuffix(p.File().Dir(), helpers.FilePathSeparator)
@@ -297,6 +293,13 @@ func (l PermalinkExpander) pageToPermalinkSections(p Page, _ string) (string, er
 	return p.CurrentSection().SectionsPath(), nil
 }
 
+func (l PermalinkExpander) translationBaseName(p Page) string {
+	if p.File().IsZero() {
+		return ""
+	}
+	return p.File().TranslationBaseName()
+}
+
 var (
 	nilSliceFunc = func(s []string) []string {
 		return nil
@@ -349,7 +352,10 @@ func (l PermalinkExpander) toSliceFunc(cut string) func(s []string) []string {
 		return func(ss []string) int {
 			// Prevent out of bound situations. It would not make
 			// much sense to panic here.
-			if n > len(ss) {
+			if n >= len(ss) {
+				if low {
+					return -1
+				}
 				return len(ss)
 			}
 			return n
@@ -365,7 +371,11 @@ func (l PermalinkExpander) toSliceFunc(cut string) func(s []string) []string {
 			if len(s) == 0 {
 				return nil
 			}
-			v := s[toN(s)]
+			n := toN(s)
+			if n < 0 {
+				return []string{}
+			}
+			v := s[n]
 			if v == "" {
 				return nil
 			}
@@ -379,7 +389,59 @@ func (l PermalinkExpander) toSliceFunc(cut string) func(s []string) []string {
 		if len(s) == 0 {
 			return nil
 		}
-		return s[toN1(s):toN2(s)]
+		n1, n2 := toN1(s), toN2(s)
+		if n1 < 0 || n2 < 0 {
+			return []string{}
+		}
+		return s[n1:n2]
 	}
 
 }
+
+var permalinksKindsSuppurt = []string{KindPage, KindSection, KindTaxonomy, KindTerm}
+
+// DecodePermalinksConfig decodes the permalinks configuration in the given map
+func DecodePermalinksConfig(m map[string]any) (map[string]map[string]string, error) {
+	permalinksConfig := make(map[string]map[string]string)
+
+	permalinksConfig[KindPage] = make(map[string]string)
+	permalinksConfig[KindSection] = make(map[string]string)
+	permalinksConfig[KindTaxonomy] = make(map[string]string)
+	permalinksConfig[KindTerm] = make(map[string]string)
+
+	config := maps.CleanConfigStringMap(m)
+	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
+			permalinksConfig[KindPage][k] = v
+			permalinksConfig[KindTerm][k] = v
+
+		case maps.Params:
+			// [permalinks.key]
+			//   xyz = ???
+
+			if helpers.InStringArray(permalinksKindsSuppurt, k) {
+				// TODO: warn if we overwrite an already set value
+				for k2, v2 := range v {
+					switch v2 := v2.(type) {
+					case string:
+						permalinksConfig[k][k2] = v2
+
+					default:
+						return nil, fmt.Errorf("permalinks configuration invalid: unknown value %q for key %q for kind %q", v2, k2, k)
+					}
+				}
+			} else {
+				return nil, fmt.Errorf("permalinks configuration not supported for kind %q, supported kinds are %v", k, permalinksKindsSuppurt)
+			}
+
+		default:
+			return nil, fmt.Errorf("permalinks configuration invalid: unknown value %q for key %q", v, k)
+		}
+	}
+	return permalinksConfig, nil
+}
diff --git a/resources/page/permalinks_integration_test.go b/resources/page/permalinks_integration_test.go
new file mode 100644
index 000000000..6c2411ad7
--- /dev/null
+++ b/resources/page/permalinks_integration_test.go
@@ -0,0 +1,198 @@
+// Copyright 2023 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package page_test
+
+import (
+	"testing"
+
+	"github.com/bep/logg"
+	qt "github.com/frankban/quicktest"
+	"github.com/gohugoio/hugo/hugolib"
+)
+
+func TestPermalinks(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- layouts/_default/list.html --
+List|{{ .Kind }}|{{ .RelPermalink }}|
+-- layouts/_default/single.html --
+Single|{{ .Kind }}|{{ .RelPermalink }}|
+-- hugo.toml --
+[taxonomies]
+tag = "tags"
+[permalinks.page]
+withpageslug = '/pageslug/:slug/'
+withallbutlastsection = '/:sections[:last]/:slug/'
+[permalinks.section]
+withfilefilename = '/sectionwithfilefilename/:filename/'
+withfilefiletitle = '/sectionwithfilefiletitle/:title/'
+withfileslug = '/sectionwithfileslug/:slug/'
+nofileslug = '/sectionnofileslug/:slug/'
+nofilefilename = '/sectionnofilefilename/:filename/'
+nofiletitle1 = '/sectionnofiletitle1/:title/'
+nofiletitle2 = '/sectionnofiletitle2/:sections[:last]/'
+[permalinks.term]
+tags = '/tagsslug/tag/:slug/'
+[permalinks.taxonomy]
+tags = '/tagsslug/:slug/'
+-- content/withpageslug/p1.md --
+---
+slug: "p1slugvalue"
+tags: ["mytag"]
+---
+-- content/withfilefilename/_index.md --
+-- content/withfileslug/_index.md --
+---
+slug: "withfileslugvalue"
+---
+-- content/nofileslug/p1.md --
+-- content/nofilefilename/p1.md --
+-- content/nofiletitle1/p1.md --
+-- content/nofiletitle2/asdf/p1.md --
+-- content/withallbutlastsection/subsection/p1.md --
+-- content/tags/_index.md --
+---
+slug: "tagsslug"
+---
+-- content/tags/mytag/_index.md --
+---
+slug: "mytagslug"
+---
+
+
+`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			LogLevel:    logg.LevelWarn,
+		}).Build()
+
+	t.Log(b.LogString())
+	// No .File.TranslationBaseName on zero object etc. warnings.
+	b.Assert(b.H.Log.LoggCount(logg.LevelWarn), qt.Equals, 0)
+	b.AssertFileContent("public/pageslug/p1slugvalue/index.html", "Single|page|/pageslug/p1slugvalue/|")
+	b.AssertFileContent("public/sectionwithfilefilename/index.html", "List|section|/sectionwithfilefilename/|")
+	b.AssertFileContent("public/sectionwithfileslug/withfileslugvalue/index.html", "List|section|/sectionwithfileslug/withfileslugvalue/|")
+	b.AssertFileContent("public/sectionnofilefilename/index.html", "List|section|/sectionnofilefilename/|")
+	b.AssertFileContent("public/sectionnofileslug/nofileslugs/index.html", "List|section|/sectionnofileslug/nofileslugs/|")
+	b.AssertFileContent("public/sectionnofiletitle1/nofiletitle1s/index.html", "List|section|/sectionnofiletitle1/nofiletitle1s/|")
+	b.AssertFileContent("public/sectionnofiletitle2/index.html", "List|section|/sectionnofiletitle2/|")
+
+	b.AssertFileContent("public/tagsslug/tag/mytagslug/index.html", "List|term|/tagsslug/tag/mytagslug/|")
+	b.AssertFileContent("public/tagsslug/tagsslug/index.html", "List|taxonomy|/tagsslug/tagsslug/|")
+
+	permalinksConf := b.H.Configs.Base.Permalinks
+	b.Assert(permalinksConf, qt.DeepEquals, map[string]map[string]string{
+		"page":     {"withallbutlastsection": "/:sections[:last]/:slug/", "withpageslug": "/pageslug/:slug/"},
+		"section":  {"nofilefilename": "/sectionnofilefilename/:filename/", "nofileslug": "/sectionnofileslug/:slug/", "nofiletitle1": "/sectionnofiletitle1/:title/", "nofiletitle2": "/sectionnofiletitle2/:sections[:last]/", "withfilefilename": "/sectionwithfilefilename/:filename/", "withfilefiletitle": "/sectionwithfilefiletitle/:title/", "withfileslug": "/sectionwithfileslug/:slug/"},
+		"taxonomy": {"tags": "/tagsslug/:slug/"},
+		"term":     {"tags": "/tagsslug/tag/:slug/"},
+	})
+
+}
+
+func TestPermalinksOldSetup(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- layouts/_default/list.html --
+List|{{ .Kind }}|{{ .RelPermalink }}|
+-- layouts/_default/single.html --
+Single|{{ .Kind }}|{{ .RelPermalink }}|
+-- hugo.toml --
+[permalinks]
+withpageslug = '/pageslug/:slug/'
+-- content/withpageslug/p1.md --
+---
+slug: "p1slugvalue"
+---
+
+
+
+
+`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			LogLevel:    logg.LevelWarn,
+		}).Build()
+
+	t.Log(b.LogString())
+	// No .File.TranslationBaseName on zero object etc. warnings.
+	b.Assert(b.H.Log.LoggCount(logg.LevelWarn), qt.Equals, 0)
+	b.AssertFileContent("public/pageslug/p1slugvalue/index.html", "Single|page|/pageslug/p1slugvalue/|")
+
+	permalinksConf := b.H.Configs.Base.Permalinks
+	b.Assert(permalinksConf, qt.DeepEquals, map[string]map[string]string{
+		"page":     {"withpageslug": "/pageslug/:slug/"},
+		"section":  {},
+		"taxonomy": {},
+		"term":     {"withpageslug": "/pageslug/:slug/"},
+	})
+
+}
+
+func TestPermalinksNestedSections(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- hugo.toml --
+[permalinks.page]
+books = '/libros/:sections[1:]/:filename'
+
+[permalinks.section]
+books = '/libros/:sections[1:]'
+-- content/books/_index.md --
+---
+title: Books
+---
+-- content/books/fiction/_index.md --
+---
+title: Fiction
+---
+-- content/books/fiction/2023/_index.md --
+---
+title: 2023
+---
+-- content/books/fiction/2023/book1/index.md --
+---
+title: Book 1
+---
+-- layouts/_default/single.html --
+Single.
+-- layouts/_default/list.html --
+List.
+`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			LogLevel:    logg.LevelWarn,
+		}).Build()
+
+	t.Log(b.LogString())
+	// No .File.TranslationBaseName on zero object etc. warnings.
+	b.Assert(b.H.Log.LoggCount(logg.LevelWarn), qt.Equals, 0)
+
+	b.AssertFileContent("public/libros/index.html", "List.")
+	b.AssertFileContent("public/libros/fiction/index.html", "List.")
+	b.AssertFileContent("public/libros/fiction/2023/book1/index.html", "Single.")
+
+}
diff --git a/resources/page/permalinks_test.go b/resources/page/permalinks_test.go
index 24eb27f5b..194387d5c 100644
--- a/resources/page/permalinks_test.go
+++ b/resources/page/permalinks_test.go
@@ -179,36 +179,45 @@ func TestPermalinkExpansionSliceSyntax(t *testing.T) {
 	c := qt.New(t)
 	exp, err := NewPermalinkExpander(urlize, nil)
 	c.Assert(err, qt.IsNil)
-	slice := []string{"a", "b", "c", "d"}
-	fn := func(s string) []string {
-		return exp.toSliceFunc(s)(slice)
+	slice4 := []string{"a", "b", "c", "d"}
+	fn4 := func(s string) []string {
+		return exp.toSliceFunc(s)(slice4)
+	}
+
+	slice1 := []string{"a"}
+	fn1 := func(s string) []string {
+		return exp.toSliceFunc(s)(slice1)
 	}
 
 	c.Run("Basic", func(c *qt.C) {
-		c.Assert(fn("[1:3]"), qt.DeepEquals, []string{"b", "c"})
-		c.Assert(fn("[1:]"), qt.DeepEquals, []string{"b", "c", "d"})
-		c.Assert(fn("[:2]"), qt.DeepEquals, []string{"a", "b"})
-		c.Assert(fn("[0:2]"), qt.DeepEquals, []string{"a", "b"})
-		c.Assert(fn("[:]"), qt.DeepEquals, []string{"a", "b", "c", "d"})
-		c.Assert(fn(""), qt.DeepEquals, []string{"a", "b", "c", "d"})
-		c.Assert(fn("[last]"), qt.DeepEquals, []string{"d"})
-		c.Assert(fn("[:last]"), qt.DeepEquals, []string{"a", "b", "c"})
+		c.Assert(fn4("[1:3]"), qt.DeepEquals, []string{"b", "c"})
+		c.Assert(fn4("[1:]"), qt.DeepEquals, []string{"b", "c", "d"})
+		c.Assert(fn4("[:2]"), qt.DeepEquals, []string{"a", "b"})
+		c.Assert(fn4("[0:2]"), qt.DeepEquals, []string{"a", "b"})
+		c.Assert(fn4("[:]"), qt.DeepEquals, []string{"a", "b", "c", "d"})
+		c.Assert(fn4(""), qt.DeepEquals, []string{"a", "b", "c", "d"})
+		c.Assert(fn4("[last]"), qt.DeepEquals, []string{"d"})
+		c.Assert(fn4("[:last]"), qt.DeepEquals, []string{"a", "b", "c"})
+		c.Assert(fn1("[last]"), qt.DeepEquals, []string{"a"})
+		c.Assert(fn1("[:last]"), qt.DeepEquals, []string{})
+		c.Assert(fn1("[1:last]"), qt.DeepEquals, []string{})
+		c.Assert(fn1("[1]"), qt.DeepEquals, []string{})
 
 	})
 
 	c.Run("Out of bounds", func(c *qt.C) {
-		c.Assert(fn("[1:5]"), qt.DeepEquals, []string{"b", "c", "d"})
-		c.Assert(fn("[-1:5]"), qt.DeepEquals, []string{"a", "b", "c", "d"})
-		c.Assert(fn("[5:]"), qt.DeepEquals, []string{})
-		c.Assert(fn("[5:]"), qt.DeepEquals, []string{})
-		c.Assert(fn("[5:32]"), qt.DeepEquals, []string{})
+		c.Assert(fn4("[1:5]"), qt.DeepEquals, []string{"b", "c", "d"})
+		c.Assert(fn4("[-1:5]"), qt.DeepEquals, []string{"a", "b", "c", "d"})
+		c.Assert(fn4("[5:]"), qt.DeepEquals, []string{})
+		c.Assert(fn4("[5:]"), qt.DeepEquals, []string{})
+		c.Assert(fn4("[5:32]"), qt.DeepEquals, []string{})
 		c.Assert(exp.toSliceFunc("[:1]")(nil), qt.DeepEquals, []string(nil))
 		c.Assert(exp.toSliceFunc("[:1]")([]string{}), qt.DeepEquals, []string(nil))
 
 		// These all return nil
-		c.Assert(fn("[]"), qt.IsNil)
-		c.Assert(fn("[1:}"), qt.IsNil)
-		c.Assert(fn("foo"), qt.IsNil)
+		c.Assert(fn4("[]"), qt.IsNil)
+		c.Assert(fn4("[1:}"), qt.IsNil)
+		c.Assert(fn4("foo"), qt.IsNil)
 
 	})
 
diff --git a/resources/page/zero_file.autogen.go b/resources/page/zero_file.autogen.go
index 979f92a0f..72d98998e 100644
--- a/resources/page/zero_file.autogen.go
+++ b/resources/page/zero_file.autogen.go
@@ -18,7 +18,6 @@ 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"
 )
 
@@ -35,11 +34,6 @@ 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