Create a struct with all of Hugo's config options

Primary motivation is documentation, but it will also hopefully simplify the code.

Also,

* Lower case the default output format names; this is in line with the custom ones (map keys) and how
it's treated all the places. This avoids doing `stringds.EqualFold` everywhere.

Closes #10896
Closes #10620

63 files changed, 1913 insertions, 4140 deletions

diff --git a/hugolib/alias.go b/hugolib/alias.go
index 071f73d41..1bc0e5424 100644
--- a/hugolib/alias.go
+++ b/hugolib/alias.go
@@ -101,7 +101,7 @@ func (s *Site) publishDestAlias(allowRoot bool, path, permalink string, outputFo
 		OutputFormat: outputFormat,
 	}
 
-	if s.Info.relativeURLs || s.Info.canonifyURLs {
+	if s.conf.RelativeURLs || s.conf.CanonifyURLs {
 		pd.AbsURLPath = s.absURLPath(targetPath)
 	}
 
diff --git a/hugolib/breaking_changes_test.go b/hugolib/breaking_changes_test.go
index 495baff3e..533205deb 100644
--- a/hugolib/breaking_changes_test.go
+++ b/hugolib/breaking_changes_test.go
@@ -1,4 +1,4 @@
-// Copyright 2020 The Hugo Authors. All rights reserved.
+// 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.
@@ -12,119 +12,3 @@
 // limitations under the License.
 
 package hugolib
-
-import (
-	"fmt"
-	"testing"
-
-	qt "github.com/frankban/quicktest"
-)
-
-func Test073(t *testing.T) {
-	assertDisabledTaxonomyAndTerm := func(b *sitesBuilder, taxonomy, term bool) {
-		b.Assert(b.CheckExists("public/tags/index.html"), qt.Equals, taxonomy)
-		b.Assert(b.CheckExists("public/tags/tag1/index.html"), qt.Equals, term)
-	}
-
-	assertOutputTaxonomyAndTerm := func(b *sitesBuilder, taxonomy, term bool) {
-		b.Assert(b.CheckExists("public/tags/index.json"), qt.Equals, taxonomy)
-		b.Assert(b.CheckExists("public/tags/tag1/index.json"), qt.Equals, term)
-	}
-
-	for _, this := range []struct {
-		name   string
-		config string
-		assert func(err error, out string, b *sitesBuilder)
-	}{
-		{
-			"Outputs for both taxonomy and taxonomyTerm",
-			`[outputs]
- taxonomy = ["JSON"]
- taxonomyTerm = ["JSON"]
-
-`,
-			func(err error, out string, b *sitesBuilder) {
-				b.Assert(err, qt.IsNil)
-				assertOutputTaxonomyAndTerm(b, true, true)
-			},
-		},
-		{
-			"Outputs for taxonomyTerm",
-			`[outputs]
-taxonomyTerm = ["JSON"]
-
-`,
-			func(err error, out string, b *sitesBuilder) {
-				b.Assert(err, qt.IsNil)
-				assertOutputTaxonomyAndTerm(b, true, false)
-			},
-		},
-		{
-			"Outputs for taxonomy only",
-			`[outputs]
-taxonomy = ["JSON"]
-
-`,
-			func(err error, out string, b *sitesBuilder) {
-				b.Assert(err, qt.Not(qt.IsNil))
-				b.Assert(out, qt.Contains, `ignoreErrors = ["error-output-taxonomy"]`)
-			},
-		},
-		{
-			"Outputs for taxonomy only, ignore error",
-			`
-ignoreErrors = ["error-output-taxonomy"]
-[outputs]
-taxonomy = ["JSON"]
-
-`,
-			func(err error, out string, b *sitesBuilder) {
-				b.Assert(err, qt.IsNil)
-				assertOutputTaxonomyAndTerm(b, true, false)
-			},
-		},
-		{
-			"Disable both taxonomy and taxonomyTerm",
-			`disableKinds = ["taxonomy", "taxonomyTerm"]`,
-			func(err error, out string, b *sitesBuilder) {
-				b.Assert(err, qt.IsNil)
-				assertDisabledTaxonomyAndTerm(b, false, false)
-			},
-		},
-		{
-			"Disable only taxonomyTerm",
-			`disableKinds = ["taxonomyTerm"]`,
-			func(err error, out string, b *sitesBuilder) {
-				b.Assert(err, qt.IsNil)
-				assertDisabledTaxonomyAndTerm(b, false, true)
-			},
-		},
-		{
-			"Disable only taxonomy",
-			`disableKinds = ["taxonomy"]`,
-			func(err error, out string, b *sitesBuilder) {
-				b.Assert(err, qt.Not(qt.IsNil))
-				b.Assert(out, qt.Contains, `ignoreErrors = ["error-disable-taxonomy"]`)
-			},
-		},
-		{
-			"Disable only taxonomy, ignore error",
-			`disableKinds = ["taxonomy"]
-			ignoreErrors = ["error-disable-taxonomy"]`,
-			func(err error, out string, b *sitesBuilder) {
-				b.Assert(err, qt.IsNil)
-				assertDisabledTaxonomyAndTerm(b, false, true)
-			},
-		},
-	} {
-		t.Run(this.name, func(t *testing.T) {
-			b := newTestSitesBuilder(t).WithConfigFile("toml", this.config)
-			b.WithTemplatesAdded("_default/list.json", "JSON")
-			out, err := captureStdout(func() error {
-				return b.BuildE(BuildCfg{})
-			})
-			fmt.Println(out)
-			this.assert(err, out, b)
-		})
-	}
-}
diff --git a/hugolib/cascade_test.go b/hugolib/cascade_test.go
index dff2082b6..0f607ecb5 100644
--- a/hugolib/cascade_test.go
+++ b/hugolib/cascade_test.go
@@ -159,33 +159,33 @@ func TestCascade(t *testing.T) {
 		b.Build(BuildCfg{})
 
 		b.AssertFileContent("public/index.html", `
-12|term|categories/cool/_index.md|Cascade Category|cat.png|categories|HTML-|
-12|term|categories/catsect1|catsect1|cat.png|categories|HTML-|
-12|term|categories/funny|funny|cat.png|categories|HTML-|
-12|taxonomy|categories/_index.md|My Categories|cat.png|categories|HTML-|
-32|term|categories/sad/_index.md|Cascade Category|sad.png|categories|HTML-|
-42|term|tags/blue|blue|home.png|tags|HTML-|
-42|taxonomy|tags|Cascade Home|home.png|tags|HTML-|
-42|section|sectnocontent|Cascade Home|home.png|sectnocontent|HTML-|
-42|section|sect3|Cascade Home|home.png|sect3|HTML-|
-42|page|bundle1/index.md|Cascade Home|home.png|page|HTML-|
-42|page|p2.md|Cascade Home|home.png|page|HTML-|
-42|page|sect2/p2.md|Cascade Home|home.png|sect2|HTML-|
-42|page|sect3/nofrontmatter.md|Cascade Home|home.png|sect3|HTML-|
-42|page|sect3/p1.md|Cascade Home|home.png|sect3|HTML-|
-42|page|sectnocontent/p1.md|Cascade Home|home.png|sectnocontent|HTML-|
-42|section|sectnofrontmatter/_index.md|Cascade Home|home.png|sectnofrontmatter|HTML-|
-42|term|tags/green|green|home.png|tags|HTML-|
-42|home|_index.md|Home|home.png|page|HTML-|
-42|page|p1.md|p1|home.png|page|HTML-|
-42|section|sect1/_index.md|Sect1|sect1.png|stype|HTML-|
-42|section|sect1/s1_2/_index.md|Sect1_2|sect1.png|stype|HTML-|
-42|page|sect1/s1_2/p1.md|Sect1_2_p1|sect1.png|stype|HTML-|
-42|page|sect1/s1_2/p2.md|Sect1_2_p2|sect1.png|stype|HTML-|
-42|section|sect2/_index.md|Sect2|home.png|sect2|HTML-|
-42|page|sect2/p1.md|Sect2_p1|home.png|sect2|HTML-|
-52|page|sect4/p1.md|Cascade Home|home.png|sect4|RSS-|
-52|section|sect4/_index.md|Sect4|home.png|sect4|RSS-|
+12|term|categories/cool/_index.md|Cascade Category|cat.png|categories|html-|
+12|term|categories/catsect1|catsect1|cat.png|categories|html-|
+12|term|categories/funny|funny|cat.png|categories|html-|
+12|taxonomy|categories/_index.md|My Categories|cat.png|categories|html-|
+32|term|categories/sad/_index.md|Cascade Category|sad.png|categories|html-|
+42|term|tags/blue|blue|home.png|tags|html-|
+42|taxonomy|tags|Cascade Home|home.png|tags|html-|
+42|section|sectnocontent|Cascade Home|home.png|sectnocontent|html-|
+42|section|sect3|Cascade Home|home.png|sect3|html-|
+42|page|bundle1/index.md|Cascade Home|home.png|page|html-|
+42|page|p2.md|Cascade Home|home.png|page|html-|
+42|page|sect2/p2.md|Cascade Home|home.png|sect2|html-|
+42|page|sect3/nofrontmatter.md|Cascade Home|home.png|sect3|html-|
+42|page|sect3/p1.md|Cascade Home|home.png|sect3|html-|
+42|page|sectnocontent/p1.md|Cascade Home|home.png|sectnocontent|html-|
+42|section|sectnofrontmatter/_index.md|Cascade Home|home.png|sectnofrontmatter|html-|
+42|term|tags/green|green|home.png|tags|html-|
+42|home|_index.md|Home|home.png|page|html-|
+42|page|p1.md|p1|home.png|page|html-|
+42|section|sect1/_index.md|Sect1|sect1.png|stype|html-|
+42|section|sect1/s1_2/_index.md|Sect1_2|sect1.png|stype|html-|
+42|page|sect1/s1_2/p1.md|Sect1_2_p1|sect1.png|stype|html-|
+42|page|sect1/s1_2/p2.md|Sect1_2_p2|sect1.png|stype|html-|
+42|section|sect2/_index.md|Sect2|home.png|sect2|html-|
+42|page|sect2/p1.md|Sect2_p1|home.png|sect2|html-|
+52|page|sect4/p1.md|Cascade Home|home.png|sect4|rss-|
+52|section|sect4/_index.md|Sect4|home.png|sect4|rss-|
 `)
 
 		// Check that type set in cascade gets the correct layout.
diff --git a/hugolib/codeowners.go b/hugolib/codeowners.go
index 162ee16ae..c1a6a2b7b 100644
--- a/hugolib/codeowners.go
+++ b/hugolib/codeowners.go
@@ -18,7 +18,6 @@ import (
 	"path"
 
 	"github.com/gohugoio/hugo/common/herrors"
-	"github.com/gohugoio/hugo/config"
 	"github.com/gohugoio/hugo/resources/page"
 	"github.com/hairyhenderson/go-codeowners"
 	"github.com/spf13/afero"
@@ -52,9 +51,7 @@ func (c *codeownerInfo) forPage(p page.Page) []string {
 	return c.owners.Owners(p.File().Filename())
 }
 
-func newCodeOwners(cfg config.Provider) (*codeownerInfo, error) {
-	workingDir := cfg.GetString("workingDir")
-
+func newCodeOwners(workingDir string) (*codeownerInfo, error) {
 	r, err := findCodeOwnersFile(workingDir)
 	if err != nil || r == nil {
 		return nil, err
diff --git a/hugolib/config.go b/hugolib/config.go
index 059424e85..af3f0647f 100644
--- a/hugolib/config.go
+++ b/hugolib/config.go
@@ -16,526 +16,170 @@ package hugolib
 import (
 	"os"
 	"path/filepath"
-	"strings"
-
-	"github.com/gohugoio/hugo/common/hexec"
-	"github.com/gohugoio/hugo/common/types"
-
-	"github.com/gohugoio/hugo/common/maps"
-	cpaths "github.com/gohugoio/hugo/common/paths"
-
-	"github.com/gobwas/glob"
-	hglob "github.com/gohugoio/hugo/hugofs/glob"
-
-	"github.com/gohugoio/hugo/common/loggers"
-
-	"github.com/gohugoio/hugo/cache/filecache"
-
-	"github.com/gohugoio/hugo/parser/metadecoders"
-
-	"errors"
-
-	"github.com/gohugoio/hugo/common/herrors"
-	"github.com/gohugoio/hugo/common/hugo"
-	"github.com/gohugoio/hugo/langs"
-	"github.com/gohugoio/hugo/modules"
 
 	"github.com/gohugoio/hugo/config"
-	"github.com/gohugoio/hugo/config/privacy"
-	"github.com/gohugoio/hugo/config/security"
-	"github.com/gohugoio/hugo/config/services"
-	"github.com/gohugoio/hugo/helpers"
+	"github.com/gohugoio/hugo/config/allconfig"
 	"github.com/spf13/afero"
 )
 
-var ErrNoConfigFile = errors.New("Unable to locate config file or config directory. Perhaps you need to create a new site.\n       Run `hugo help new` for details.\n")
-
-// LoadConfig loads Hugo configuration into a new Viper and then adds
-// a set of defaults.
-func LoadConfig(d ConfigSourceDescriptor, doWithConfig ...func(cfg config.Provider) error) (config.Provider, []string, error) {
-	if d.Environment == "" {
-		d.Environment = hugo.EnvironmentProduction
-	}
-
-	if len(d.Environ) == 0 && !hugo.IsRunningAsTest() {
-		d.Environ = os.Environ()
-	}
-
-	var configFiles []string
-
-	l := configLoader{ConfigSourceDescriptor: d, cfg: config.New()}
-	// Make sure we always do this, even in error situations,
-	// as we have commands (e.g. "hugo mod init") that will
-	// use a partial configuration to do its job.
-	defer l.deleteMergeStrategies()
-
-	names := d.configFilenames()
-
-	if names != nil {
-		for _, name := range names {
-			var filename string
-			filename, err := l.loadConfig(name)
-			if err == nil {
-				configFiles = append(configFiles, filename)
-			} else if err != ErrNoConfigFile {
-				return nil, nil, l.wrapFileError(err, filename)
-			}
-		}
-	} else {
-		for _, name := range config.DefaultConfigNames {
-			var filename string
-			filename, err := l.loadConfig(name)
-			if err == nil {
-				configFiles = append(configFiles, filename)
-				break
-			} else if err != ErrNoConfigFile {
-				return nil, nil, l.wrapFileError(err, filename)
-			}
-		}
-	}
-
-	if d.AbsConfigDir != "" {
-
-		dcfg, dirnames, err := config.LoadConfigFromDir(l.Fs, d.AbsConfigDir, l.Environment)
-
-		if err == nil {
-			if len(dirnames) > 0 {
-				l.cfg.Set("", dcfg.Get(""))
-				configFiles = append(configFiles, dirnames...)
-			}
-		} else if err != ErrNoConfigFile {
-			if len(dirnames) > 0 {
-				return nil, nil, l.wrapFileError(err, dirnames[0])
-			}
-			return nil, nil, err
-		}
-	}
-
-	if err := l.applyConfigDefaults(); err != nil {
-		return l.cfg, configFiles, err
-	}
-
-	l.cfg.SetDefaultMergeStrategy()
-
-	// We create languages based on the settings, so we need to make sure that
-	// all configuration is loaded/set before doing that.
-	for _, d := range doWithConfig {
-		if err := d(l.cfg); err != nil {
-			return l.cfg, configFiles, err
-		}
-	}
-
-	// Some settings are used before we're done collecting all settings,
-	// so apply OS environment both before and after.
-	if err := l.applyOsEnvOverrides(d.Environ); err != nil {
-		return l.cfg, configFiles, err
-	}
-
-	modulesConfig, err := l.loadModulesConfig()
+// DefaultConfig returns the default configuration.
+func DefaultConfig() *allconfig.Config {
+	fs := afero.NewMemMapFs()
+	all, err := allconfig.LoadConfig(allconfig.ConfigSourceDescriptor{Fs: fs})
 	if err != nil {
-		return l.cfg, configFiles, err
-	}
-
-	// Need to run these after the modules are loaded, but before
-	// they are finalized.
-	collectHook := func(m *modules.ModulesConfig) error {
-		// We don't need the merge strategy configuration anymore,
-		// remove it so it doesn't accidentally show up in other settings.
-		l.deleteMergeStrategies()
-
-		if err := l.loadLanguageSettings(nil); err != nil {
-			return err
-		}
-
-		mods := m.ActiveModules
-
-		// Apply default project mounts.
-		if err := modules.ApplyProjectConfigDefaults(l.cfg, mods[0]); err != nil {
-			return err
-		}
-
-		return nil
-	}
-
-	_, modulesConfigFiles, modulesCollectErr := l.collectModules(modulesConfig, l.cfg, collectHook)
+		panic(err)
+	}
+	return all.Base
+}
+
+// ExampleConfig returns the some example configuration for documentation.
+func ExampleConfig() (*allconfig.Config, error) {
+	// Apply some example settings for