Add Hugo Modules

This commit implements Hugo Modules.

This is a broad subject, but some keywords include:

* A new `module` configuration section where you can import almost anything. You can configure both your own file mounts nd the file mounts of the modules you import. This is the new recommended way of configuring what you earlier put in `configDir`, `staticDir` etc. And it also allows you to mount folders in non-Hugo-projects, e.g. the `SCSS` folder in the Bootstrap GitHub project.
* A module consists of a set of mounts to the standard 7 component types in Hugo: `static`, `content`, `layouts`, `data`, `assets`, `i18n`, and `archetypes`. Yes, Theme Components can now include content, which should be very useful, especially in bigger multilingual projects.
* Modules not in your local file cache will be downloaded automatically and even "hot replaced" while the server is running.
* Hugo Modules supports and encourages semver versioned modules, and uses the minimal version selection algorithm to resolve versions.
* A new set of CLI commands are provided to manage all of this: `hugo mod init`,  `hugo mod get`,  `hugo mod graph`,  `hugo mod tidy`, and  `hugo mod vendor`.

All of the above is backed by Go Modules.

Fixes #5973
Fixes #5996
Fixes #6010
Fixes #5911
Fixes #5940
Fixes #6074
Fixes #6082
Fixes #6092

3 files changed, 113 insertions, 61 deletions

diff --git a/create/content.go b/create/content.go
index e48dfc078..0e05adf93 100644
--- a/create/content.go
+++ b/create/content.go
@@ -25,6 +25,8 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/gohugoio/hugo/hugofs/files"
+
 	"github.com/gohugoio/hugo/hugofs"
 
 	"github.com/gohugoio/hugo/helpers"
@@ -50,7 +52,10 @@ func NewContent(
 
 	if isDir {
 
-		langFs := hugofs.NewLanguageFs(s.Language().Lang, sites.LanguageSet(), archetypeFs)
+		langFs, err := hugofs.NewLanguageFs(sites.LanguageSet(), archetypeFs)
+		if err != nil {
+			return err
+		}
 
 		cm, err := mapArcheTypeDir(ps, langFs, archetypeFilename)
 		if err != nil {
@@ -64,7 +69,7 @@ func NewContent(
 		}
 
 		name := filepath.Base(targetPath)
-		return newContentFromDir(archetypeFilename, sites, archetypeFs, sourceFs, cm, name, contentPath)
+		return newContentFromDir(archetypeFilename, sites, sourceFs, cm, name, contentPath)
 	}
 
 	// Building the sites can be expensive, so only do it if really needed.
@@ -111,9 +116,9 @@ func NewContent(
 	return nil
 }
 
-func targetSite(sites *hugolib.HugoSites, fi *hugofs.LanguageFileInfo) *hugolib.Site {
+func targetSite(sites *hugolib.HugoSites, fi hugofs.FileMetaInfo) *hugolib.Site {
 	for _, s := range sites.Sites {
-		if fi.Lang() == s.Language().Lang {
+		if fi.Meta().Lang() == s.Language().Lang {
 			return s
 		}
 	}
@@ -123,13 +128,14 @@ func targetSite(sites *hugolib.HugoSites, fi *hugofs.LanguageFileInfo) *hugolib.
 func newContentFromDir(
 	archetypeDir string,
 	sites *hugolib.HugoSites,
-	sourceFs, targetFs afero.Fs,
+	targetFs afero.Fs,
 	cm archetypeMap, name, targetPath string) error {
 
 	for _, f := range cm.otherFiles {
-		filename := f.Filename()
+		meta := f.Meta()
+		filename := meta.Path()
 		// Just copy the file to destination.
-		in, err := sourceFs.Open(filename)
+		in, err := meta.Open()
 		if err != nil {
 			return errors.Wrap(err, "failed to open non-content file")
 		}
@@ -156,7 +162,7 @@ func newContentFromDir(
 	}
 
 	for _, f := range cm.contentFiles {
-		filename := f.Filename()
+		filename := f.Meta().Path()
 		s := targetSite(sites, f)
 		targetFilename := filepath.Join(targetPath, strings.TrimPrefix(filename, archetypeDir))
 
@@ -177,9 +183,9 @@ func newContentFromDir(
 
 type archetypeMap struct {
 	// These needs to be parsed and executed as Go templates.
-	contentFiles []*hugofs.LanguageFileInfo
+	contentFiles []hugofs.FileMetaInfo
 	// These are just copied to destination.
-	otherFiles []*hugofs.LanguageFileInfo
+	otherFiles []hugofs.FileMetaInfo
 	// If the templates needs a fully built site. This can potentially be
 	// expensive, so only do when needed.
 	siteUsed bool
@@ -192,7 +198,7 @@ func mapArcheTypeDir(
 
 	var m archetypeMap
 
-	walkFn := func(filename string, fi os.FileInfo, err error) error {
+	walkFn := func(path string, fi hugofs.FileMetaInfo, err error) error {
 
 		if err != nil {
 			return err
@@ -202,12 +208,12 @@ func mapArcheTypeDir(
 			return nil
 		}
 
-		fil := fi.(*hugofs.LanguageFileInfo)
+		fil := fi.(hugofs.FileMetaInfo)
 
-		if hugolib.IsContentFile(filename) {
+		if files.IsContentFile(path) {
 			m.contentFiles = append(m.contentFiles, fil)
 			if !m.siteUsed {
-				m.siteUsed, err = usesSiteVar(fs, filename)
+				m.siteUsed, err = usesSiteVar(fs, path)
 				if err != nil {
 					return err
 				}
@@ -220,7 +226,15 @@ func mapArcheTypeDir(
 		return nil
 	}
 
-	if err := helpers.SymbolicWalk(fs, archetypeDir, walkFn); err != nil {
+	walkCfg := hugofs.WalkwayConfig{
+		WalkFn: walkFn,
+		Fs:     fs,
+		Root:   archetypeDir,
+	}
+
+	w := hugofs.NewWalkway(walkCfg)
+
+	if err := w.Walk(); err != nil {
 		return m, errors.Wrapf(err, "failed to walk archetype dir %q", archetypeDir)
 	}
 
@@ -254,17 +268,29 @@ func resolveContentPath(sites *hugolib.HugoSites, fs afero.Fs, targetPath string
 		}
 	}
 
-	for _, ss := range sites.Sites {
-		contentDir := ss.PathSpec.ContentDir
+	var dirLang string
+
+	for _, dir := range sites.BaseFs.Content.Dirs {
+		meta := dir.Meta()
+		contentDir := meta.Filename()
+
 		if !strings.HasSuffix(contentDir, helpers.FilePathSeparator) {
 			contentDir += helpers.FilePathSeparator
 		}
+
 		if strings.HasPrefix(targetPath, contentDir) {
-			siteContentDir = ss.PathSpec.ContentDir
-			if s == nil {
+			siteContentDir = contentDir
+			dirLang = meta.Lang()
+			break
+		}
+	}
+
+	if s == nil && dirLang != "" {
+		for _, ss := range sites.Sites {
+			if ss.Lang() == dirLang {
 				s = ss
+				break
 			}
-			break
 		}
 	}
 
@@ -280,12 +306,22 @@ func resolveContentPath(sites *hugolib.HugoSites, fs afero.Fs, targetPath string
 		}
 	}
 
+	if siteContentDir == "" {
+
+	}
+
 	if siteContentDir != "" {
 		pp := filepath.Join(siteContentDir, strings.TrimPrefix(targetPath, siteContentDir))
 		return s.PathSpec.AbsPathify(pp), s
-
 	} else {
-		return s.PathSpec.AbsPathify(filepath.Join(first.PathSpec.ContentDir, targetPath)), s
+		var contentDir string
+		for _, dir := range sites.BaseFs.Content.Dirs {
+			contentDir = dir.Meta().Filename()
+			if dir.Meta().Lang() == s.Lang() {
+				break
+			}
+		}
+		return s.PathSpec.AbsPathify(filepath.Join(contentDir, targetPath)), s
 	}
 
 }
diff --git a/create/content_template_handler.go b/create/content_template_handler.go
index 5a8b4f63c..1576fabdb 100644
--- a/create/content_template_handler.go
+++ b/create/content_template_handler.go
@@ -90,7 +90,10 @@ func executeArcheTypeAsTemplate(s *hugolib.Site, name, kind, targetPath, archety
 		err               error
 	)
 
-	f := s.SourceSpec.NewFileInfo("", targetPath, false, nil)
+	f, err := s.SourceSpec.NewFileInfoFrom(targetPath, targetPath)
+	if err != nil {
+		return nil, err
+	}
 
 	if name == "" {
 		name = f.TranslationBaseName()
diff --git a/create/content_test.go b/create/content_test.go
index e321900bc..6a3852d29 100644
--- a/create/content_test.go
+++ b/create/content_test.go
@@ -35,7 +35,6 @@ import (
 )
 
 func TestNewContent(t *testing.T) {
-	assert := require.New(t)
 
 	cases := []struct {
 		kind     string
@@ -50,12 +49,12 @@ func TestNewContent(t *testing.T) {
 		{"product", "product/sample-4.md", []string{`title = "SAMPLE-4"`}}, // empty archetype front matter
 		{"lang", "post/lang-1.md", []string{`Site Lang: en|Name: Lang 1|i18n: Hugo Rocks!`}},
 		{"lang", "post/lang-2.en.md", []string{`Site Lang: en|Name: Lang 2|i18n: Hugo Rocks!`}},
-		{"lang", "post/lang-3.nn.md", []string{`Site Lang: nn|Name: Lang 3|i18n: Hugo Rokkar!`}},
+		{"lang", "content/post/lang-3.nn.md", []string{`Site Lang: nn|Name: Lang 3|i18n: Hugo Rokkar!`}},
 		{"lang", "content_nn/post/lang-4.md", []string{`Site Lang: nn|Name: Lang 4|i18n: Hugo Rokkar!`}},
 		{"lang", "content_nn/post/lang-5.en.md", []string{`Site Lang: en|Name: Lang 5|i18n: Hugo Rocks!`}},
 		{"lang", "post/my-bundle/index.md", []string{`Site Lang: en|Name: My Bundle|i18n: Hugo Rocks!`}},
 		{"lang", "post/my-bundle/index.en.md", []string{`Site Lang: en|Name: My Bundle|i18n: Hugo Rocks!`}},
-		{"lang", "post/my-bundle/index.nn.md", []string{`Site Lang: nn|Name: My Bundle|i18n: Hugo Rokkar!`}},
+		{"lang", "content/post/my-bundle/index.nn.md", []string{`Site Lang: nn|Name: My Bundle|i18n: Hugo Rokkar!`}},
 		{"shortcodes", "shortcodes/go.md", []string{
 			`title = "GO"`,
 			"{{< myshortcode >}}",
@@ -64,37 +63,43 @@ func TestNewContent(t *testing.T) {
 	}
 
 	for i, c := range cases {
-		cfg, fs := newTestCfg(assert)
-		assert.NoError(initFs(fs))
-		h, err := hugolib.NewHugoSites(deps.DepsCfg{Cfg: cfg, Fs: fs})
-		assert.NoError(err)
-
-		assert.NoError(create.NewContent(h, c.kind, c.path))
-
-		fname := filepath.FromSlash(c.path)
-		if !strings.HasPrefix(fname, "content") {
-			fname = filepath.Join("content", fname)
-		}
-		content := readFileFromFs(t, fs.Source, fname)
-		for _, v := range c.expected {
-			found := strings.Contains(content, v)
-			if !found {
-				t.Fatalf("[%d] %q missing from output:\n%q", i, v, content)
+		c := c
+		t.Run(fmt.Sprintf("%s-%d", c.kind, i), func(t *testing.T) {
+			t.Parallel()
+			assert := require.New(t)
+			mm := afero.NewMemMapFs()
+			assert.NoError(initFs(mm))
+			cfg, fs := newTestCfg(assert, mm)
+			h, err := hugolib.NewHugoSites(deps.DepsCfg{Cfg: cfg, Fs: fs})
+			assert.NoError(err)
+
+			assert.NoError(create.NewContent(h, c.kind, c.path))
+
+			fname := filepath.FromSlash(c.path)
+			if !strings.HasPrefix(fname, "content") {
+				fname = filepath.Join("content", fname)
 			}
-		}
+			content := readFileFromFs(t, fs.Source, fname)
+			for _, v := range c.expected {
+				found := strings.Contains(content, v)
+				if !found {
+					t.Fatalf("[%d] %q missing from output:\n%q", i, v, content)
+				}
+			}
+		})
+
 	}
 }
 
 func TestNewContentFromDir(t *testing.T) {
+	mm := afero.NewMemMapFs()
 	assert := require.New(t)
-	cfg, fs := newTestCfg(assert)
-	assert.NoError(initFs(fs))
 
 	archetypeDir := filepath.Join("archetypes", "my-bundle")
-	assert.NoError(fs.Source.Mkdir(archetypeDir, 0755))
+	assert.NoError(mm.MkdirAll(archetypeDir, 0755))
 
 	archetypeThemeDir := filepath.Join("themes", "mytheme", "archetypes", "my-theme-bundle")
-	assert.NoError(fs.Source.Mkdir(archetypeThemeDir, 0755))
+	assert.NoError(mm.MkdirAll(archetypeThemeDir, 0755))
 
 	contentFile := `
 File: %s
@@ -103,15 +108,18 @@ Name: {{ replace .Name "-" " " | title }}
 i18n: {{ T "hugo" }}
 `
 
-	assert.NoError(afero.WriteFile(fs.Source, filepath.Join(archetypeDir, "index.md"), []byte(fmt.Sprintf(contentFile, "index.md")), 0755))
-	assert.NoError(afero.WriteFile(fs.Source, filepath.Join(archetypeDir, "index.nn.md"), []byte(fmt.Sprintf(contentFile, "index.nn.md")), 0755))
+	assert.NoError(afero.WriteFile(mm, filepath.Join(archetypeDir, "index.md"), []byte(fmt.Sprintf(contentFile, "index.md")), 0755))
+	assert.NoError(afero.WriteFile(mm, filepath.Join(archetypeDir, "index.nn.md"), []byte(fmt.Sprintf(contentFile, "index.nn.md")), 0755))
 
-	assert.NoError(afero.WriteFile(fs.Source, filepath.Join(archetypeDir, "pages", "bio.md"), []byte(fmt.Sprintf(contentFile, "bio.md")), 0755))
-	assert.NoError(afero.WriteFile(fs.Source, filepath.Join(archetypeDir, "resources", "hugo1.json"), []byte(`hugo1: {{ printf "no template handling in here" }}`), 0755))
-	assert.NoError(afero.WriteFile(fs.Source, filepath.Join(archetypeDir, "resources", "hugo2.xml"), []byte(`hugo2: {{ printf "no template handling in here" }}`), 0755))
+	assert.NoError(afero.WriteFile(mm, filepath.Join(archetypeDir, "pages", "bio.md"), []byte(fmt.Sprintf(contentFile, "bio.md")), 0755))
+	assert.NoError(afero.WriteFile(mm, filepath.Join(archetypeDir, "resources", "hugo1.json"), []byte(`hugo1: {{ printf "no template handling in here" }}`), 0755))
+	assert.NoError(afero.WriteFile(mm, filepath.Join(archetypeDir, "resources", "hugo2.xml"), []byte(`hugo2: {{ printf "no template handling in here" }}`), 0755))
 
-	assert.NoError(afero.WriteFile(fs.Source, filepath.Join(archetypeThemeDir, "index.md"), []byte(fmt.Sprintf(contentFile, "index.md")), 0755))
-	assert.NoError(afero.WriteFile(fs.Source, filepath.Join(archetypeThemeDir, "resources", "hugo1.json"), []byte(`hugo1: {{ printf "no template handling in here" }}`), 0755))
+	assert.NoError(afero.WriteFile(mm, filepath.Join(archetypeThemeDir, "index.md"), []byte(fmt.Sprintf(contentFile, "index.md")), 0755))
+	assert.NoError(afero.WriteFile(mm, filepath.Join(archetypeThemeDir, "resources", "hugo1.json"), []byte(`hugo1: {{ printf "no template handling in here" }}`), 0755))
+
+	assert.NoError(initFs(mm))
+	cfg, fs := newTestCfg(assert, mm)
 
 	h, err := hugolib.NewHugoSites(deps.DepsCfg{Cfg: cfg, Fs: fs})
 	assert.NoError(err)
@@ -135,7 +143,7 @@ i18n: {{ T "hugo" }}
 
 }
 
-func initFs(fs *hugofs.Fs) error {
+func initFs(fs afero.Fs) error {
 	perm := os.FileMode(0755)
 	var err error
 
@@ -146,8 +154,8 @@ func initFs(fs *hugofs.Fs) error {
 		filepath.Join("themes", "sample", "archetypes"),
 	}
 	for _, dir := range dirs {
-		err = fs.Source.Mkdir(dir, perm)
-		if err != nil {
+		err = fs.Mkdir(dir, perm)
+		if err != nil && !os.IsExist(err) {
 			return err
 		}
 	}
@@ -198,7 +206,7 @@ Some text.
 `,
 		},
 	} {
-		f, err := fs.Source.Create(v.path)
+		f, err := fs.Create(v.path)
 		if err != nil {
 			return err
 		}
@@ -221,6 +229,7 @@ func assertContains(assert *require.Assertions, v interface{}, matches ...string
 
 // TODO(bep) extract common testing package with this and some others
 func readFileFromFs(t *testing.T, fs afero.Fs, filename string) string {
+	t.Helper()
 	filename = filepath.FromSlash(filename)
 	b, err := afero.ReadFile(fs, filename)
 	if err != nil {
@@ -238,12 +247,11 @@ func readFileFromFs(t *testing.T, fs afero.Fs, filename string) string {
 	return string(b)
 }
 
-func newTestCfg(assert *require.Assertions) (*viper.Viper, *hugofs.Fs) {
+func newTestCfg(assert *require.Assertions, mm afero.Fs) (*viper.Viper, *hugofs.Fs) {
 
 	cfg := `
 
 theme = "mytheme"
-	
 [languages]
 [languages.en]
 weight = 1
@@ -254,8 +262,13 @@ languageName = "Nynorsk"
 contentDir = "content_nn"
 
 `
+	if mm == nil {
+		mm = afero.NewMemMapFs()
+	}
 
-	mm := afero.NewMemMapFs()
+	mm.MkdirAll(filepath.FromSlash("content_nn"), 0777)
+
+	mm.MkdirAll(filepath.FromSlash("themes/mytheme"), 0777)
 
 	assert.NoError(afero.WriteFile(mm, filepath.Join("i18n", "en.toml"), []byte(`[hugo]
 other = "Hugo Rocks!"`), 0755))