Add backMatter support

pkg/mdformatter/mdformatter.go

@@ -35,6 +35,11 @@ type FrontMatterTransformer interface {
 	Close(ctx SourceContext) error
 }
 
+type BackMatterTransformer interface {
+	TransformBackMatter(ctx SourceContext) ([]byte, error)
+	Close(ctx SourceContext) error
+}
+
 type LinkTransformer interface {
 	TransformDestination(ctx SourceContext, destination []byte) ([]byte, error)
 	Close(ctx SourceContext) error
@@ -49,6 +54,7 @@ type Formatter struct {
 	ctx context.Context
 
 	fm   FrontMatterTransformer
+	bm   BackMatterTransformer
 	link LinkTransformer
 	cb   CodeBlockTransformer
 }
@@ -63,6 +69,13 @@ func WithFrontMatterTransformer(fm FrontMatterTransformer) Option {
 	}
 }
 
+// WithBackMatterTransformer allows you to override the default BackMatterTransformer.
+func WithBackMatterTransformer(bm BackMatterTransformer) Option {
+	return func(m *Formatter) {
+		m.bm = bm
+	}
+}
+
 // WithLinkTransformer allows you to override the default LinkTransformer.
 func WithLinkTransformer(l LinkTransformer) Option {
 	return func(m *Formatter) {
@@ -276,6 +289,18 @@ func (f *Formatter) Format(file *os.File, out io.Writer) error {
 		}
 	}
 
+	if f.bm != nil {
+		back, err := f.bm.TransformBackMatter(sourceCtx)
+		if err != nil {
+			return err
+		}
+
+		content = append(content, back...)
+		if err := f.fm.Close(sourceCtx); err != nil {
+			return err
+		}
+	}
+
 	// Hack: run Convert two times to ensure deterministic whitespace alignment.
 	// This also immediately show transformers which are not working well together etc.
 	tmp := bytes.Buffer{}

pkg/transform/config.go

@@ -69,7 +69,10 @@ type TransformationConfig struct {
 	Path string
 
 	// FrontMatter holds front matter transformations.
-	FrontMatter *FrontMatterConfig `yaml:"frontMatter"`
+	FrontMatter *MatterConfig `yaml:"frontMatter"`
+
+	// BackMatter holds back matter transformations.
+	BackMatter *MatterConfig `yaml:"backMatter"`
 }
 
 func (tr TransformationConfig) targetRelPath(relPath string) (_ string, err error) {
@@ -106,11 +109,11 @@ func (tr TransformationConfig) targetRelPath(relPath string) (_ string, err erro
 	return filepath.Join(targetDir, targetSuffix), nil
 }
 
-type FrontMatterConfig struct {
+type MatterConfig struct {
 	_template *template.Template
 
-	// Template represents Go template that will be rendered as font matter.
-	// This will override any existing font matter.1
+	// Template represents Go template that will be rendered as matter.
+	// This will override any existing matter.
 	// TODO(bwplotka): Add add only option?
 	Template string
 }
@@ -158,7 +161,14 @@ func ParseConfig(c []byte) (Config, error) {
 		if f.FrontMatter != nil {
 			f.FrontMatter._template, err = template.New("").Parse(f.FrontMatter.Template)
 			if err != nil {
-				return Config{}, errors.Wrapf(err, "compiling template %v", f.FrontMatter.Template)
+				return Config{}, errors.Wrapf(err, "compiling frontMatter template %v", f.FrontMatter.Template)
+			}
+		}
+
+		if f.BackMatter != nil {
+			f.BackMatter._template, err = template.New("").Parse(f.BackMatter.Template)
+			if err != nil {
+				return Config{}, errors.Wrapf(err, "compiling backMatter template %v", f.BackMatter.Template)
 			}
 		}
 	}

pkg/transform/testdata/expected/test3/3/Proposals/README.md

@@ -0,0 +1,15 @@
+---
+title: Proposals
+slug: README.md
+lastmod: 'TODO: Allow testing last mod .Origin.LastMod'
+---
+
+[RelLink](../_index.md)
+
+[RelLink](../Team/doc.md)
+
+This should not work: [RelLink](../../test.md)
+
+---
+
+Found a typo, inconsistency or missing information in our docs? Help us to improve [Thanos](https://thanos.io) documentation by proposing a fix [on GitHub here](https://github.com/thanos-io/thanos/edit/main/docs/README.md) :heart:

pkg/transform/testdata/expected/test3/3/Team/doc.md

@@ -0,0 +1,11 @@
+# Some Doc
+
+[RelLink](#some-doc)
+
+[RelLink](../_index.md#group-handbook)
+
+[RelLink](../Proposals/README.md)
+
+---
+
+Found a typo, inconsistency or missing information in our docs? Help us to improve [Thanos](https://thanos.io) documentation by proposing a fix [on GitHub here](https://github.com/thanos-io/thanos/edit/main/docs/doc.md) :heart:

pkg/transform/testdata/expected/test3/3/_index.md

@@ -0,0 +1,23 @@
+---
+title: Group Handbook
+cascade:
+    - _target:
+        path: /**
+      type: docs
+---
+
+Yolo
+
+[RelLink](Proposals/README.md)
+
+[RelLink](Team/doc.md)
+
+![Image](logo.png)
+
+![Image](images/logo2.png)
+
+![Outside](../../../../main.go)
+
+---
+
+Found a typo, inconsistency or missing information in our docs? Help us to improve [Thanos](https://thanos.io) documentation by proposing a fix [on GitHub here](https://github.com/thanos-io/thanos/edit/main/docs/README.md) :heart:

pkg/transform/testdata/mdox3.yaml

@@ -0,0 +1,45 @@
+version: 1
+
+inputDir: "testdata/testproj"
+outputDir: "testdata/tmp/test3/3"
+
+gitIgnored: true
+
+transformations:
+  - glob: "README.md"
+    path: _index.md
+    frontMatter:
+      template: |
+        title: "{{ .Origin.FirstHeader }}"
+
+        cascade:
+        - type: "docs"
+          _target:
+            path: "/**"
+    backMatter:
+      template: |
+        Found a typo, inconsistency or missing information in our docs?
+        Help us to improve [Thanos](https://thanos.io) documentation by proposing a fix [on GitHub here](https://github.com/thanos-io/thanos/edit/main/docs/{{ .Origin.Filename }}) :heart:
+
+
+  - glob: "**/README.md"
+    frontMatter:
+      template: |
+        title: "{{ .Origin.FirstHeader }}"
+        lastmod: "TODO: Allow testing last mod .Origin.LastMod"
+        slug: "{{ .Target.FileName }}"
+    backMatter:
+      template: |
+        Found a typo, inconsistency or missing information in our docs?
+        Help us to improve [Thanos](https://thanos.io) documentation by proposing a fix [on GitHub here](https://github.com/thanos-io/thanos/edit/main/docs/{{ .Origin.Filename }}) :heart:
+
+
+  - glob: "**.md"
+    backMatter:
+      template: |
+        Found a typo, inconsistency or missing information in our docs?
+        Help us to improve [Thanos](https://thanos.io) documentation by proposing a fix [on GitHub here](https://github.com/thanos-io/thanos/edit/main/docs/{{ .Origin.Filename }}) :heart:
+
+
+  - glob: "**"
+    path: "/../3static/**"

pkg/transform/transform.go

@@ -184,12 +184,30 @@ func (t *transformer) transformFile(path string, info os.FileInfo, err error) er
 		opts = append(opts, mdformatter.WithFrontMatterTransformer(&frontMatterTransformer{
 			localLinksStyle: t.c.LocalLinksStyle,
 			c:               tr.FrontMatter,
-			origin: FrontMatterOrigin{
+			origin: MatterOrigin{
 				Filename:    originFilename,
 				FirstHeader: firstHeader,
 				LastMod:     info.ModTime().String(),
 			},
-			target: FrontMatterTarget{
+			target: MatterTarget{
+				FileName: targetFilename,
+			},
+		}))
+	}
+
+	if tr.BackMatter != nil {
+		if !isMDFile(target) {
+			return errors.Errorf("back matter option set on file that after transformation is non-markdown: %v", target)
+		}
+		_, originFilename := filepath.Split(path)
+		_, targetFilename := filepath.Split(target)
+		opts = append(opts, mdformatter.WithBackMatterTransformer(&backMatterTransformer{
+			b: tr.BackMatter,
+			origin: MatterOrigin{
+				Filename: originFilename,
+				LastMod:  info.ModTime().String(),
+			},
+			target: MatterTarget{
 				FileName: targetFilename,
 			},
 		}))
@@ -276,28 +294,36 @@ func (r *relLinkTransformer) Close(mdformatter.SourceContext) error { return nil
 
 type frontMatterTransformer struct {
 	localLinksStyle LocalLinksStyle
-	c               *FrontMatterConfig
+	c               *MatterConfig
+
+	// Vars.
+	origin MatterOrigin
+	target MatterTarget
+}
+
+type backMatterTransformer struct {
+	b *MatterConfig
 
 	// Vars.
-	origin FrontMatterOrigin
-	target FrontMatterTarget
+	origin MatterOrigin
+	target MatterTarget
 }
 
-type FrontMatterOrigin struct {
+type MatterOrigin struct {
 	Filename    string
 	FirstHeader string
 	LastMod     string
 }
 
-type FrontMatterTarget struct {
+type MatterTarget struct {
 	FileName string
 }
 
 func (f *frontMatterTransformer) TransformFrontMatter(ctx mdformatter.SourceContext, frontMatter map[string]interface{}) ([]byte, error) {
 	b := bytes.Buffer{}
 	if err := f.c._template.Execute(&b, struct {
-		Origin      FrontMatterOrigin
-		Target      FrontMatterTarget
+		Origin      MatterOrigin
+		Target      MatterTarget
 		FrontMatter map[string]interface{}
 	}{
 		Origin:      f.origin,
@@ -323,6 +349,29 @@ func (f *frontMatterTransformer) TransformFrontMatter(ctx mdformatter.SourceCont
 
 func (f *frontMatterTransformer) Close(mdformatter.SourceContext) error { return nil }
 
+func (f *backMatterTransformer) TransformBackMatter(ctx mdformatter.SourceContext) ([]byte, error) {
+	b := bytes.Buffer{}
+	if err := f.b._template.Execute(&b, struct {
+		Origin MatterOrigin
+		Target MatterTarget
+	}{
+		Origin: f.origin,
+		Target: f.target,
+	}); err != nil {
+		return nil, err
+	}
+
+	// Add demarkation to back matter.
+	demark := "\n\n---\n"
+	m := b.Bytes()
+	m = append([]byte(demark), m...)
+
+	// Back matter is not parsed as YAML since it is generally assumed to be a block of text.
+	return m, nil
+}
+
+func (f *backMatterTransformer) Close(mdformatter.SourceContext) error { return nil }
+
 func firstMatch(absRelPath string, trs []*TransformationConfig) (*TransformationConfig, bool) {
 	for _, tr := range trs {
 		if tr._glob.Match(absRelPath) {

pkg/transform/transform_e2e_test.go

@@ -40,6 +40,13 @@ func TestTransform(t *testing.T) {
 		assertDirContent(t, filepath.Join(testData, "expected", "test2"), filepath.Join(tmpDir, "test2"))
 
 	})
+	t.Run("mdox3.yaml", func(t *testing.T) {
+		mdox2, err := ioutil.ReadFile(filepath.Join(testData, "mdox3.yaml"))
+		testutil.Ok(t, err)
+		testutil.Ok(t, transform.Dir(context.Background(), logger, mdox2))
+		assertDirContent(t, filepath.Join(testData, "expected", "test3"), filepath.Join(tmpDir, "test3"))
+
+	})
 }
 
 func assertDirContent(t *testing.T, expectedDir string, gotDir string) {