From aacc4c864c5e8a599f3cf3f54b40136ea5c46f8f Mon Sep 17 00:00:00 2001
From: Tim Hockin <thockin@google.com>
Date: Fri, 17 Jul 2015 10:33:31 -0700
Subject: [PATCH] Add a munger for header lines

---
 cmd/mungedocs/headers.go      | 71 +++++++++++++++++++++++++++++++++++
 cmd/mungedocs/headers_test.go | 71 +++++++++++++++++++++++++++++++++++
 cmd/mungedocs/mungedocs.go    |  1 +
 3 files changed, 143 insertions(+)
 create mode 100644 cmd/mungedocs/headers.go
 create mode 100644 cmd/mungedocs/headers_test.go

diff --git a/cmd/mungedocs/headers.go b/cmd/mungedocs/headers.go
new file mode 100644
index 00000000000..0f45f609423
--- /dev/null
+++ b/cmd/mungedocs/headers.go
@@ -0,0 +1,71 @@
+/*
+Copyright 2015 The Kubernetes 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 main
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+var headerRegex = regexp.MustCompile(`^(#+)\s*(.*)$`)
+var whitespaceRegex = regexp.MustCompile(`^\s*$`)
+
+func fixHeaderLines(fileBytes []byte) []byte {
+	lines := splitLines(fileBytes)
+	out := []string{}
+	for i := range lines {
+		matches := headerRegex.FindStringSubmatch(lines[i])
+		if matches == nil {
+			out = append(out, lines[i])
+			continue
+		}
+		if i > 0 && !whitespaceRegex.Match([]byte(out[len(out)-1])) {
+			out = append(out, "")
+		}
+		out = append(out, fmt.Sprintf("%s %s", matches[1], matches[2]))
+		if i+1 < len(lines) && !whitespaceRegex.Match([]byte(lines[i+1])) {
+			out = append(out, "")
+		}
+	}
+	final := strings.Join(out, "\n")
+	// Preserve the end of the file.
+	if len(fileBytes) > 0 && fileBytes[len(fileBytes)-1] == '\n' {
+		final += "\n"
+	}
+	return []byte(final)
+}
+
+// Header lines need whitespace around them and after the #s.
+func checkHeaderLines(filePath string, fileBytes []byte) ([]byte, error) {
+	fbs := splitByPreformatted(fileBytes)
+	fbs = append([]fileBlock{{false, []byte{}}}, fbs...)
+	fbs = append(fbs, fileBlock{false, []byte{}})
+
+	for i := range fbs {
+		block := &fbs[i]
+		if block.preformatted {
+			continue
+		}
+		block.data = fixHeaderLines(block.data)
+	}
+	output := []byte{}
+	for _, block := range fbs {
+		output = append(output, block.data...)
+	}
+	return output, nil
+}
diff --git a/cmd/mungedocs/headers_test.go b/cmd/mungedocs/headers_test.go
new file mode 100644
index 00000000000..d2864377072
--- /dev/null
+++ b/cmd/mungedocs/headers_test.go
@@ -0,0 +1,71 @@
+/*
+Copyright 2015 The Kubernetes 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 main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestHeaderLines(t *testing.T) {
+	var cases = []struct {
+		in  string
+		out string
+	}{
+		{"", ""},
+		{
+			"# ok",
+			"# ok",
+		},
+		{
+			"## ok",
+			"## ok",
+		},
+		{
+			"##### ok",
+			"##### ok",
+		},
+		{
+			"##fix",
+			"## fix",
+		},
+		{
+			"foo\n\n##fix\n\nbar",
+			"foo\n\n## fix\n\nbar",
+		},
+		{
+			"foo\n##fix\nbar",
+			"foo\n\n## fix\n\nbar",
+		},
+		{
+			"foo\n```\n##fix\n```\nbar",
+			"foo\n```\n##fix\n```\nbar",
+		},
+		{
+			"foo\n#fix1\n##fix2\nbar",
+			"foo\n\n# fix1\n\n## fix2\n\nbar",
+		},
+	}
+	for i, c := range cases {
+		actual, err := checkHeaderLines("filename.md", []byte(c.in))
+		assert.NoError(t, err)
+		if string(actual) != c.out {
+			t.Errorf("case[%d]: expected %q got %q", i, c.out, string(actual))
+		}
+	}
+}
diff --git a/cmd/mungedocs/mungedocs.go b/cmd/mungedocs/mungedocs.go
index f6db77c6c94..ac644ceb736 100644
--- a/cmd/mungedocs/mungedocs.go
+++ b/cmd/mungedocs/mungedocs.go
@@ -48,6 +48,7 @@ Examples:
 		{"table-of-contents", updateTOC},
 		{"check-links", checkLinks},
 		{"blank-lines-surround-preformatted", checkPreformatted},
+		{"header-lines", checkHeaderLines},
 		{"unversioned-warning", updateUnversionedWarning},
 		{"analytics", checkAnalytics},
 		{"kubectl-dash-f", checkKubectlFileTargets},