From d730b4d43cfaf03ba4ea3437564eb71e7a406f9f Mon Sep 17 00:00:00 2001
From: Noah Petherbridge <root@kirsle.net>
Date: Sat, 2 Dec 2017 10:47:21 -0800
Subject: [PATCH] Import wiki pages, render Markdown pages w/ Pygments

---
 README.md                  |  13 +++++
 cmd/rophako-import/main.go | 116 +++++++++++++++++++++++++++++++++++--
 core/markdown.go           | 103 +++++++++++++++++++++++++++++++-
 core/pages.go              |  22 +++++++
 core/responses.go          |  13 ++++-
 root/.errors/500.gohtml    |   6 ++
 root/.markdown.gohtml      |   6 ++
 7 files changed, 271 insertions(+), 8 deletions(-)
 create mode 100644 root/.errors/500.gohtml
 create mode 100644 root/.markdown.gohtml

diff --git a/README.md b/README.md
index a3c6177..2c27d60 100644
--- a/README.md
+++ b/README.md
@@ -16,6 +16,19 @@ cd ~/go/src/github.com/kirsle/blog
 make run
 ```
 
+## Syntax Highlighting with Pygments
+
+To enable syntax highlighting within Markdown files (like with GitHub Flavored
+Markdown), install [pygments](http://pygments.org) on your system. For example:
+
+```
+# Fedora/RHEL
+sudo dnf install python3-pygments python3-pygments-markdown-lexer
+
+# Debian
+sudo apt install python3-pygments
+```
+
 # License
 
 MIT.
diff --git a/cmd/rophako-import/main.go b/cmd/rophako-import/main.go
index 517e050..39e1559 100644
--- a/cmd/rophako-import/main.go
+++ b/cmd/rophako-import/main.go
@@ -6,8 +6,10 @@ import (
 	"bufio"
 	"flag"
 	"fmt"
+	"io/ioutil"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strconv"
 	"strings"
 	"time"
@@ -26,6 +28,9 @@ var (
 	log   *golog.Logger
 	inDB  *jsondb.DB
 	outDB *jsondb.DB
+
+	urlSafe  = regexp.MustCompile(`[^A-Za-z0-9/]`)
+	wikiLink = regexp.MustCompile(`\[\[(.+?)\]\]`)
 )
 
 func init() {
@@ -45,15 +50,13 @@ func main() {
 	if inPath == "" || outPath == "" {
 		log.Error("Usage: rophako-import -in /opt/rophako/db -out /path/to/blog/root")
 		os.Exit(1)
-	}
-
-	if !strings.Contains(outPath, "/.private") {
-		outPath = strings.TrimSuffix(filepath.Join(outPath, ".private"), "/")
-		log.Info("Note: rewriting -out to: %s", outPath)
+	} else if strings.Contains(outPath, "/.private") {
+		log.Error("Do not provide the /.private suffix to -out, only the parent web root")
+		os.Exit(1)
 	}
 
 	inDB = jsondb.New(inPath)
-	outDB = jsondb.New(outPath)
+	outDB = jsondb.New(strings.TrimSuffix(filepath.Join(outPath, ".private"), "/"))
 	fmt.Printf(
 		"Importing Rophako DB from: %s\n"+
 			"Writing output JsonDB to: %s\n"+
@@ -72,6 +75,7 @@ func main() {
 	// Migrate everything over.
 	migrateBlog()
 	migrateComments()
+	migrateWiki()
 }
 
 func migrateBlog() {
@@ -197,6 +201,94 @@ func migrateComments() {
 	}
 }
 
+func migrateWiki() {
+	log.Warn("Migrating wiki...")
+
+	threads, err := inDB.List("wiki/pages")
+	if err != nil {
+		log.Error("No pages found: %s", err.Error())
+		return
+	}
+
+	// Prepare the output directory.
+	wikiPath := filepath.Join(outPath, "wiki")
+	if _, err = os.Stat(wikiPath); os.IsNotExist(err) {
+		err = os.Mkdir(wikiPath, 0755)
+		if err != nil {
+			log.Error("Can't create wiki root %s: %s", wikiPath, err)
+			return
+		}
+	}
+
+	for _, doc := range threads {
+		parts := strings.Split(doc, "/")
+		title := parts[len(parts)-1]
+
+		// File name is the title but with hyphens, to match the URL version.
+		filename := makeURLSafe(title)
+
+		page := &legacyWiki{}
+		err = inDB.Get(doc, &page)
+		if err != nil {
+			log.Error("Error reading wiki DB %s: %s", doc, err)
+			continue
+		}
+
+		// Take the highest revision as the current version to use.
+		var highest *legacyRevision
+		for _, rev := range page.Revisions {
+			if highest == nil || rev.Time > highest.Time {
+				highest = &rev
+			}
+		}
+		if highest == nil {
+			log.Error("Wiki page %s has no revisions?", doc)
+			continue
+		}
+
+		// Insert the title as the first <h1> in the Markdown.
+		markdown := fmt.Sprintf("# %s\n\n%s", title, highest.Body)
+
+		// Find and replace inter-wiki links with normal URIs.
+		links := wikiLink.FindAllStringSubmatch(markdown, -1)
+		for _, match := range links {
+			href, label := match[1], match[1]
+			if strings.Contains(label, "|") {
+				parts := strings.SplitN(label, "|", 2)
+				label, href = parts[0], parts[1]
+			}
+			href = "/wiki/" + makeURLSafe(href)
+
+			markdown = strings.Replace(
+				markdown,
+				match[0],
+				fmt.Sprintf("[%s](%s)", label, href),
+				1,
+			)
+		}
+
+		// Write the body into Markdown files.
+		path := filepath.Join(wikiPath, fmt.Sprintf("%s.md", filename))
+		log.Debug("Writing page '%s' to: %s", title, path)
+		err = ioutil.WriteFile(path, []byte(markdown), 0644)
+		if err != nil {
+			log.Error("Error writing: %s", err)
+		}
+	}
+}
+
+func makeURLSafe(input string) string {
+	return strings.Trim(
+		strings.Replace(
+			urlSafe.ReplaceAllString(input, "-"),
+			"--",
+			"-",
+			0,
+		),
+		"-",
+	)
+}
+
 func commit(document string, v interface{}) {
 	err := outDB.Commit(document, v)
 	if err != nil {
@@ -229,3 +321,15 @@ type legacyComment struct {
 type legacyThread map[string]legacyComment
 
 type legacySubscribers map[string]float64
+
+type legacyWiki struct {
+	Revisions []legacyRevision `json:"revisions"`
+}
+
+type legacyRevision struct {
+	Body   string  `json:"body"`
+	Author int     `json:"author"`
+	Time   float64 `json:"time"`
+	Note   string  `json:"note"`
+	ID     string  `json:"id"`
+}
diff --git a/core/markdown.go b/core/markdown.go
index 68ade81..a54a39f 100644
--- a/core/markdown.go
+++ b/core/markdown.go
@@ -1,10 +1,52 @@
 package core
 
 import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os/exec"
+	"regexp"
+	"strings"
+
 	"github.com/microcosm-cc/bluemonday"
 	"github.com/shurcooL/github_flavored_markdown"
 )
 
+// Regexps for Markdown use cases.
+var (
+	// Match title from the first `# h1` heading.
+	reMarkdownTitle = regexp.MustCompile(`(?m:^#([^#\r\n]+)$)`)
+
+	// Match fenced code blocks with languages defined.
+	reFencedCode = regexp.MustCompile("```" + `([a-z]*)\n([\s\S]*?)\n\s*` + "```")
+
+	// Regexp to match fenced code blocks in rendered Markdown HTML.
+	// Tweak this if you change Markdown engines later.
+	reCodeBlock   = regexp.MustCompile(`<div class="highlight highlight-(.+?)"><pre>(.+?)</pre></div>`)
+	reDecodeBlock = regexp.MustCompile(`\[?FENCED_CODE_%d_BLOCK?\]`)
+)
+
+// A container for parsed code blocks.
+type codeBlock struct {
+	placeholder int
+	language    string
+	source      string
+}
+
+// TitleFromMarkdown tries to find a title from the source of a Markdown file.
+//
+// On error, returns "Untitled" along with the error. So if you're lazy and
+// want a suitable default, you can safely ignore the error.
+func TitleFromMarkdown(body string) (string, error) {
+	m := reMarkdownTitle.FindStringSubmatch(body)
+	if len(m) > 0 {
+		return m[1], nil
+	}
+	return "Untitled", errors.New(
+		"did not find a single h1 (denoted by # prefix) for Markdown title",
+	)
+}
+
 // RenderMarkdown renders markdown to HTML, safely. It uses blackfriday to
 // render Markdown to HTML and then Bluemonday to sanitize the resulting HTML.
 func (b *Blog) RenderMarkdown(input string) string {
@@ -22,6 +64,65 @@ func (b *Blog) RenderMarkdown(input string) string {
 // bluemonday filtering afterward. This is for blog posts and website
 // Markdown pages, not for user-submitted comments or things.
 func (b *Blog) RenderTrustedMarkdown(input string) string {
-	html := github_flavored_markdown.Markdown([]byte(input))
+	// Find and hang on to fenced code blocks.
+	codeBlocks := []codeBlock{}
+	log.Info("RE: %s", reFencedCode.String())
+	matches := reFencedCode.FindAllStringSubmatch(input, -1)
+	for i, m := range matches {
+		language, source := m[1], m[2]
+		if language == "" {
+			continue
+		}
+		codeBlocks = append(codeBlocks, codeBlock{i, language, source})
+
+		input = strings.Replace(input, m[0], fmt.Sprintf(
+			"[?FENCED_CODE_%d_BLOCK?]",
+			i,
+		), 1)
+	}
+
+	// Render the HTML out.
+	html := string(github_flavored_markdown.Markdown([]byte(input)))
+
+	// Substitute fenced codes back in.
+	for _, block := range codeBlocks {
+		highlighted, _ := Pygmentize(block.language, block.source)
+		html = strings.Replace(html,
+			fmt.Sprintf("[?FENCED_CODE_%d_BLOCK?]", block.placeholder),
+			highlighted,
+			1,
+		)
+	}
+
 	return string(html)
 }
+
+// Pygmentize searches for fenced code blocks in rendered Markdown HTML
+// and runs Pygments to syntax highlight it.
+//
+// On error the original given source is returned back.
+//
+// TODO: this takes ~0.6s per go, we need something faster.
+func Pygmentize(language, source string) (string, error) {
+	bin := "pygmentize"
+
+	if _, err := exec.LookPath(bin); err != nil {
+		return source, errors.New("pygmentize not installed")
+	}
+
+	cmd := exec.Command(bin, "-l"+language, "-f"+"html", "-O encoding=utf-8")
+	cmd.Stdin = strings.NewReader(source)
+
+	var out bytes.Buffer
+	cmd.Stdout = &out
+
+	var stderr bytes.Buffer
+	cmd.Stderr = &stderr
+
+	if err := cmd.Run(); err != nil {
+		log.Error("Error running pygments: %s", stderr.String())
+		return source, err
+	}
+
+	return out.String(), nil
+}
diff --git a/core/pages.go b/core/pages.go
index dc37291..7ce6de0 100644
--- a/core/pages.go
+++ b/core/pages.go
@@ -2,6 +2,8 @@ package core
 
 import (
 	"errors"
+	"html/template"
+	"io/ioutil"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -42,6 +44,26 @@ func (b *Blog) PageHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Is it a Markdown file?
+	if strings.HasSuffix(filepath.URI, ".md") || strings.HasSuffix(filepath.URI, ".markdown") {
+		source, err := ioutil.ReadFile(filepath.Absolute)
+		if err != nil {
+			b.Error(w, r, "Couldn't read Markdown source!")
+			return
+		}
+
+		// Render it to HTML and find out its title.
+		body := string(source)
+		html := b.RenderTrustedMarkdown(body)
+		title, _ := TitleFromMarkdown(body)
+
+		b.RenderTemplate(w, r, ".markdown", NewVars(map[interface{}]interface{}{
+			"Title": title,
+			"HTML":  template.HTML(html),
+		}))
+		return
+	}
+
 	http.ServeFile(w, r, filepath.Absolute)
 }
 
diff --git a/core/responses.go b/core/responses.go
index 87451fa..11126b3 100644
--- a/core/responses.go
+++ b/core/responses.go
@@ -60,9 +60,20 @@ func (b *Blog) Forbidden(w http.ResponseWriter, r *http.Request, message ...stri
 	}
 }
 
+// Error sends an HTTP 500 Internal Server Error response.
+func (b *Blog) Error(w http.ResponseWriter, r *http.Request, message ...string) {
+	w.WriteHeader(http.StatusInternalServerError)
+	err := b.RenderTemplate(w, r, ".errors/500", &Vars{
+		Message: message[0],
+	})
+	if err != nil {
+		log.Error(err.Error())
+		w.Write([]byte("Unrecoverable template error for Error()"))
+	}
+}
+
 // BadRequest sends an HTTP 400 Bad Request.
 func (b *Blog) BadRequest(w http.ResponseWriter, r *http.Request, message ...string) {
-	log.Error("HERE 4")
 	w.WriteHeader(http.StatusBadRequest)
 	err := b.RenderTemplate(w, r, ".errors/400", &Vars{
 		Message: message[0],
diff --git a/root/.errors/500.gohtml b/root/.errors/500.gohtml
new file mode 100644
index 0000000..2ca412f
--- /dev/null
+++ b/root/.errors/500.gohtml
@@ -0,0 +1,6 @@
+{{ define "title" }}Internal Server Error{{ end }}
+{{ define "content" }}
+<h1>500 Internal Server Error</h1>
+
+{{ .Message }}
+{{ end }}
diff --git a/root/.markdown.gohtml b/root/.markdown.gohtml
new file mode 100644
index 0000000..43a7881
--- /dev/null
+++ b/root/.markdown.gohtml
@@ -0,0 +1,6 @@
+{{ define "title" }}{{ .Data.Title }}{{ end }}
+{{ define "content" }}
+
+{{ .Data.HTML }}
+
+{{ end }}