From 8f542c71208b1944979b2e50ad1a328aab98f230 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C5=99emysl=20Eric=20Janouch?= <p@janouch.name>
Date: Mon, 21 Sep 2020 19:00:37 +0200
Subject: [PATCH] hswg: execute a template given on standard input

So that information can be extracted from documents easily.
---
 hswg/main.go | 58 ++++++++++++++++++++++++++++++++++------------------
 1 file changed, 38 insertions(+), 20 deletions(-)

diff --git a/hswg/main.go b/hswg/main.go
index b8e6e40..fef3278 100644
--- a/hswg/main.go
+++ b/hswg/main.go
@@ -6,6 +6,7 @@ import (
 	"bytes"
 	"encoding/xml"
 	"fmt"
+	"html/template"
 	"io"
 	"io/ioutil"
 	"log"
@@ -127,13 +128,14 @@ func Render(r io.Reader, config configuration.Configuration) (
 	return
 }
 
-// entry contains all context information about a single page.
-type entry struct {
-	path      string    // path
-	mtime     time.Time // modification time
-	metadata  Metadata  // metadata
-	document  []byte    // inner document with expanded LinkWords
-	backlinks []string  // what documents link back here
+// Entry contains all context information about a single page.
+type Entry struct {
+	PathSource      string    // path to source AsciiDoc
+	PathDestination string    // path to destination HTML
+	mtime           time.Time // modification time
+	Metadata        Metadata  // metadata
+	document        []byte    // inner document with expanded LinkWords
+	backlinks       []string  // what documents link back here
 }
 
 var extRE = regexp.MustCompile(`\.[^/.]*$`)
@@ -149,17 +151,17 @@ func resultPath(path string) string {
 	return path + ".html"
 }
 
-func makeLink(m *map[string]*entry, name string) string {
+func makeLink(m *map[string]*Entry, name string) string {
 	e := (*m)[name]
-	return fmt.Sprintf("<a href='%s'>%s</a>", resultPath(e.path), name)
+	return fmt.Sprintf("<a href='%s'>%s</a>", e.PathDestination, name)
 }
 
 var linkWordRE = regexp.MustCompile(`\b\p{Lu}\p{L}*\b`)
 
-func expand(m *map[string]*entry, name string, chunk []byte) []byte {
+func expand(m *map[string]*Entry, name string, chunk []byte) []byte {
 	return linkWordRE.ReplaceAllFunc(chunk, func(match []byte) []byte {
 		if link, ok := (*m)[string(match)]; ok && string(match) != name &&
-			!link.metadata.IsDraft() {
+			!link.Metadata.IsDraft() {
 			link.backlinks = append(link.backlinks, name)
 			return []byte(makeLink(m, string(match)))
 		}
@@ -195,7 +197,7 @@ func main() {
 	}
 
 	// Create a map from document names to their page entries.
-	entries := map[string]*entry{}
+	entries := map[string]*Entry{}
 	for _, glob := range os.Args[2:] {
 		matches, err := filepath.Glob(glob)
 		if err != nil {
@@ -204,15 +206,18 @@ func main() {
 		for _, path := range matches {
 			name := stripExtension(filepath.Base(path))
 			if conflict, ok := entries[name]; ok {
-				log.Fatalf("%s: conflicts with %s\n", name, conflict.path)
+				log.Fatalf("%s: conflicts with %s\n", name, conflict.PathSource)
+			}
+			entries[name] = &Entry{
+				PathSource:      path,
+				PathDestination: resultPath(path),
 			}
-			entries[name] = &entry{path: path}
 		}
 	}
 
 	tagRE := regexp.MustCompile(`<[^<>]+>`)
 	for name, e := range entries {
-		f, err := os.Open(e.path)
+		f, err := os.Open(e.PathSource)
 		if err != nil {
 			log.Fatalln(err)
 		}
@@ -224,8 +229,8 @@ func main() {
 		}
 
 		var html *bytes.Buffer
-		if html, e.metadata, err = Render(f, configuration.NewConfiguration(
-			configuration.WithFilename(e.path),
+		if html, e.Metadata, err = Render(f, configuration.NewConfiguration(
+			configuration.WithFilename(e.PathSource),
 			configuration.WithLastUpdated(e.mtime),
 		)); err != nil {
 			log.Fatalln(err)
@@ -243,15 +248,16 @@ func main() {
 		e.document = expanded.Bytes()
 	}
 
+	// TODO(p): These should be run through html/template.
 	for name, e := range entries {
-		f, err := os.Create(resultPath(e.path))
+		f, err := os.Create(e.PathDestination)
 		if err != nil {
 			log.Fatalln(err)
 		}
 
 		_, _ = f.Write(header)
 
-		title := e.metadata.Title
+		title := e.Metadata.Title
 		if title == "" {
 			title = name
 		}
@@ -277,6 +283,18 @@ func main() {
 		_, _ = f.Write(e.document)
 		_, _ = f.WriteString(fmt.Sprintf("<p id=footer>Last updated: %s"+
 			" &mdash; <a href='%s'>Source</p>\n",
-			e.metadata.LastUpdated, e.path))
+			e.Metadata.LastUpdated, e.PathSource))
+	}
+
+	// Execute a template from the standard input.
+	var input []byte
+	if input, err = ioutil.ReadAll(os.Stdin); err != nil {
+		log.Fatalln(err)
+	}
+
+	// TODO(p): Splitting content to categories would be nice.
+	t, err := template.New("-").Parse(string(input))
+	if err = t.Execute(os.Stdout, entries); err != nil {
+		log.Fatalln(err)
 	}
 }