TIL-7 Tags into pages

Signed-off-by: Chris Cummer <chriscummer@me.com>

main.go

@@ -112,11 +112,23 @@ func main() {
 
 func buildContent() {
 	pages := loadPages()
+	buildContentPages(pages)
 	tagMap := buildTagPages(pages)
 
 	buildIndexPage(pages, tagMap)
 }
 
+// buildContentPages loops through all the pages and tells them to save themselves
+// to disk. This process writes any auto-generated content into the pages
+func buildContentPages(pages []*pages.Page) {
+	for _, page := range pages {
+		if page.IsContentPage() {
+			page.AppendTagsToContent()
+			page.Save()
+		}
+	}
+}
+
 // buildIndexPage creates the main index.md page that is the root of the site
 func buildIndexPage(pageSet []*pages.Page, tagMap *pages.TagMap) {
 	src.Info(statusIdxBuild)

pages/page.go

@@ -5,6 +5,7 @@ import (
 	"io/ioutil"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"time"
 
@@ -50,6 +51,47 @@ func NewPage(title string, targetDir string) *Page {
 	return page
 }
 
+// AppendTagsToContent programatically modifies the page content to save auto-included
+// content like the tag list
+func (page *Page) AppendTagsToContent() bool {
+	if len(page.Tags()) == 0 {
+		return true
+	}
+
+	tagLinks := []string{}
+	for _, tag := range page.Tags() {
+		if tag.Link() != "" {
+			tagLinks = append(tagLinks, tag.Link())
+		}
+	}
+
+	tagList := strings.Join(tagLinks, ", ")
+
+	// Tags
+	tagsStartStr := "<!-- TAGS:START -->"
+	tagsEndStr := "<!-- TAGS:END -->"
+
+	re := fmt.Sprintf("`%s\n.*\n%s`", tagsStartStr, tagsEndStr)
+	rg := regexp.MustCompile(re)
+
+	newContent := rg.ReplaceAllString(page.Content, tagList)
+
+	if page.Content != newContent {
+		// Swap the old content with the new content
+		page.Content = newContent
+	} else {
+		// Append the tag list to the end of the page
+		page.Content += fmt.Sprintf(
+			"\n%s\n%s\n%s\n",
+			tagsStartStr,
+			tagList,
+			tagsEndStr,
+		)
+	}
+
+	return true
+}
+
 // PageFromFilePath creates and returns a Page instance from a file path
 func PageFromFilePath(filePath string) *Page {
 	page := new(Page)