From a9337d346ca6d82bbe203d50b176af9b7c146db0 Mon Sep 17 00:00:00 2001
From: Alan Pearce
Date: Wed, 5 Jun 2024 22:15:05 +0200
Subject: generate sitemap and robots.txt

---
 internal/builder/builder.go | 62 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 61 insertions(+), 1 deletion(-)

(limited to 'internal/builder/builder.go')

diff --git a/internal/builder/builder.go b/internal/builder/builder.go
index 0a774fb..aec41e3 100644
--- a/internal/builder/builder.go
+++ b/internal/builder/builder.go
@@ -7,12 +7,14 @@ import (
 	"os"
 	"path"
 	"slices"
+	"time"
 
 	"website/internal/config"
 	"website/internal/log"
 
 	cp "github.com/otiai10/copy"
 	"github.com/pkg/errors"
+	"github.com/snabb/sitemap"
 )
 
 type IOConfig struct {
@@ -43,6 +45,21 @@ func outputToFile(output io.Reader, filename ...string) error {
 	return nil
 }
 
+func writerToFile(writer io.WriterTo, filename ...string) error {
+	log.Debug("outputting file", "filename", path.Join(filename...))
+	file, err := os.OpenFile(path.Join(filename...), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		return errors.WithMessage(err, "could not open output file")
+	}
+	defer file.Close()
+
+	if _, err := writer.WriteTo(file); err != nil {
+		return errors.WithMessage(err, "could not write output file")
+	}
+
+	return nil
+}
+
 func build(outDir string, config config.Config) error {
 	log.Debug("output", "dir", outDir)
 	privateDir := path.Join(outDir, "private")
@@ -71,11 +88,21 @@ func build(outDir string, config config.Config) error {
 		return err
 	}
 
+	sm := NewSitemap(config)
+	lastMod := time.Now()
+	if len(posts) > 0 {
+		lastMod = posts[0].Date
+	}
+
 	for _, post := range posts {
 		if err := mkdirp(publicDir, "post", post.Basename); err != nil {
 			return errors.WithMessage(err, "could not create directory for post")
 		}
 		log.Debug("rendering post", "post", post.Basename)
+		sm.Add(&sitemap.URL{
+			Loc:     post.URL,
+			LastMod: &post.Date,
+		})
 		output, err := renderPost(post, config)
 		if err != nil {
 			return errors.WithMessagef(err, "could not render post %s", post.Input)
@@ -96,6 +123,10 @@ func build(outDir string, config config.Config) error {
 	if err := outputToFile(output, publicDir, "tags", "index.html"); err != nil {
 		return err
 	}
+	sm.Add(&sitemap.URL{
+		Loc:     "/tags/",
+		LastMod: &lastMod,
+	})
 
 	for _, tag := range tags.ToSlice() {
 		matchingPosts := []Post{}
@@ -108,13 +139,18 @@ func build(outDir string, config config.Config) error {
 			return errors.WithMessage(err, "could not create directory")
 		}
 		log.Debug("rendering tags page", "tag", tag)
-		output, err := renderListPage(tag, config, matchingPosts, "/tags/"+tag)
+		url := "/tags/" + tag
+		output, err := renderListPage(tag, config, matchingPosts, url)
 		if err != nil {
 			return errors.WithMessage(err, "could not render tag page")
 		}
 		if err := outputToFile(output, publicDir, "tags", tag, "index.html"); err != nil {
 			return err
 		}
+		sm.Add(&sitemap.URL{
+			Loc:     url,
+			LastMod: &matchingPosts[0].Date,
+		})
 
 		log.Debug("rendering tags feed", "tag", tag)
 		output, err = renderFeed(
@@ -139,6 +175,10 @@ func build(outDir string, config config.Config) error {
 	if err := outputToFile(listPage, publicDir, "post", "index.html"); err != nil {
 		return err
 	}
+	sm.Add(&sitemap.URL{
+		Loc:     "/post/",
+		LastMod: &lastMod,
+	})
 
 	log.Debug("rendering feed")
 	feed, err := renderFeed(config.Title, config, posts, "feed")
@@ -166,6 +206,12 @@ func build(outDir string, config config.Config) error {
 	if err := outputToFile(homePage, publicDir, "index.html"); err != nil {
 		return err
 	}
+	// it would be nice to set LastMod here, but using the latest post
+	// date would be wrong as the homepage has its own content file
+	// without a date, which could be newer
+	sm.Add(&sitemap.URL{
+		Loc: "/",
+	})
 
 	log.Debug("rendering 404 page")
 	notFound, err := render404(config, "/404.html")
@@ -176,6 +222,20 @@ func build(outDir string, config config.Config) error {
 		return err
 	}
 
+	log.Debug("rendering sitemap")
+	if err := writerToFile(sm, publicDir, "sitemap.xml"); err != nil {
+		return err
+	}
+
+	log.Debug("rendering robots.txt")
+	rob, err := renderRobotsTXT(config)
+	if err != nil {
+		return err
+	}
+	if err := outputToFile(rob, publicDir, "robots.txt"); err != nil {
+		return err
+	}
+
 	return nil
 }
 
-- 
cgit 1.4.1