prose/server/server.go

package server

import (
	"bytes"
	"log"
	"net/http"
	"prose/common"
	"prose/errorcatcher"
	"prose/postmap"
	"prose/stylemap"
	"prose/tplmap"
	"prose/watcher"
	"strings"

	"github.com/aymerick/raymond"
)

type server struct {
	staticHandler http.Handler

	templates watcher.AutoMap[string, *raymond.Template]
	posts     watcher.OrderedAutoMap[string, *postmap.Post]
	styles    watcher.AutoMap[string, string]
	homeImage []byte
}

func New() error {
	s := &server{
		staticHandler: http.FileServer(http.Dir("static/")),
	}

	var imgBuffer bytes.Buffer
	err := common.CreateImage(common.BlogTitle, common.BlogSummary, common.BlogURL, &imgBuffer)
	if err != nil {
		return err
	}
	s.homeImage = imgBuffer.Bytes()

	s.posts, err = postmap.New()
	if err != nil {
		return err
	}

	s.templates, err = tplmap.New()
	if err != nil {
		return err
	}

	s.styles, err = stylemap.New()
	if err != nil {
		return err
	}

	handlers := map[string]http.HandlerFunc{
		"GET /{$}":              s.serveGetHome,
		"GET /banner.png":       s.serveGetImage(s.homeImage),
		"GET /rss.xml":          s.serveGetRSS,
		"GET /{slug}":           s.serveGetPost,
		"GET /img/banner/{img}": s.serveGetPostImage,
		"GET /css/{filename}":   s.serveGetStylesheet,
		"GET /":                 s.staticHandler.ServeHTTP,
	}

	for pattern, handler := range handlers {
		http.Handle(pattern, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			w = errorcatcher.New(w, r, s.templates)
			handler(w, r)
		}))
	}

	return nil
}

func (s *server) errorInRequest(res http.ResponseWriter, req *http.Request, err error) {
	res.WriteHeader(http.StatusInternalServerError)
	log.Printf("ERR %s: %s", req.URL.Path, err)
}

func (s *server) createWebPage(title, subtitle, contents, banner string) (string, error) {
	ctx := map[string]interface{}{
		"title":    title,
		"subtitle": subtitle,
		"contents": contents,
		"banner":   banner,
	}
	tpl, _ := s.templates.Get("page.html")
	return tpl.Exec(ctx)
}

func (s *server) serveGetPost(w http.ResponseWriter, r *http.Request) {
	p, ok := s.posts.Get(r.PathValue("slug"))
	if !ok {
		w.WriteHeader(http.StatusNotFound)
		return
	}
	w.Header().Add("content-type", "text/html; charset=utf-8")
	tpl, _ := s.templates.Get("fullpost.html")
	contents, err := p.Render(tpl)
	if err != nil {
		s.errorInRequest(w, r, err)
		return
	}
	page, err := s.createWebPage(p.Metadata.Title, p.Metadata.Summary, contents, "/img/banner/"+p.Slug+".png")
	if err != nil {
		s.errorInRequest(w, r, err)
		return
	}
	w.Write([]byte(page))
}

func (s *server) serveGetHome(w http.ResponseWriter, r *http.Request) {
	w.Header().Add("content-type", "text/html; charset=utf-8")

	var posts string

	summaryTpl, _ := s.templates.Get("summary.html")
	for _, p := range s.posts.All() {
		summary, err := p.Render(summaryTpl)
		if err != nil {
			log.Printf("could not render post summary for %s", p.Slug)
		}
		posts = posts + summary
	}

	page, err := s.createWebPage("Home", common.BlogSummary, posts, "/banner.png")

	if err != nil {
		s.errorInRequest(w, r, err)
		return
	}

	w.Write([]byte(page))
}

func (s *server) serveGetPostImage(w http.ResponseWriter, r *http.Request) {
	slug, ok := strings.CutSuffix(r.PathValue("img"), ".png")
	if !ok {
		w.WriteHeader(http.StatusNotFound)
		return
	}
	post, ok := s.posts.Get(slug)
	if !ok {
		w.WriteHeader(http.StatusNotFound)
		return
	}
	s.serveGetImage(post.Image)(w, r)
}

func (s *server) serveGetImage(img []byte) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		w.Header().Add("content-type", "image/png")
		w.Write(img)
	}
}

func (s *server) serveGetRSS(w http.ResponseWriter, r *http.Request) {
	w.Header().Add("content-type", "text/xml; charset=utf-8")

	var posts, pubDate string

	rssItemTpl, _ := s.templates.Get("rss-item.xml")
	for _, p := range s.posts.All() {
		if pubDate != "" {
			pubDate = common.RSSDatetime(p.Metadata.Time)
		}
		summary, err := p.Render(rssItemTpl)
		if err != nil {
			log.Printf("could not render post summary for %s", p.Slug)
		}
		posts = posts + summary
	}
	if pubDate == "" {
		pubDate = common.RSSDatetime(0)
	}

	rssPageTpl, _ := s.templates.Get("rss-channel.xml")
	page, err := rssPageTpl.Exec(map[string]string{
		"title":       common.BlogTitle,
		"description": common.BlogSummary,
		"link":        common.BlogURL,
		"pubDate":     pubDate,
		"items":       posts,
	})

	if err != nil {
		s.errorInRequest(w, r, err)
		return
	}

	w.Write([]byte(page))
}

func (s *server) serveGetStylesheet(w http.ResponseWriter, r *http.Request) {
	contents, ok := s.styles.Get(r.PathValue("filename"))
	if !ok {
		w.WriteHeader(http.StatusNotFound)
		return
	}
	w.Header().Add("content-type", "text/css")
	w.Write([]byte(contents))
}