Refactor how preprocess functions work a bit

7 files changed, 72 insertions, 64 deletions

diff --git a/src/gmi/posts_preprocess_funcs.go b/src/gmi/posts_preprocess_funcs.go
new file mode 100644
index 0000000..f8fcda6
--- /dev/null
+++ b/src/gmi/posts_preprocess_funcs.go
@@ -0,0 +1,26 @@
+package gmi
+
+import (
+	"fmt"
+
+	"dev.mediocregopher.com/mediocre-blog.git/src/render"
+)
+
+type postPreprocessFuncs struct {
+	urlBuilder render.URLBuilder
+}
+
+func (f postPreprocessFuncs) Image(args ...string) (string, error) {
+	var (
+		id    = args[0]
+		descr = "Image"
+	)
+
+	if len(args) > 1 {
+		descr = args[1]
+	}
+
+	return fmt.Sprintf(
+		"\n=> %s %s", f.urlBuilder.Asset(id), descr,
+	), nil
+}
diff --git a/src/gmi/tpl.go b/src/gmi/tpl.go
index fb62a17..5ea114d 100644
--- a/src/gmi/tpl.go
+++ b/src/gmi/tpl.go
@@ -34,24 +34,10 @@ var tplFS embed.FS
 
 func (a *api) tplHandler() (gemini.Handler, error) {
 
-	preprocessFuncs := post.PreprocessFunctions{
-		Image: func(args ...string) (string, error) {
-			var (
-				id    = args[0]
-				descr = "Image"
-			)
-
-			if len(args) > 1 {
-				descr = args[1]
-			}
-
-			return fmt.Sprintf(
-				"\n=> %s %s", a.urlBuilder.Asset(id), descr,
-			), nil
-		},
-	}
-
-	allTpls := template.New("")
+	var (
+		postPreprocessFuncs = postPreprocessFuncs{a.urlBuilder}
+		allTpls             = template.New("")
+	)
 
 	err := fs.WalkDir(tplFS, "tpl", func(path string, d fs.DirEntry, err error) error {
 
@@ -122,7 +108,7 @@ func (a *api) tplHandler() (gemini.Handler, error) {
 			a.params.PostStore,
 			nil, // asset.Store, not supported by gemini endpoint
 			nil, // post.DraftStore, not supported by gemini endpoint
-			preprocessFuncs,
+			postPreprocessFuncs,
 		))
 
 		if errors.Is(err, post.ErrPostNotFound) {
diff --git a/src/http/http.go b/src/http/http.go
index 6e57a77..4403a69 100644
--- a/src/http/http.go
+++ b/src/http/http.go
@@ -126,9 +126,10 @@ type api struct {
 	params Params
 	srv    *http.Server
 
-	redirectTpl *template.Template
-	auther      Auther
-	urlBuilder  render.URLBuilder
+	redirectTpl         *template.Template
+	auther              Auther
+	urlBuilder          render.URLBuilder
+	postPreprocessFuncs postPreprocessFuncs
 }
 
 // New initializes and returns a new API instance, including setting up all
@@ -156,12 +157,12 @@ func New(params Params) (API, error) {
 		),
 	}
 
+	a.postPreprocessFuncs = newPostPreprocessFuncs(a.urlBuilder)
 	a.redirectTpl = mustParseTpl(template.New(""), "redirect.html")
 
 	a.srv = &http.Server{Handler: a.handler()}
 
 	go func() {
-
 		err := a.srv.Serve(l)
 		if err != nil && !errors.Is(err, http.ErrServerClosed) {
 			ctx := mctx.WithAnnotator(context.Background(), &a.params)
diff --git a/src/http/posts.go b/src/http/posts.go
index 8488996..1bc65c8 100644
--- a/src/http/posts.go
+++ b/src/http/posts.go
@@ -5,10 +5,10 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"html/template"
 	"net/http"
 	"path/filepath"
 	"strings"
-	txttpl "text/template"
 	"time"
 
 	"dev.mediocregopher.com/mediocre-blog.git/src/http/apiutil"
@@ -18,7 +18,18 @@ import (
 	"dev.mediocregopher.com/mediocre-go-lib.git/mctx"
 )
 
-func (a *api) postPreprocessFuncImage(args ...string) (string, error) {
+type postPreprocessFuncs struct {
+	urlBuilder render.URLBuilder
+	imageTpl   *template.Template
+}
+
+func newPostPreprocessFuncs(urlBuilder render.URLBuilder) postPreprocessFuncs {
+	imageTpl := template.New("image.html")
+	imageTpl = template.Must(imageTpl.Parse(mustReadTplFile("image.html")))
+	return postPreprocessFuncs{urlBuilder, imageTpl}
+}
+
+func (f postPreprocessFuncs) Image(args ...string) (string, error) {
 
 	var (
 		id    = args[0]
@@ -29,39 +40,29 @@ func (a *api) postPreprocessFuncImage(args ...string) (string, error) {
 		descr = args[1]
 	}
 
-	tpl := txttpl.New("image.html")
-	tpl = txttpl.Must(tpl.Parse(mustReadTplFile("image.html")))
-
-	tplPayload := struct {
-		RootURL   render.URLBuilder
-		ID        string
-		Descr     string
-		Resizable bool
-	}{
-		RootURL: render.NewURLBuilder(
-			a.params.PublicURL,
-			a.params.PublicURL, // httpURL
-			a.params.GeminiPublicURL,
-		),
-		ID:        id,
-		Descr:     descr,
-		Resizable: asset.IsImageResizable(id),
-	}
+	var (
+		tplPayload = struct {
+			RootURL   render.URLBuilder
+			ID        string
+			Descr     string
+			Resizable bool
+		}{
+			RootURL:   f.urlBuilder,
+			ID:        id,
+			Descr:     descr,
+			Resizable: asset.IsImageResizable(id),
+		}
+		buf = new(bytes.Buffer)
+	)
 
-	buf := new(bytes.Buffer)
-	if err := tpl.ExecuteTemplate(buf, "image.html", tplPayload); err != nil {
+	err := f.imageTpl.ExecuteTemplate(buf, "image.html", tplPayload)
+	if err != nil {
 		return "", err
 	}
 
 	return buf.String(), nil
 }
 
-func (a *api) postPreprocessFuncs() post.PreprocessFunctions {
-	return post.PreprocessFunctions{
-		Image: a.postPreprocessFuncImage,
-	}
-}
-
 func (a *api) getPostsHandler() http.Handler {
 	var (
 		tpl            = a.mustParseBasedTpl("posts.html")
diff --git a/src/http/tpl.go b/src/http/tpl.go
index 47cea80..42341a2 100644
--- a/src/http/tpl.go
+++ b/src/http/tpl.go
@@ -66,7 +66,7 @@ func (a *api) newTPLData(r *http.Request, payload interface{}) tplData {
 			a.params.PostStore,
 			a.params.PostAssetStore,
 			a.params.PostDraftStore,
-			a.postPreprocessFuncs(),
+			a.postPreprocessFuncs,
 		),
 		Payload: payload,
 		Title:   "mediocregopher's lil web corner",
diff --git a/src/post/preprocess.go b/src/post/preprocess.go
index 7aceee2..2f3e091 100644
--- a/src/post/preprocess.go
+++ b/src/post/preprocess.go
@@ -1,14 +1,13 @@
 package post
 
 // PreprocessFunctions are functions which can be used by posts themselves to
-// interleave dynamic content into their bodies. Usually this is used for
-// properly constructing URLs, but also for things like displaying images.
-type PreprocessFunctions struct {
+// interleave dynamic content into their bodies.
+type PreprocessFunctions interface {
 	// Image returns a string which should be inlined into the post body in
-	// order to display an.
+	// order to render an image.
 	//
 	// The first argument to Image _must_ be the ID of an image asset. The
 	// second argument _may_ be a description of the image which will be used as
 	// alt text, or possibly displayed to the user with the image.
-	Image func(args ...string) (string, error)
+	Image(args ...string) (string, error)
 }
diff --git a/src/render/methods.go b/src/render/methods.go
index a671f7e..a28f6b5 100644
--- a/src/render/methods.go
+++ b/src/render/methods.go
@@ -194,11 +194,7 @@ func (m *Methods) GetPostSeriesNextPrevious(
 
 type preprocessPostPayload struct {
 	RootURL URLBuilder
-	image   func(args ...string) (string, error)
-}
-
-func (p preprocessPostPayload) Image(args ...string) (string, error) {
-	return p.image(args...)
+	post.PreprocessFunctions
 }
 
 // preprocessPostBody interprets the Post's Body as a text template which may
@@ -213,8 +209,7 @@ func (m *Methods) preprocessPostBody(into io.Writer, p post.Post) error {
 	}
 
 	err = tpl.Execute(into, preprocessPostPayload{
-		RootURL: m.RootURL(),
-		image:   m.preprocessFuncs.Image,
+		m.RootURL(), m.preprocessFuncs,
 	})
 	if err != nil {
 		return fmt.Errorf("executing post body as template: %w", err)