go: refactor template rendering

* create pkg 'modules/template'
* move template rendering code from 'handlers' to 'modules/template'
* update call sites
* walk the 'templates' dir to discover nested hierarchies
* solidify LiveMode handling (vs embedded assets)
* break out funcMap to it's own file
* general clean-up

app/assets.go

@@ -59,7 +59,7 @@ func (a *App) getTemplates() fs.FS {
 
 	a.logger.Info("templates loaded in embed mode")
 
-	fsys, err := fs.Sub(a.embeds.templates, "templates")
+	fsys, err := fs.Sub(a.embeds.templates, ".")
 	if err != nil {
 		panic(err)
 	}

app/routes.go

@@ -4,6 +4,7 @@ import (
 	"net/http"
 
 	"git.dotya.ml/mirre-mt/pcmt/handlers"
+	modtmpl "git.dotya.ml/mirre-mt/pcmt/modules/template"
 	"github.com/labstack/echo/v4"
 	"github.com/labstack/echo/v4/middleware"
 )
@@ -14,9 +15,11 @@ func (a *App) SetupRoutes() {
 	assets := http.FileServer(a.getAssets())
 	tmpls := a.getTemplates()
 
+	modtmpl.Init(setting, tmpls)
 	// run this before declaring any handler funcs.
-	handlers.InitHandlers(setting, tmpls)
+	handlers.InitHandlers(setting)
-	e.Renderer = handlers.Renderer
+
+	e.Renderer = modtmpl.Renderer
 
 	// keep /static/* as a compatibility fallback for /assets.
 	e.GET(

handlers/config.go

@@ -1,8 +1,6 @@
 package handlers
 
 import (
-	"io/fs"
-
 	"git.dotya.ml/mirre-mt/pcmt/app/settings"
 	"git.dotya.ml/mirre-mt/pcmt/slogging"
 	"golang.org/x/exp/slog"
@@ -13,10 +11,9 @@ var (
 	appver  string
 	slogger *slogging.Logger
 	log     slogging.Logger
-	tmplPath string
 )
 
-func InitHandlers(s *settings.Settings, tmpls fs.FS) {
+func InitHandlers(s *settings.Settings) {
 	slogger = slogging.GetLogger()
 	log = *slogger // have a local copy.
 	log.Logger = log.Logger.With(
@@ -25,11 +22,5 @@ func InitHandlers(s *settings.Settings, tmpls fs.FS) {
 
 	setting = s
 
-	tmplPath = setting.TemplatesPath()
-
 	appver = setting.Version()
-
-	log.Debugf("tmpls: %+v", tmpls)
-
-	initTemplates(tmpls)
 }

handlers/handlers.go

@@ -1,113 +1,13 @@
 package handlers
 
 import (
-	"html/template"
-	"io/fs"
 	"net/http"
-	"path/filepath"
-	"strings"
 
+	modtmpl "git.dotya.ml/mirre-mt/pcmt/modules/template"
 	"github.com/labstack/echo-contrib/session"
 	"github.com/labstack/echo/v4"
-	"github.com/microcosm-cc/bluemonday"
 )
 
-type tplMap map[string]*template.Template
-
-var (
-	// tmpl      *template.Template.
-	// tmpls            = template.New("").
-	templateMap      tplMap
-	tmplFS           fs.FS
-	bluemondayPolicy = bluemonday.UGCPolicy()
-)
-
-func listAllTmpls() []string {
-	files, err := filepath.Glob(tmplPath + "/*.tmpl")
-	if err != nil {
-		panic(err)
-	}
-
-	for i, v := range files {
-		files[i] = strings.TrimPrefix(v, tmplPath+"/")
-	}
-
-	log.Debug("returning files")
-
-	return files
-}
-
-// TODO: mimic https://github.com/drone/funcmap/blob/master/funcmap.go
-func setFuncMap(t *template.Template) {
-	t.Funcs(getFuncMap())
-}
-
-func getFuncMap() template.FuncMap {
-	return template.FuncMap{
-		"ifIE":    func() template.HTML { return template.HTML("<!--[if IE]>") },
-		"endifIE": func() template.HTML { return template.HTML("<![endif]>") },
-		"htmlSafe": func(html string) template.HTML {
-			return template.HTML( //nolint:gosec
-				bluemondayPolicy.Sanitize(html),
-			)
-		},
-		"pageIs": func(want, got string) bool {
-			return want == got
-		},
-	}
-}
-
-func initTemplates(f fs.FS) {
-	if f != nil || f != tmplFS {
-		tmplFS = f
-	}
-
-	setFuncMap(Renderer.tmpls)
-
-	allTmpls := listAllTmpls()
-
-	// ensure this fails at compile time, if at all ("Must").
-	Renderer.tmpls = template.Must(Renderer.tmpls.ParseFS(tmplFS, allTmpls...))
-	makeTplMap(Renderer.tmpls)
-}
-
-func makeTplMap(tpl *template.Template) {
-	allTmpls := listAllTmpls()
-
-	var tp tplMap
-
-	if templateMap == nil {
-		tp = make(tplMap, len(allTmpls))
-	} else {
-		tp = templateMap
-	}
-
-	for _, v := range allTmpls {
-		tp[v] = tpl.Lookup(v)
-	}
-
-	templateMap = tp
-}
-
-func getTmpl(name string) *template.Template {
-	liveMode := setting.IsLive()
-
-	if liveMode {
-		log.Debug("re-reading tmpls") // TODO: only re-read the tmpl in question.
-
-		tpl := template.New("")
-
-		setFuncMap(tpl)
-
-		allTmpls := listAllTmpls()
-
-		// ensure this fails at compile time, if at all ("Must").
-		Renderer.tmpls = template.Must(tpl.ParseFS(tmplFS, allTmpls...))
-	}
-
-	return Renderer.tmpls.Lookup(name)
-}
-
 func Admin() echo.HandlerFunc {
 	return func(c echo.Context) error {
 		return echo.NewHTTPError(http.StatusUnauthorized, "Invalid credentials")
@@ -123,7 +23,7 @@ func Index() echo.HandlerFunc {
 			return c.Redirect(http.StatusFound, "/home")
 		}
 
-		tpl := getTmpl("index.tmpl")
+		tpl := modtmpl.Get("index.tmpl")
 		csrf := c.Get("csrf").(string)
 
 		err := tpl.Execute(c.Response().Writer,

handlers/templates.go

@@ -1,22 +0,0 @@
-package handlers
-
-import (
-	"html/template"
-	"io"
-
-	"github.com/labstack/echo/v4"
-)
-
-type TemplateRenderer struct {
-	tmpls *template.Template
-}
-
-var Renderer = &TemplateRenderer{tmpls: template.New("")}
-
-func (t *TemplateRenderer) Render(w io.Writer, name string, data any, c echo.Context) error {
-	c.Logger().Debugf("rendering template %s", name)
-
-	tpl := getTmpl(name)
-
-	return tpl.Execute(w, data)
-}

modules/template/funcmap.go

@@ -0,0 +1,23 @@
+package template
+
+import "html/template"
+
+func FuncMap() template.FuncMap {
+	return template.FuncMap{
+		"ifIE":    func() template.HTML { return template.HTML("<!--[if IE]>") },
+		"endifIE": func() template.HTML { return template.HTML("<![endif]>") },
+		"htmlSafe": func(html string) template.HTML {
+			return template.HTML( //nolint:gosec
+				bluemondayPolicy.Sanitize(html),
+			)
+		},
+		"pageIs": func(want, got string) bool {
+			return want == got
+		},
+	}
+}
+
+// TODO: mimic https://github.com/drone/funcmap/blob/master/funcmap.go
+func setFuncMap(t *template.Template) { //nolint:unused
+	t.Funcs(FuncMap())
+}

modules/template/helper.go

@@ -0,0 +1,71 @@
+package template
+
+import (
+	"io/fs"
+	"path/filepath"
+)
+
+// globDir lists files inside a dir that match the suffix provided.
+func globDir(dir, suffix string) ([]string, error) {
+	files := []string{}
+
+	err := filepath.WalkDir(dir, func(path string, de fs.DirEntry, err error) error {
+		if de.IsDir() {
+			return nil
+		}
+
+		if filepath.Ext(path) == suffix {
+			files = append(files, path)
+		}
+
+		return nil
+	})
+
+	return files, err
+}
+
+// globFS lists files inside a dir of a fs that match the suffix provided.
+func globFS(fspls fs.FS, dir, suffix string) ([]string, error) {
+	files := []string{}
+
+	err := fs.WalkDir(fspls, dir, func(path string, de fs.DirEntry, err error) error {
+		if de.IsDir() {
+			return nil
+		}
+
+		if filepath.Ext(path) == suffix {
+			files = append(files, path)
+		}
+
+		return nil
+	})
+
+	return files, err
+}
+
+// listAll returns template file names as []string and panics on error.
+// uses filepath.WalkDir via glob* funcs. TODO: don't panic.
+func listAll(pattern string) []string {
+	files := make([]string, 0)
+
+	switch {
+	case !setting.IsLive():
+		f, err := globFS(tmplFS, ".", pattern)
+		if err != nil {
+			log.Errorf("error: %q", err)
+			panic(err)
+		}
+
+		files = f
+
+	case setting.IsLive():
+		f, err := globDir(tmplPath, pattern)
+		if err != nil {
+			panic(err)
+		}
+
+		files = f
+	}
+
+	return files
+}

modules/template/render.go

@@ -0,0 +1,22 @@
+package template
+
+import (
+	"html/template"
+	"io"
+
+	"github.com/labstack/echo/v4"
+)
+
+type TplRenderer struct {
+	tmpls *template.Template
+}
+
+var Renderer = &TplRenderer{tmpls: template.New("")}
+
+func (t *TplRenderer) Render(w io.Writer, name string, data any, c echo.Context) error {
+	c.Logger().Debugf("rendering template %s", name)
+
+	tpl := Get(name)
+
+	return tpl.Execute(w, data)
+}

modules/template/template.go

@@ -0,0 +1,142 @@
+package template
+
+import (
+	"html/template"
+	"io/fs"
+	"io/ioutil"
+	"strings"
+
+	"git.dotya.ml/mirre-mt/pcmt/app/settings"
+	"git.dotya.ml/mirre-mt/pcmt/slogging"
+	"github.com/microcosm-cc/bluemonday"
+	"golang.org/x/exp/slog"
+)
+
+type tplMap map[string]*template.Template
+
+var (
+	templateMap tplMap
+	// embedded templates.
+	tmplFS           fs.FS
+	bluemondayPolicy = bluemonday.UGCPolicy()
+	setting          *settings.Settings
+	// global logger.
+	slogger *slogging.Logger
+	// local logger copy.
+	log slogging.Logger
+	// path to "templates" folder (empty if LiveMode).
+	tmplPath   string
+	tmplSuffix = ".tmpl"
+)
+
+// Init saves settings and embedded templates to package-level state and also
+// "initialises" template rendering.
+func Init(s *settings.Settings, tmpls fs.FS) {
+	slogger = slogging.GetLogger()
+	log = *slogger // have a local copy.
+	log.Logger = log.Logger.With(
+		slog.Group("pcmt extra", slog.String("module", "modules/template")),
+	)
+
+	setting = s
+
+	tmplPath = setting.TemplatesPath() // will be empty if LiveMode.
+
+	initTemplates(tmpls)
+
+	log.Debug(Renderer.tmpls.DefinedTemplates())
+}
+
+// Get returns a template requested either from the tmplPath (in LiveMode) or
+// from the pre-compiled tmpl list set directly to Renderer.
+func Get(name string) *template.Template {
+	liveMode := setting.IsLive()
+
+	if liveMode {
+		log.Debug("re-reading tmpls") // TODO: only re-read the tmpl in question.
+
+		allTmpls := listAll(tmplSuffix)
+
+		// create fresh tmpl root.
+		t := template.New("")
+
+		for i, v := range allTmpls {
+			rawfile, err := ioutil.ReadFile(v)
+			if err != nil {
+				panic(err)
+			}
+
+			allTmpls[i] = strings.TrimPrefix(v, tmplPath+"/")
+
+			t = t.New(allTmpls[i]).Funcs(FuncMap())
+
+			template.Must(t.Parse(string(rawfile)))
+		}
+
+		Renderer.tmpls = t
+	}
+
+	return Renderer.tmpls.Lookup(name)
+}
+
+func initTemplates(f fs.FS) {
+	if !setting.IsLive() {
+		if f != nil || f != tmplFS {
+			tmplFS = f
+		}
+	}
+
+	allTmpls := listAll(tmplSuffix)
+	t := Renderer.tmpls
+
+	// ensure this fails at compile time, if at all ("Must").
+	if !setting.IsLive() {
+		for i, v := range allTmpls {
+			rawfile, err := fs.ReadFile(tmplFS, v)
+			if err != nil {
+				panic(err)
+			}
+
+			allTmpls[i] = strings.TrimPrefix(v, "templates/")
+
+			t := Renderer.tmpls.New(allTmpls[i]).Funcs(FuncMap())
+			template.Must(t.Parse(string(rawfile)))
+		}
+
+		Renderer.tmpls = t
+	} else {
+		for i, v := range allTmpls {
+			rawfile, err := ioutil.ReadFile(v)
+			if err != nil {
+				panic(err)
+			}
+
+			allTmpls[i] = strings.TrimPrefix(v, tmplPath+"/")
+			t = Renderer.tmpls.New(allTmpls[i]).Funcs(FuncMap())
+
+			template.Must(t.Parse(string(rawfile)))
+		}
+
+		Renderer.tmpls = t
+	}
+
+	makeTplMap(Renderer.tmpls, allTmpls)
+}
+
+func makeTplMap(tpl *template.Template, tplList []string) {
+	allTmpls := tplList
+
+	var tp tplMap
+
+	if templateMap == nil {
+		tp = make(tplMap, len(allTmpls))
+	} else {
+		tp = templateMap
+	}
+
+	for _, v := range allTmpls {
+		tp[v] = tpl.Lookup(v)
+	}
+
+	templateMap = tp
+}