custom: Allow override of home page

internal/dis/component/control/home/home.html

@@ -6,11 +6,13 @@
 {{ end }}
 
 {{ define "content" }}
+{{ block "@custom/about" . }}
 <div class="pure-u-1">
     <p>
         For more information, see <a href="{{ .SelfRedirect }}">{{ .SelfRedirect }}</a>.
     </p>
 </div>
+{{ end }}
 
 <div class="pure-u-1">
     <h2>WissKIs on this Distillery</h2>

internal/dis/component/control/static/custom/assets.go

@@ -11,8 +11,8 @@ func (custom *Custom) CustomAssetsPath() string {
 	return filepath.Join(custom.Config.DeployRoot, "core", "assets")
 }
 
-func (custom *Custom) FooterPath() string {
+func (custom *Custom) CustomAssetPath(name string) string {
-	return filepath.Join(custom.CustomAssetsPath(), "footer.html")
+	return filepath.Join(custom.CustomAssetsPath(), name)
 }
 
 func (custom *Custom) BackupName() string { return "custom" }

internal/dis/component/control/static/custom/template.go

@@ -8,35 +8,56 @@ import (
 	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
-const footerName = "footer"
+const (
+	footerName = "@custom/footer"
+	aboutName  = "@custom/about"
+)
 
 //go:embed "footer.html"
-var defaultTemplateStr string
+var footerTemplateStr string
-var defaultTemplate = template.Must(template.New("footer.html").Parse(defaultTemplateStr))
+var defaultFooterTemplate = template.Must(template.New("footer.html").Parse(footerTemplateStr))
 
 // Template creates a copy of template with shared template parts updated accordingly.
 // Any template using this should use one of the template contexts in this package.
 func (custom *Custom) Template(tpl *template.Template) *template.Template {
-	tree := custom.footerTemplate()
+	// create a clone of the template
+	clone := template.Must(tpl.Clone())
 
-	clone := template.Must(tpl.Clone())                 // create a clone of the template
+	// add all the fixed parse trees
-	template.Must(clone.AddParseTree(footerName, tree)) // add the parse tree to it
+	footerTree := custom.getTemplateAsset(defaultFooterTemplate)
+	template.Must(clone.AddParseTree(footerName, footerTree))
+
+	// optionally add the about asset
+	if aboutTree := custom.readTemplateAsset("about.html"); clone.Lookup(aboutName) != nil && aboutTree != nil {
+		template.Must(clone.AddParseTree(aboutName, aboutTree))
+	}
 	return clone // and return the tree
 }
 
-// footerTemplate returns a new copy of the footer template
+// getTemplateAsset returns an overridable template asset.
-func (custom *Custom) footerTemplate() *parse.Tree {
+//
-	footer, err := (func() (*template.Template, error) {
+// If the asset named can successfully be parsed, it is returned.
-		data, err := environment.ReadFile(custom.Environment, custom.FooterPath())
+// If it can not be parsed, the default template is returned.
+func (custom *Custom) getTemplateAsset(dflt *template.Template) *parse.Tree {
+	tree := custom.readTemplateAsset(dflt.Name())
+	if tree == nil {
+		return dflt.Tree.Copy()
+	}
+	return tree
+}
+
+// readTemplateAsset is like getTemplateAssets, but takes an explicit name to read.
+// when the asset does not exist, or cannot be opened, returns nil.
+func (custom *Custom) readTemplateAsset(name string) *parse.Tree {
+	template, err := (func() (*template.Template, error) {
+		data, err := environment.ReadFile(custom.Environment, custom.CustomAssetPath(name))
 		if err != nil {
 			return nil, err
 		}
-		return template.New("footer.html").Parse(string(data))
+		return template.New(name).Parse(string(data))
 	})()
-
 	if err != nil {
-		return defaultTemplate.Tree.Copy()
+		return nil
 	}
-
+	return template.Tree
-	return footer.Tree
 }

internal/dis/component/control/static/templates/_base.html

@@ -21,8 +21,10 @@
     </main>
 
     <footer>
-        {{ block "footer" .BaseContext }}
+        {{ block "@custom/footer" .BaseContext }}
-            <!-- no footer -->
+            <div style="z-index:10000;position:fixed;top:0;left:0;width:100vh;height:100vw;background:red;text-align:center;padding:10vh 10vw;font-size:xx-large;font-weight:bold">
+                <code>.Custom.Template()</code> not called
+            </div>
         {{ end }}
     </footer>