From 810628aa70a03ba71b3f2adba188ed9256e28229 Mon Sep 17 00:00:00 2001
From: Peter Sanchez <peter@netlandish.com>
Date: Mon, 4 Mar 2024 18:32:49 -0600
Subject: [PATCH] Adding proper template rendering instead of full template
 mashup

---
 server/server.go     | 25 ++++++++++++++
 validate/template.go | 78 +++++++++++++++++++++++++++++++++++---------
 2 files changed, 88 insertions(+), 15 deletions(-)

diff --git a/server/server.go b/server/server.go
index ae88a3f..f0f82e5 100644
--- a/server/server.go
+++ b/server/server.go
@@ -129,6 +129,31 @@ func (c *Context) Render(code int, name string, data interface{}) (err error) {
 	return c.HTMLBlob(code, buf.Bytes())
 }
 
+// RenderTemplate is like Render except it accepts a *template.Template instance
+// to render from.
+func (c *Context) RenderTemplate(
+	tmpl *template.Template, code int, name string, data interface{}) (err error) {
+	if c.Server.e.Renderer == nil {
+		return echo.ErrRendererNotRegistered
+	}
+	vtmpl := c.Server.e.Renderer.(*validate.Template)
+	buf := new(bytes.Buffer)
+	if err = vtmpl.RenderTemplate(tmpl, buf, name, data, c); err != nil {
+		return
+	}
+	return c.HTMLBlob(code, buf.Bytes())
+}
+
+// NewTemplate will return a new template.Template instance based on the
+// current templateBase (see validate.Template)
+func (c *Context) NewTemplate(tfs fs.FS, filenames ...string) (*template.Template, error) {
+	if c.Server.e.Renderer == nil {
+		return nil, echo.ErrRendererNotRegistered
+	}
+	vtmpl := c.Server.e.Renderer.(*validate.Template)
+	return vtmpl.New(tfs, filenames...)
+}
+
 // Error is needed because otherwise it will send an instance of
 // *echo.context, and we want the user info, etc. from the gobwebs
 // Context struct
diff --git a/validate/template.go b/validate/template.go
index 60cd80a..22cbcaa 100644
--- a/validate/template.go
+++ b/validate/template.go
@@ -9,9 +9,6 @@ import (
 	"github.com/labstack/echo/v4"
 	"github.com/labstack/echo/v4/middleware"
 	"netlandish.com/x/gobwebs"
-
-	// Postgres
-	_ "github.com/lib/pq"
 )
 
 type (
@@ -24,16 +21,47 @@ type (
 
 	// Template defines the template registry struct
 	Template struct {
-		templates *template.Template
+		templateBase *template.Template
+		templates    *template.Template
 
 		staticMap   Map
 		staticFuncs []func(c echo.Context) Map
+		cloned      bool
 	}
 )
 
 // NewTemplate returns a *Template instance
 func NewTemplate() *Template {
-	return &Template{templates: template.New(""), staticMap: make(Map)}
+	return &Template{
+		templateBase: template.New(""),
+		templates:    template.New(""),
+		staticMap:    make(Map),
+	}
+}
+
+// New will return a clone of `t.templateBase` having
+// already parsed the given files. This is used when you don't want to use
+// the larger mix of already processed templates.
+func (t *Template) New(tfs fs.FS, filenames ...string) (*template.Template, error) {
+	tmpl, err := t.CloneBase()
+	if err != nil {
+		return nil, err
+	}
+	if tfs != nil {
+		tmpl, err = tmpl.ParseFS(tfs, filenames...)
+	} else {
+		tmpl, err = tmpl.ParseFiles(filenames...)
+	}
+	if err != nil {
+		return nil, err
+	}
+	return tmpl, nil
+}
+
+// Clone will clone the `t.templateBase` Template to ensure all added static
+// funcs and variables are available
+func (t *Template) CloneBase() (*template.Template, error) {
+	return t.templateBase.Clone()
 }
 
 // Templates returns local *template.Template object
@@ -74,42 +102,62 @@ func (t *Template) tmplPayload(c echo.Context, data Map) (Map, error) {
 	return input, nil
 }
 
-// Render implements e.Renderer interface
-func (t *Template) Render(w io.Writer, name string, data any, c echo.Context) error {
+func (t *Template) render(
+	tmpl *template.Template, w io.Writer, name string, data any, c echo.Context) error {
 	// Add global methods if data is a map. Should be reached 99% of time
 	if viewContext, ok := data.(Map); ok {
 		input, err := t.tmplPayload(c, viewContext)
 		if err != nil {
 			return err
 		}
-		return t.templates.ExecuteTemplate(w, name, input)
+		return tmpl.ExecuteTemplate(w, name, input)
 	}
-	return t.templates.ExecuteTemplate(w, name, data)
+	return tmpl.ExecuteTemplate(w, name, data)
+}
+
+// Render implements e.Renderer interface
+func (t *Template) Render(w io.Writer, name string, data any, c echo.Context) error {
+	return t.render(t.templates, w, name, data, c)
+}
+
+// RenderTemplate takes a *template.Template object and populates it's
+// context with the static values already provided by `t`.
+func (t *Template) RenderTemplate(
+	tmpl *template.Template, w io.Writer, name string, data any, c echo.Context) error {
+	return t.render(tmpl, w, name, data, c)
 }
 
 // LoadTemplates parses templates given the glob pattern path
 func (t *Template) LoadTemplates(path string, tfs fs.FS) error {
-	// XXX Why do we have to use the tmp var here?
 	var (
-		tmpt *template.Template
 		err  error
+		tmpl *template.Template
 	)
 
+	if !t.cloned {
+		vtmpl, err := t.CloneBase()
+		if err != nil {
+			return err
+		}
+		t.templates = vtmpl
+		t.cloned = true
+	}
+
 	if tfs != nil {
-		tmpt, err = t.templates.ParseFS(tfs, path)
+		tmpl, err = t.templates.ParseFS(tfs, path)
 	} else {
-		tmpt, err = t.templates.ParseGlob(path)
+		tmpl, err = t.templates.ParseGlob(path)
 	}
 	if err != nil {
 		return err
 	}
-	t.templates = tmpt
+	t.templates = tmpl
 	return nil
 }
 
 // AddFuncs adds template functions to the rendering template
 func (t *Template) AddFuncs(funcs template.FuncMap) {
-	t.templates = t.templates.Funcs(funcs)
+	t.templateBase.Funcs(funcs)
 }
 
 // AddStaticFunc adds a function to be called when building the default
-- 
2.45.2