added views

templating/layout_registry.go

@@ -0,0 +1,113 @@
+package templating
+
+import (
+	"fmt"
+	"html/template"
+	"io/fs"
+	"sync"
+
+	"github.com/yalue/merged_fs"
+)
+
+// TODO: Implement Handler interface, maybe in template? But then template would need to know about the layout registry
+// Function signature: func (t *templateHandler) ServeHTTP(w http.ResponseWriter, r *http.Request)
+// A static Handler could incoporate both the layout registry and the template registry and serve templates that dont need any data
+// INFO: this ist thread-safe and safe to call in a handler or middleware
+type LayoutRegistry struct {
+	layoutsFS fs.FS
+	once      sync.Once
+	// INFO: Layout & cache keys are template directory names
+	layouts map[string]TemplateContext
+	// WARNING: maybe this is too early for caching?
+	cache sync.Map
+	funcs template.FuncMap
+}
+
+func NewLayoutRegistry(routes fs.FS) *LayoutRegistry {
+	return &LayoutRegistry{
+		layoutsFS: routes,
+		funcs: template.FuncMap{
+			"safe": func(s string) template.HTML {
+				return template.HTML(s)
+			},
+		},
+	}
+}
+
+// NOTE: Upon registering a new layout dir, we return a new LayoutRegistry
+func (r *LayoutRegistry) Register(fs fs.FS) *LayoutRegistry {
+	return NewLayoutRegistry(merged_fs.MergeMultiple(fs, r.layoutsFS))
+}
+
+// TODO: Funcs are not used in executing the templates yet
+func (r *LayoutRegistry) RegisterFuncs(funcs template.FuncMap) {
+	for k, v := range funcs {
+		r.funcs[k] = v
+	}
+}
+
+func (r *LayoutRegistry) Parse() error {
+	layouts := make(map[string]TemplateContext)
+	rootcontext := NewTemplateContext(".")
+	err := rootcontext.Parse(r.layoutsFS)
+	if err != nil {
+		return err
+	}
+
+	globals := rootcontext.Globals()
+
+	entries, err := fs.ReadDir(r.layoutsFS, ".")
+	if err != nil {
+		return NewError(FileAccessError, ".")
+	}
+
+	for _, e := range entries {
+		if !e.IsDir() || e.Name() == TEMPLATE_COMPONENT_DIRECTORY {
+			continue
+		}
+
+		url := FSPathToPath(e.Name())
+		context := NewTemplateContext(url)
+		context.SetGlobals(globals)
+		context.Parse(r.layoutsFS)
+
+		layouts[e.Name()] = context
+	}
+
+	r.layouts = layouts
+	return nil
+}
+
+func (r *LayoutRegistry) Layout(name string) (*template.Template, error) {
+	cached, ok := r.cache.Load(name)
+	if ok {
+		return cached.(*template.Template), nil
+	}
+
+	// TODO: What todo on errors?
+	r.once.Do(func() {
+		err := r.Parse()
+		if err != nil {
+			fmt.Println(err)
+			panic(-1)
+		}
+	})
+
+	context, ok := r.layouts[name]
+	if !ok {
+		return nil, NewError(NoTemplateError, name)
+	}
+
+	t, err := context.Template(r.layoutsFS)
+	if err != nil {
+		return nil, err
+	}
+
+	r.cache.Store(name, t)
+
+	return t, nil
+}
+
+func (r *LayoutRegistry) Default() (*template.Template, error) {
+	return r.Layout(DEFAULT_LAYOUT_NAME)
+}