Files
kgpz_web/templating/layout_registry.go
2024-11-22 00:35:27 +01:00

109 lines
2.6 KiB
Go

package templating
import (
"html/template"
"io/fs"
"sync"
"github.com/Theodor-Springmann-Stiftung/kgpz_web/helpers"
"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
}
func NewLayoutRegistry(routes fs.FS) *LayoutRegistry {
return &LayoutRegistry{
layoutsFS: routes,
}
}
// 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))
}
func (r *LayoutRegistry) Reset() error {
r.cache.Clear()
r.once = sync.Once{}
return nil
}
func (r *LayoutRegistry) Load() error {
r.once.Do(func() {
err := r.load()
helpers.Assert(err, "Error loading layouts. Exiting.")
})
return nil
}
func (r *LayoutRegistry) load() 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, funcmap *template.FuncMap) (*template.Template, error) {
cached, ok := r.cache.Load(name)
if ok {
return cached.(*template.Template), nil
}
// TODO: What todo on errors?
r.Load()
context, ok := r.layouts[name]
if !ok {
return nil, NewError(NoTemplateError, name)
}
t, err := context.Template(r.layoutsFS, funcmap)
if err != nil {
return nil, err
}
r.cache.Store(name, t)
return t, nil
}
func (r *LayoutRegistry) Default(funcmap *template.FuncMap) (*template.Template, error) {
return r.Layout(DEFAULT_LAYOUT_NAME, funcmap)
}