package templ

import (
	"embed"
	"html/template"
	"sync"
)

//go:embed *.tpl
var fs embed.FS

var templates = make(map[string]*template.Template)
var muTpl sync.RWMutex

var baseTpl *template.Template

func init() {
	baseTpl = template.Must(template.ParseFS(fs, "base.tpl"))
}

func Lookup(name string) *template.Template {
	muTpl.RLock()
	tpl := templates[name]
	muTpl.RUnlock()

	if tpl == nil {
		return parse(name)
	}
	return tpl
}

func parse(name string) *template.Template {
	muTpl.Lock()
	defer muTpl.Unlock()

	if tpl := templates[name]; tpl != nil {
		// might've been created by another goroutine
		return tpl
	}

	b := template.Must(baseTpl.Clone())
	t := template.Must(b.ParseFS(fs, name+".tpl"))
	templates[name] = t
	return t
}