package core

import (
	"fmt"
	"html/template"
	"io/fs"
	"path"
)

// LoadTemplates parses each views/*.html into its own tree alongside every
// layouts/*.html. Returns a set keyed by view filename.
//
// Placeholder funcs are installed at parse time; the real ones are bound
// per render, when a Ctx exists to close over.
func LoadTemplates(fsys fs.FS) (TemplateSet, error) {
	layouts, err := fs.Glob(fsys, "layouts/*.html")
	if err != nil {
		return nil, err
	}
	views, err := fs.Glob(fsys, "views/*.html")
	if err != nil {
		return nil, err
	}
	if len(views) == 0 {
		return nil, fmt.Errorf("no templates under views/")
	}

	set := TemplateSet{}
	for _, v := range views {
		name := path.Base(v)
		t := template.New(name).Funcs(FuncMap(&Ctx{}))
		files := append(append([]string{}, layouts...), v)
		if t, err = t.ParseFS(fsys, files...); err != nil {
			return nil, fmt.Errorf("parse %s: %w", v, err)
		}
		set[name] = t
	}
	return set, nil
}