package pongo

import (
	"fmt"
	"io"
	"io/fs"

	"github.com/flosch/pongo2/v6"
)

// fsLoader adapts an fs.FS to pongo2's TemplateLoader interface.
type fsLoader struct {
	fsys fs.FS
}

func (l *fsLoader) Abs(base, name string) string {
	return name
}

func (l *fsLoader) Get(path string) (io.Reader, error) {
	return l.fsys.Open(path)
}

// multiLoader chains multiple loaders, returning the first hit.
// Plugin templates can {% extends "base.html" %} where base.html
// lives in the core embedded FS rather than the plugin FS.
type multiLoader struct {
	loaders []pongo2.TemplateLoader
}

func (l *multiLoader) Abs(base, name string) string {
	return name
}

func (l *multiLoader) Get(path string) (io.Reader, error) {
	for _, loader := range l.loaders {
		r, err := loader.Get(path)
		if err == nil {
			return r, nil
		}
	}
	return nil, fmt.Errorf("pongo: template %q not found in any loader", path)
}