package genny

import (
	"github.com/markbates/safe"
	"github.com/pkg/errors"
)

type TransformerFn func(File) (File, error)

type Transformer struct {
	Ext      string
	StripExt bool
	fn       TransformerFn
}

func (t Transformer) Transform(f File) (File, error) {
	if !HasExt(f, t.Ext) {
		return f, nil
	}
	if t.fn == nil {
		return f, nil
	}
	err := safe.RunE(func() error {
		var e error
		f, e = t.fn(f)
		if e != nil {
			return errors.WithStack(e)
		}
		return nil
	})
	if err != nil {
		return f, errors.WithStack(err)
	}
	if t.StripExt {
		return StripExt(f, t.Ext), nil
	}
	return f, nil
}

func NewTransformer(ext string, fn TransformerFn) Transformer {
	return Transformer{
		Ext: ext,
		fn:  fn,
	}
}