package ui

import "io"

var _ Resources = &fallbackResources{}

type fallbackResources struct {
	resources Resources
	fallback  Resources
}

// NewFallbackResources creates a Resources that first will try to access resources and on failure will try to access the fallback resources. Will take ownership of both resources (Destroy).
func NewFallbackResources(resources, fallback Resources) Resources {
	return &fallbackResources{resources, fallback}
}

func (r *fallbackResources) OpenResource(name string) (io.ReadCloser, error) {
	if reader, err := r.resources.OpenResource(name); err == nil {
		return reader, nil
	}
	return r.fallback.OpenResource(name)
}

func (r *fallbackResources) Destroy() error {
	errResources := r.resources.Destroy()
	errFallback := r.fallback.Destroy()
	if errResources != nil {
		return errResources
	}
	if errFallback != nil {
		return errFallback
	}
	return nil
}