package zim

import "github.com/pkg/errors"

func (z *ZimReader) Favicon() (*Article, error) {
	illustration, err := z.getMetadataIllustration()
	if err != nil && !errors.Is(err, ErrNotFound) {
		return nil, errors.WithStack(err)
	}

	if illustration != nil {
		return illustration, nil
	}

	namespaces := []string{"-", "I"}
	entryNames := []string{"favicon", "favicon.png"}

	for _, ns := range namespaces {
		for _, en := range entryNames {
			article, err := z.GetPageNoIndex(ns + "/" + en)
			if err != nil && !errors.Is(err, ErrNotFound) {
				return nil, errors.WithStack(err)
			}

			if article != nil {
				return article, nil
			}
		}
	}

	return nil, errors.WithStack(ErrNotFound)
}

func (z *ZimReader) getMetadataIllustration() (*Article, error) {
	metadata, err := z.Metadata(MetadataIllustration96x96at2, MetadataIllustration48x48at1)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	if _, exists := metadata[MetadataIllustration96x96at2]; exists {
		return z.GetPageNoIndex("M/" + string(MetadataIllustration96x96at2))
	}

	if _, exists := metadata[MetadataIllustration48x48at1]; exists {
		return z.GetPageNoIndex("M/" + string(MetadataIllustration48x48at1))
	}

	return nil, errors.WithStack(ErrNotFound)
}