package useCases

import (
	"RenewCMS/internal/domain/image"
	"context"
)

func (u *ServeVariantUseCase) Generate(ctx context.Context, variant image.Variant, storedName string) (image.VariantFile, error) {
	source, err := u.storage.Open(storedName)
	if err != nil {
		return image.VariantFile{}, err
	}
	defer source.Content.Close()

	if servedAsIs(storedName, source.Content) {
		return image.VariantFile{}, image.ErrVariantSourceUnsupported
	}
	if source.Size > u.maxSourceBytes {
		return image.VariantFile{}, image.ErrSourceTooLarge
	}

	settings := variant.Settings()
	fingerprint := settings.Fingerprint()
	served, existing, hit, err := u.lookupCached(variant.Name, storedName, fingerprint, image.VariantETag(settings, storedName))
	if err != nil {
		return image.VariantFile{}, err
	}
	if hit {
		_ = served.Content.Close()
		return existing, nil
	}
	return u.generated(ctx, variant, storedName, fingerprint, existing)
}