package s3key

import (
	"path"
	"strings"

	"git.sendico.io/tech/sxchnge/bff/pkg/merrors"
)

// Join confines an object reference to a relative S3 prefix.
func Join(prefix, reference string) (string, error) {
	cleanPrefix, err := cleanRelative(prefix, "prefix")
	if err != nil {
		return "", err
	}
	cleanReference, err := cleanRelative(reference, "obj_ref")
	if err != nil {
		return "", err
	}
	return path.Join(cleanPrefix, cleanReference), nil
}

func cleanRelative(value, argument string) (string, error) {
	value = strings.TrimSpace(value)
	for _, segment := range strings.Split(value, "/") {
		if segment == ".." {
			return "", merrors.InvalidArgument(argument+" is invalid", argument)
		}
	}
	clean := path.Clean(value)
	if value == "" || clean == "." || path.IsAbs(clean) || clean == ".." || strings.HasPrefix(clean, "../") {
		return "", merrors.InvalidArgument(argument+" is invalid", argument)
	}
	return clean, nil
}