func ParseImageURI()

in ecr/ref.go [70:135]
46 lines of code
9 McCabe index (conditional complexity)

func ParseImageURI(input string) (ECRSpec, error) {
	input = strings.TrimPrefix(input, "https://")

	// Matching on account, region
	matches := ecrRegex.FindStringSubmatch(input)
	if len(matches) < 3 {
		return ECRSpec{}, errInvalidImageURI
	}
	account := matches[1]
	region := matches[2]

	// Get the correct partition given its region
	partition, found := endpoints.PartitionForRegion(endpoints.DefaultPartitions(), region)
	if !found {
		return ECRSpec{}, errInvalidImageURI
	}

	// Need to include the full repository path and the imageID (e.g. /eks/image-name:tag)
	tokens := strings.SplitN(input, "/", 2)
	if len(tokens) != 2 {
		return ECRSpec{}, errInvalidImageURI
	}

	fullRepoPath := tokens[len(tokens)-1]
	// Run simple checks on the provided repository.
	switch {
	case
		// Must not be empty
		fullRepoPath == "",
		// Must not have a partial/unsupplied label
		strings.HasSuffix(fullRepoPath, ":"),
		// Must not have a partial/unsupplied digest specifier
		strings.HasSuffix(fullRepoPath, "@"):
		return ECRSpec{}, errors.New("incomplete reference provided")
	}

	// Parse out image reference's to validate.
	ref, err := reference.Parse(repositoryPrefix + fullRepoPath)
	if err != nil {
		return ECRSpec{}, err
	}
	// If the digest is provided, check that it is valid.
	if ref.Digest() != "" {
		err := ref.Digest().Validate()
		// Digest may not be supported by the client despite it passing against
		// a rudimentary check. The error is different in the passing case, so
		// that's considered a passing check for unavailable digesters.
		//
		// https://github.com/opencontainers/go-digest/blob/ea51bea511f75cfa3ef6098cc253c5c3609b037a/digest.go#L110-L115
		if err != nil && err != digest.ErrDigestUnsupported {
			return ECRSpec{}, errors.Wrap(err, errInvalidImageURI.Error())
		}
	}

	return ECRSpec{
		Repository: strings.TrimPrefix(ref.Locator, repositoryPrefix),
		Object:     ref.Object,
		arn: arn.ARN{
			Partition: partition.ID(),
			Service:   arnServiceID,
			Region:    region,
			AccountID: account,
			Resource:  ref.Locator,
		},
	}, nil
}