package image

import (
	"strings"

	"github.com/containers/image/docker/reference"
	"github.com/pkg/errors"
)

// imageParts describes the parts of an image's name
type imageParts struct {
	unnormalizedRef reference.Named // WARNING: Did not go through docker.io[/library] normalization
	registry        string
	name            string
	tag             string
	isTagged        bool
	hasRegistry     bool
}

// Registries must contain a ":" or a "." or be localhost
func isRegistry(name string) bool {
	return strings.ContainsAny(name, ".:") || name == "localhost"
}

// GetImageBaseName uses decompose and string splits to obtain the base
// name of an image.  Doing this here because it beats changing the
// imageParts struct names to be exported as well.
func GetImageBaseName(input string) (string, error) {
	decomposedImage, err := decompose(input)
	if err != nil {
		return "", err
	}
	splitImageName := strings.Split(decomposedImage.name, "/")
	return splitImageName[len(splitImageName)-1], nil
}

// decompose breaks an input name into an imageParts description
func decompose(input string) (imageParts, error) {
	var (
		parts       imageParts
		hasRegistry bool
		tag         string
	)
	imgRef, err := reference.Parse(input)
	if err != nil {
		return parts, err
	}
	unnormalizedNamed := imgRef.(reference.Named)
	ntag, isTagged := imgRef.(reference.NamedTagged)
	if !isTagged {
		tag = "latest"
		if _, hasDigest := imgRef.(reference.Digested); hasDigest {
			tag = "none"
		}
	} else {
		tag = ntag.Tag()
	}
	registry := reference.Domain(unnormalizedNamed)
	imageName := reference.Path(unnormalizedNamed)
	// Is this a registry or a repo?
	if isRegistry(registry) {
		hasRegistry = true
	} else {
		if registry != "" {
			imageName = registry + "/" + imageName
			registry = ""
		}
	}
	return imageParts{
		unnormalizedRef: unnormalizedNamed,
		registry:        registry,
		hasRegistry:     hasRegistry,
		name:            imageName,
		tag:             tag,
		isTagged:        isTagged,
	}, nil
}

// referenceWithRegistry returns a (normalized) reference.Named composed of ip (with !ip.hasRegistry)
// qualified with registry.
func (ip *imageParts) referenceWithRegistry(registry string) (reference.Named, error) {
	if ip.hasRegistry {
		return nil, errors.Errorf("internal error: referenceWithRegistry called on imageParts with a registry (%#v)", *ip)
	}
	// We could build a reference.WithName+WithTag/WithDigest here, but we need to round-trip via a string
	// and a ParseNormalizedNamed anyway to get the right normalization of docker.io/library, so
	// just use a string directly.
	qualified := registry + "/" + ip.unnormalizedRef.String()
	ref, err := reference.ParseNormalizedNamed(qualified)
	if err != nil {
		return nil, errors.Wrapf(err, "error normalizing registry+unqualified reference %#v", qualified)
	}
	return ref, nil
}