// getDisks builds the raw spec for the disks that should be attached to
// the new instances and returns it. This will always include a root
// disk with characteristics determined by the provides args and
// constraints.
func getDisks(spec *instances.InstanceSpec, cons constraints.Value, os jujuos.OSType) ([]google.DiskSpec, error) {
	size := common.MinRootDiskSizeGiB
	if cons.RootDisk != nil && *cons.RootDisk > size {
		size = common.MiBToGiB(*cons.RootDisk)
	}
	var imageURL string
	switch os {
	case jujuos.Ubuntu:
		imageURL = ubuntuImageBasePath
	case jujuos.Windows:
		imageURL = windowsImageBasePath
	default:
		return nil, errors.Errorf("os %s is not supported on the gce provider", os.String())
	}
	dSpec := google.DiskSpec{
		SizeHintGB: size,
		ImageURL:   imageURL + spec.Image.Id,
		Boot:       true,
		AutoDelete: true,
	}
	if cons.RootDisk != nil && dSpec.TooSmall() {
		msg := "Ignoring root-disk constraint of %dM because it is smaller than the GCE image size of %dG"
		logger.Infof(msg, *cons.RootDisk, google.MinDiskSizeGB)
	}
	return []google.DiskSpec{dSpec}, nil
}

func (VsphereRenderer) EncodeUserdata(udata []byte, os jujuos.OSType) ([]byte, error) {
	switch os {
	case jujuos.Ubuntu, jujuos.CentOS:
		return renderers.ToBase64(udata), nil
	default:
		return nil, errors.Errorf("Cannot encode userdata for OS: %s", os.String())
	}
}

func (CloudSigmaRenderer) Render(cfg cloudinit.CloudConfig, os jujuos.OSType) ([]byte, error) {
	switch os {
	case jujuos.Ubuntu, jujuos.CentOS:
		return renderers.RenderYAML(cfg, renderers.ToBase64)
	default:
		return nil, errors.Errorf("Cannot encode userdata for OS: %s", os.String())
	}
}

// getMetadata builds the raw "user-defined" metadata for the new
// instance (relative to the provided args) and returns it.
func getMetadata(args environs.StartInstanceParams, os jujuos.OSType) (map[string]string, error) {
	userData, err := providerinit.ComposeUserData(args.InstanceConfig, nil, GCERenderer{})
	if err != nil {
		return nil, errors.Annotate(err, "cannot make user data")
	}
	logger.Debugf("GCE user data; %d bytes", len(userData))

	metadata := make(map[string]string)
	if isController(args.InstanceConfig) {
		metadata[metadataKeyIsState] = metadataValueTrue
	} else {
		metadata[metadataKeyIsState] = metadataValueFalse
	}
	switch os {
	case jujuos.Ubuntu:
		// We store a gz snapshop of information that is used by
		// cloud-init and unpacked in to the /var/lib/cloud/instances folder
		// for the instance. Due to a limitation with GCE and binary blobs
		// we base64 encode the data before storing it.
		metadata[metadataKeyCloudInit] = string(userData)
		// Valid encoding values are determined by the cloudinit GCE data source.
		// See: http://cloudinit.readthedocs.org
		metadata[metadataKeyEncoding] = "base64"

		authKeys, err := google.FormatAuthorizedKeys(args.InstanceConfig.AuthorizedKeys, "ubuntu")
		if err != nil {
			return nil, errors.Trace(err)
		}

		metadata[metadataKeySSHKeys] = authKeys
	case jujuos.Windows:
		metadata[metadataKeyWindowsUserdata] = string(userData)

		validChars := append(utils.UpperAlpha, append(utils.LowerAlpha, utils.Digits...)...)

		// The hostname must have maximum 15 characters
		winHostname := "juju" + utils.RandomString(11, validChars)
		metadata[metadataKeyWindowsSysprep] = fmt.Sprintf(winSetHostnameScript, winHostname)
	default:
		return nil, errors.Errorf("cannot pack metadata for os %s on the gce provider", os.String())
	}

	return metadata, nil
}