// ProviderClient stores details that are required to interact with any
// services within a specific provider's API.
//
// Generally, you acquire a ProviderClient by calling the NewClient method in
// the appropriate provider's child package, providing whatever authentication
// credentials are required.
type ProviderClient struct {
	// IdentityBase is the base URL used for a particular provider's identity
	// service - it will be used when issuing authenticatation requests. It
	// should point to the root resource of the identity service, not a specific
	// identity version.
	IdentityBase string

	// IdentityEndpoint is the identity endpoint. This may be a specific version
	// of the identity service. If this is the case, this endpoint is used rather
	// than querying versions first.
	IdentityEndpoint string

	// TokenID is the ID of the most recently issued valid token.
	TokenID string

	// EndpointLocator describes how this provider discovers the endpoints for
	// its constituent services.
	EndpointLocator EndpointLocator

	// HTTPClient allows users to interject arbitrary http, https, or other transit behaviors.
	HTTPClient http.Client

	// UserAgent represents the User-Agent header in the HTTP request.
	UserAgent UserAgent

	// ReauthFunc is the function used to re-authenticate the user if the request
	// fails with a 401 HTTP response code. This a needed because there may be multiple
	// authentication functions for different Identity service versions.
	ReauthFunc func() error

	Debug bool
}

// Request performs an HTTP request using the ProviderClient's current HTTPClient. An authentication
// header will automatically be provided.
func (client *ProviderClient) Request(method, url string, options *RequestOpts) (*http.Response, error) 

// ServiceClient stores details required to interact with a specific service API implemented by a provider.
// Generally, you'll acquire these by calling the appropriate `New` method on a ProviderClient.
type ServiceClient struct {
	// ProviderClient is a reference to the provider that implements this service.
	*ProviderClient

	// Endpoint is the base URL of the service's API, acquired from a service catalog.
	// It MUST end with a /.
	Endpoint string

	// ResourceBase is the base URL shared by the resources within a service's API. It should include
	// the API version and, like Endpoint, MUST end with a / if set. If not set, the Endpoint is used
	// as-is, instead.
	ResourceBase string

	// This is the service client type (e.g. compute, sharev2).
	// NOTE: FOR INTERNAL USE ONLY. DO NOT SET. GOPHERCLOUD WILL SET THIS.
	// It is only exported because it gets set in a different package.
	Type string

	// The microversion of the service to use. Set this to use a particular microversion.
	Microversion string
}

// NewComputeV2 creates a ServiceClient that may be used with the v2 compute
// package.
func NewComputeV2(client *gophercloud.ProviderClient, eo gophercloud.EndpointOpts) (*gophercloud.ServiceClient, error) {
	return initClientOpts(client, eo, "compute")
}

// NewNetworkV2 creates a ServiceClient that may be used with the v2 network
// package.
func NewNetworkV2(client *gophercloud.ProviderClient, eo gophercloud.EndpointOpts) (*gophercloud.ServiceClient, error) {
	sc, err := initClientOpts(client, eo, "network")
	sc.ResourceBase = sc.Endpoint + "v2.0/"
	return sc, err
}

// NewBlockStorageV1 creates a ServiceClient that may be used to access the v1
// block storage service.
func NewBlockStorageV1(client *gophercloud.ProviderClient, eo gophercloud.EndpointOpts) (*gophercloud.ServiceClient, error) {
	return initClientOpts(client, eo, "volume")
}

A basic example of using this would be:
	ao, err := openstack.AuthOptionsFromEnv()
	provider, err := openstack.NewClient(ao.IdentityEndpoint)
	client, err := openstack.NewIdentityV3(provider, gophercloud.EndpointOpts{})
*/
func NewClient(endpoint string) (*gophercloud.ProviderClient, error)

// Create will create a new Volume based on the values in CreateOpts. To extract
// the Volume object from the response, call the Extract method on the
// CreateResult.
func Create(client *gophercloud.ServiceClient, opts CreateOptsBuilder) (r CreateResult) {
	b, err := opts.ToVolumeCreateMap()
	if err != nil {
		r.Err = err
		return
	}
	_, r.Err = client.Post(createURL(client), b, &r.Body, &gophercloud.RequestOpts{
		OkCodes: []int{202},
	})
	return
}

func createURL(c *gophercloud.ServiceClient) string {
	return c.ServiceURL("volumes")
}

        v3Client, err := NewIdentityV3(client, eo)
	if err != nil {
		return err
	}

	if endpoint != "" {
		v3Client.Endpoint = endpoint
	}

	result := tokens3.Create(v3Client, opts)

	token, err := result.ExtractToken()
	if err != nil {
		return err
	}

	catalog, err := result.ExtractServiceCatalog()
	if err != nil {
		return err
	}

	client.TokenID = token.ID

	if opts.CanReauth() {
		client.ReauthFunc = func() error {
			client.TokenID = ""
			return v3auth(client, endpoint, opts, eo)
		}
	}
	client.EndpointLocator = func(opts gophercloud.EndpointOpts) (string, error) {
		return V3EndpointURL(catalog, opts)
	}

for _, entry := range catalog.Entries {
		if (entry.Type == opts.Type) && (opts.Name == "" || entry.Name == opts.Name) {
			for _, endpoint := range entry.Endpoints {
				if opts.Availability != gophercloud.AvailabilityAdmin &&
					opts.Availability != gophercloud.AvailabilityPublic &&
					opts.Availability != gophercloud.AvailabilityInternal {
					err := &ErrInvalidAvailabilityProvided{}
					err.Argument = "Availability"
					err.Value = opts.Availability
					return "", err
				}
				if (opts.Availability == gophercloud.Availability(endpoint.Interface)) &&
					(opts.Region == "" || endpoint.Region == opts.Region) {
					endpoints = append(endpoints, endpoint)
				}
			}
		}
	}

func initClientOpts(client *gophercloud.ProviderClient, eo gophercloud.EndpointOpts, clientType string) (*gophercloud.ServiceClient, error) {
    sc := new(gophercloud.ServiceClient)
	eo.ApplyDefaults(clientType)
	url, err := client.EndpointLocator(eo)
	if err != nil {
		return sc, err
	}
	sc.ProviderClient = client
	sc.Endpoint = url
	sc.Type = clientType
	return sc, nil
}

// ResourceBaseURL returns the base URL of any resources used by this service. It MUST end with a /.
func (client *ServiceClient) ResourceBaseURL() string {
	if client.ResourceBase != "" {
		return client.ResourceBase
	}
	return client.Endpoint
}

// ServiceURL constructs a URL for a resource belonging to this provider.
func (client *ServiceClient) ServiceURL(parts ...string) string {
	return client.ResourceBaseURL() + strings.Join(parts, "/")
}