// Auth performs an authentication request for a Swauth-based user.
func Auth(c *gophercloud.ProviderClient, opts AuthOptsBuilder) (r GetAuthResult) {
	h := make(map[string]string)

	if opts != nil {
		headers, err := opts.ToAuthOptsMap()
		if err != nil {
			r.Err = err
			return
		}

		for k, v := range headers {
			h[k] = v
		}
	}

	resp, err := c.Request("GET", getURL(c), &gophercloud.RequestOpts{
		MoreHeaders: h,
		OkCodes:     []int{200},
	})

	if resp != nil {
		r.Header = resp.Header
	}

	r.Err = err

	return r
}

// NewDBV1 creates a ServiceClient that may be used to access the v1 DB service.
func NewDBV1(client *gophercloud.ProviderClient, eo gophercloud.EndpointOpts) (*gophercloud.ServiceClient, error) {
	eo.ApplyDefaults("database")
	url, err := client.EndpointLocator(eo)
	if err != nil {
		return nil, err
	}
	return &gophercloud.ServiceClient{ProviderClient: client, Endpoint: url}, nil
}

// NewBlockStorageV2 creates a ServiceClient that may be used to access the v2 block storage service.
func NewBlockStorageV2(client *gophercloud.ProviderClient, eo gophercloud.EndpointOpts) (*gophercloud.ServiceClient, error) {
	eo.ApplyDefaults("volumev2")
	url, err := client.EndpointLocator(eo)
	if err != nil {
		return nil, err
	}
	return &gophercloud.ServiceClient{ProviderClient: client, Endpoint: url}, nil
}

// NewSharedFileSystemV2 creates a ServiceClient that may be used to access the v2 shared file system service.
func NewSharedFileSystemV2(client *gophercloud.ProviderClient, eo gophercloud.EndpointOpts) (*gophercloud.ServiceClient, error) {
	eo.ApplyDefaults("sharev2")
	url, err := client.EndpointLocator(eo)
	if err != nil {
		return nil, err
	}
	return &gophercloud.ServiceClient{ProviderClient: client, Endpoint: url}, nil
}

// NewImageServiceV2 creates a ServiceClient that may be used to access the v2 image service.
func NewImageServiceV2(client *gophercloud.ProviderClient, eo gophercloud.EndpointOpts) (*gophercloud.ServiceClient, error) {
	eo.ApplyDefaults("image")
	url, err := client.EndpointLocator(eo)
	if err != nil {
		return nil, err
	}
	return &gophercloud.ServiceClient{ProviderClient: client,
		Endpoint:     url,
		ResourceBase: url + "v2/"}, nil
}

// NewIdentityV3 creates a ServiceClient that may be used to access the v3 identity service.
func NewIdentityV3(client *gophercloud.ProviderClient, eo gophercloud.EndpointOpts) (*gophercloud.ServiceClient, error) {
	endpoint := client.IdentityBase + "v3/"
	var err error
	if !reflect.DeepEqual(eo, gophercloud.EndpointOpts{}) {
		eo.ApplyDefaults("identity")
		endpoint, err = client.EndpointLocator(eo)
		if err != nil {
			return nil, err
		}
	}

	return &gophercloud.ServiceClient{
		ProviderClient: client,
		Endpoint:       endpoint,
	}, nil
}

func v2auth(client *gophercloud.ProviderClient, endpoint string, options gophercloud.AuthOptions, eo gophercloud.EndpointOpts) error {
	v2Client, err := NewIdentityV2(client, eo)
	if err != nil {
		return err
	}

	if endpoint != "" {
		v2Client.Endpoint = endpoint
	}

	v2Opts := tokens2.AuthOptions{
		IdentityEndpoint: options.IdentityEndpoint,
		Username:         options.Username,
		Password:         options.Password,
		TenantID:         options.TenantID,
		TenantName:       options.TenantName,
		AllowReauth:      options.AllowReauth,
		TokenID:          options.TokenID,
	}

	result := tokens2.Create(v2Client, v2Opts)

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

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

	if options.AllowReauth {
		client.ReauthFunc = func() error {
			client.TokenID = ""
			return v2auth(client, endpoint, options, eo)
		}
	}
	client.TokenID = token.ID
	client.EndpointLocator = func(opts gophercloud.EndpointOpts) (string, error) {
		return V2EndpointURL(catalog, opts)
	}

	return nil
}

func v3auth(client *gophercloud.ProviderClient, endpoint string, opts tokens3.AuthOptionsBuilder, eo gophercloud.EndpointOpts) error {
	// Override the generated service endpoint with the one returned by the version endpoint.
	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)
	}

	return nil
}

func v3auth(client *gophercloud.ProviderClient, endpoint string, options gophercloud.AuthOptions, eo gophercloud.EndpointOpts) error {
	// Override the generated service endpoint with the one returned by the version endpoint.
	v3Client, err := NewIdentityV3(client, eo)
	if err != nil {
		return err
	}

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

	// copy the auth options to a local variable that we can change. `options`
	// needs to stay as-is for reauth purposes
	v3Options := options

	var scope *tokens3.Scope
	if options.TenantID != "" {
		scope = &tokens3.Scope{
			ProjectID: options.TenantID,
		}
		v3Options.TenantID = ""
		v3Options.TenantName = ""
	} else {
		if options.TenantName != "" {
			scope = &tokens3.Scope{
				ProjectName: options.TenantName,
				DomainID:    options.DomainID,
				DomainName:  options.DomainName,
			}
			v3Options.TenantName = ""
		}
	}

	v3Opts := tokens3.AuthOptions{
		IdentityEndpoint: v3Options.IdentityEndpoint,
		Username:         v3Options.Username,
		UserID:           v3Options.UserID,
		Password:         v3Options.Password,
		DomainID:         v3Options.DomainID,
		DomainName:       v3Options.DomainName,
		TenantID:         v3Options.TenantID,
		TenantName:       v3Options.TenantName,
		AllowReauth:      v3Options.AllowReauth,
		TokenID:          v3Options.TokenID,
	}

	result := tokens3.Create(v3Client, v3Opts, scope)

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

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

	client.TokenID = token.ID

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

	return nil
}

// ChooseVersion queries the base endpoint of an API to choose the most recent non-experimental alternative from a service's
// published versions.
// It returns the highest-Priority Version among the alternatives that are provided, as well as its corresponding endpoint.
func ChooseVersion(client *gophercloud.ProviderClient, recognized []*Version) (*Version, string, error) {
	type linkResp struct {
		Href string `json:"href"`
		Rel  string `json:"rel"`
	}

	type valueResp struct {
		ID     string     `json:"id"`
		Status string     `json:"status"`
		Links  []linkResp `json:"links"`
	}

	type versionsResp struct {
		Values []valueResp `json:"values"`
	}

	type response struct {
		Versions versionsResp `json:"versions"`
	}

	normalize := func(endpoint string) string {
		if !strings.HasSuffix(endpoint, "/") {
			return endpoint + "/"
		}
		return endpoint
	}
	identityEndpoint := normalize(client.IdentityEndpoint)

	// If a full endpoint is specified, check version suffixes for a match first.
	for _, v := range recognized {
		if strings.HasSuffix(identityEndpoint, v.Suffix) {
			return v, identityEndpoint, nil
		}
	}

	var resp response
	_, err := client.Request("GET", client.IdentityBase, &gophercloud.RequestOpts{
		JSONResponse: &resp,
		OkCodes:      []int{200, 300},
	})

	if err != nil {
		return nil, "", err
	}

	byID := make(map[string]*Version)
	for _, version := range recognized {
		byID[version.ID] = version
	}

	var highest *Version
	var endpoint string

	for _, value := range resp.Versions.Values {
		href := ""
		for _, link := range value.Links {
			if link.Rel == "self" {
				href = normalize(link.Href)
			}
		}

		if matching, ok := byID[value.ID]; ok {
			// Prefer a version that exactly matches the provided endpoint.
			if href == identityEndpoint {
				if href == "" {
					return nil, "", fmt.Errorf("Endpoint missing in version %s response from %s", value.ID, client.IdentityBase)
				}
				return matching, href, nil
			}

			// Otherwise, find the highest-priority version with a whitelisted status.
			if goodStatus[strings.ToLower(value.Status)] {
				if highest == nil || matching.Priority > highest.Priority {
					highest = matching
					endpoint = href
				}
			}
		}
	}

	if highest == nil {
		return nil, "", fmt.Errorf("No supported version available from endpoint %s", client.IdentityBase)
	}
	if endpoint == "" {
		return nil, "", fmt.Errorf("Endpoint missing in version %s response from %s", highest.ID, client.IdentityBase)
	}

	return highest, endpoint, nil
}