// 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
}
