Gnocchi: implement resource types List method (gophercloud#55)

* Gnocchi: implement resource types List method

Add new resourcetypes package with List method.
Add tests and a documentation example.

* Gnocchi: change resource type attributes

Rename resource type attributes to Attributes struct, use cutom field
"Extra" with map[string]interface{} type instead of different fields.
Those fields will be different for different attribute types.

* Gnocchi: change resource type attributes struct

Migrate from list to map representation for the attribute details to
make it more similar to the actual Gnocchi response JSON.

acceptance/gnocchi/metric/v1/resourcetypes_test.go

@@ -0,0 +1,32 @@
+// +build acceptance metric resourcetypes
+
+package v1
+
+import (
+	"testing"
+
+	"github.com/gophercloud/gophercloud/acceptance/tools"
+	"github.com/gophercloud/utils/acceptance/clients"
+	"github.com/gophercloud/utils/gnocchi/metric/v1/resourcetypes"
+)
+
+func TestResourceTypesList(t *testing.T) {
+	client, err := clients.NewGnocchiV1Client()
+	if err != nil {
+		t.Fatalf("Unable to create a Gnocchi client: %v", err)
+	}
+
+	allPages, err := resourcetypes.List(client).AllPages()
+	if err != nil {
+		t.Fatalf("Unable to list resource types: %v", err)
+	}
+
+	allResourceTypes, err := resourcetypes.ExtractResourceTypes(allPages)
+	if err != nil {
+		t.Fatalf("Unable to extract resource types: %v", err)
+	}
+
+	for _, resourceType := range allResourceTypes {
+		tools.PrintResource(t, resourceType)
+	}
+}

gnocchi/metric/v1/resourcetypes/doc.go

@@ -0,0 +1,20 @@
+/*
+Package resourcetypes provides ability to manage resource types through the Gnocchi API.
+
+Example of Listing resource types
+
+  allPages, err := resourcetypes.List(client).AllPages()
+  if err != nil {
+    panic(err)
+	}
+
+  allResourceTypes, err := resourcetypes.ExtractResourceTypes(allPages)
+  if err != nil {
+    panic(err)
+	}
+
+  for _, resourceType := range allResourceTypes {
+    fmt.Printf("%+v\n", resourceType)
+  }
+*/
+package resourcetypes

gnocchi/metric/v1/resourcetypes/requests.go

@@ -0,0 +1,13 @@
+package resourcetypes
+
+import (
+	"github.com/gophercloud/gophercloud"
+	"github.com/gophercloud/gophercloud/pagination"
+)
+
+// List makes a request against the Gnocchi API to list resource types.
+func List(client *gophercloud.ServiceClient) pagination.Pager {
+	return pagination.NewPager(client, listURL(client), func(r pagination.PageResult) pagination.Page {
+		return ResourceTypePage{pagination.SinglePageBase(r)}
+	})
+}

gnocchi/metric/v1/resourcetypes/results.go

@@ -0,0 +1,121 @@
+package resourcetypes
+
+import (
+	"encoding/json"
+
+	"github.com/gophercloud/gophercloud"
+	"github.com/gophercloud/gophercloud/pagination"
+)
+
+type commonResult struct {
+	gophercloud.Result
+}
+
+// Extract is a function that accepts a result and extracts a Gnocchi resource type.
+func (r commonResult) Extract() (*ResourceType, error) {
+	var s *ResourceType
+	err := r.ExtractInto(&s)
+	return s, err
+}
+
+// GetResult represents the result of a get operation. Call its Extract
+// method to interpret it as a Gnocchi resource type.
+type GetResult struct {
+	commonResult
+}
+
+// ResourceType represents custom Gnocchi resource type.
+type ResourceType struct {
+	// Attributes is a collection of keys and values of different resource types.
+	Attributes map[string]Attribute `json:"-"`
+
+	// Name is a human-readable resource type identifier.
+	Name string `json:"name"`
+
+	// State represents current status of a resource type.
+	State string `json:"state"`
+}
+
+// Attribute represents single attribute of a Gnocchi resource type.
+type Attribute struct {
+	// Type is an attribute type.
+	Type string `json:"type"`
+
+	// Details represents different attribute fields.
+	Details map[string]interface{}
+}
+
+// UnmarshalJSON helps to unmarshal ResourceType fields into needed values.
+func (r *ResourceType) UnmarshalJSON(b []byte) error {
+	type tmp ResourceType
+	var s struct {
+		tmp
+		Attributes map[string]interface{} `json:"attributes"`
+	}
+	err := json.Unmarshal(b, &s)
+	if err != nil {
+		return err
+	}
+	*r = ResourceType(s.tmp)
+
+	if s.Attributes == nil {
+		return nil
+	}
+
+	// Populate attributes from the JSON map structure.
+	attributes := make(map[string]Attribute)
+	for attributeName, attributeValues := range s.Attributes {
+		attribute := new(Attribute)
+		attribute.Details = make(map[string]interface{})
+
+		attributeValuesMap, ok := attributeValues.(map[string]interface{})
+		if !ok {
+			// Got some strange resource type attribute representation, skip it.
+			continue
+		}
+
+		// Populate extra and type attribute values.
+		for k, v := range attributeValuesMap {
+			if k == "type" {
+				if attributeType, ok := v.(string); ok {
+					attribute.Type = attributeType
+				}
+			} else {
+				attribute.Details[k] = v
+			}
+		}
+		attributes[attributeName] = *attribute
+	}
+
+	r.Attributes = attributes
+
+	return err
+}
+
+// ResourceTypePage abstracts the raw results of making a List() request against
+// the Gnocchi API.
+//
+// As Gnocchi API may freely alter the response bodies of structures
+// returned to the client, you may only safely access the data provided through
+// the ExtractResources call.
+type ResourceTypePage struct {
+	pagination.SinglePageBase
+}
+
+// IsEmpty checks whether a ResourceTypePage struct is empty.
+func (r ResourceTypePage) IsEmpty() (bool, error) {
+	is, err := ExtractResourceTypes(r)
+	return len(is) == 0, err
+}
+
+// ExtractResourceTypes interprets the results of a single page from a List() call,
+// producing a slice of ResourceType structs.
+func ExtractResourceTypes(r pagination.Page) ([]ResourceType, error) {
+	var s []ResourceType
+	err := (r.(ResourceTypePage)).ExtractInto(&s)
+	if err != nil {
+		return nil, err
+	}
+
+	return s, err
+}

gnocchi/metric/v1/resourcetypes/testing/doc.go

@@ -0,0 +1,2 @@
+// resource types unit tests
+package testing

gnocchi/metric/v1/resourcetypes/testing/fixtures.go

@@ -0,0 +1,71 @@
+package testing
+
+import "github.com/gophercloud/utils/gnocchi/metric/v1/resourcetypes"
+
+// ResourceTypeListResult represents raw server response from a server to a list call.
+const ResourceTypeListResult = `[
+    {
+        "attributes": {},
+        "name": "generic",
+        "state": "active"
+    },
+    {
+        "attributes": {
+            "parent_id": {
+                "required": false,
+                "type": "uuid"
+            }
+        },
+        "name": "identity_project",
+        "state": "active"
+    },
+    {
+        "attributes": {
+            "host": {
+                "max_length": 128,
+                "min_length": 0,
+                "required": true,
+                "type": "string"
+            }
+        },
+        "name": "compute_instance",
+        "state": "active"
+    }
+]`
+
+// ResourceType1 is an expected representation of a first resource from the ResourceTypeListResult.
+var ResourceType1 = resourcetypes.ResourceType{
+	Name:       "generic",
+	State:      "active",
+	Attributes: map[string]resourcetypes.Attribute{},
+}
+
+// ResourceType2 is an expected representation of a first resource from the ResourceTypeListResult.
+var ResourceType2 = resourcetypes.ResourceType{
+	Name:  "identity_project",
+	State: "active",
+	Attributes: map[string]resourcetypes.Attribute{
+		"parent_id": resourcetypes.Attribute{
+			Type: "uuid",
+			Details: map[string]interface{}{
+				"required": false,
+			},
+		},
+	},
+}
+
+// ResourceType3 is an expected representation of a first resource from the ResourceTypeListResult.
+var ResourceType3 = resourcetypes.ResourceType{
+	Name:  "compute_instance",
+	State: "active",
+	Attributes: map[string]resourcetypes.Attribute{
+		"host": resourcetypes.Attribute{
+			Type: "string",
+			Details: map[string]interface{}{
+				"max_length": float64(128),
+				"min_length": float64(0),
+				"required":   true,
+			},
+		},
+	},
+}

gnocchi/metric/v1/resourcetypes/testing/requests_test.go

@@ -0,0 +1,52 @@
+package testing
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+
+	"github.com/gophercloud/gophercloud/pagination"
+	th "github.com/gophercloud/gophercloud/testhelper"
+	"github.com/gophercloud/utils/gnocchi/metric/v1/resourcetypes"
+	fake "github.com/gophercloud/utils/gnocchi/testhelper/client"
+)
+
+func TestList(t *testing.T) {
+	th.SetupHTTP()
+	defer th.TeardownHTTP()
+
+	th.Mux.HandleFunc("/v1/resource_type", func(w http.ResponseWriter, r *http.Request) {
+		th.TestMethod(t, r, "GET")
+		th.TestHeader(t, r, "X-Auth-Token", fake.TokenID)
+
+		w.Header().Add("Content-Type", "application/json")
+		w.WriteHeader(http.StatusOK)
+
+		fmt.Fprintf(w, ResourceTypeListResult)
+	})
+
+	count := 0
+
+	resourcetypes.List(fake.ServiceClient()).EachPage(func(page pagination.Page) (bool, error) {
+		count++
+		actual, err := resourcetypes.ExtractResourceTypes(page)
+		if err != nil {
+			t.Errorf("Failed to extract resource types: %v", err)
+			return false, nil
+		}
+
+		expected := []resourcetypes.ResourceType{
+			ResourceType1,
+			ResourceType2,
+			ResourceType3,
+		}
+
+		th.CheckDeepEquals(t, expected, actual)
+
+		return true, nil
+	})
+
+	if count != 1 {
+		t.Errorf("Expected 1 page, got %d", count)
+	}
+}

gnocchi/metric/v1/resourcetypes/urls.go

@@ -0,0 +1,13 @@
+package resourcetypes
+
+import "github.com/gophercloud/gophercloud"
+
+const resourcePath = "resource_type"
+
+func rootURL(c *gophercloud.ServiceClient) string {
+	return c.ServiceURL(resourcePath)
+}
+
+func listURL(c *gophercloud.ServiceClient) string {
+	return rootURL(c)
+}