support custom fields of list/scalar/map types (#268)

Adds functionality for the generator.yaml file to contain a
`FieldConfig.Type` attribute that is the Go type override string for a
field. If the Go type of the field cannot be inferred via the Create
Input/Output shape *or* via the `FieldConfig.From` (SourceFieldConfig)
value, we can look at this new `FieldConfig.Type` value and construct a
`aws-sdk-go/private/model/api:ShapeRef` object manually.

Thus, with this patch, we can do something like this (example from the
iam-controller's generator.yaml file, which is what I tested this patch
on):

```yaml
resources:
  Role:
    fields:
      Policies:
        type: "[]*string"
```

Signed-off-by: Jay Pipes <[email protected]>

Author: jaypipes

Diff for: pkg/generate/config/field.go

@@ -352,5 +352,22 @@ type FieldConfig struct {
 	LateInitialize *LateInitializeConfig `json:"late_initialize,omitempty"`
 	// References instructs the code generator how to refer this field from
 	// other custom resource
-	References     *ReferencesConfig     `json:"references,omitempty"`
+	References *ReferencesConfig `json:"references,omitempty"`
+	// Type *overrides* the inferred Go type of the field. This is required for
+	// custom fields that are not inferred either as a Create Input/Output
+	// shape or via the SourceFieldConfig attribute.
+	//
+	// As an example, assume you have a Role resource where you want to add a
+	// custom spec field called Policies that is a slice of string pointers.
+	// The generator.yaml file might look like this:
+	//
+	// resources:
+	//   Role:
+	//     fields:
+	//       Policies:
+	//         type: []*string
+	//
+	// TODO(jaypipes,crtbry): Figure out if we can roll the CustomShape stuff
+	// into this type override...
+	Type *string `json:"type,omitempty"`
 }

Diff for: pkg/model/field_test.go

@@ -104,3 +104,41 @@ func TestMemberFields_Containers_MapOfStruct(t *testing.T) {
 	assert.Equal(valueField.ShapeRef.Shape.Type, "string")
 	assert.Equal(valueField.Path, "InputArtifacts.Value")
 }
+
+func TestCustomFieldType(t *testing.T) {
+	assert := assert.New(t)
+	require := require.New(t)
+
+	g := testutil.NewModelForService(t, "iam")
+
+	crds, err := g.GetCRDs()
+	require.Nil(err)
+
+	crd := getCRDByName("Role", crds)
+	require.NotNil(crd)
+
+	// The Role resource has a custom field called Policies that is of type
+	// []*string. This field is custom because it is not inferred via either
+	// the Create Input/Output shape or the SourceFieldConfig attribute in the
+	// generator.yaml file but rather via a `type` attribute of the
+	// FieldConfig, which overrides the Go type of the custom field.
+	policiesField := crd.Fields["Policies"]
+	require.NotNil(policiesField)
+
+	assert.Equal("[]*string", policiesField.GoType)
+	require.NotNil(policiesField.ShapeRef)
+
+	// A map and a scalar custom field are also added in the testdata
+	// generator.yaml file.
+	logConfigField := crd.Fields["LoggingConfig"]
+	require.NotNil(logConfigField)
+
+	assert.Equal("map[string]*bool", logConfigField.GoType)
+	require.NotNil(logConfigField.ShapeRef)
+
+	myIntField := crd.Fields["MyCustomInteger"]
+	require.NotNil(myIntField)
+
+	assert.Equal("*int64", myIntField.GoType)
+	require.NotNil(myIntField.ShapeRef)
+}

Diff for: pkg/model/model.go

@@ -183,6 +183,13 @@ func (m *Model) GetCRDs() ([]*CRD, error) {
 					)
 					panic(msg)
 				}
+			} else if fieldConfig.Type != nil {
+				// We have a custom field that has a type override and has not
+				// been inferred via the normal Create Input shape or via the
+				// SourceFieldConfig. Manually construct the field and its
+				// shape reference here.
+				typeOverride := *fieldConfig.Type
+				memberShapeRef = m.SDKAPI.GetShapeRefFromType(typeOverride)
 			} else {
 				// Spec field is not well defined
 				continue

Diff for: pkg/model/sdk_api.go

@@ -14,6 +14,7 @@
 package model
 
 import (
+	"fmt"
 	"strings"
 
 	awssdkmodel "github.com/aws/aws-sdk-go/private/model/api"
@@ -30,6 +31,19 @@ const (
 	ConflictingNameSuffix = "_SDK"
 )
 
+var (
+	// GoTypeToSDKShapeType is a map of Go types to aws-sdk-go
+	// private/model/api.Shape types
+	GoTypeToSDKShapeType = map[string]string{
+		"int":       "integer",
+		"int64":     "integer",
+		"float64":   "float",
+		"string":    "string",
+		"bool":      "boolean",
+		"time.Time": "timestamp",
+	}
+)
+
 // SDKAPI contains an API model for a single AWS service API
 type SDKAPI struct {
 	API            *awssdkmodel.API
@@ -76,6 +90,72 @@ func (a *SDKAPI) GetOperationMap(cfg *ackgenconfig.Config) *OperationMap {
 	return &opMap
 }
 
+// GetShapeRefFromType returns a ShapeRef given a string representing the Go
+// type. If no shape can be determined, returns nil.
+func (a *SDKAPI) GetShapeRefFromType(
+	typeOverride string,
+) *awssdkmodel.ShapeRef {
+	elemType := typeOverride
+	isSlice := strings.HasPrefix(typeOverride, "[]")
+	// TODO(jaypipes): Only handling maps with string keys at the moment...
+	isMap := strings.HasPrefix(typeOverride, "map[string]")
+	if isMap {
+		elemType = typeOverride[11:len(typeOverride)]
+	}
+	if isSlice {
+		elemType = typeOverride[2:len(typeOverride)]
+	}
+	isPtrElem := strings.HasPrefix(elemType, "*")
+	if isPtrElem {
+		elemType = elemType[1:len(elemType)]
+	}
+	// first check to see if the element type is a scalar and if it is, just
+	// create a ShapeRef to represent the type.
+	switch elemType {
+	case "string", "bool", "int", "int64", "float64", "time.Time":
+		sdkType, found := GoTypeToSDKShapeType[elemType]
+		if !found {
+			msg := fmt.Sprintf("GetShapeRefFromType: unsupported element type %s", elemType)
+			panic(msg)
+		}
+		if isSlice {
+			return &awssdkmodel.ShapeRef{
+				Shape: &awssdkmodel.Shape{
+					Type: "list",
+					MemberRef: awssdkmodel.ShapeRef{
+						Shape: &awssdkmodel.Shape{
+							Type: sdkType,
+						},
+					},
+				},
+			}
+		} else if isMap {
+			return &awssdkmodel.ShapeRef{
+				Shape: &awssdkmodel.Shape{
+					Type: "map",
+					KeyRef: awssdkmodel.ShapeRef{
+						Shape: &awssdkmodel.Shape{
+							Type: sdkType,
+						},
+					},
+					ValueRef: awssdkmodel.ShapeRef{
+						Shape: &awssdkmodel.Shape{
+							Type: sdkType,
+						},
+					},
+				},
+			}
+		} else {
+			return &awssdkmodel.ShapeRef{
+				Shape: &awssdkmodel.Shape{
+					Type: sdkType,
+				},
+			}
+		}
+	}
+	return nil
+}
+
 // GetCustomShapeRef finds a ShapeRef for a custom shape using either its member
 // or its value shape name.
 func (a *SDKAPI) GetCustomShapeRef(shapeName string) *awssdkmodel.ShapeRef {

Diff for: pkg/testdata/models/apis/iam/0000-00-00/generator.yaml

@@ -35,3 +35,11 @@ resources:
         set:
           # The input and output shapes are different...
           - from: PermissionsBoundary.PermissionsBoundaryArn
+      # Test the custom field creation inference for simple scalar, list or map
+      # fields
+      Policies:
+        type: "[]*string"
+      LoggingConfig:
+        type: "map[string]*bool"
+      MyCustomInteger:
+        type: "*int64"