Add NewResolveReferences in its most basic form

Signed-off-by: Muvaffak Onus <me@muvaf.com>

cmd/angryjet/main.go

@@ -45,11 +45,17 @@ const (
 	CoreAlias  = "corev1"
 	CoreImport = "k8s.io/api/core/v1"
 
+	ClientAlias  = "client"
+	ClientImport = "sigs.k8s.io/controller-runtime/pkg/client"
+
 	RuntimeAlias  = "xpv1"
 	RuntimeImport = "github.com/crossplane/crossplane-runtime/apis/common/v1"
 
 	ResourceAlias  = "resource"
 	ResourceImport = "github.com/crossplane/crossplane-runtime/pkg/resource"
+
+	ReferenceAlias  = "reference"
+	ReferenceImport = "github.com/crossplane/crossplane-runtime/pkg/reference"
 )
 
 func main() {
@@ -209,3 +215,26 @@ func GenerateProviderConfigUsageList(filename, header string, p *packages.Packag
 
 	return errors.Wrap(err, "cannot write provider config usage list methods")
 }
+
+// GenerateReferences generates reference resolver calls.
+func GenerateReferences(filename, header string, p *packages.Package) error {
+	receiver := "mg"
+
+	methods := method.Set{
+		"ResolveReferences": method.NewResolveReferences(receiver, ClientImport, ReferenceImport),
+	}
+
+	err := generate.WriteMethods(p, methods, filepath.Join(filepath.Dir(p.GoFiles[0]), filename),
+		generate.WithHeaders(header),
+		generate.WithImportAliases(map[string]string{
+			ClientImport:    ClientAlias,
+			ReferenceImport: ReferenceAlias,
+		}),
+		generate.WithMatcher(match.AllOf(
+			match.Managed(),
+			match.DoesNotHaveMarker(comments.In(p), DisableMarker, "false")),
+		),
+	)
+
+	return errors.Wrap(err, "cannot write reference resolver methods")
+}

internal/method/reference.go

@@ -0,0 +1,61 @@
+/*
+Copyright 2021 The Crossplane Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package method
+
+import (
+	"go/types"
+
+	"github.com/dave/jennifer/jen"
+)
+
+// NewResolveReferences returns a NewMethod that writes a SetProviderConfigReference
+// method for the supplied Object to the supplied file.
+func NewResolveReferences(receiver, clientPath, referencePath string) New {
+	return func(f *jen.File, o types.Object) {
+		f.Commentf("ResolveReferences of this %s.", o.Name())
+		f.Func().Params(jen.Id(receiver).Op("*").Id(o.Name())).Id("ResolveReferences").
+			Params(
+				jen.Id("ctx").Qual("context", "Context"),
+				jen.Id("c").Qual(clientPath, "Reader"),
+			).Block(
+			jen.Id("r").Op(":=").Qual(referencePath, "NewAPIResolver").Call(jen.Id("c"), jen.Id(receiver)),
+			jen.Line(),
+			jen.List(jen.Id("resp"), jen.Err()).Op(":=").Id("r").Dot("Resolve").Call(
+				jen.Id("ctx"),
+				jen.Qual(referencePath, "ResolutionRequest").Values(jen.Dict{
+					jen.Id("CurrentValue"): jen.Id(receiver).Dot("Spec").Dot("ForProvider").Dot("ApiId"),
+					jen.Id("Reference"):    jen.Id(receiver).Dot("Spec").Dot("ForProvider").Dot("ApiIdRef"),
+					jen.Id("Selector"):     jen.Id(receiver).Dot("Spec").Dot("ForProvider").Dot("ApiIdSelector"),
+					jen.Id("To"): jen.Qual(referencePath, "To").Values(jen.Dict{
+						jen.Id("Managed"): jen.Op("&").Id("Apigatewayv2Api").Values(),
+						jen.Id("List"):    jen.Op("&").Id("Apigatewayv2ApiList").Values(),
+					}),
+					jen.Id("Extract"): jen.Qual(referencePath, "ExternalName").Call(),
+				},
+				),
+			),
+			jen.If(jen.Err().Op("!=").Nil()).Block(
+				jen.Return(jen.Qual("github.com/pkg/errors", "Wrap").Call(jen.Err(), jen.Lit("Spec.ForProvider.ApiId"))),
+			),
+			jen.Line(),
+			jen.Id(receiver).Dot("Spec").Dot("ForProvider").Dot("ApiId").Op("=").Id("resp").Dot("ResolvedValue"),
+			jen.Id(receiver).Dot("Spec").Dot("ForProvider").Dot("ApiIdRef").Op("=").Id("resp").Dot("ResolvedReference"),
+			jen.Line(),
+			jen.Return(jen.Nil()),
+		)
+	}
+}

internal/method/reference_test.go

@@ -0,0 +1,66 @@
+/*
+Copyright 2021 The Crossplane Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package method
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/dave/jennifer/jen"
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestNewResolveReferences(t *testing.T) {
+	want := `package pkg
+
+import (
+	"context"
+	client "example.org/client"
+	reference "example.org/reference"
+	errors "github.com/pkg/errors"
+)
+
+// ResolveReferences of this Type.
+func (t *Type) ResolveReferences(ctx context.Context, c client.Reader) {
+	r := reference.NewAPIResolver(c, t)
+
+	resp, err := r.Resolve(ctx, reference.ResolutionRequest{
+		CurrentValue: t.Spec.ForProvider.ApiId,
+		Extract:      reference.ExternalName(),
+		Reference:    t.Spec.ForProvider.ApiIdRef,
+		Selector:     t.Spec.ForProvider.ApiIdSelector,
+		To: reference.To{
+			List:    &Apigatewayv2ApiList{},
+			Managed: &Apigatewayv2Api{},
+		},
+	})
+	if err != nil {
+		return errors.Wrap(err, "Spec.ForProvider.ApiId")
+	}
+
+	t.Spec.ForProvider.ApiId = resp.ResolvedValue
+	t.Spec.ForProvider.ApiIdRef = resp.ResolvedReference
+
+	return nil
+}
+`
+	f := jen.NewFile("pkg")
+	NewResolveReferences("t", "example.org/client", "example.org/reference")(f, MockObject{Named: "Type"})
+	if diff := cmp.Diff(want, fmt.Sprintf("%#v", f)); diff != "" {
+		t.Errorf("NewResolveReferences(): -want, +got\n%s", diff)
+	}
+}