backend: Extending GitHub service to have the ability to get files ba…

…sed on a path (#3012)

backend/mock/service/githubmock/githubmock.go

@@ -25,6 +25,10 @@ func (s svc) GetFile(ctx context.Context, ref *github.RemoteRef, path string) (*
 	panic("implement me")
 }
 
+func (s svc) GetDirectory(ctx context.Context, ref *github.RemoteRef, path string) (*github.Directory, error) {
+	panic("implement me")
+}
+
 func (s svc) CreateBranch(ctx context.Context, req *github.CreateBranchRequest) error {
 	panic("implement me")
 }

backend/service/github/github.go

@@ -96,9 +96,22 @@ type File struct {
 	LastModifiedSHA  string
 }
 
+type Entry struct {
+	Name string
+	Type string
+}
+
+type Directory struct {
+	Path             string
+	LastModifiedTime time.Time
+	LastModifiedSHA  string
+	Entries          []*Entry
+}
+
 // Client allows various interactions with remote repositories on GitHub.
 type Client interface {
 	GetFile(ctx context.Context, ref *RemoteRef, path string) (*File, error)
+	GetDirectory(ctx context.Context, ref *RemoteRef, path string) (*Directory, error)
 	CreateBranch(ctx context.Context, req *CreateBranchRequest) error
 	CreatePullRequest(ctx context.Context, ref *RemoteRef, base, title, body string) (*PullRequestInfo, error)
 	CreateRepository(ctx context.Context, req *sourcecontrolv1.CreateRepositoryRequest) (*sourcecontrolv1.CreateRepositoryResponse, error)
@@ -469,6 +482,47 @@ func (s *svc) GetFile(ctx context.Context, ref *RemoteRef, path string) (*File,
 	return f, nil
 }
 
+func (s *svc) GetDirectory(ctx context.Context, ref *RemoteRef, path string) (*Directory, error) {
+	q := &getDirectoryQuery{}
+
+	params := map[string]interface{}{
+		"owner":   githubv4.String(ref.RepoOwner),
+		"name":    githubv4.String(ref.RepoName),
+		"path":    githubv4.String(path),
+		"ref":     githubv4.String(ref.Ref),
+		"refPath": githubv4.String(fmt.Sprintf("%s:%s", ref.Ref, path)),
+	}
+
+	err := s.graphQL.Query(ctx, q, params)
+	if err != nil {
+		return nil, err
+	}
+
+	switch {
+	case q.Repository.Ref.Commit.ID == nil:
+		return nil, errors.New("ref not found")
+	case len(q.Repository.Object.Tree.Entries) == 0:
+		return nil, errors.New("directory not found")
+	}
+
+	var entries []*Entry
+	for _, obj := range q.Repository.Object.Tree.Entries {
+		entries = append(entries, &Entry{
+			Name: string(obj.Name),
+			Type: string(obj.Type),
+		})
+	}
+
+	d := &Directory{
+		Path:             path,
+		Entries:          entries,
+		LastModifiedTime: q.Repository.Ref.Commit.History.Nodes[0].CommittedDate.Time,
+		LastModifiedSHA:  string(q.Repository.Ref.Commit.History.Nodes[0].OID),
+	}
+
+	return d, nil
+}
+
 /*
  * Rather than calling GetCommit() multiple times, we can use CompareCommits to get a range of commits
  */

backend/service/github/github_test.go

@@ -43,6 +43,14 @@ type getfileMock struct {
 	truncated, binary bool
 }
 
+type getdirectoryMock struct {
+	v4client
+
+	queryError   bool
+	refID, objID string
+	entries      []*Entry
+}
+
 func (g *getfileMock) Query(ctx context.Context, query interface{}, variables map[string]interface{}) error {
 	q, ok := query.(*getFileQuery)
 	if !ok {
@@ -76,6 +84,40 @@ func (g *getfileMock) Query(ctx context.Context, query interface{}, variables ma
 	return nil
 }
 
+func (g *getdirectoryMock) Query(ctx context.Context, query interface{}, variables map[string]interface{}) error {
+	q, ok := query.(*getDirectoryQuery)
+	if !ok {
+		panic("not a query")
+	}
+
+	if g.queryError {
+		return errors.New(problem)
+	}
+
+	if g.refID != "" {
+		q.Repository.Ref.Commit.ID = g.refID
+		q.Repository.Ref.Commit.OID = githubv4.GitObjectID(g.refID)
+	}
+	if g.objID != "" {
+		q.Repository.Object.Tree.Entries = append(
+			q.Repository.Object.Tree.Entries,
+			struct {
+				Name githubv4.String
+				Type githubv4.String
+			}{Name: githubv4.String(g.entries[0].Name), Type: githubv4.String(g.entries[0].Type)})
+	}
+
+	q.Repository.Ref.Commit.History.Nodes = append(
+		q.Repository.Ref.Commit.History.Nodes,
+		struct {
+			CommittedDate githubv4.DateTime
+			OID           githubv4.GitObjectID
+		}{githubv4.DateTime{Time: timestamp}, "otherSHA"},
+	)
+
+	return nil
+}
+
 type mockRoundTripper struct {
 	http.RoundTripper
 	resp *http.Response
@@ -235,6 +277,69 @@ func TestGetFile(t *testing.T) {
 	}
 }
 
+var directoryEntries = []*Entry{{Name: "foo", Type: "blob"}}
+
+var getDirectoryTests = []struct {
+	name    string
+	v4      getdirectoryMock
+	errText string
+}{
+	{
+		name:    "queryError",
+		v4:      getdirectoryMock{queryError: true},
+		errText: problem,
+	},
+	{
+		name:    "noRef",
+		v4:      getdirectoryMock{},
+		errText: "ref not found",
+	},
+	{
+		name:    "noObject",
+		v4:      getdirectoryMock{refID: "abcdef12345"},
+		errText: "directory not found",
+	},
+	{
+		name: "happyPath",
+		v4:   getdirectoryMock{refID: "abcdef12345", objID: "abcdef12345", entries: directoryEntries},
+	},
+}
+
+func TestGetDirectory(t *testing.T) {
+	for _, tt := range getDirectoryTests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			a := assert.New(t)
+
+			s := &svc{graphQL: &tt.v4}
+			f, err := s.GetDirectory(context.Background(),
+				&RemoteRef{
+					RepoOwner: "owner",
+					RepoName:  "myRepo",
+					Ref:       "master",
+				},
+				"data/foo",
+			)
+
+			if tt.errText != "" {
+				a.Error(err)
+				a.Contains(err.Error(), tt.errText)
+				return
+			}
+			if err != nil {
+				a.FailNow("unexpected error")
+				return
+			}
+
+			a.Equal("data/foo", f.Path)
+			a.Equal(directoryEntries, f.Entries)
+			a.Equal("otherSHA", f.LastModifiedSHA)
+			a.Equal(timestamp, f.LastModifiedTime)
+		})
+	}
+}
+
 type mockRepositories struct {
 	actualOrg  string
 	actualRepo *githubv3.Repository

backend/service/github/graphql.go

@@ -37,6 +37,34 @@ type getFileQuery struct {
 	} `graphql:"repository(owner:$owner,name:$name)"`
 }
 
+type getDirectoryQuery struct {
+	Repository struct {
+		// Get more information about desired ref and last modified ref for the file.
+		Ref struct {
+			Commit struct {
+				ID      githubv4.ID
+				OID     githubv4.GitObjectID
+				History struct {
+					Nodes []struct {
+						CommittedDate githubv4.DateTime
+						OID           githubv4.GitObjectID
+					}
+				} `graphql:"history(path:$path,first:1)"`
+			} `graphql:"... on Commit"`
+		} `graphql:"ref: object(expression:$ref)"`
+
+		// Fetch requested tree and its entries.
+		Object struct {
+			Tree struct {
+				Entries []struct {
+					Name githubv4.String
+					Type githubv4.String
+				} `graphql:"entries"`
+			} `graphql:"... on Tree"`
+		} `graphql:"object(expression:$refPath)"`
+	} `graphql:"repository(owner:$owner,name:$name)"`
+}
+
 type getRepositoryQuery struct {
 	Repository struct {
 		DefaultBranchRef struct {