Add support for commit-based lookup to GitHub APIs (#1612)

Co-authored-by: Azeem Shaikh <azeems@google.com>

clients/githubrepo/client.go

@@ -52,6 +52,7 @@ type Client struct {
 
 // InitRepo sets up the GitHub repo in local storage for improving performance and GitHub token usage efficiency.
 func (client *Client) InitRepo(inputRepo clients.Repo) error {
+	commitSHA := "HEAD"
 	ghRepo, ok := inputRepo.(*repoURL)
 	if !ok {
 		return fmt.Errorf("%w: %v", errInputRepoType, inputRepo)
@@ -67,12 +68,13 @@ func (client *Client) InitRepo(inputRepo clients.Repo) error {
 	client.repoName = repo.GetName()
 
 	// Init tarballHandler.
-	if err := client.tarball.init(client.ctx, client.repo); err != nil {
+	if err := client.tarball.init(client.ctx, client.repo, commitSHA); err != nil {
 		return fmt.Errorf("error during tarballHandler.init: %w", err)
 	}
 
 	// Setup GraphQL.
-	client.graphClient.init(client.ctx, client.owner, client.repoName)
+	client.graphClient.init(client.ctx, client.owner, client.repoName,
+		client.repo.GetDefaultBranch(), commitSHA)
 
 	// Setup contributorsHandler.
 	client.contributors.init(client.ctx, client.owner, client.repoName)

clients/githubrepo/graphql.go

@@ -17,6 +17,7 @@ package githubrepo
 import (
 	"context"
 	"fmt"
+	"strings"
 	"sync"
 	"time"
 
@@ -39,8 +40,7 @@ const (
 type graphqlData struct {
 	Repository struct {
 		IsArchived githubv4.Boolean
-		DefaultBranchRef struct {
-			Target struct {
+		Object     struct {
 			Commit struct {
 				History struct {
 					Nodes []struct {
@@ -95,8 +95,7 @@ type graphqlData struct {
 					}
 				} `graphql:"history(first: $commitsToAnalyze)"`
 			} `graphql:"... on Commit"`
-			}
-		}
+		} `graphql:"object(expression: $commitExpression)"`
 		Issues struct {
 			Nodes []struct {
 				// nolint: revive,stylecheck // naming according to githubv4 convention.
@@ -122,15 +121,19 @@ type graphqlHandler struct {
 	errSetup      error
 	owner         string
 	repo          string
+	defaultBranch string
+	commitSHA     string
 	commits       []clients.Commit
 	issues        []clients.Issue
 	archived      bool
 }
 
-func (handler *graphqlHandler) init(ctx context.Context, owner, repo string) {
+func (handler *graphqlHandler) init(ctx context.Context, owner, repo, defaultBranch, commitSHA string) {
 	handler.ctx = ctx
 	handler.owner = owner
 	handler.repo = repo
+	handler.defaultBranch = defaultBranch
+	handler.commitSHA = commitSHA
 	handler.data = new(graphqlData)
 	handler.errSetup = nil
 	handler.once = new(sync.Once)
@@ -138,6 +141,12 @@ func (handler *graphqlHandler) init(ctx context.Context, owner, repo string) {
 
 func (handler *graphqlHandler) setup() error {
 	handler.once.Do(func() {
+		commitExpression := handler.commitSHA
+		if strings.EqualFold(handler.commitSHA, "HEAD") {
+			// TODO(#575): Confirm that this works as expected.
+			commitExpression = fmt.Sprintf("heads/%s", handler.defaultBranch)
+		}
+
 		vars := map[string]interface{}{
 			"owner":                  githubv4.String(handler.owner),
 			"name":                   githubv4.String(handler.repo),
@@ -147,6 +156,7 @@ func (handler *graphqlHandler) setup() error {
 			"reviewsToAnalyze":       githubv4.Int(reviewsToAnalyze),
 			"labelsToAnalyze":        githubv4.Int(labelsToAnalyze),
 			"commitsToAnalyze":       githubv4.Int(commitsToAnalyze),
+			"commitExpression":       githubv4.String(commitExpression),
 		}
 		if err := handler.client.Query(handler.ctx, handler.data, vars); err != nil {
 			handler.errSetup = sce.WithMessage(sce.ErrScorecardInternal, fmt.Sprintf("githubv4.Query: %v", err))
@@ -186,7 +196,7 @@ func (handler *graphqlHandler) isArchived() (bool, error) {
 // nolint: unparam
 func commitsFrom(data *graphqlData, repoOwner, repoName string) ([]clients.Commit, error) {
 	ret := make([]clients.Commit, 0)
-	for _, commit := range data.Repository.DefaultBranchRef.Target.Commit.History.Nodes {
+	for _, commit := range data.Repository.Object.Commit.History.Nodes {
 		var committer string
 		if commit.Committer.User.Login != nil {
 			committer = *commit.Committer.User.Login

clients/githubrepo/tarball.go

@@ -68,14 +68,14 @@ type tarballHandler struct {
 	files       []string
 }
 
-func (handler *tarballHandler) init(ctx context.Context, repo *github.Repository) error {
+func (handler *tarballHandler) init(ctx context.Context, repo *github.Repository, commitSHA string) error {
 	// Cleanup any previous state.
 	if err := handler.cleanup(); err != nil {
 		return sce.WithMessage(sce.ErrScorecardInternal, err.Error())
 	}
 
 	// Setup temp dir/files and download repo tarball.
-	if err := handler.getTarball(ctx, repo); errors.Is(err, errTarballNotFound) {
+	if err := handler.getTarball(ctx, repo, commitSHA); errors.Is(err, errTarballNotFound) {
 		log.Printf("unable to get tarball %v. Skipping...", err)
 		return nil
 	} else if err != nil {
@@ -93,10 +93,14 @@ func (handler *tarballHandler) init(ctx context.Context, repo *github.Repository
 	return nil
 }
 
-func (handler *tarballHandler) getTarball(ctx context.Context, repo *github.Repository) error {
+func (handler *tarballHandler) getTarball(ctx context.Context, repo *github.Repository, commitSHA string) error {
 	url := repo.GetArchiveURL()
 	url = strings.Replace(url, "{archive_format}", "tarball/", 1)
+	if strings.EqualFold(commitSHA, "HEAD") {
 		url = strings.Replace(url, "{/ref}", "", 1)
+	} else {
+		url = strings.Replace(url, "{/ref}", commitSHA, 1)
+	}
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
 	if err != nil {
 		return fmt.Errorf("http.NewRequestWithContext: %w", err)