@@ -17,11 +17,11 @@ type Service interface {
	Count(ctx context.Context, repo string, opt ListOptions) (uint64, error)

	// Get a change.
	Get(ctx context.Context, repo string, id uint64) (Change, error)
	// ListCommits lists change commits.
	ListCommits(ctx context.Context, repo string, id uint64, opt *ListCommitsOptions) ([]Commit, error)
	ListCommits(ctx context.Context, repo string, id uint64) ([]Commit, error)
	// Get a change diff.
	GetDiff(ctx context.Context, repo string, id uint64, opt *ListCommitsOptions) ([]byte, error)

	// ListComments lists comments for specified change id.
	ListComments(ctx context.Context, repo string, id uint64, opt *ListCommentsOptions) ([]issues.Comment, error)

@@ -124,47 +124,32 @@ func state(status string) changes.State {
	default:
		panic("unreachable")
	}
}

func (s service) ListCommits(ctx context.Context, _ string, id uint64, opt *changes.ListCommitsOptions) ([]changes.Commit, error) {
func (s service) ListCommits(ctx context.Context, _ string, id uint64) ([]changes.Commit, error) {
	change, _, err := s.cl.Changes.GetChange(fmt.Sprint(id), &gerrit.ChangeOptions{
		AdditionalFields: []string{"DETAILED_ACCOUNTS", "ALL_REVISIONS"},
		//AdditionalFields: []string{"ALL_REVISIONS", "ALL_COMMITS"}, // TODO: Consider using git committer/author instead...
	})
	if err != nil {
		return nil, err
	}
	if change.Status == "DRAFT" {
		return nil, os.ErrNotExist
	}
	switch opt {
	case nil:
		commits := make([]changes.Commit, len(change.Revisions))
		for sha, r := range change.Revisions {
			commits[r.Number-1] = changes.Commit{
				SHA:     sha,
				Message: fmt.Sprintf("Patch Set %d", r.Number),
				// TODO: r.Uploader and r.Created describe the committer, not author.
				Author:     s.gerritUser(r.Uploader),
				AuthorTime: time.Time(r.Created),
			}
		}
		return commits, nil
	default:
		r, ok := change.Revisions[opt.Commit]
		if !ok {
			return nil, os.ErrNotExist
		}
		return []changes.Commit{{
			SHA:     opt.Commit,
	commits := make([]changes.Commit, len(change.Revisions))
	for sha, r := range change.Revisions {
		commits[r.Number-1] = changes.Commit{
			SHA:     sha,
			Message: fmt.Sprintf("Patch Set %d", r.Number),
			// TODO: r.Uploader and r.Created describe the committer, not author.
			Author:     s.gerritUser(r.Uploader),
			AuthorTime: time.Time(r.Created),
		}}, nil
		}
	}
	return commits, nil
}

func (s service) GetDiff(ctx context.Context, _ string, id uint64, opt *changes.ListCommitsOptions) ([]byte, error) {
	switch opt {
	case nil:

@@ -207,44 +207,30 @@ func (s service) Get(ctx context.Context, rs string, id uint64) (changes.Change,
		CreatedAt: pr.CreatedAt.Time,
		Commits:   pr.Commits.TotalCount,
	}, nil
}

func (s service) ListCommits(ctx context.Context, rs string, id uint64, opt *changes.ListCommitsOptions) ([]changes.Commit, error) {
func (s service) ListCommits(ctx context.Context, rs string, id uint64) ([]changes.Commit, error) {
	repo, err := ghRepoSpec(rs)
	if err != nil {
		// TODO: Map to 400 Bad Request HTTP error.
		return nil, err
	}
	switch opt {
	case nil:
		cs, _, err := s.clV3.PullRequests.ListCommits(ctx, repo.Owner, repo.Repo, int(id), nil)
		if err != nil {
			return nil, err
		}
		var commits []changes.Commit
		for _, c := range cs {
			commits = append(commits, changes.Commit{
				SHA:        *c.SHA,
				Message:    *c.Commit.Message,
				Author:     ghUser(c.Author),
				AuthorTime: *c.Commit.Author.Date,
			})
		}
		return commits, nil
	default:
		c, _, err := s.clV3.Repositories.GetCommit(ctx, repo.Owner, repo.Repo, opt.Commit)
		if err != nil {
			return nil, err
		}
		return []changes.Commit{{
	cs, _, err := s.clV3.PullRequests.ListCommits(ctx, repo.Owner, repo.Repo, int(id), nil)
	if err != nil {
		return nil, err
	}
	var commits []changes.Commit
	for _, c := range cs {
		commits = append(commits, changes.Commit{
			SHA:        *c.SHA,
			Message:    *c.Commit.Message,
			Author:     ghUser(c.Author),
			AuthorTime: *c.Commit.Author.Date,
		}}, nil
		})
	}
	return commits, nil
}

func (s service) GetDiff(ctx context.Context, rs string, id uint64, opt *changes.ListCommitsOptions) ([]byte, error) {
	repo, err := ghRepoSpec(rs)
	if err != nil {

@@ -104,11 +104,11 @@ func (s service) Count(_ context.Context, repo string, opt changes.ListOptions)
func (s service) Get(ctx context.Context, _ string, id uint64) (changes.Change, error) {
	// TODO.
	return changes.Change{}, fmt.Errorf("Get: not implemented")
}

func (s service) ListCommits(ctx context.Context, _ string, id uint64, opt *changes.ListCommitsOptions) ([]changes.Commit, error) {
func (s service) ListCommits(ctx context.Context, _ string, id uint64) ([]changes.Commit, error) {
	return nil, fmt.Errorf("ListCommits: not implemented")
}

func (s service) GetDiff(ctx context.Context, _ string, id uint64, opt *changes.ListCommitsOptions) ([]byte, error) {
	// TODO.