@@ -164,17 +164,103 @@ func (s service) ListCommits(ctx context.Context, _ string, id uint64, opt *chan
		}}, nil
	}
}

func (s service) GetDiff(ctx context.Context, _ string, id uint64, opt *changes.ListCommitsOptions) ([]byte, error) {
	diff, _, err := s.cl.Changes.GetPatch(fmt.Sprint(id), "current", &gerrit.PatchOptions{
		Path: "src", // TODO.
	})
	if err != nil {
		return nil, err
	switch opt {
	case nil:
		diff, _, err := s.cl.Changes.GetPatch(fmt.Sprint(id), "current", &gerrit.PatchOptions{
			Path: "src", // TODO.
		})
		if err != nil {
			return nil, err
		}
		return []byte(*diff), nil
	default:
		change, _, err := s.cl.Changes.GetChange(fmt.Sprint(id), &gerrit.ChangeOptions{
			AdditionalFields: []string{"ALL_REVISIONS"},
		})
		if err != nil {
			return nil, err
		}
		if change.Status == "DRAFT" {
			return nil, os.ErrNotExist
		}
		r, ok := change.Revisions[opt.Commit]
		if !ok {
			return nil, os.ErrNotExist
		}
		var base string
		switch r.Number {
		case 1:
			base = ""
		default:
			base = fmt.Sprint(r.Number - 1)
		}
		files, _, err := s.cl.Changes.ListFiles(fmt.Sprint(id), opt.Commit, &gerrit.FilesOptions{
			Base: base,
		})
		if err != nil {
			return nil, err
		}
		var sortedFiles []string
		for file := range *files {
			sortedFiles = append(sortedFiles, file)
		}
		sort.Strings(sortedFiles)
		var diff string
		for _, file := range sortedFiles {
			diffInfo, _, err := s.cl.Changes.GetDiff(fmt.Sprint(id), opt.Commit, file, &gerrit.DiffOptions{
				Base:    base,
				Context: "5",
			})
			if err != nil {
				return nil, err
			}
			diff += strings.Join(diffInfo.DiffHeader, "\n") + "\n"
			for i, c := range diffInfo.Content {
				if i == 0 {
					diff += "@@ -154,6 +154,7 @@\n" // TODO.
				}
				switch {
				case len(c.AB) > 0:
					if len(c.AB) <= 10 {
						for _, line := range c.AB {
							diff += " " + line + "\n"
						}
					} else {
						switch i {
						case 0:
							for _, line := range c.AB[len(c.AB)-5:] {
								diff += " " + line + "\n"
							}
						default:
							for _, line := range c.AB[:5] {
								diff += " " + line + "\n"
							}
							diff += "@@ -154,6 +154,7 @@\n" // TODO.
							for _, line := range c.AB[len(c.AB)-5:] {
								diff += " " + line + "\n"
							}
						case len(diffInfo.Content) - 1:
							for _, line := range c.AB[:5] {
								diff += " " + line + "\n"
							}
						}
					}
				case len(c.A) > 0 || len(c.B) > 0:
					for _, line := range c.A {
						diff += "-" + line + "\n"
					}
					for _, line := range c.B {
						diff += "+" + line + "\n"
					}
				}
			}
		}
		return []byte(diff), nil
	}
	return []byte(*diff), nil
}

func (s service) ListComments(ctx context.Context, _ string, id uint64, opt *changes.ListCommentsOptions) ([]issues.Comment, error) {
	// TODO: Pagination. Respect opt.Start and opt.Length, if given.