feat: read git history with go-git, not the git binary (#15)

2026-08-13 18:07:56 +01:00
parent de632ba6cc
commit a8675ac33b
15 changed files with 755 additions and 278 deletions
@@ -0,0 +1,180 @@
+// Package gitlog reads commit history with go-git (no git binary).
+package gitlog
+
+import (
+	"errors"
+	"fmt"
+	"path"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing/object"
+)
+
+type Options struct {
+	Limit int
+	Since time.Time
+}
+
+type Commit struct {
+	SHA     string   `json:"sha"`
+	Author  string   `json:"author"`
+	Email   string   `json:"email"`
+	Date    string   `json:"date"`
+	Subject string   `json:"subject"`
+	Files   []string `json:"files"`
+}
+
+type Leaf struct {
+	Source  string `json:"source"`
+	Repo    string `json:"repo"`
+	Heading string `json:"heading"`
+	Text    string `json:"text"`
+	Type    string `json:"type"`
+	Status  string `json:"status"`
+	Related string `json:"related"`
+}
+
+// Log walks commits from HEAD, newest first, skipping merges.
+func Log(repo string, opt Options) ([]Commit, error) {
+	r, err := git.PlainOpen(repo)
+	if err != nil {
+		return nil, err
+	}
+	logOpt := &git.LogOptions{Order: git.LogOrderCommitterTime}
+	if !opt.Since.IsZero() {
+		t := opt.Since
+		logOpt.Since = &t
+	}
+	iter, err := r.Log(logOpt)
+	if err != nil {
+		return nil, err
+	}
+	defer iter.Close()
+
+	var out []Commit
+	err = iter.ForEach(func(c *object.Commit) error {
+		if c.NumParents() > 1 {
+			return nil
+		}
+		if opt.Limit > 0 && len(out) >= opt.Limit {
+			return Stop
+		}
+		files, ferr := changedFiles(c)
+		if ferr != nil {
+			return ferr
+		}
+		out = append(out, Commit{
+			SHA:     c.Hash.String(),
+			Author:  c.Author.Name,
+			Email:   c.Author.Email,
+			Date:    c.Author.When.Format(time.RFC3339),
+			Subject: firstLine(c.Message),
+			Files:   files,
+		})
+		return nil
+	})
+	if errors.Is(err, Stop) {
+		err = nil
+	}
+	return out, err
+}
+
+// Stop ends a log walk early (limit reached).
+var Stop = fmt.Errorf("gitlog: stop")
+
+func changedFiles(c *object.Commit) ([]string, error) {
+	var names []string
+	if c.NumParents() == 0 {
+		t, err := c.Tree()
+		if err != nil {
+			return nil, err
+		}
+		err = t.Files().ForEach(func(f *object.File) error {
+			names = append(names, f.Name)
+			return nil
+		})
+		sort.Strings(names)
+		return names, err
+	}
+	parent, err := c.Parent(0)
+	if err != nil {
+		return nil, err
+	}
+	from, err := parent.Tree()
+	if err != nil {
+		return nil, err
+	}
+	to, err := c.Tree()
+	if err != nil {
+		return nil, err
+	}
+	changes, err := object.DiffTree(from, to)
+	if err != nil {
+		return nil, err
+	}
+	for _, ch := range changes {
+		name := ch.To.Name
+		if name == "" {
+			name = ch.From.Name
+		}
+		if name != "" {
+			names = append(names, name)
+		}
+	}
+	sort.Strings(names)
+	return names, nil
+}
+
+func firstLine(msg string) string {
+	msg = strings.ReplaceAll(msg, "\r\n", "\n")
+	if i := strings.IndexByte(msg, '\n'); i >= 0 {
+		return strings.TrimSpace(msg[:i])
+	}
+	return strings.TrimSpace(msg)
+}
+
+func ToLeaf(c Commit, repo string) Leaf {
+	short := c.SHA
+	if len(short) > 12 {
+		short = short[:12]
+	}
+	head := fmt.Sprintf("commit %s — %s", short, c.Subject)
+	body := []string{
+		fmt.Sprintf("commit %s in %s — %s", short, repo, c.Subject),
+		fmt.Sprintf("Author: %s <%s>", c.Author, c.Email),
+		fmt.Sprintf("Date: %s", c.Date),
+	}
+	if len(c.Files) > 0 {
+		body = append(body, "Changing: "+strings.Join(c.Files, ", "))
+	}
+	return Leaf{
+		Source:  repo + "@" + c.SHA,
+		Repo:    repo,
+		Heading: head,
+		Text:    strings.Join(body, "\n"),
+		Type:    "commit",
+		Status:  "current",
+		Related: strings.Join(c.Files, ","),
+	}
+}
+
+func RepoName(repo string) (string, error) {
+	r, err := git.PlainOpen(repo)
+	if err != nil {
+		return filepath.Base(repo), err
+	}
+	rem, err := r.Remote("origin")
+	if err != nil {
+		return filepath.Base(repo), nil
+	}
+	urls := rem.Config().URLs
+	if len(urls) == 0 {
+		return filepath.Base(repo), nil
+	}
+	u := strings.TrimSuffix(strings.TrimSuffix(urls[0], "/"), ".git")
+	return path.Base(strings.ReplaceAll(u, "\\", "/")), nil
+}
@@ -0,0 +1,243 @@
+package gitlog
+
+import (
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/config"
+	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/object"
+)
+
+func TestLogReadsCommitsWithoutGitBinary(t *testing.T) {
+	dir := initRepo(t, []commitSpec{
+		{
+			when:    time.Date(2026, 8, 10, 12, 0, 0, 0, time.FixedZone("CEST", 3600)),
+			name:    "Ada Lovelace",
+			email:   "ada@example.com",
+			subject: "feat: first commit",
+			files:   map[string]string{"README.md": "hi\n", "src/main.c": "int main(){}\n"},
+		},
+		{
+			when:    time.Date(2026, 8, 11, 9, 30, 0, 0, time.FixedZone("CEST", 3600)),
+			name:    "Bob Babbage",
+			email:   "bob@example.com",
+			subject: "fix: typo",
+			files:   map[string]string{"docs/notes.md": "note\n"},
+		},
+	})
+
+	cs, err := Log(dir, Options{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(cs) != 2 {
+		t.Fatalf("commits = %d, want 2", len(cs))
+	}
+	if cs[0].Subject != "fix: typo" {
+		t.Fatalf("head subject = %q, want fix: typo", cs[0].Subject)
+	}
+	if cs[1].Author != "Ada Lovelace" || cs[1].Email != "ada@example.com" {
+		t.Fatalf("author = %s <%s>", cs[1].Author, cs[1].Email)
+	}
+	sort.Strings(cs[1].Files)
+	if got := cs[1].Files; len(got) != 2 || got[0] != "README.md" || got[1] != "src/main.c" {
+		t.Fatalf("first commit files = %v", got)
+	}
+	if cs[0].Files[0] != "docs/notes.md" {
+		t.Fatalf("second commit files = %v", cs[0].Files)
+	}
+}
+
+func TestLogSkipsMerges(t *testing.T) {
+	dir := initRepo(t, []commitSpec{{
+		when: time.Now(), name: "Ada Lovelace", email: "ada@example.com",
+		subject: "base", files: map[string]string{"a.txt": "a\n"},
+	}})
+	r, err := git.PlainOpen(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	head, err := r.Head()
+	if err != nil {
+		t.Fatal(err)
+	}
+	c, err := r.CommitObject(head.Hash())
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Second parent: duplicate the same tree so we do not need a real branch.
+	merge := &object.Commit{
+		Author:       object.Signature{Name: "Ada Lovelace", Email: "ada@example.com", When: time.Now()},
+		Committer:    object.Signature{Name: "Ada Lovelace", Email: "ada@example.com", When: time.Now()},
+		Message:      "merge",
+		TreeHash:     c.TreeHash,
+		ParentHashes: []plumbing.Hash{c.Hash, c.Hash},
+	}
+	obj := r.Storer.NewEncodedObject()
+	if err := merge.Encode(obj); err != nil {
+		t.Fatal(err)
+	}
+	h, err := r.Storer.SetEncodedObject(obj)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := r.Storer.SetReference(plumbing.NewHashReference(head.Name(), h)); err != nil {
+		t.Fatal(err)
+	}
+
+	cs, err := Log(dir, Options{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, x := range cs {
+		if x.Subject == "merge" {
+			t.Fatal("merge commit was not skipped")
+		}
+	}
+	if len(cs) != 1 || cs[0].Subject != "base" {
+		t.Fatalf("after skip merges: %+v", subjects(cs))
+	}
+}
+
+func TestLogSinceAndLimit(t *testing.T) {
+	old := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
+	neu := time.Date(2026, 6, 1, 0, 0, 0, 0, time.UTC)
+	dir := initRepo(t, []commitSpec{
+		{when: old, name: "Ada Lovelace", email: "ada@example.com", subject: "old", files: map[string]string{"old.md": "x"}},
+		{when: neu, name: "Ada Lovelace", email: "ada@example.com", subject: "new", files: map[string]string{"new.md": "y"}},
+	})
+	cs, err := Log(dir, Options{Since: neu.Add(-time.Hour)})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(cs) != 1 || cs[0].Subject != "new" {
+		t.Fatalf("since filter: %v", subjects(cs))
+	}
+	cs, err = Log(dir, Options{Limit: 1})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(cs) != 1 {
+		t.Fatalf("limit=1 got %d", len(cs))
+	}
+}
+
+func TestLeafShape(t *testing.T) {
+	c := Commit{
+		SHA:     "a1b2c3d4e5f6aaaa",
+		Author:  "Ada Lovelace",
+		Email:   "ada@example.com",
+		Date:    "2026-08-10T12:00:00+01:00",
+		Subject: "feat: first commit",
+		Files:   []string{"README.md", "src/main.c"},
+	}
+	lf := ToLeaf(c, "sample-repo")
+	if lf.Type != "commit" || lf.Repo != "sample-repo" {
+		t.Fatalf("leaf meta = %+v", lf)
+	}
+	if lf.Source != "sample-repo@a1b2c3d4e5f6aaaa" {
+		t.Fatalf("source = %s", lf.Source)
+	}
+	if lf.Related != "README.md,src/main.c" {
+		t.Fatalf("related = %s", lf.Related)
+	}
+	if lf.Heading != "commit a1b2c3d4e5f6 — feat: first commit" {
+		t.Fatalf("heading = %q", lf.Heading)
+	}
+	if !strings.Contains(lf.Text, "Ada Lovelace") || !strings.Contains(lf.Text, "README.md") {
+		t.Fatalf("text = %s", lf.Text)
+	}
+}
+
+func TestRepoNameFromOrigin(t *testing.T) {
+	dir := initRepo(t, []commitSpec{{
+		when: time.Now(), name: "Ada Lovelace", email: "ada@example.com",
+		subject: "init", files: map[string]string{"README.md": "x"},
+	}})
+	r, err := git.PlainOpen(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := r.CreateRemote(&config.RemoteConfig{
+		Name: "origin",
+		URLs: []string{"https://git.example.com/eSlider/sample-repo.git"},
+	}); err != nil {
+		t.Fatal(err)
+	}
+	name, err := RepoName(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if name != "sample-repo" {
+		t.Fatalf("RepoName = %q, want sample-repo", name)
+	}
+}
+
+func TestRepoNameFallsBackToDir(t *testing.T) {
+	dir := initRepo(t, []commitSpec{{
+		when: time.Now(), name: "Ada Lovelace", email: "ada@example.com",
+		subject: "init", files: map[string]string{"README.md": "x"},
+	}})
+	name, err := RepoName(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if name != filepath.Base(dir) {
+		t.Fatalf("RepoName = %q, want %s", name, filepath.Base(dir))
+	}
+}
+
+type commitSpec struct {
+	when    time.Time
+	name    string
+	email   string
+	subject string
+	files   map[string]string
+}
+
+func initRepo(t *testing.T, specs []commitSpec) string {
+	t.Helper()
+	dir := t.TempDir()
+	r, err := git.PlainInit(dir, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w, err := r.Worktree()
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, s := range specs {
+		for path, body := range s.files {
+			full := filepath.Join(dir, path)
+			if err := os.MkdirAll(filepath.Dir(full), 0o755); err != nil && !os.IsExist(err) {
+				t.Fatal(err)
+			}
+			if err := os.WriteFile(full, []byte(body), 0o644); err != nil {
+				t.Fatal(err)
+			}
+			if _, err := w.Add(path); err != nil {
+				t.Fatal(err)
+			}
+		}
+		if _, err := w.Commit(s.subject, &git.CommitOptions{
+			Author: &object.Signature{Name: s.name, Email: s.email, When: s.when},
+		}); err != nil {
+			t.Fatal(err)
+		}
+	}
+	return dir
+}
+
+func subjects(cs []Commit) []string {
+	out := make([]string, len(cs))
+	for i, c := range cs {
+		out[i] = c.Subject
+	}
+	return out
+}