feat: read git history with go-git, not the git binary

internal/gitlog/gitlog.go

@@ -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
+}