✨ feat: Initial commit

internal/scanner/scanner.go

@@ -0,0 +1,139 @@
+package scanner
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+type Entry struct {
+	Name          string
+	Email         string
+	Field         string // "Author", "Committer", or a trailer name like "Co-authored-by"
+	Repo          string
+	CommitSHA     string
+	Date          string
+	PushedByLogin string `json:",omitempty"` // GitHub login that pushed this commit, per the public Events API
+}
+
+const (
+	unitSep   = "\x1f"
+	recordSep = "\x1e"
+)
+
+var logFormat = "%H" + unitSep + "%an" + unitSep + "%ae" + unitSep + "%cn" + unitSep + "%ce" + unitSep + "%aI" + unitSep + "%B" + recordSep
+
+var trailerPattern = regexp.MustCompile(`(?m)^([A-Za-z][A-Za-z-]*-by):\s*(.+?)\s*<([^>]+)>\s*$`)
+
+func Clone(repoFullName, repoURL, token string) (dir string, cleanup func(), err error) {
+	tmpDir, err := os.MkdirTemp("", "git-identity-audit-*")
+	if err != nil {
+		return "", nil, fmt.Errorf("creating temp dir: %w", err)
+	}
+	cleanup = func() { os.RemoveAll(tmpDir) }
+
+	authURL := injectToken(repoURL, token)
+
+	cmd := exec.Command("git", "clone", "--bare", "--filter=blob:none", "--quiet", authURL, tmpDir)
+	cmd.Env = append(os.Environ(), "GIT_TERMINAL_PROMPT=0")
+	var stderr bytes.Buffer
+	cmd.Stderr = &stderr
+	if err := cmd.Run(); err != nil {
+		cleanup()
+		return "", nil, fmt.Errorf("cloning %s: %w: %s", repoFullName, err, stderr.String())
+	}
+
+	return tmpDir, cleanup, nil
+}
+
+func CountCommits(gitDir string) (int, error) {
+	cmd := exec.Command("git", "--git-dir", gitDir, "rev-list", "--all", "--count")
+	out, err := cmd.Output()
+	if err != nil {
+		return 0, fmt.Errorf("counting commits: %w", err)
+	}
+	n, err := strconv.Atoi(strings.TrimSpace(string(out)))
+	if err != nil {
+		return 0, fmt.Errorf("parsing commit count: %w", err)
+	}
+	return n, nil
+}
+
+func StreamLog(gitDir, repoFullName string, onCommit func(entries []Entry)) error {
+	cmd := exec.Command("git", "--git-dir", gitDir, "log", "--all", "--format="+logFormat)
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return fmt.Errorf("opening log stream: %w", err)
+	}
+	var stderr bytes.Buffer
+	cmd.Stderr = &stderr
+
+	if err := cmd.Start(); err != nil {
+		return fmt.Errorf("starting log stream: %w", err)
+	}
+
+	scanner := bufio.NewScanner(stdout)
+	scanner.Buffer(make([]byte, 0, 64*1024), 16*1024*1024)
+	scanner.Split(splitOnRecordSep)
+
+	for scanner.Scan() {
+		record := strings.Trim(scanner.Text(), "\n")
+		if record == "" {
+			continue
+		}
+		onCommit(parseRecord(record, repoFullName))
+	}
+	scanErr := scanner.Err()
+
+	waitErr := cmd.Wait()
+	if waitErr != nil {
+		return fmt.Errorf("reading log for %s: %w: %s", repoFullName, waitErr, stderr.String())
+	}
+	if scanErr != nil {
+		return fmt.Errorf("reading log for %s: %w", repoFullName, scanErr)
+	}
+	return nil
+}
+
+func splitOnRecordSep(data []byte, atEOF bool) (advance int, token []byte, err error) {
+	if atEOF && len(data) == 0 {
+		return 0, nil, nil
+	}
+	if i := bytes.IndexByte(data, recordSep[0]); i >= 0 {
+		return i + 1, data[:i], nil
+	}
+	if atEOF {
+		return len(data), data, nil
+	}
+	return 0, nil, nil
+}
+
+func injectToken(repoURL, token string) string {
+	const prefix = "https://"
+	if !strings.HasPrefix(repoURL, prefix) {
+		return repoURL
+	}
+	return prefix + "x-access-token:" + token + "@" + strings.TrimPrefix(repoURL, prefix)
+}
+
+func parseRecord(record, repoFullName string) []Entry {
+	fields := strings.SplitN(record, unitSep, 7)
+	if len(fields) < 7 {
+		return nil
+	}
+	sha, authorName, authorEmail, committerName, committerEmail, date, body := fields[0], fields[1], fields[2], fields[3], fields[4], fields[5], fields[6]
+
+	entries := []Entry{
+		{Name: authorName, Email: authorEmail, Field: "Author", Repo: repoFullName, CommitSHA: sha, Date: date},
+		{Name: committerName, Email: committerEmail, Field: "Committer", Repo: repoFullName, CommitSHA: sha, Date: date},
+	}
+	for _, match := range trailerPattern.FindAllStringSubmatch(body, -1) {
+		entries = append(entries, Entry{Name: match[2], Email: match[3], Field: match[1], Repo: repoFullName, CommitSHA: sha, Date: date})
+	}
+	return entries
+}