Fix commit and contributors counts

Aka: a short and painful reminder that the Git history is a graph.

Thankfully, libgit2 knows about walking the revision graph.

quit.go

func (fr *FancyRepo) CommitCount() (int, error) {
	if fr.commitCount < 0 {
		walk, err := fr.repo.Walk()
		if err != nil {
			return -1, err
		}
		head, err := fr.repo.Head()
		if err != nil {
			return -1, err
		}
		commit, err := fr.repo.LookupCommit(head.Target())
		err = walk.Push(head.Target())
		if err != nil {
			return -1, err
		}
		c := 1
		for {
			commit = commit.Parent(0)
			if commit == nil {
				break
			}
		c := 0
		err = walk.Iterate(func(commit *git.Commit) bool {
			c += 1
			return true
		})
		if err != nil {
			return -1, err
		}
		fr.commitCount = c
	}
	return fr.commitCount, nil
func (fr *FancyRepo) Contributors() ([]*git.Signature, error) {
	if fr.contributors == nil {
		walk, err := fr.repo.Walk()
		if err != nil {
			return nil, err
		}
		head, err := fr.repo.Head()
		if err != nil {
			return nil, err
		}
		commit, err := fr.repo.LookupCommit(head.Target())
		err = walk.Push(head.Target())
		if err != nil {
			return nil, err
		}
		authors := make(map[string]*git.Signature)
		authors[commit.Author().Name] = commit.Author()
		for {
			commit = commit.Parent(0)
			if commit == nil {
				break
			}
		err = walk.Iterate(func(commit *git.Commit) bool {
			authors[commit.Author().Name] = commit.Author()
			return true
		})
		if err != nil {
			return nil, err
		}
		for _, author := range authors {
			fr.contributors = append(fr.contributors, author)
		}