Refactor packages structure

- Isolate files into their own packages
- Create new printer package and interface
- Refactor Repo stuct to embed the go-git *Repository directly
- Simplify cmd package

git/status.go

@@ -0,0 +1,264 @@
+package git
+
+import (
+	"sort"
+	"strings"
+
+	"github.com/go-git/go-billy/v5/osfs"
+
+	"github.com/go-git/go-git/v5/plumbing/format/gitignore"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/pkg/errors"
+)
+
+const (
+	StatusUnknown     = "unknown"
+	StatusDetached    = "detached HEAD"
+	StatusNoUpstream  = "no upstream"
+	StatusAhead       = "ahead"
+	StatusBehind      = "behind"
+	StatusOk          = "ok"
+	StatusUncommitted = "uncommitted"
+	StatusUntracked   = "untracked"
+)
+
+type RepoStatus struct {
+	HasUntrackedFiles     bool
+	HasUncommittedChanges bool
+	CurrentBranch         string
+	Branches              []*BranchStatus
+}
+
+type BranchStatus struct {
+	Name      string
+	Upstream  string
+	NeedsPull bool
+	NeedsPush bool
+}
+
+func (r *Repo) LoadStatus() error {
+	wt, err := r.Worktree()
+	if err != nil {
+		return errors.Wrap(err, "Failed getting worktree")
+	}
+
+	// worktree.Status doesn't load gitignore patterns that may be defined outside of .gitignore file using excludesfile
+	// We need to load them explicitly here
+	// TODO: variables are not expanded so if excludesfile is declared like "~/gitignore_global" or "$HOME/gitignore_global", this will fail to open it
+	globalPatterns, err := gitignore.LoadGlobalPatterns(osfs.New(""))
+	if err != nil {
+		return errors.Wrap(err, "Failed loading global gitignore patterns")
+	}
+	wt.Excludes = append(wt.Excludes, globalPatterns...)
+
+	systemPatterns, err := gitignore.LoadSystemPatterns(osfs.New(""))
+	if err != nil {
+		return errors.Wrap(err, "Failed loading system gitignore patterns")
+	}
+	wt.Excludes = append(wt.Excludes, systemPatterns...)
+
+	status, err := wt.Status()
+	if err != nil {
+		return errors.Wrap(err, "Failed getting worktree status")
+	}
+
+	r.Status.HasUncommittedChanges = hasUncommitted(status)
+	r.Status.HasUntrackedFiles = hasUntracked(status)
+	r.Status.CurrentBranch = currentBranch(r)
+
+	err = r.loadBranchesStatus()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// hasUntracked returns true if there are any untracked files in the worktree
+func hasUntracked(status git.Status) bool {
+	for _, fs := range status {
+		if fs.Worktree == git.Untracked || fs.Staging == git.Untracked {
+			return true
+		}
+	}
+
+	return false
+}
+
+// hasUncommitted returns true if there are any uncommitted (but tracked) files in the worktree
+func hasUncommitted(status git.Status) bool {
+	// If repo is clean it means every file in worktree and staging has 'Unmodified' state
+	if status.IsClean() {
+		return false
+	}
+
+	// If repo is not clean, check if any file has state different than 'Untracked' - it means they are tracked and have uncommitted modifications
+	for _, fs := range status {
+		if fs.Worktree != git.Untracked || fs.Staging != git.Untracked {
+			return true
+		}
+	}
+
+	return false
+}
+
+func currentBranch(r *Repo) string {
+	head, err := r.Head()
+	if err != nil {
+		return StatusUnknown
+	}
+
+	if head.Name().Short() == plumbing.HEAD.String() {
+		return StatusDetached
+	}
+
+	return head.Name().Short()
+}
+
+func (r *Repo) loadBranchesStatus() error {
+	iter, err := r.Branches()
+	if err != nil {
+		return errors.Wrap(err, "Failed getting branches iterator")
+	}
+
+	err = iter.ForEach(func(reference *plumbing.Reference) error {
+		bs, err := r.newBranchStatus(reference.Name().Short())
+		if err != nil {
+			return err
+		}
+
+		r.Status.Branches = append(r.Status.Branches, bs)
+		return nil
+	})
+	if err != nil {
+		return errors.Wrap(err, "Failed iterating over branches")
+	}
+
+	// Sort branches by name (but with "master" always at the top). It's useful to have them sorted for printing and testing.
+	sort.Slice(r.Status.Branches, func(i, j int) bool {
+		if r.Status.Branches[i].Name == "master" {
+			return true
+		}
+
+		return strings.Compare(r.Status.Branches[i].Name, r.Status.Branches[j].Name) < 0
+	})
+	return nil
+}
+
+func (r *Repo) newBranchStatus(branch string) (*BranchStatus, error) {
+	bs := &BranchStatus{
+		Name: branch,
+	}
+
+	upstream, err := r.upstream(branch)
+	if err != nil {
+		return nil, err
+	}
+
+	if upstream == "" {
+		return bs, nil
+	}
+
+	needsPull, needsPush, err := r.needsPullOrPush(branch, upstream)
+	if err != nil {
+		return nil, err
+	}
+
+	bs.Upstream = upstream
+	bs.NeedsPush = needsPush
+	bs.NeedsPull = needsPull
+
+	return bs, nil
+}
+
+// upstream finds if a given branch tracks an upstream.
+// Returns found upstream branch name (eg, origin/master) or empty string if branch doesn't track an upstream.
+//
+// Information about upstream is taken from .git/config file.
+// If a branch has an upstream, there's a [branch] section in the file with two fields:
+// "remote" - name of the remote containing upstream branch (or "." if upstream is a local branch)
+// "merge" - full ref name of the upstream branch (eg, ref/heads/master)
+func (r *Repo) upstream(branch string) (string, error) {
+	cfg, err := r.Config()
+	if err != nil {
+		return "", errors.Wrap(err, "Failed getting repo config")
+	}
+
+	// Check if our branch exists in "branch" config sections. If not, it doesn't have an upstream configured.
+	bcfg := cfg.Branches[branch]
+	if bcfg == nil {
+		return "", nil
+	}
+
+	remote := bcfg.Remote
+	if remote == "" {
+		return "", nil
+	}
+
+	merge := bcfg.Merge.Short()
+	if merge == "" {
+		return "", nil
+	}
+	return remote + "/" + merge, nil
+}
+
+func (r *Repo) needsPullOrPush(localBranch string, upstreamBranch string) (needsPull bool, needsPush bool, err error) {
+	localHash, err := r.ResolveRevision(plumbing.Revision(localBranch))
+	if err != nil {
+		return false, false, errors.Wrapf(err, "Failed resolving revision %s", localBranch)
+	}
+
+	upstreamHash, err := r.ResolveRevision(plumbing.Revision(upstreamBranch))
+	if err != nil {
+		return false, false, errors.Wrapf(err, "Failed resolving revision %s", upstreamBranch)
+	}
+
+	localCommit, err := r.CommitObject(*localHash)
+	if err != nil {
+		return false, false, errors.Wrapf(err, "Failed finding a commit for hash %s", localHash.String())
+	}
+
+	upstreamCommit, err := r.CommitObject(*upstreamHash)
+	if err != nil {
+		return false, false, errors.Wrapf(err, "Failed finding a commit for hash %s", upstreamHash.String())
+	}
+
+	// If local branch hash is the same as upstream, it means there is no difference between local and upstream
+	if *localHash == *upstreamHash {
+		return false, false, nil
+	}
+
+	commons, err := localCommit.MergeBase(upstreamCommit)
+	if err != nil {
+		return false, false, errors.Wrapf(err, "Failed finding common ancestors for branches %s & %s", localBranch, upstreamBranch)
+	}
+
+	if len(commons) == 0 {
+		// TODO: No common ancestors. This should be an error
+		return false, false, nil
+	}
+
+	if len(commons) > 1 {
+		// TODO: multiple best ancestors. How to handle this?
+		return false, false, nil
+	}
+
+	mergeBase := commons[0]
+
+	// If merge base is the same as upstream branch, local branch is ahead and push is needed
+	// If merge base is the same as local branch, local branch is behind and pull is needed
+	// If merge base is something else, branches have diverged and merge is needed (both pull and push)
+	// ref: https://stackoverflow.com/a/17723781/1085632
+
+	if mergeBase.Hash == *upstreamHash {
+		return false, true, nil
+	}
+
+	if mergeBase.Hash == *localHash {
+		return true, false, nil
+	}
+
+	return true, true, nil
+}