Restrucure project in a way where it is more modular

pkg/git/branch_list_builder.go

@@ -0,0 +1,134 @@
+package git
+
+import (
+	"regexp"
+	"strings"
+
+	"gopkg.in/src-d/go-git.v4/plumbing"
+)
+
+// context:
+// we want to only show 'safe' branches (ones that haven't e.g. been deleted)
+// which `git branch -a` gives us, but we also want the recency data that
+// git reflog gives us.
+// So we get the HEAD, then append get the reflog branches that intersect with
+// our safe branches, then add the remaining safe branches, ensuring uniqueness
+// along the way
+
+type branchListBuilder struct{}
+
+func newBranchListBuilder() *branchListBuilder {
+	return &branchListBuilder{}
+}
+
+func (b *branchListBuilder) obtainCurrentBranch() Branch {
+	// I used go-git for this, but that breaks if you've just done a git init,
+	// even though you're on 'master'
+	branchName, _ := runDirectCommand("git symbolic-ref --short HEAD")
+	return Branch{Name: strings.TrimSpace(branchName), Recency: "  *"}
+}
+
+func (*branchListBuilder) obtainReflogBranches() []Branch {
+	branches := make([]Branch, 0)
+	rawString, err := runDirectCommand("git reflog -n100 --pretty='%cr|%gs' --grep-reflog='checkout: moving' HEAD")
+	if err != nil {
+		return branches
+	}
+
+	branchLines := splitLines(rawString)
+	for _, line := range branchLines {
+		timeNumber, timeUnit, branchName := branchInfoFromLine(line)
+		timeUnit = abbreviatedTimeUnit(timeUnit)
+		branch := Branch{Name: branchName, Recency: timeNumber + timeUnit}
+		branches = append(branches, branch)
+	}
+	return branches
+}
+
+func (b *branchListBuilder) obtainSafeBranches() []Branch {
+	branches := make([]Branch, 0)
+
+	bIter, err := r.Branches()
+	if err != nil {
+		panic(err)
+	}
+	err = bIter.ForEach(func(b *plumbing.Reference) error {
+		name := b.Name().Short()
+		branches = append(branches, Branch{Name: name})
+		return nil
+	})
+
+	return branches
+}
+
+func (b *branchListBuilder) appendNewBranches(finalBranches, newBranches, existingBranches []Branch, included bool) []Branch {
+	for _, newBranch := range newBranches {
+		if included == branchIncluded(newBranch.Name, existingBranches) {
+			finalBranches = append(finalBranches, newBranch)
+		}
+	}
+	return finalBranches
+}
+
+func sanitisedReflogName(reflogBranch Branch, safeBranches []Branch) string {
+	for _, safeBranch := range safeBranches {
+		if strings.ToLower(safeBranch.Name) == strings.ToLower(reflogBranch.Name) {
+			return safeBranch.Name
+		}
+	}
+	return reflogBranch.Name
+}
+
+func (b *branchListBuilder) build() []Branch {
+	branches := make([]Branch, 0)
+	head := b.obtainCurrentBranch()
+	safeBranches := b.obtainSafeBranches()
+	if len(safeBranches) == 0 {
+		return append(branches, head)
+	}
+	reflogBranches := b.obtainReflogBranches()
+	reflogBranches = uniqueByName(append([]Branch{head}, reflogBranches...))
+	for i, reflogBranch := range reflogBranches {
+		reflogBranches[i].Name = sanitisedReflogName(reflogBranch, safeBranches)
+	}
+
+	branches = b.appendNewBranches(branches, reflogBranches, safeBranches, true)
+	branches = b.appendNewBranches(branches, safeBranches, branches, false)
+
+	return branches
+}
+
+func uniqueByName(branches []Branch) []Branch {
+	finalBranches := make([]Branch, 0)
+	for _, branch := range branches {
+		if branchIncluded(branch.Name, finalBranches) {
+			continue
+		}
+		finalBranches = append(finalBranches, branch)
+	}
+	return finalBranches
+}
+
+// A line will have the form '10 days ago master' so we need to strip out the
+// useful information from that into timeNumber, timeUnit, and branchName
+func branchInfoFromLine(line string) (string, string, string) {
+	r := regexp.MustCompile("\\|.*\\s")
+	line = r.ReplaceAllString(line, " ")
+	words := strings.Split(line, " ")
+	return words[0], words[1], words[3]
+}
+
+func abbreviatedTimeUnit(timeUnit string) string {
+	r := regexp.MustCompile("s$")
+	timeUnit = r.ReplaceAllString(timeUnit, "")
+	timeUnitMap := map[string]string{
+		"hour":   "h",
+		"minute": "m",
+		"second": "s",
+		"week":   "w",
+		"year":   "y",
+		"day":    "d",
+		"month":  "m",
+	}
+	return timeUnitMap[timeUnit]
+}