Proof of concept implementation

Author: giannimassi

branch.go

@@ -0,0 +1,160 @@
+package main
+
+import (
+	"os"
+	"os/exec"
+	"regexp"
+	"strings"
+
+	"github.com/fatih/color"
+)
+
+func cmdOutput(command string, args ...string) (string, error) {
+	cmd := exec.Command(command, args...)
+	b, err := cmd.CombinedOutput()
+	return string(b), err
+}
+
+func cmdRun(command string, args ...string) error {
+	cmd := exec.Command(command, args...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+	return nil
+}
+
+// branch describes a Git branch.
+type branch struct {
+	name      string
+	isCurrent bool
+}
+
+// branchesState provides the state for the application, based on CQRS
+// Includes view and command methods
+type branchesState struct {
+	branches []branch
+	selected int
+}
+
+func (b *branchesState) init(args []string) error {
+	args = append([]string{"branch"}, args...)
+	out, err := cmdOutput("git", args...)
+	if err != nil {
+		println(out)
+		return err
+	}
+	b.branches = splitBranches(out)
+	b.selectCurrent()
+	return nil
+}
+
+func splitBranches(output string) []branch {
+	names := strings.Split(output, "\n")
+	var branches []branch
+	for _, name := range names {
+		if len(name) == 0 {
+			continue
+		}
+		isCurrent := false
+		if strings.Contains(name, "*") {
+			name = strings.Replace(name, "*", "", -1)
+			isCurrent = true
+		}
+
+		name = strings.TrimSpace(name)
+		branches = append(branches, branch{name: name, isCurrent: isCurrent})
+	}
+	return branches
+}
+
+func extractBranch(name string) string {
+	if strings.Contains(name, "->") {
+		s := strings.Split(name, "->")
+		return strings.TrimSpace(s[0])
+	}
+	return name
+}
+
+// Commands
+// These methods allow to mutate state
+
+func (b *branchesState) selectCurrent() {
+	for ; !b.branches[b.selected].isCurrent; b.selected++ {
+	}
+}
+
+func (b *branchesState) selectNext() {
+	b.selected = (b.selected + len(b.branches) - 1) % len(b.branches)
+}
+
+func (b *branchesState) selectPrevious() {
+	b.selected = ((b.selected + 1) % len(b.branches))
+}
+
+// View
+// These methods allow to present the state
+
+func (b *branchesState) selectedBranchName() string {
+	return b.branches[b.selected].name
+}
+
+func (b *branchesState) selectedBranchWithColor() string {
+	formatted := []string{}
+	fields := strings.Split(b.selectedBranchName(), "/")
+	for _, f := range fields {
+		formatted = append(formatted, withColor(f, colorDefaults))
+	}
+	out := strings.Join(formatted, withColor("/", colorDefaults))
+	if b.branches[b.selected].isCurrent {
+		out += "\t(" + withColor("currently checked-out", colorDefaults) + ")"
+	}
+	return out
+}
+
+type formatFunc func(format string, a ...interface{}) string
+
+type colorFormatter struct {
+	pattern *regexp.Regexp
+	format  formatFunc
+}
+
+func newColorFormatter(pattern string, format formatFunc) colorFormatter {
+	return colorFormatter{
+		pattern: regexp.MustCompile(pattern),
+		format:  format,
+	}
+}
+
+func withColor(str string, colors []colorFormatter) string {
+	for _, f := range colors {
+		if f.pattern.MatchString(str) {
+			return f.format(str)
+		}
+	}
+	return str
+}
+
+var colorDefaults = []colorFormatter{
+	newColorFormatter("feature", color.GreenString),
+	newColorFormatter("test", color.GreenString),
+
+	newColorFormatter("improvement", color.YellowString),
+	newColorFormatter("refactor", color.YellowString),
+	newColorFormatter("currently checked-out", color.YellowString),
+
+	newColorFormatter("fix", color.RedString),
+	newColorFormatter("bugfix", color.RedString),
+	newColorFormatter("bug", color.RedString),
+	newColorFormatter("fixup", color.RedString),
+	newColorFormatter("debug", color.RedString),
+	newColorFormatter("backup", color.RedString),
+
+	newColorFormatter("master", color.CyanString),
+
+	newColorFormatter("remotes", color.MagentaString),
+	newColorFormatter("origin", color.MagentaString),
+
+	newColorFormatter(".*", color.WhiteString),
+}

branch_test.go

@@ -0,0 +1,19 @@
+package main
+
+import "testing"
+
+func Test_extractBranch(t *testing.T) {
+	tests := []struct {
+		name string
+		want string
+	}{
+		{"feature", "feature"},
+		{"hotfix", "hotfix"},
+		{"origin/HEAD -> origin/master", "origin/HEAD"},
+	}
+	for _, tt := range tests {
+		if got := extractBranch(tt.name); got != tt.want {
+			t.Errorf("extractBranch() = %v, want %v", got, tt.want)
+		}
+	}
+}

go.mod

@@ -0,0 +1,11 @@
+module github.com/giannimassi/git-checkout-interactive
+
+go 1.13
+
+require (
+	github.com/eiannone/keyboard v0.0.0-20200508000154-caf4b762e807
+	github.com/fatih/color v1.9.0
+	github.com/gosuri/uilive v0.0.4
+	github.com/mattn/go-isatty v0.0.12 // indirect
+	golang.org/x/sys v0.0.0-20200622214017-ed371f2e16b4 // indirect
+)

go.sum

@@ -0,0 +1,17 @@
+github.com/eiannone/keyboard v0.0.0-20200508000154-caf4b762e807 h1:jdjd5e68T4R/j4PWxfZqcKY8KtT9oo8IPNVuV4bSXDQ=
+github.com/eiannone/keyboard v0.0.0-20200508000154-caf4b762e807/go.mod h1:Xoiu5VdKMvbRgHuY7+z64lhu/7lvax/22nzASF6GrO8=
+github.com/fatih/color v1.9.0 h1:8xPHl4/q1VyqGIPif1F+1V3Y3lSmrq01EabUW3CoW5s=
+github.com/fatih/color v1.9.0/go.mod h1:eQcE1qtQxscV5RaZvpXrrb8Drkc3/DdQ+uUYCNjL+zU=
+github.com/gosuri/uilive v0.0.4 h1:hUEBpQDj8D8jXgtCdBu7sWsy5sbW/5GhuO8KBwJ2jyY=
+github.com/gosuri/uilive v0.0.4/go.mod h1:V/epo5LjjlDE5RJUcqx8dbw+zc93y5Ya3yg8tfZ74VI=
+github.com/mattn/go-colorable v0.1.4 h1:snbPLB8fVfU9iwbbo30TPtbLRzwWu6aJS6Xh4eaaviA=
+github.com/mattn/go-colorable v0.1.4/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
+github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
+github.com/mattn/go-isatty v0.0.11/go.mod h1:PhnuNfih5lzO57/f3n+odYbM4JtupLOxQOAqxQCu2WE=
+github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHXY=
+github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
+golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200622214017-ed371f2e16b4 h1:5/PjkGUjvEU5Gl6BxmvKRPpqo2uNMv4rcHBMwzk/st8=
+golang.org/x/sys v0.0.0-20200622214017-ed371f2e16b4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

main.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/eiannone/keyboard"
+	"github.com/gosuri/uilive"
+)
+
+func main() {
+	if err := run(os.Args[1:]); err != nil {
+		println("Unexpected error: " + err.Error())
+	}
+}
+
+func run(args []string) error {
+	// Init state
+	view := &branchesState{}
+	if err := view.init(args); err != nil {
+		return err
+	}
+
+	// Setup key input
+	keyCh, err := keyboard.GetKeys(10)
+	if err != nil {
+		return err
+	}
+	defer keyboard.Close()
+
+	// Setup writer and start with currently selected branch
+	stdout := uilive.New()
+	fmt.Fprintf(stdout, "→	%s\n", view.selectedBranchWithColor())
+	stdout.Flush()
+
+	// Listen for keyboard events and term signal
+	for {
+		select {
+		case ev := <-keyCh:
+			done, err := handleKeyEvent(stdout, view, ev)
+			if !done {
+				continue
+			}
+			return err
+		}
+	}
+}
+
+func handleKeyEvent(wf writerFlusher, view *branchesState, ev keyboard.KeyEvent) (bool, error) {
+	if ev.Err != nil {
+		return true, ev.Err
+	}
+	switch {
+	// Exit
+	case ev.Key == keyboard.KeyCtrlC:
+		fallthrough
+	case ev.Key == keyboard.KeyEsc:
+		return true, nil
+
+	// Up
+	case ev.Key == keyboard.KeyArrowUp:
+		fallthrough
+	case ev.Key == keyboard.KeyArrowLeft:
+		fallthrough
+	case ev.Rune == 'h':
+		view.selectPrevious()
+		fmt.Fprintf(wf, "→	%s\n", view.selectedBranchWithColor())
+		wf.Flush()
+
+	// Down
+	case ev.Key == keyboard.KeyArrowDown:
+		fallthrough
+	case ev.Key == keyboard.KeyArrowRight:
+		fallthrough
+	case ev.Rune == 'j':
+		view.selectNext()
+		fmt.Fprintf(wf, "→	%s\n", view.selectedBranchWithColor())
+		wf.Flush()
+
+	// Enter
+	case ev.Key == keyboard.KeyEnter:
+		return true, cmdRun("git", "checkout", extractBranch(view.selectedBranchName()))
+
+	default:
+		return false, nil
+	}
+	return false, nil
+}
+
+type writerWrapper struct {
+	io.Writer
+}
+
+func (w *writerWrapper) Flush() error {
+	return nil
+}
+
+type writerFlusher interface {
+	io.Writer
+	Flush() error
+}