clearer separation of concerns when bootstrapping application

pkg/app/daemon/daemon.go

@@ -0,0 +1,107 @@
+package daemon
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/jesseduffield/lazygit/pkg/common"
+	"github.com/jesseduffield/lazygit/pkg/env"
+)
+
+// Sometimes lazygit will be invoked in daemon mode from a parent lazygit process.
+// We do this when git lets us supply a program to run within a git command.
+// For example, if we want to ensure that a git command doesn't hang due to
+// waiting for an editor to save a commit message, we can tell git to invoke lazygit
+// as the editor via 'GIT_EDITOR=lazygit', and use the env var
+// 'LAZYGIT_DAEMON_KIND=EXIT_IMMEDIATELY' to specify that we want to run lazygit
+// as a daemon which simply exits immediately. Any additional arguments we want
+// to pass to a daemon can be done via other env vars.
+
+type DaemonKind string
+
+const (
+	InteractiveRebase DaemonKind = "INTERACTIVE_REBASE"
+	ExitImmediately   DaemonKind = "EXIT_IMMEDIATELY"
+)
+
+const (
+	DaemonKindEnvKey string = "LAZYGIT_DAEMON_KIND"
+	RebaseTODOEnvKey string = "LAZYGIT_REBASE_TODO"
+)
+
+type Daemon interface {
+	Run() error
+}
+
+func Handle(common *common.Common) {
+	d := getDaemon(common)
+	if d == nil {
+		return
+	}
+
+	if err := d.Run(); err != nil {
+		log.Fatal(err)
+	}
+
+	os.Exit(0)
+}
+
+func InDaemonMode() bool {
+	return getDaemonKind() != ""
+}
+
+func getDaemon(common *common.Common) Daemon {
+	switch getDaemonKind() {
+	case InteractiveRebase:
+		return &rebaseDaemon{c: common}
+	case ExitImmediately:
+		return &exitImmediatelyDaemon{c: common}
+	}
+
+	return nil
+}
+
+func getDaemonKind() DaemonKind {
+	return DaemonKind(os.Getenv(DaemonKindEnvKey))
+}
+
+type rebaseDaemon struct {
+	c *common.Common
+}
+
+func (self *rebaseDaemon) Run() error {
+	self.c.Log.Info("Lazygit invoked as interactive rebase demon")
+	self.c.Log.Info("args: ", os.Args)
+
+	if strings.HasSuffix(os.Args[1], "git-rebase-todo") {
+		if err := ioutil.WriteFile(os.Args[1], []byte(os.Getenv(RebaseTODOEnvKey)), 0o644); err != nil {
+			return err
+		}
+	} else if strings.HasSuffix(os.Args[1], filepath.Join(gitDir(), "COMMIT_EDITMSG")) { // TODO: test
+		// if we are rebasing and squashing, we'll see a COMMIT_EDITMSG
+		// but in this case we don't need to edit it, so we'll just return
+	} else {
+		self.c.Log.Info("Lazygit demon did not match on any use cases")
+	}
+
+	return nil
+}
+
+func gitDir() string {
+	dir := env.GetGitDirEnv()
+	if dir == "" {
+		return ".git"
+	}
+	return dir
+}
+
+type exitImmediatelyDaemon struct {
+	c *common.Common
+}
+
+func (self *exitImmediatelyDaemon) Run() error {
+	return nil
+}