feat:#10 added new minimal backend

datamanager/backend/backend.go

@@ -0,0 +1,188 @@
+package backend
+
+import (
+	"datamanager/backend/cmd"
+	"datamanager/backend/core"
+	"github.com/fatih/color"
+	"github.com/spf13/cobra"
+	"io"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"strings"
+	"syscall"
+)
+
+var _ core.App = (*Backend)(nil)
+
+// Version of Backend
+var Version = "(untracked)"
+
+type appWrapper struct {
+	core.App
+}
+
+type Backend struct {
+	*appWrapper
+
+	devFlag           bool
+	dataDirFlag       string
+	encryptionEnvFlag string
+	hideStartBanner   bool
+
+	// RootCmd is the main console command
+	RootCmd *cobra.Command
+}
+
+func New() *Backend {
+	_, isUsingGoRun := inspectRuntime()
+
+	return NewWithConfig(Config{
+		DefaultDev: isUsingGoRun,
+		DBUsername: "neo4j",
+		DBPassword: "htwkalender-db",
+	})
+}
+
+// inspectRuntime tries to find the base executable directory and how it was run.
+func inspectRuntime() (baseDir string, withGoRun bool) {
+	if strings.HasPrefix(os.Args[0], os.TempDir()) {
+		// probably ran with go run
+		withGoRun = true
+		baseDir, _ = os.Getwd()
+	} else {
+		// probably ran with go build
+		withGoRun = false
+		baseDir = filepath.Dir(os.Args[0])
+	}
+	return
+}
+
+type Config struct {
+	// optional default values for the console flags
+	DefaultDev     bool
+	DefaultDataDir string // if not set, it will fallback to "./pb_data"
+	DBUsername     string
+	DBPassword     string
+}
+
+func NewWithConfig(config Config) *Backend {
+	// initialize a default data directory based on the executable baseDir
+	if config.DefaultDataDir == "" {
+		baseDir, _ := inspectRuntime()
+		config.DefaultDataDir = filepath.Join(baseDir, "data")
+	}
+
+	backend := &Backend{
+		RootCmd: &cobra.Command{
+			Use:     filepath.Base(os.Args[0]),
+			Short:   "Backend CLI",
+			Version: Version,
+			FParseErrWhitelist: cobra.FParseErrWhitelist{
+				UnknownFlags: true,
+			},
+			// no need to provide the default cobra completion command
+			CompletionOptions: cobra.CompletionOptions{
+				DisableDefaultCmd: true,
+			},
+		},
+		devFlag:     config.DefaultDev,
+		dataDirFlag: config.DefaultDataDir,
+	}
+
+	// replace with a colored stderr writer
+	backend.RootCmd.SetErr(newErrWriter())
+
+	// parse base flags
+	// (errors are ignored, since the full flags parsing happens on Execute())
+	_ = backend.eagerParseFlags(&config)
+
+	// initialize the app instance
+	backend.appWrapper = &appWrapper{core.NewBaseApp(core.BaseAppConfig{
+		IsDev:      backend.devFlag,
+		DataDir:    backend.dataDirFlag,
+		DBUsername: config.DBUsername,
+		DBPassword: config.DBPassword,
+	})}
+
+	// hide the default help command (allow only `--help` flag)
+	backend.RootCmd.SetHelpCommand(&cobra.Command{Hidden: true})
+
+	return backend
+}
+
+func newErrWriter() *coloredWriter {
+	return &coloredWriter{
+		w: os.Stderr,
+		c: color.New(color.FgRed),
+	}
+}
+
+// coloredWriter is a small wrapper struct to construct a [color.Color] writter.
+type coloredWriter struct {
+	w io.Writer
+	c *color.Color
+}
+
+// Write writes the p bytes using the colored writer.
+func (colored *coloredWriter) Write(p []byte) (n int, err error) {
+	colored.c.SetWriter(colored.w)
+	defer colored.c.UnsetWriter(colored.w)
+
+	return colored.c.Print(string(p))
+}
+
+func (backend *Backend) eagerParseFlags(config *Config) error {
+	backend.RootCmd.PersistentFlags().StringVar(
+		&backend.dataDirFlag,
+		"dir",
+		config.DefaultDataDir,
+		"the PocketBase data directory",
+	)
+
+	backend.RootCmd.PersistentFlags().BoolVar(
+		&backend.devFlag,
+		"dev",
+		config.DefaultDev,
+		"enable dev mode, aka. printing logs and cypher/sql statements to the console",
+	)
+
+	return backend.RootCmd.ParseFlags(os.Args[1:])
+}
+
+func (backend *Backend) Start() error {
+	// register system commands
+	backend.RootCmd.AddCommand(cmd.NewServeCommand(backend, !backend.hideStartBanner))
+
+	return backend.Execute()
+}
+
+func (backend *Backend) Execute() error {
+	done := make(chan bool, 1)
+
+	// listen for interrupt signal to gracefully shutdown the application
+	go func() {
+		sigch := make(chan os.Signal, 1)
+		signal.Notify(sigch, os.Interrupt, syscall.SIGTERM)
+		<-sigch
+
+		done <- true
+	}()
+
+	// execute the root command
+	go func() {
+		// note: leave to the commands to decide whether to print their error
+		_ = backend.RootCmd.Execute()
+
+		done <- true
+	}()
+
+	<-done
+
+	// trigger cleanups
+	return backend.OnTerminate().Trigger(&core.TerminateEvent{
+		App: backend,
+	}, func(e *core.TerminateEvent) error {
+		return e.App.ResetBootstrapState()
+	})
+}