htwkalender/datamanager/backend/backend.go

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()
	})
}