mbrts/main.go

package main

import (
	"context"
	_ "embed"
	"errors"
	"flag"
	"fmt"
	"log/slog"
	"os"
	"os/signal"
	"strings"
	"sync"
	"syscall"
	"time"
)

//go:embed VERSION
var versionRaw string

var version = strings.TrimSpace(versionRaw)

func main() {
	showVersion := flag.Bool("version", false, "print version and exit")
	configPath := flag.String("config", defaultConfigPath(), "path to config file")
	logLevel := flag.String("log-level", "", "log level: debug, info, warn, error")

	// Single-account flags — when --name is set, these define the account
	// directly without requiring a config file.
	name := flag.String("name", "", "account name")
	maildirPath := flag.String("maildir-path", "", "path to the account's maildir")
	mbsyncAccount := flag.String("mbsync-account", "", "mbsync channel/group name (defaults to account name)")
	passwordCommand := flag.String("password-command", "", "shell command that prints the JMAP bearer token")
	tokenFile := flag.String("token-file", "", "path to file containing the JMAP bearer token")
	tokenEnv := flag.String("token-env", "", "environment variable containing the JMAP bearer token")

	flag.Parse()

	if *showVersion {
		fmt.Println(version)
		return
	}

	// Load config file if it exists; a missing default path is not an error.
	var cfg Config
	if data, err := os.ReadFile(*configPath); err == nil {
		if err := (&cfg).unmarshal(data); err != nil {
			fmt.Fprintf(os.Stderr, "config: %v\n", err)
			os.Exit(1)
		}
	} else if *configPath != defaultConfigPath() || !errors.Is(err, os.ErrNotExist) {
		fmt.Fprintf(os.Stderr, "config: %v\n", err)
		os.Exit(1)
	}

	// CLI account flags override / replace config file accounts.
	if *name != "" {
		cfg.Accounts = []AccountConfig{{
			Name:            *name,
			MaildirPath:     *maildirPath,
			MbsyncAccount:   *mbsyncAccount,
			PasswordCommand: *passwordCommand,
			TokenFile:       *tokenFile,
			TokenEnv:        *tokenEnv,
		}}
	}

	// CLI log level overrides config file.
	if *logLevel != "" {
		cfg.LogLevel = *logLevel
	}
	if cfg.LogLevel == "" {
		cfg.LogLevel = "info"
	}

	var level slog.Level
	if err := level.UnmarshalText([]byte(cfg.LogLevel)); err != nil {
		fmt.Fprintf(os.Stderr, "invalid log level %q: %v\n", cfg.LogLevel, err)
		os.Exit(1)
	}
	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: level})))

	if len(cfg.Accounts) == 0 {
		fmt.Fprintln(os.Stderr, "no accounts configured — provide a config file or use --name with token flags")
		os.Exit(1)
	}
	for _, a := range cfg.Accounts {
		if err := a.validate(); err != nil {
			fmt.Fprintf(os.Stderr, "config: %v\n", err)
			os.Exit(1)
		}
	}

	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	var wg sync.WaitGroup
	for _, a := range cfg.Accounts {
		wg.Add(1)
		go func(a AccountConfig) {
			defer wg.Done()
			watchWithRetry(ctx, a)
		}(a)
	}

	<-ctx.Done()
	wg.Wait()
	slog.Info("shutdown complete")
}

func watchWithRetry(ctx context.Context, a AccountConfig) {
	for {
		if ctx.Err() != nil {
			return
		}
		if err := watch(ctx, a); err != nil {
			slog.Error("watch error", "account", a.Name, "err", err)
		}
		select {
		case <-ctx.Done():
			return
		case <-time.After(10 * time.Second):
			slog.Info("reconnecting", "account", a.Name)
		}
	}
}