archivmail/cmd/archivmail/main.go

package main

import (
	"context"
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"flag"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	"golang.org/x/crypto/hkdf"

	"github.com/archivmail/config"
	"github.com/archivmail/internal/api"
	"github.com/archivmail/internal/audit"
	"github.com/archivmail/internal/auth"
	imapstore "github.com/archivmail/internal/imap"
	"github.com/archivmail/internal/imapserver"
	"github.com/archivmail/internal/index"
	"github.com/archivmail/internal/labelstore"
	ldapcfg "github.com/archivmail/internal/ldapconfig"
	pop3store "github.com/archivmail/internal/pop3"
	"github.com/archivmail/internal/smtpd"
	"github.com/archivmail/internal/storage"
	tenantstore "github.com/archivmail/internal/tenantstore"
	"github.com/archivmail/internal/userstore"
	"github.com/archivmail/pkg/mailparser"
)

func main() {
	if len(os.Args) > 1 {
		switch os.Args[1] {
		case "import":
			runImport(os.Args[2:])
			return
		case "import-piler":
			runImportPiler(os.Args[2:])
			return
		case "export":
			runExport(os.Args[2:])
			return
		case "migrate-tenants":
			runMigrateTenants(os.Args[2:])
			return
		case "version":
			fmt.Printf("archivmail %s\n", version)
			return
		case "help", "--help", "-h":
			printHelp()
			return
		case "serve":
			// strip "serve" from args so flag.Parse works normally below
			os.Args = append(os.Args[:1], os.Args[2:]...)
		}
	}

	configPath := flag.String("config", "/etc/archivmail/config.yml", "path to config file")
	flag.Parse()

	logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelInfo}))

	cfg, err := config.Load(*configPath)
	if err != nil {
		logger.Error("failed to load config", "path", *configPath, "err", err)
		os.Exit(1)
	}

	// SEC-08: Derive separate keys from the master secret to prevent key reuse.
	// jwtSecret is used for JWT token signing only.
	// aesKey is used for AES-256-GCM encryption of stored passwords (IMAP, POP3, LDAP).
	// HKDF is deterministic: same cfg.API.Secret always produces the same derived keys.
	// NOTE: After this change, existing stored IMAP/POP3/LDAP passwords must be
	// re-entered once, as they were encrypted with the old undivided key.
	masterKey := []byte(cfg.API.Secret)
	jwtKeyRaw := make([]byte, 32)
	if _, err := io.ReadFull(hkdf.New(sha256.New, masterKey, []byte("archivmail-jwt-v1"), nil), jwtKeyRaw); err != nil {
		logger.Error("key derivation failed", "err", err)
		os.Exit(1)
	}
	aesKeyRaw := make([]byte, 32)
	if _, err := io.ReadFull(hkdf.New(sha256.New, masterKey, []byte("archivmail-aes-v1"), nil), aesKeyRaw); err != nil {
		logger.Error("key derivation failed", "err", err)
		os.Exit(1)
	}
	jwtSecret := hex.EncodeToString(jwtKeyRaw)
	aesKey := hex.EncodeToString(aesKeyRaw)

	// Storage with encryption + DB metadata
	storeCfg := storage.Config{
		Dir:     cfg.Storage.StorePath,
		Keyfile: cfg.Storage.Keyfile,
		DSN:     cfg.Database.DSN(),
	}
	mailStore, err := storage.New(storeCfg)
	if err != nil {
		logger.Error("storage init failed", "err", err)
		os.Exit(1)
	}
	defer mailStore.Close()

	// Index — per-tenant index manager (PROJ-21 Phase 4)
	indexBackend := cfg.Index.Backend
	if indexBackend == "" {
		indexBackend = "xapian"
	}
	batchSize := cfg.Index.BatchSize
	if batchSize <= 0 {
		batchSize = 100
	}
	idxMgr, err := index.NewTenantIndexManager(cfg.Index.Path, batchSize, indexBackend)
	if err != nil {
		logger.Error("index manager init failed", "err", err)
		os.Exit(1)
	}
	defer idxMgr.Close()

	// Global index reference for backward compatibility (IMAP importer, etc.)
	idx := idxMgr.Global()

	// Async index worker — tenant-aware (routes docs to correct per-tenant index)
	asyncQueueSize := cfg.Index.AsyncQueueSize
	if asyncQueueSize <= 0 {
		asyncQueueSize = 1000
	}
	tenantWorker := index.NewTenantWorker(idxMgr, asyncQueueSize, logger)
	tenantWorker.Start()
	defer tenantWorker.Stop()

	// User store
	users, err := userstore.New(cfg.Database.DSN())
	if err != nil {
		logger.Error("userstore init failed", "err", err)
		os.Exit(1)
	}
	defer users.Close()

	// Audit log
	audlog, err := audit.New(cfg.Database.DSN(), cfg.Audit.LogPath, logger)
	if err != nil {
		logger.Error("audit init failed", "err", err)
		os.Exit(1)
	}
	defer audlog.Close()

	// Seed default users on first run
	if err := seedDefaultUsers(users, logger); err != nil {
		logger.Error("seed users failed", "err", err)
	}

	// LDAP config store
	ldapSt, err := ldapcfg.New(cfg.Database.DSN(), aesKey)
	if err != nil {
		logger.Error("ldap config store init failed", "err", err)
		os.Exit(1)
	}
	defer ldapSt.Close()

	// Auth manager (with LDAP fallback + TOTP AES key)
	authMgr := auth.New(users, ldapSt, jwtSecret, aesKey)

	// API server
	apiCfg := config.APIConfig{
		Bind:   cfg.API.Bind,
		Secret: jwtSecret,
	}
	srv := api.New(apiCfg, mailStore, idx, authMgr, users, audlog, logger)

	bind := cfg.API.Bind
	if bind == "" {
		bind = fmt.Sprintf(":%d", cfg.Server.APIPort)
	}

	httpServer := &http.Server{
		Addr:    bind,
		Handler: srv,
	}

	// Tenant store (Multi-Tenancy Phase 1+2) — must be initialised before SMTP daemon
	tenantSt, err := tenantstore.New(cfg.Database.DSN())
	if err != nil {
		logger.Error("tenant store init failed", "err", err)
		os.Exit(1)
	}
	defer tenantSt.Close()
	srv.SetTenants(tenantSt)
	srv.SetIndexManager(idxMgr)

	// PROJ-9: Label store
	labelSt, err := labelstore.New(cfg.Database.DSN())
	if err != nil {
		logger.Error("label store init failed", "err", err)
		os.Exit(1)
	}
	defer labelSt.Close()
	srv.SetLabels(labelSt)

	// PROJ-26: IMAP Archive Server (read-only access for IMAP clients)
	if cfg.IMAPServer.Enabled {
		imapSrv := imapserver.New(cfg.IMAPServer, mailStore, users, labelSt, audlog, authMgr, logger)
		if err := imapSrv.Start(); err != nil {
			logger.Error("IMAP server failed to start", "err", err)
			os.Exit(1)
		}
		defer imapSrv.Stop()
		imapBind := cfg.IMAPServer.Bind
		if imapBind == "" {
			imapBind = "127.0.0.1:1143"
		}
		logger.Info("IMAP archive server started", "addr", imapBind)
	}

	// Start SMTP daemon with index worker integration
	if cfg.SMTP.Bind == "" {
		cfg.SMTP.Bind = fmt.Sprintf(":%d", cfg.Server.SMTPPort)
	}
	smtpDaemon := smtpd.New(cfg.SMTP, mailStore, logger)
	smtpDaemon.SetIndexCallback(func(raw []byte, id string) {
		// Look up the tenant_id for this email from DB metadata.
		tenantID, _ := mailStore.GetTenantForMail(context.Background(), id)
		submitToWorker(tenantWorker, mailStore, raw, id, tenantID, logger)
	})
	// Wire tenant routing into SMTP daemon
	if cfg.SMTP.TenantRouting == "domain" {
		var defaultTenantID *int64
		if cfg.SMTP.DefaultTenantID != 0 {
			id := cfg.SMTP.DefaultTenantID
			defaultTenantID = &id
		}
		smtpDaemon.SetDomainToTenant(func(ctx context.Context, domain string) (*int64, error) {
			t, err := tenantSt.GetByDomain(ctx, domain)
			if err != nil || t == nil {
				return nil, err
			}
			id := t.ID
			return &id, nil
		}, defaultTenantID)
	}
	if err := smtpDaemon.Start(); err != nil {
		logger.Error("SMTP daemon failed to start", "err", err)
		os.Exit(1)
	}
	defer smtpDaemon.Stop()

	// Wire LDAP config store into API server
	srv.SetLDAP(ldapSt)

	// PROJ-23: Per-tenant LDAP config store
	tenantLdapSt, err := ldapcfg.NewTenantStore(cfg.Database.DSN(), aesKey)
	if err != nil {
		logger.Error("tenant ldap store init failed", "err", err)
		os.Exit(1)
	}
	defer tenantLdapSt.Close()
	srv.SetTenantLDAP(tenantLdapSt)
	authMgr.SetTenantLDAP(tenantLdapSt, tenantSt)

	// Wire SMTP daemon into API server for status endpoint
	srv.SetSMTPDaemon(smtpDaemon)

	// IMAP store + importer + scheduler (wired to use async worker)
	imapSt, err := imapstore.New(cfg.Database.DSN(), aesKey)
	if err != nil {
		logger.Error("imap store init failed", "err", err)
		os.Exit(1)
	}
	defer imapSt.Close()
	imapImp := imapstore.NewImporter(imapSt, mailStore, idx, logger)
	imapSched := imapstore.NewScheduler(imapSt, imapImp, logger)
	imapSched.Start()
	defer imapSched.Stop()
	srv.SetImap(imapSt, imapImp, imapSched)

	// POP3 store + importer
	pop3St, err := pop3store.New(cfg.Database.DSN(), aesKey)
	if err != nil {
		logger.Error("pop3 store init failed", "err", err)
		os.Exit(1)
	}
	defer pop3St.Close()
	pop3Imp := pop3store.NewImporter(pop3St, mailStore, idx, logger)
	srv.SetPop3(pop3St, pop3Imp)

	// Backfill in background: migrate existing files into DB metadata + re-index
	go runBackfill(context.Background(), mailStore, idx, tenantWorker, logger)

	// Background integrity verification — runs every 5 minutes
	go runIntegrityCheck(context.Background(), mailStore, logger)

	// Start HTTP API
	go func() {
		logger.Info("starting API server", "addr", bind)
		if err := httpServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			logger.Error("API server error", "err", err)
		}
	}()

	// Graceful shutdown
	quit := make(chan os.Signal, 1)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
	<-quit

	logger.Info("shutting down...")
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	httpServer.Shutdown(ctx)
}

// submitToWorker parses a raw email and submits it to the async index worker.
// tenantID may be nil for global context.
func submitToWorker(worker *index.TenantIndexWorker, store *storage.Store, raw []byte, id string, tenantID *int64, logger *slog.Logger) {
	pm, err := mailparser.Parse(raw)
	if err != nil {
		logger.Warn("index: parse failed, skipping indexing", "id", id, "err", err)
		return
	}

	var attachNames []string
	for _, a := range pm.Attachments {
		if a.Filename != "" {
			attachNames = append(attachNames, a.Filename)
		}
	}

	doc := index.MailDocument{
		ID:            id,
		From:          pm.From,
		To:            strings.Join(pm.To, ", "),
		Subject:       pm.Subject,
		Body:          pm.TextBody,
		AttachNames:   strings.Join(attachNames, " "),
		HasAttachment: len(pm.Attachments) > 0,
		Date:          pm.Date,
		Size:          int64(len(raw)),
		TenantID:      tenantID,
	}

	worker.Submit(doc)

	// Mark as indexed in DB
	if err := store.SetIndexedAt(context.Background(), id); err != nil {
		logger.Warn("index: set indexed_at failed", "id", id, "err", err)
	}
}

// runBackfill walks the store, inserts missing DB metadata, and indexes
// emails that have not yet been indexed. Per-tenant indexing is handled by
// looking up each email's tenant_id from the DB.
func runBackfill(ctx context.Context, store *storage.Store, idx index.Indexer, worker *index.TenantIndexWorker, logger *slog.Logger) {
	logger.Info("backfill: starting")

	count := 0
	needIndex := 0
	errCount := 0

	err := store.WalkStore(ctx, func(id string) error {
		count++

		raw, err := store.Load(id)
		if err != nil {
			logger.Warn("backfill: load failed", "id", id, "err", err)
			errCount++
			return nil
		}

		pm, err := mailparser.Parse(raw)
		if err != nil {
			logger.Warn("backfill: parse failed", "id", id, "err", err)
			errCount++
			return nil
		}

		// Upsert metadata into DB
		if err := store.SaveMeta(ctx, id, pm, len(raw)); err != nil {
			logger.Warn("backfill: save meta failed", "id", id, "err", err)
		}

		// Check if already indexed
		alreadyIndexed, err := store.IsIndexed(ctx, id)
		if err != nil {
			logger.Warn("backfill: check indexed failed", "id", id, "err", err)
		}

		if !alreadyIndexed {
			needIndex++
			tenantID, _ := store.GetTenantForMail(ctx, id)
			submitToWorker(worker, store, raw, id, tenantID, logger)
		}

		if count%100 == 0 {
			logger.Info("backfill: progress", "processed", count, "need_index", needIndex, "errors", errCount)
		}

		return nil
	})

	if err != nil {
		logger.Error("backfill failed", "err", err)
		return
	}

	logger.Info("backfill: complete", "total", count, "submitted_for_index", needIndex, "errors", errCount)
}

// reindexTenant re-indexes all emails belonging to a specific tenant.
// Used during migration when switching from global index to per-tenant indexes.
func reindexTenant(ctx context.Context, store *storage.Store, mgr *index.TenantIndexManager, tenantID int64, logger *slog.Logger) error {
	tid := tenantID
	ids, err := store.GetAllIDsByTenant(ctx, &tid)
	if err != nil {
		return fmt.Errorf("reindex tenant %d: get IDs: %w", tenantID, err)
	}

	logger.Info("reindex tenant: starting", "tenant_id", tenantID, "count", len(ids))

	idx := mgr.ForTenant(&tid)
	indexed := 0
	errCount := 0

	for _, id := range ids {
		raw, err := store.Load(id)
		if err != nil {
			logger.Warn("reindex tenant: load failed", "tenant_id", tenantID, "id", id, "err", err)
			errCount++
			continue
		}

		pm, parseErr := mailparser.Parse(raw)
		if parseErr != nil {
			logger.Warn("reindex tenant: parse failed", "tenant_id", tenantID, "id", id, "err", parseErr)
			errCount++
			continue
		}

		var attachNames []string
		for _, a := range pm.Attachments {
			if a.Filename != "" {
				attachNames = append(attachNames, a.Filename)
			}
		}

		doc := index.MailDocument{
			ID:            id,
			From:          pm.From,
			To:            strings.Join(pm.To, ", "),
			Subject:       pm.Subject,
			Body:          pm.TextBody,
			AttachNames:   strings.Join(attachNames, " "),
			HasAttachment: len(pm.Attachments) > 0,
			Date:          pm.Date,
			Size:          int64(len(raw)),
			TenantID:      &tid,
		}

		if err := idx.IndexSync(doc); err != nil {
			logger.Warn("reindex tenant: index failed", "tenant_id", tenantID, "id", id, "err", err)
			errCount++
			continue
		}
		indexed++
	}

	logger.Info("reindex tenant: complete", "tenant_id", tenantID, "indexed", indexed, "errors", errCount)
	return nil
}

// runIntegrityCheck verifies all stored emails every 5 minutes by re-computing
// their SHA-256 and comparing it to the stored file ID.
func runIntegrityCheck(ctx context.Context, store *storage.Store, logger *slog.Logger) {
	// run once at startup, then every 5 minutes
	doVerify := func() {
		ids, err := store.GetAllIDs(ctx)
		if err != nil {
			logger.Error("integrity check: get IDs failed", "err", err)
			return
		}
		ok := 0
		fail := 0
		for _, id := range ids {
			verified, err := store.VerifyIntegrity(ctx, id)
			if err != nil {
				fail++
				continue
			}
			if verified {
				ok++
			} else {
				fail++
				logger.Warn("integrity check: FAILED", "id", id)
			}
		}
		logger.Info("integrity check: complete", "ok", ok, "failed", fail, "total", len(ids))
	}

	doVerify()
	ticker := time.NewTicker(5 * time.Minute)
	defer ticker.Stop()
	for {
		select {
		case <-ticker.C:
			doVerify()
		case <-ctx.Done():
			return
		}
	}
}

// seedDefaultUsers creates default admin and auditor accounts if no users exist yet.
// Passwords are randomly generated and printed once to stdout — there is no way to
// recover them afterwards; they must be changed immediately after the first login.
func seedDefaultUsers(users *userstore.Store, logger *slog.Logger) error {
	all, err := users.List("")
	if err != nil {
		return fmt.Errorf("list users: %w", err)
	}
	if len(all) > 0 {
		return nil // already seeded
	}

	superadminPw, err := randomPassword()
	if err != nil {
		return fmt.Errorf("generate superadmin password: %w", err)
	}
	adminPw, err := randomPassword()
	if err != nil {
		return fmt.Errorf("generate admin password: %w", err)
	}
	auditorPw, err := randomPassword()
	if err != nil {
		return fmt.Errorf("generate auditor password: %w", err)
	}

	defaults := []userstore.CreateUserRequest{
		{Username: "superadmin", Email: "superadmin@archivmail.local", Password: superadminPw, Role: userstore.RoleSuperAdmin},
		{Username: "admin", Email: "admin@archivmail.local", Password: adminPw, Role: userstore.RoleAdmin},
		{Username: "auditor", Email: "auditor@archivmail.local", Password: auditorPw, Role: userstore.RoleAuditor},
	}
	for _, req := range defaults {
		if _, err := users.Create(req); err != nil {
			return fmt.Errorf("create default user %s: %w", req.Username, err)
		}
	}

	// Print credentials prominently — this is the only time they are visible.
	fmt.Println()
	fmt.Println("╔══════════════════════════════════════════════════════════════╗")
	fmt.Println("║         ARCHIVMAIL — ERSTMALIGE EINRICHTUNG                 ║")
	fmt.Println("║  Initiale Zugangsdaten (NUR EINMAL ANGEZEIGT):              ║")
	fmt.Printf( "║  superadmin : %-47s ║\n", superadminPw)
	fmt.Printf( "║  admin      : %-47s ║\n", adminPw)
	fmt.Printf( "║  auditor    : %-47s ║\n", auditorPw)
	fmt.Println("║  Passwörter sofort nach dem ersten Login ändern!            ║")
	fmt.Println("╚══════════════════════════════════════════════════════════════╝")
	fmt.Println()

	logger.Warn("default users created — change passwords immediately!")
	return nil
}

// randomPassword generates a cryptographically random 16-byte hex password.
func randomPassword() (string, error) {
	b := make([]byte, 16)
	if _, err := rand.Read(b); err != nil {
		return "", err
	}
	return hex.EncodeToString(b), nil
}