// ©AngelaMos | 2026
// main.go

package main

import (
	"context"
	"errors"
	"flag"
	"log/slog"
	"os"
	"os/signal"
	"path/filepath"
	"syscall"
	"time"

	"github.com/go-chi/chi/v5"
	"golang.org/x/sync/errgroup"

	"github.com/carterperez-dev/monitor-the-situation/backend/internal/admin"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/auth"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/bus"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/collectors/cfradar"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/collectors/coinbase"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/collectors/cve"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/collectors/dshield"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/collectors/heartbeat"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/collectors/kev"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/collectors/ransomware"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/collectors/state"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/config"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/core"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/health"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/middleware"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/server"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/snapshot"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/user"
	"github.com/carterperez-dev/monitor-the-situation/backend/internal/ws"
)

const (
	drainDelay = 5 * time.Second
)

func main() {
	configPath := flag.String("config", "config.yaml", "path to config file")
	flag.Parse()

	if err := run(*configPath); err != nil {
		slog.Error("application error", "error", err)
		os.Exit(1)
	}
}

//nolint:funlen // bootstrap code is inherently verbose
func run(configPath string) error {
	ctx, stop := signal.NotifyContext(
		context.Background(),
		syscall.SIGINT,
		syscall.SIGTERM,
	)
	defer stop()

	cfg, err := config.Load(configPath)
	if err != nil {
		return err
	}

	logger := setupLogger(cfg.Log)
	slog.SetDefault(logger)

	logger.Info("starting application",
		"name", cfg.App.Name,
		"version", cfg.App.Version,
		"environment", cfg.App.Environment,
	)

	var telemetry *core.Telemetry
	if cfg.Otel.Enabled {
		tel, telErr := core.NewTelemetry(ctx, cfg.Otel, cfg.App)
		if telErr != nil {
			logger.Warn("failed to initialize telemetry", "error", telErr)
		} else {
			telemetry = tel
			logger.Info("OpenTelemetry tracer initialized",
				"endpoint", cfg.Otel.Endpoint,
			)
		}
	}

	db, err := core.NewDatabase(ctx, cfg.Database)
	if err != nil {
		return err
	}
	logger.Info("database connected",
		"max_open_conns", cfg.Database.MaxOpenConns,
		"max_idle_conns", cfg.Database.MaxIdleConns,
	)

	redis, err := core.NewRedis(ctx, cfg.Redis)
	if err != nil {
		return err
	}
	logger.Info("redis connected",
		"pool_size", cfg.Redis.PoolSize,
	)

	if err := ensureJWTKeys(cfg.JWT, logger); err != nil {
		return err
	}

	jwtManager, err := auth.NewJWTManager(cfg.JWT)
	if err != nil {
		return err
	}
	logger.Info("JWT manager initialized",
		"algorithm", "ES256",
		"key_id", jwtManager.GetKeyID(),
	)

	userRepo := user.NewRepository(db.DB)
	userSvc := user.NewService(userRepo)
	userHandler := user.NewHandler(userSvc)

	authRepo := auth.NewRepository(db.DB)
	authSvc := auth.NewService(authRepo, jwtManager, userSvc, redis.Client)
	authHandler := auth.NewHandler(authSvc)

	healthHandler := health.NewHandler(db, redis)

	adminHandler := admin.NewHandler(admin.HandlerConfig{
		DBStats:    db.Stats,
		RedisStats: redis.PoolStats,
		DBPing:     db.Ping,
		RedisPing:  redis.Ping,
	})

	snapStore := snapshot.NewStore(redis.Client)
	snapHandler := snapshot.NewHandler(snapStore)

	hub := ws.NewHub(ws.HubConfig{Logger: logger})
	wsHandler := ws.NewHandler(hub)

	eventBus := bus.New(bus.Config{
		BufferSize:  512,
		Persister:   snapshot.StorePersister{Store: snapStore},
		Broadcaster: ws.HubBroadcaster{Hub: hub},
		Logger:      logger,
	})

	beat := heartbeat.New(heartbeat.Config{
		Interval: 5 * time.Second,
		Emitter:  eventBus,
	})

	collectorState := state.NewRepo(db.DB)

	collectorGroup, collectorCtx := errgroup.WithContext(ctx)
	collectorGroup.Go(func() error { return eventBus.Run(collectorCtx) })
	collectorGroup.Go(func() error { return beat.Run(collectorCtx) })

	if cfg.Collectors.DShield.Enabled {
		coll := dshield.NewCollector(dshield.CollectorConfig{
			Interval:  cfg.Collectors.DShield.Interval,
			Fetcher:   dshield.NewClient(dshield.ClientConfig{}),
			Persister: dshield.NewRepo(db.DB),
			Emitter:   eventBus,
			State:     collectorState,
			Logger:    logger.With("collector", "dshield"),
		})
		collectorGroup.Go(func() error { return coll.Run(collectorCtx) })
	}

	if cfg.Collectors.CFRadar.Enabled {
		coll := cfradar.NewCollector(cfradar.CollectorConfig{
			Interval:      cfg.Collectors.CFRadar.Interval,
			MinConfidence: cfg.Collectors.CFRadar.MinConfidence,
			Fetcher:       cfradar.NewClient(cfradar.ClientConfig{BearerToken: cfg.Collectors.CFRadar.BearerToken}),
			Repo:          cfradar.NewRepo(db.DB),
			Emitter:       eventBus,
			State:         collectorState,
			Logger:        logger.With("collector", "cfradar"),
		})
		collectorGroup.Go(func() error { return coll.Run(collectorCtx) })
	}

	if cfg.Collectors.CVE.Enabled {
		coll := cve.NewCollector(cve.CollectorConfig{
			Interval: cfg.Collectors.CVE.Interval,
			Window:   cfg.Collectors.CVE.Window,
			NVD:      cve.NewNVDClient(cve.NVDClientConfig{APIKey: cfg.Collectors.CVE.NVDAPIKey}),
			EPSS:     cve.NewEPSSClient(cve.EPSSClientConfig{}),
			Repo:     cve.NewRepo(db.DB),
			Emitter:  eventBus,
			State:    collectorState,
			Logger:   logger.With("collector", "cve"),
		})
		collectorGroup.Go(func() error { return coll.Run(collectorCtx) })
	}

	if cfg.Collectors.KEV.Enabled {
		coll := kev.NewCollector(kev.CollectorConfig{
			Interval: cfg.Collectors.KEV.Interval,
			Fetcher:  kev.NewClient(kev.ClientConfig{}),
			Repo:     kev.NewRepo(db.DB),
			Emitter:  eventBus,
			State:    collectorState,
			Logger:   logger.With("collector", "kev"),
		})
		collectorGroup.Go(func() error { return coll.Run(collectorCtx) })
	}

	if cfg.Collectors.Ransomware.Enabled {
		coll := ransomware.NewCollector(ransomware.CollectorConfig{
			Interval: cfg.Collectors.Ransomware.Interval,
			Fetcher:  ransomware.NewClient(ransomware.ClientConfig{}),
			Repo:     ransomware.NewRepo(db.DB),
			Emitter:  eventBus,
			State:    collectorState,
			Logger:   logger.With("collector", "ransomware"),
		})
		collectorGroup.Go(func() error { return coll.Run(collectorCtx) })
	}

	if cfg.Collectors.Coinbase.Enabled {
		coll := coinbase.NewCollector(coinbase.CollectorConfig{
			URL:        cfg.Collectors.Coinbase.URL,
			ProductIDs: cfg.Collectors.Coinbase.ProductIDs,
			Repo:       coinbase.NewRepo(db.DB),
			Emitter:    eventBus,
			State:      collectorState,
			Throttle:   cfg.Collectors.Coinbase.Throttle,
			Logger:     logger.With("collector", "coinbase"),
		})
		collectorGroup.Go(func() error { return coll.Run(collectorCtx) })
	}

	logger.Info("collectors started",
		"heartbeat", true,
		"dshield", cfg.Collectors.DShield.Enabled,
		"cfradar", cfg.Collectors.CFRadar.Enabled,
		"cve", cfg.Collectors.CVE.Enabled,
		"kev", cfg.Collectors.KEV.Enabled,
		"ransomware", cfg.Collectors.Ransomware.Enabled,
		"coinbase", cfg.Collectors.Coinbase.Enabled,
	)

	srv := server.New(server.Config{
		ServerConfig:  cfg.Server,
		HealthHandler: healthHandler,
		Logger:        logger,
	})

	router := srv.Router()

	router.Use(middleware.RequestID)
	router.Use(middleware.Logger(logger))
	router.Use(
		middleware.NewRateLimiter(redis.Client, middleware.RateLimitConfig{
			Limit: middleware.PerMinute(
				cfg.RateLimit.Requests,
				cfg.RateLimit.Burst,
			),
			FailOpen: true,
		}).Handler,
	)
	router.Use(middleware.SecurityHeaders(cfg.App.Environment == "production"))
	router.Use(middleware.CORS(cfg.CORS))

	healthHandler.RegisterRoutes(router)

	router.Get("/.well-known/jwks.json", jwtManager.GetJWKSHandler())

	authenticator := middleware.Authenticator(jwtManager)
	adminOnly := middleware.RequireAdmin

	router.Route("/v1", func(r chi.Router) {
		r.Get("/healthz", healthHandler.Liveness)
		r.Get("/readyz", healthHandler.Readiness)

		r.Get("/snapshot", snapHandler.ServeHTTP)
		r.Get("/ws", wsHandler.ServeHTTP)

		authHandler.RegisterRoutes(r, authenticator)

		r.Post("/users", authHandler.Register)

		userHandler.RegisterRoutes(r, authenticator)
		userHandler.RegisterAdminRoutes(r, authenticator, adminOnly)
		adminHandler.RegisterRoutes(r, authenticator, adminOnly)
	})

	errChan := make(chan error, 1)
	go func() {
		errChan <- srv.Start()
	}()

	select {
	case err := <-errChan:
		return err
	case <-ctx.Done():
		logger.Info("shutdown signal received")
	}

	shutdownCtx, cancel := context.WithTimeout(
		context.Background(),
		cfg.Server.ShutdownTimeout+drainDelay+5*time.Second,
	)
	defer cancel()

	if err := srv.Shutdown(shutdownCtx, drainDelay); err != nil {
		logger.Error("server shutdown error", "error", err)
	}

	if telemetry != nil {
		if err := telemetry.Shutdown(shutdownCtx); err != nil {
			logger.Error("telemetry shutdown error", "error", err)
		}
	}

	if err := collectorGroup.Wait(); err != nil &&
		!errors.Is(err, context.Canceled) &&
		!errors.Is(err, context.DeadlineExceeded) {
		logger.Error("collector group exit", "error", err)
	}

	if err := redis.Close(); err != nil {
		logger.Error("redis close error", "error", err)
	}

	if err := db.Close(); err != nil {
		logger.Error("database close error", "error", err)
	}

	logger.Info("application stopped")
	return nil
}

func ensureJWTKeys(cfg config.JWTConfig, logger *slog.Logger) error {
	if _, err := os.Stat(cfg.PrivateKeyPath); err == nil {
		return nil
	} else if !errors.Is(err, os.ErrNotExist) {
		return err
	}

	if dir := filepath.Dir(cfg.PrivateKeyPath); dir != "" && dir != "." {
		if err := os.MkdirAll(dir, 0o700); err != nil {
			return err
		}
	}
	if dir := filepath.Dir(cfg.PublicKeyPath); dir != "" && dir != "." {
		if err := os.MkdirAll(dir, 0o700); err != nil {
			return err
		}
	}

	logger.Warn("JWT keys missing, generating",
		"private", cfg.PrivateKeyPath,
		"public", cfg.PublicKeyPath,
	)
	return auth.GenerateKeyPair(cfg.PrivateKeyPath, cfg.PublicKeyPath)
}

func setupLogger(cfg config.LogConfig) *slog.Logger {
	var handler slog.Handler

	level := slog.LevelInfo
	switch cfg.Level {
	case "debug":
		level = slog.LevelDebug
	case "warn":
		level = slog.LevelWarn
	case "error":
		level = slog.LevelError
	}

	opts := &slog.HandlerOptions{Level: level}

	if cfg.Format == "json" {
		handler = slog.NewJSONHandler(os.Stdout, opts)
	} else {
		handler = slog.NewTextHandler(os.Stdout, opts)
	}

	return slog.New(handler)
}