package main

import (
	"context"
	"flag"
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/pingcap/log"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"go.uber.org/zap"

	"github.com/tidbcloud/service-proxy/pkg/audit"
	"github.com/tidbcloud/service-proxy/pkg/checker"
	"github.com/tidbcloud/service-proxy/pkg/config"
	"github.com/tidbcloud/service-proxy/pkg/observability"
	"github.com/tidbcloud/service-proxy/pkg/proxy"
	"github.com/tidbcloud/service-proxy/pkg/route"
	"github.com/tidbcloud/service-proxy/pkg/secret"
)

var (
	configPath = flag.String("config", "/etc/config.yaml", "path to config file")
	debug      = flag.Bool("debug", false, "enable debug mode")
)

func main() {
	flag.Parse()

	// Initialize logger
	if err := observability.InitLogger(*debug); err != nil {
		fmt.Fprintf(os.Stderr, "failed to create logger: %v\n", err)
		os.Exit(1)
	}

	// Load configuration
	cfgManager := config.NewManager(*configPath)
	if err := cfgManager.Load(); err != nil {
		log.Fatal("failed to load config", zap.Error(err))
	}

	cfg := cfgManager.Get()
	log.Info("configuration loaded",
		zap.String("addr", cfg.Server.Addr),
		zap.Int("port", cfg.Server.Port),
	)

	// Initialize components
	metrics := observability.NewMetrics()
	health := observability.NewHealthChecker()

	secretManager, err := secret.NewProvider()
	if err != nil {
		log.Warn("failed to create secret manager, running without k8s secrets", zap.Error(err))
		secretManager = nil
	}

	// Initialize router
	router, err := route.NewRouter(cfg)
	if err != nil {
		log.Fatal("failed to create router", zap.Error(err))
	}

	// Initialize audit manager (handles logger lifecycle for hot-reload)
	auditManager, err := audit.NewManager(&cfg.Audit)
	if err != nil {
		log.Fatal("failed to create audit manager", zap.Error(err))
	}

	// Initialize config watcher for hot-reload
	var configWatcher *config.Watcher
	var watcherCancel context.CancelFunc
	configWatcher, err = config.NewWatcher(cfgManager)
	if err != nil {
		log.Warn("failed to create config watcher, hot reload disabled", zap.Error(err))
	} else {
		configWatcher.RegisterAuditHandler(auditManager)
		var watcherCtx context.Context
		watcherCtx, watcherCancel = context.WithCancel(context.Background())
		go func() {
			if err := configWatcher.Run(watcherCtx); err != nil && err != context.Canceled {
				log.Error("config watcher error", zap.Error(err))
			}
		}()
		log.Info("config watcher started, audit hot reload enabled")
	}

	// Initialize proxy handler
	proxyHandler := proxy.NewHandler(router, secretManager, metrics, auditManager)

	// Initialize checker handler
	checkerHandler := checker.NewHandler(nil, auditManager)

	// Setup HTTP mux
	mux := http.NewServeMux()

	// Proxy routes
	mux.Handle("/proxy/", proxyHandler)

	// Connectivity check endpoint
	mux.Handle("/check", checkerHandler)

	// Health endpoints
	mux.HandleFunc("/healthz", health.LivenessHandler())
	mux.HandleFunc("/readyz", health.ReadinessHandler())

	// Create main server
	mainServer := &http.Server{
		Addr:         fmt.Sprintf("%s:%d", cfg.Server.Addr, cfg.Server.Port),
		Handler:      mux,
		ReadTimeout:  30 * time.Second,
		WriteTimeout: 30 * time.Second,
		IdleTimeout:  120 * time.Second,
	}

	// Create metrics server if enabled
	var metricsServer *http.Server
	if cfg.Metrics.Enabled {
		metricsMux := http.NewServeMux()
		metricsMux.Handle(cfg.Metrics.Path, promhttp.Handler())

		metricsServer = &http.Server{
			Addr:    fmt.Sprintf(":%d", cfg.Metrics.Port),
			Handler: metricsMux,
		}
	}

	// Start servers

	// Start main server
	go func() {
		log.Info("starting main server", zap.String("addr", mainServer.Addr))
		if err := mainServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatal("main server error", zap.Error(err))
		}
	}()

	// Start metrics server
	if metricsServer != nil {
		go func() {
			log.Info("starting metrics server", zap.String("addr", metricsServer.Addr))
			if err := metricsServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
				log.Error("metrics server error", zap.Error(err))
			}
		}()
	}

	// Mark service as ready
	health.SetReady(true)
	log.Info("service-proxy is ready")

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

	log.Info("shutting down...")
	health.SetReady(false)

	// Graceful shutdown
	shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer shutdownCancel()

	if err := mainServer.Shutdown(shutdownCtx); err != nil {
		log.Error("main server shutdown error", zap.Error(err))
	}

	if metricsServer != nil {
		if err := metricsServer.Shutdown(shutdownCtx); err != nil {
			log.Error("metrics server shutdown error", zap.Error(err))
		}
	}

	// Close proxy handler to release all cached connections
	if err := proxyHandler.Close(); err != nil {
		log.Error("proxy handler close error", zap.Error(err))
	}

	// Close config watcher
	if watcherCancel != nil {
		watcherCancel() // Cancel context first to trigger Run() exit
	}
	if configWatcher != nil {
		if err := configWatcher.Close(); err != nil {
			log.Error("config watcher close error", zap.Error(err))
		}
	}

	// Close audit manager to flush remaining logs to disk
	if err := auditManager.Close(); err != nil {
		log.Error("audit manager close error", zap.Error(err))
	}

	log.Info("service-proxy stopped")
}