package main

import (
	"context"
	"fmt"
	"log"
	"net"
	"net/http"
	"os"
	"os/signal"
	"time"

	"git.k6n.net/mats/go-cart-actor/internal/ucp"
	"git.k6n.net/mats/go-cart-actor/pkg/actor"
	"git.k6n.net/mats/go-cart-actor/pkg/cart"
	"git.k6n.net/mats/go-cart-actor/pkg/checkout"
	"git.k6n.net/mats/go-cart-actor/pkg/proxy"
	"git.k6n.net/mats/go-cart-actor/pkg/telemetry"
	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
	"github.com/adyen/adyen-go-api-library/v21/src/adyen"
	"github.com/adyen/adyen-go-api-library/v21/src/common"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
	amqp "github.com/rabbitmq/amqp091-go"
	"github.com/redis/go-redis/v9"
	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
)

var (
	grainSpawns = promauto.NewCounter(prometheus.CounterOpts{
		Name: "checkout_grain_spawned_total",
		Help: "The total number of spawned checkout grains",
	})
)

func init() {
	os.Mkdir("data", 0755)
}

type App struct {
	pool         *actor.SimpleGrainPool[checkout.CheckoutGrain]
	server       *CheckoutPoolServer
	klarnaClient *KlarnaClient
	cartClient   *CartClient // For internal communication to cart
}

var podIp = os.Getenv("POD_IP")
var name = os.Getenv("POD_NAME")
var amqpUrl = os.Getenv("AMQP_URL")
var redisAddress = os.Getenv("REDIS_ADDRESS")
var redisPassword = os.Getenv("REDIS_PASSWORD")
var cartInternalUrl = os.Getenv("CART_INTERNAL_URL") // e.g., http://cart-service:8081

// selectTaxProvider picks the tax provider from the environment.
// Default is NordicTaxProvider with SE as the default country.
// Set TAX_PROVIDER=static for dev and tests (no country awareness).
func selectTaxProvider() cart.TaxProvider {
	switch os.Getenv("TAX_PROVIDER") {
	case "static":
		return cart.NewStaticTaxProvider()
	case "nordic":
		return cart.NewNordicTaxProvider(envOrDefault("TAX_DEFAULT_COUNTRY", "SE"))
	default:
		return cart.NewNordicTaxProvider(envOrDefault("TAX_DEFAULT_COUNTRY", "SE"))
	}
}

func envOrDefault(key, def string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return def
}

// loadUCPCheckoutSigner loads the UCP ECDSA signing key from the path specified in
// the UCP_SIGNING_KEY_PATH environment variable. Returns nil if unset or unreadable.
func loadUCPCheckoutSigner() *ucp.SigningConfig {
	path := os.Getenv("UCP_SIGNING_KEY_PATH")
	if path == "" {
		return nil
	}
	pemData, err := os.ReadFile(path)
	if err != nil {
		log.Printf("ucp signing: cannot read key %s: %v", path, err)
		return nil
	}
	cfg, err := ucp.NewSigningConfigFromPEM(pemData, "k6n-ecdsa-2026")
	if err != nil {
		log.Printf("ucp signing: invalid key at %s: %v", path, err)
		return nil
	}
	return cfg
}

func main() {

	controlPlaneConfig := actor.DefaultServerConfig()

	reg := checkout.NewCheckoutMutationRegistry(checkout.NewCheckoutMutationContext())
	reg.RegisterProcessor(
		actor.NewMutationProcessor(func(ctx context.Context, g *checkout.CheckoutGrain) error {
			g.Version++
			return nil
		}),
	)
	rdb := redis.NewClient(&redis.Options{
		Addr:     redisAddress,
		Password: redisPassword,
		DB:       0,
	})
	inventoryService, err := inventory.NewRedisInventoryService(rdb)
	if err != nil {
		log.Fatalf("Error creating inventory service: %v\n", err)
	}

	reservationService, err := inventory.NewRedisCartReservationService(rdb)
	if err != nil {
		log.Fatalf("Error creating reservation service: %v\n", err)
	}

	checkoutDir := os.Getenv("CHECKOUT_DIR")
	if checkoutDir == "" {
		checkoutDir = "data"
	}
	diskStorage := actor.NewDiskStorage[checkout.CheckoutGrain](checkoutDir, reg)
	var syncedServer *CheckoutPoolServer
	poolConfig := actor.GrainPoolConfig[checkout.CheckoutGrain]{
		MutationRegistry: reg,
		Storage:          diskStorage,
		Spawn: func(ctx context.Context, id uint64) (actor.Grain[checkout.CheckoutGrain], error) {
			_, span := tracer.Start(ctx, fmt.Sprintf("Spawn checkout id %d", id))
			defer span.End()
			grainSpawns.Inc()

			ret := checkout.NewCheckoutGrain(id, 0, 0, time.Now(), nil) // version to be set later
			// Load persisted events/state for this checkout if present
			if err := diskStorage.LoadEvents(ctx, id, ret); err != nil {
				// Return the grain along with error (e.g., not found) so callers can decide
				return ret, err
			}
			return ret, nil
		},
		Destroy: func(grain actor.Grain[checkout.CheckoutGrain]) error {
			ctx := context.Background()
			state, err := grain.GetCurrentState()
			if err == nil && state != nil {
				syncedServer.releaseCartReservations(ctx, state)
			}
			return nil
		},
		SpawnHost: func(host string) (actor.Host[checkout.CheckoutGrain], error) {
			return proxy.NewRemoteHost[checkout.CheckoutGrain](host)
		},
		TTL:      1 * time.Hour, // Longer TTL for checkout
		PoolSize: 65535,
		Hostname: podIp,
	}

	pool, err := actor.NewSimpleGrainPool(poolConfig)
	if err != nil {
		log.Fatalf("Error creating checkout pool: %v\n", err)
	}

	adyenClient := adyen.NewClient(&common.Config{
		ApiKey:      os.Getenv("ADYEN_API_KEY"),
		Environment: common.TestEnv,
	})

	klarnaClient := NewKlarnaClient(KlarnaPlaygroundUrl, os.Getenv("KLARNA_API_USERNAME"), os.Getenv("KLARNA_API_PASSWORD"))

	cartClient := NewCartClient(cartInternalUrl)

	var orderClient *OrderClient
	if orderServiceURL := os.Getenv("ORDER_SERVICE_URL"); orderServiceURL != "" {
		orderClient = NewOrderClient(orderServiceURL)
		log.Printf("order client enabled: %s", orderServiceURL)
	}

	var orderHandler *AmqpOrderHandler
	conn, err := amqp.Dial(amqpUrl)
	if err != nil {
		log.Fatalf("failed to connect to RabbitMQ: %v", err)
	}
	orderHandler = NewAmqpOrderHandler(conn)
	if err := orderHandler.DefineQueue(); err != nil {
		log.Fatalf("failed to declare order queue: %v", err)
	}

	syncedServer = NewCheckoutPoolServer(pool, fmt.Sprintf("%s, %s", name, podIp), klarnaClient, cartClient, adyenClient, orderClient, orderHandler)
	syncedServer.inventoryService = inventoryService
	syncedServer.reservationService = reservationService
	syncedServer.taxProvider = selectTaxProvider()

	mux := http.NewServeMux()
	debugMux := http.NewServeMux()

	if amqpUrl == "" {
		log.Fatalf("no connection to amqp defined")
	}

	grpcSrv, err := actor.NewControlServer[checkout.CheckoutGrain](controlPlaneConfig, pool)
	if err != nil {
		log.Fatalf("Error starting control plane gRPC server: %v\n", err)
	}
	defer grpcSrv.GracefulStop()

	UseDiscovery(pool)

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
	defer stop()

	otelShutdown, err := telemetry.SetupOTelSDK(ctx)
	if err != nil {
		log.Fatalf("Unable to start otel %v", err)
	}

	syncedServer.Serve(mux)

	// UCP REST adapter — Universal Commerce Protocol checkout sessions
	// When an order service URL is configured, the complete endpoint creates
	// real orders via the order service's from-checkout API.
	var ucpOrderSvc ucp.OrderApplier
	if orderServiceURL := os.Getenv("ORDER_SERVICE_URL"); orderServiceURL != "" {
		ucpOrderSvc = ucp.NewOrderHTTPClient(orderServiceURL)
		log.Printf("ucp order applier enabled: %s", orderServiceURL)
	}
	checkoutUCP := ucp.CheckoutHandler(pool, ucpOrderSvc)
	if signer := loadUCPCheckoutSigner(); signer != nil {
		checkoutUCP = ucp.WithSigning(checkoutUCP, signer)
		log.Print("ucp signing enabled")
	}
	// StripPrefix is required because the sub-mux (CheckoutHandler) registers
	// routes like "GET /{id}" which expect a relative path; Go's ServeMux
	// passes the full request path without stripping the prefix.
	// Only the subtree pattern is registered (see comment in cmd/cart/main.go
	// for why the exact-match pattern is omitted).
	mux.Handle("/ucp/v1/checkout-sessions/", http.StripPrefix("/ucp/v1/checkout-sessions", checkoutUCP))

	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
		grainCount, capacity := pool.LocalUsage()
		if grainCount >= capacity {
			w.WriteHeader(http.StatusInternalServerError)
			w.Write([]byte("grain pool at capacity"))
			return
		}
		if !pool.IsHealthy() {
			w.WriteHeader(http.StatusInternalServerError)
			w.Write([]byte("control plane not healthy"))
			return
		}
		w.WriteHeader(http.StatusOK)
		w.Write([]byte("ok"))
	})
	mux.HandleFunc("/readyz", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte("ok"))
	})
	mux.HandleFunc("/livez", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte("ok"))
	})

	mux.HandleFunc("/version", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte("1.0.0"))
	})

	srv := &http.Server{
		Addr:         ":8080",
		BaseContext:  func(net.Listener) context.Context { return ctx },
		ReadTimeout:  10 * time.Second,
		WriteTimeout: 20 * time.Second,
		Handler:      otelhttp.NewHandler(mux, "/"),
	}

	defer func() {
		fmt.Println("Shutting down due to signal")
		otelShutdown(context.Background())
		diskStorage.Close()
		pool.Close()
	}()

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

	log.Print("Checkout server started at port 8080")

	go http.ListenAndServe(":8081", debugMux)

	select {
	case err = <-srvErr:
		log.Fatalf("Unable to start server: %v", err)
	case <-ctx.Done():
		stop()
	}
}