// Copyright 2018 The Nakama Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"context"
	cryptoRand "crypto/rand"
	"encoding/binary"
	"flag"
	"fmt"
	"math/rand"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"path/filepath"
	"runtime"
	"strings"
	"syscall"
	"time"

	"github.com/gofrs/uuid"
	"github.com/heroiclabs/nakama/v3/console"
	"github.com/heroiclabs/nakama/v3/ga"
	"github.com/heroiclabs/nakama/v3/migrate"
	"github.com/heroiclabs/nakama/v3/server"
	"github.com/heroiclabs/nakama/v3/social"
	_ "github.com/jackc/pgx/v4/stdlib"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"google.golang.org/protobuf/encoding/protojson"
)

const cookieFilename = ".cookie"

var (
	version  string = "3.0.0"
	commitID string = "dev"

	// Shared utility components.
	jsonpbMarshaler = &protojson.MarshalOptions{
		UseEnumNumbers:  true,
		EmitUnpopulated: false,
		Indent:          "",
		UseProtoNames:   true,
	}
	jsonpbUnmarshaler = &protojson.UnmarshalOptions{
		DiscardUnknown: false,
	}
)

func main() {
	semver := fmt.Sprintf("%s+%s", version, commitID)
	// Always set default timeout on HTTP client.
	http.DefaultClient.Timeout = 1500 * time.Millisecond

	tmpLogger := server.NewJSONLogger(os.Stdout, zapcore.InfoLevel, server.JSONFormat)

	if len(os.Args) > 1 {
		switch os.Args[1] {
		case "--version":
			fmt.Println(semver)
			return
		case "migrate":
			migrate.Parse(os.Args[2:], tmpLogger)
			return
		case "check":
			// Parse any command line args to look up runtime path.
			// Use full config structure even if not all of its options are available in this command.
			config := server.NewConfig(tmpLogger)
			var runtimePath string
			flags := flag.NewFlagSet("check", flag.ExitOnError)
			flags.StringVar(&runtimePath, "runtime.path", filepath.Join(config.GetDataDir(), "modules"), "Path for the server to scan for Lua and Go library files.")
			if err := flags.Parse(os.Args[2:]); err != nil {
				tmpLogger.Fatal("Could not parse check flags.")
			}
			config.GetRuntime().Path = runtimePath

			if err := server.CheckRuntime(tmpLogger, config, version); err != nil {
				// Errors are already logged in the function above.
				os.Exit(1)
			}
			return
		}
	}

	config := server.ParseArgs(tmpLogger, os.Args)
	logger, startupLogger := server.SetupLogging(tmpLogger, config)
	configWarnings := server.CheckConfig(logger, config)

	startupLogger.Info("Nakama starting")
	startupLogger.Info("Node", zap.String("name", config.GetName()), zap.String("version", semver), zap.String("runtime", runtime.Version()), zap.Int("cpu", runtime.NumCPU()), zap.Int("proc", runtime.GOMAXPROCS(0)))
	startupLogger.Info("Data directory", zap.String("path", config.GetDataDir()))

	// Initialize the global random with strongly seed.
	var seed int64
	if err := binary.Read(cryptoRand.Reader, binary.BigEndian, &seed); err != nil {
		startupLogger.Warn("Failed to get strongly random seed, fallback to a less random one.", zap.Error(err))
		seed = time.Now().UnixNano()
	}
	rand.Seed(seed)

	redactedAddresses := make([]string, 0, 1)
	for _, address := range config.GetDatabase().Addresses {
		rawURL := fmt.Sprintf("postgres://%s", address)
		parsedURL, err := url.Parse(rawURL)
		if err != nil {
			logger.Fatal("Bad connection URL", zap.Error(err))
		}
		redactedAddresses = append(redactedAddresses, strings.TrimPrefix(parsedURL.Redacted(), "postgres://"))
	}
	startupLogger.Info("Database connections", zap.Strings("dsns", redactedAddresses))

	// Global server context.
	ctx, ctxCancelFn := context.WithCancel(context.Background())

	db, dbVersion := server.DbConnect(ctx, startupLogger, config)
	startupLogger.Info("Database information", zap.String("version", dbVersion))

	// Check migration status and fail fast if the schema has diverged.
	migrate.StartupCheck(startupLogger, db)

	// Access to social provider integrations.
	socialClient := social.NewClient(logger, 5*time.Second, config.GetGoogleAuth().OAuthConfig)

	// Start up server components.
	cookie := newOrLoadCookie(config)
	metrics := server.NewLocalMetrics(logger, startupLogger, db, config)
	sessionRegistry := server.NewLocalSessionRegistry(metrics)
	sessionCache := server.NewLocalSessionCache(config.GetSession().TokenExpirySec)
	consoleSessionCache := server.NewLocalSessionCache(config.GetConsole().TokenExpirySec)
	loginAttemptCache := server.NewLocalLoginAttemptCache()
	statusRegistry := server.NewStatusRegistry(logger, config, sessionRegistry, jsonpbMarshaler)
	tracker := server.StartLocalTracker(logger, config, sessionRegistry, statusRegistry, metrics, jsonpbMarshaler)
	router := server.NewLocalMessageRouter(sessionRegistry, tracker, jsonpbMarshaler)
	leaderboardCache := server.NewLocalLeaderboardCache(logger, startupLogger, db)
	leaderboardRankCache := server.NewLocalLeaderboardRankCache(ctx, startupLogger, db, config.GetLeaderboard(), leaderboardCache)
	leaderboardScheduler := server.NewLocalLeaderboardScheduler(logger, db, config, leaderboardCache, leaderboardRankCache)
	googleRefundScheduler := server.NewGoogleRefundScheduler(logger, db, config)
	matchRegistry := server.NewLocalMatchRegistry(logger, startupLogger, config, sessionRegistry, tracker, router, metrics, config.GetName())
	tracker.SetMatchJoinListener(matchRegistry.Join)
	tracker.SetMatchLeaveListener(matchRegistry.Leave)
	streamManager := server.NewLocalStreamManager(config, sessionRegistry, tracker)
	runtime, runtimeInfo, err := server.NewRuntime(ctx, logger, startupLogger, db, jsonpbMarshaler, jsonpbUnmarshaler, config, version, socialClient, leaderboardCache, leaderboardRankCache, leaderboardScheduler, sessionRegistry, sessionCache, statusRegistry, matchRegistry, tracker, metrics, streamManager, router)
	if err != nil {
		startupLogger.Fatal("Failed initializing runtime modules", zap.Error(err))
	}
	matchmaker := server.NewLocalMatchmaker(logger, startupLogger, config, router, metrics, runtime)
	partyRegistry := server.NewLocalPartyRegistry(logger, matchmaker, tracker, streamManager, router, config.GetName())
	tracker.SetPartyJoinListener(partyRegistry.Join)
	tracker.SetPartyLeaveListener(partyRegistry.Leave)

	leaderboardScheduler.Start(runtime)
	googleRefundScheduler.Start(runtime)

	pipeline := server.NewPipeline(logger, config, db, jsonpbMarshaler, jsonpbUnmarshaler, sessionRegistry, statusRegistry, matchRegistry, partyRegistry, matchmaker, tracker, router, runtime)
	statusHandler := server.NewLocalStatusHandler(logger, sessionRegistry, matchRegistry, tracker, metrics, config.GetName())

	apiServer := server.StartApiServer(logger, startupLogger, db, jsonpbMarshaler, jsonpbUnmarshaler, config, version, socialClient, leaderboardCache, leaderboardRankCache, sessionRegistry, sessionCache, statusRegistry, matchRegistry, matchmaker, tracker, router, streamManager, metrics, pipeline, runtime)
	consoleServer := server.StartConsoleServer(logger, startupLogger, db, config, tracker, router, streamManager, metrics, sessionRegistry, sessionCache, consoleSessionCache, loginAttemptCache, statusRegistry, statusHandler, runtimeInfo, matchRegistry, configWarnings, semver, leaderboardCache, leaderboardRankCache, leaderboardScheduler, apiServer, runtime, cookie)

	gaenabled := len(os.Getenv("NAKAMA_TELEMETRY")) < 1
	console.UIFS.Nt = !gaenabled
	const gacode = "UA-89792135-1"
	var telemetryClient *http.Client
	if gaenabled {
		telemetryClient = &http.Client{
			Timeout: 1500 * time.Millisecond,
		}
		runTelemetry(telemetryClient, gacode, cookie)
	}

	// Respect OS stop signals.
	c := make(chan os.Signal, 2)
	signal.Notify(c, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)

	startupLogger.Info("Startup done")

	// Wait for a termination signal.
	<-c

	graceSeconds := config.GetShutdownGraceSec()

	// If a shutdown grace period is allowed, prepare a timer.
	var timer *time.Timer
	timerCh := make(<-chan time.Time, 1)
	if graceSeconds != 0 {
		timer = time.NewTimer(time.Duration(graceSeconds) * time.Second)
		timerCh = timer.C
		startupLogger.Info("Shutdown started - use CTRL^C to force stop server", zap.Int("grace_period_sec", graceSeconds))
	} else {
		// No grace period.
		startupLogger.Info("Shutdown started")
	}

	// Stop any running authoritative matches and do not accept any new ones.
	select {
	case <-matchRegistry.Stop(graceSeconds):
		// Graceful shutdown has completed.
		startupLogger.Info("All authoritative matches stopped")
	case <-timerCh:
		// Timer has expired, terminate matches immediately.
		startupLogger.Info("Shutdown grace period expired")
		<-matchRegistry.Stop(0)
	case <-c:
		// A second interrupt has been received.
		startupLogger.Info("Skipping graceful shutdown")
		<-matchRegistry.Stop(0)
	}
	if timer != nil {
		timer.Stop()
	}

	// Signal cancellation to the global runtime context.
	ctxCancelFn()

	// Gracefully stop remaining server components.
	apiServer.Stop()
	consoleServer.Stop()
	matchmaker.Stop()
	leaderboardScheduler.Stop()
	googleRefundScheduler.Stop()
	tracker.Stop()
	statusRegistry.Stop()
	sessionCache.Stop()
	sessionRegistry.Stop()
	metrics.Stop(logger)
	loginAttemptCache.Stop()

	if gaenabled {
		_ = ga.SendSessionStop(telemetryClient, gacode, cookie)
	}

	startupLogger.Info("Shutdown complete")

	os.Exit(0)
}

// Help improve Nakama by sending anonymous usage statistics.
//
// You can disable the telemetry completely before server start by setting the
// environment variable "NAKAMA_TELEMETRY" - i.e. NAKAMA_TELEMETRY=0 nakama
//
// These properties are collected:
// * A unique UUID v4 random identifier which is generated.
// * Version of Nakama being used which includes build metadata.
// * Amount of time the server ran for.
//
// This information is sent via Google Analytics which allows the Nakama team to
// analyze usage patterns and errors in order to help improve the server.
func runTelemetry(httpc *http.Client, gacode string, cookie string) {
	if ga.SendSessionStart(httpc, gacode, cookie) != nil {
		return
	}
	if ga.SendEvent(httpc, gacode, cookie, &ga.Event{Ec: "version", Ea: fmt.Sprintf("%s+%s", version, commitID)}) != nil {
		return
	}
	_ = ga.SendEvent(httpc, gacode, cookie, &ga.Event{Ec: "variant", Ea: "nakama"})
}

func newOrLoadCookie(config server.Config) string {
	filePath := filepath.FromSlash(config.GetDataDir() + "/" + cookieFilename)
	b, err := os.ReadFile(filePath)
	cookie := uuid.FromBytesOrNil(b)
	if err != nil || cookie == uuid.Nil {
		cookie = uuid.Must(uuid.NewV4())
		_ = os.WriteFile(filePath, cookie.Bytes(), 0644)
	}
	return cookie.String()
}
