package main

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

	"github.com/sirupsen/logrus"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/peer"
	"google.golang.org/grpc/reflection"

	"github.com/zcash-hackworks/lightwalletd/frontend"
	"github.com/zcash-hackworks/lightwalletd/walletrpc"
)

var log *logrus.Entry
var logger = logrus.New()

func init() {
	logger.SetFormatter(&logrus.TextFormatter{
		//DisableColors:          true,
		FullTimestamp:          true,
		DisableLevelTruncation: true,
	})

	log = logger.WithFields(logrus.Fields{
		"app": "frontend-grpc",
	})
}

func LoggingInterceptor() grpc.ServerOption {
	return grpc.UnaryInterceptor(logInterceptor)
}

func logInterceptor(
	ctx context.Context,
	req interface{},
	info *grpc.UnaryServerInfo,
	handler grpc.UnaryHandler,
) (interface{}, error) {
	reqLog := loggerFromContext(ctx)
	start := time.Now()

	resp, err := handler(ctx, req)

	entry := reqLog.WithFields(logrus.Fields{
		"method":   info.FullMethod,
		"duration": time.Since(start),
		"error":    err,
	})

	if err != nil {
		entry.Error("call failed")
	} else {
		entry.Info("method called")
	}

	return resp, err
}

func loggerFromContext(ctx context.Context) *logrus.Entry {
	// TODO: anonymize the addresses. cryptopan?
	if peerInfo, ok := peer.FromContext(ctx); ok {
		return log.WithFields(logrus.Fields{"peer_addr": peerInfo.Addr})
	}
	return log.WithFields(logrus.Fields{"peer_addr": "unknown"})
}

type Options struct {
	bindAddr    string `json:"bind_address,omitempty"`
	dbPath      string `json:"db_path"`
	tlsCertPath string `json:"tls_cert_path,omitempty"`
	tlsKeyPath  string `json:"tls_cert_key,omitempty"`
	logLevel    uint64 `json:"log_level,omitempty"`
	logPath     string `json:"log_file,omitempty"`
}

func main() {
	opts := &Options{}
	flag.StringVar(&opts.bindAddr, "bind-addr", "127.0.0.1:9067", "the address to listen on")
	flag.StringVar(&opts.dbPath, "db-path", "", "the path to a sqlite database file")
	flag.StringVar(&opts.tlsCertPath, "tls-cert", "", "the path to a TLS certificate (optional)")
	flag.StringVar(&opts.tlsKeyPath, "tls-key", "", "the path to a TLS key file (optional)")
	flag.Uint64Var(&opts.logLevel, "log-level", uint64(logrus.InfoLevel), "log level (logrus 1-7)")
	flag.StringVar(&opts.logPath, "log-file", "", "log file to write to")
	// TODO prod metrics
	// TODO support config from file and env vars
	flag.Parse()

	if opts.dbPath == "" {
		flag.Usage()
		os.Exit(1)
	}

	if opts.logPath != "" {
		// instead write parsable logs for logstash/splunk/etc
		output, err := os.OpenFile(opts.logPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
		if err != nil {
			log.WithFields(logrus.Fields{
				"error": err,
				"path":  opts.logPath,
			}).Fatal("couldn't open log file")
		}
		defer output.Close()
		logger.SetOutput(output)
		logger.SetFormatter(&logrus.JSONFormatter{})
	}

	logger.SetLevel(logrus.Level(opts.logLevel))

	// gRPC initialization
	var server *grpc.Server

	if opts.tlsCertPath != "" && opts.tlsKeyPath != "" {
		transportCreds, err := credentials.NewServerTLSFromFile(opts.tlsCertPath, opts.tlsKeyPath)
		if err != nil {
			log.WithFields(logrus.Fields{
				"cert_file": opts.tlsCertPath,
				"key_path":  opts.tlsKeyPath,
				"error":     err,
			}).Fatal("couldn't load TLS credentials")
		}
		server = grpc.NewServer(grpc.Creds(transportCreds), LoggingInterceptor())
	} else {
		server = grpc.NewServer(LoggingInterceptor())
	}

	// Enable reflection for debugging
	if opts.logLevel >= uint64(logrus.WarnLevel) {
		reflection.Register(server)
	}

	// Compact transaction service initialization
	service, err := frontend.NewSQLiteStreamer(opts.dbPath)
	if err != nil {
		log.WithFields(logrus.Fields{
			"db_path": opts.dbPath,
			"error":   err,
		}).Fatal("couldn't create SQL streamer")
	}
	defer service.(*frontend.SqlStreamer).GracefulStop()

	// Register service
	walletrpc.RegisterCompactTxStreamerServer(server, service)

	// Start listening
	listener, err := net.Listen("tcp", opts.bindAddr)
	if err != nil {
		log.WithFields(logrus.Fields{
			"bind_addr": opts.bindAddr,
			"error":     err,
		}).Fatal("couldn't create listener")
	}

	// Signal handler for graceful stops
	signals := make(chan os.Signal, 1)
	signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		s := <-signals
		log.WithFields(logrus.Fields{
			"signal": s.String(),
		}).Info("caught signal, stopping gRPC server")
		server.GracefulStop()
	}()

	log.Infof("Starting gRPC server on %s", opts.bindAddr)

	err = server.Serve(listener)
	if err != nil {
		log.WithFields(logrus.Fields{
			"error": err,
		}).Fatal("gRPC server exited")
	}
}