//
// Copyright (c) 2018
// Mainflux
//
// SPDX-License-Identifier: Apache-2.0
//
package main

import (
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"strconv"
	"syscall"

	rediscons "github.com/mainflux/mainflux/bootstrap/redis/consumer"
	redisprod "github.com/mainflux/mainflux/bootstrap/redis/producer"

	kitprometheus "github.com/go-kit/kit/metrics/prometheus"
	r "github.com/go-redis/redis"
	"github.com/jmoiron/sqlx"
	"github.com/mainflux/mainflux"
	"github.com/mainflux/mainflux/bootstrap"
	api "github.com/mainflux/mainflux/bootstrap/api"
	"github.com/mainflux/mainflux/bootstrap/postgres"
	mflog "github.com/mainflux/mainflux/logger"
	mfsdk "github.com/mainflux/mainflux/sdk/go"
	usersapi "github.com/mainflux/mainflux/users/api/grpc"
	stdprometheus "github.com/prometheus/client_golang/prometheus"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"
)

const (
	defLogLevel      = "error"
	defDBHost        = "localhost"
	defDBPort        = "5432"
	defDBUser        = "mainflux"
	defDBPass        = "mainflux"
	defDBName        = "bootstrap"
	defDBSSLMode     = "disable"
	defDBSSLCert     = ""
	defDBSSLKey      = ""
	defDBSSLRootCert = ""
	defClientTLS     = "false"
	defCACerts       = ""
	defPort          = "8180"
	defServerCert    = ""
	defServerKey     = ""
	defBaseURL       = "http://localhost"
	defThingsPrefix  = ""
	defUsersURL      = "localhost:8181"
	defThingsESURL   = "localhost:6379"
	defThingsESPass  = ""
	defThingsESDB    = "0"
	defESURL         = "localhost:6379"
	defESPass        = ""
	defESDB          = "0"
	defInstanceName  = "bootstrap"

	envLogLevel      = "MF_BOOTSTRAP_LOG_LEVEL"
	envDBHost        = "MF_BOOTSTRAP_DB_HOST"
	envDBPort        = "MF_BOOTSTRAP_DB_PORT"
	envDBUser        = "MF_BOOTSTRAP_DB_USER"
	envDBPass        = "MF_BOOTSTRAP_DB_PASS"
	envDBName        = "MF_BOOTSTRAP_DB"
	envDBSSLMode     = "MF_BOOTSTRAP_DB_SSL_MODE"
	envDBSSLCert     = "MF_BOOTSTRAP_DB_SSL_CERT"
	envDBSSLKey      = "MF_BOOTSTRAP_DB_SSL_KEY"
	envDBSSLRootCert = "MF_BOOTSTRAP_DB_SSL_ROOT_CERT"
	envClientTLS     = "MF_BOOTSTRAP_CLIENT_TLS"
	envCACerts       = "MF_BOOTSTRAP_CA_CERTS"
	envPort          = "MF_BOOTSTRAP_PORT"
	envServerCert    = "MF_BOOTSTRAP_SERVER_CERT"
	envServerKey     = "MF_BOOTSTRAP_SERVER_KEY"
	envBaseURL       = "MF_SDK_BASE_URL"
	envThingsPrefix  = "MF_SDK_THINGS_PREFIX"
	envUsersURL      = "MF_USERS_URL"
	envThingsESURL   = "MF_THINGS_ES_URL"
	envThingsESPass  = "MF_THINGS_ES_PASS"
	envThingsESDB    = "MF_THINGS_ES_DB"
	envESURL         = "MF_BOOTSTRAP_ES_URL"
	envESPass        = "MF_BOOTSTRAP_ES_PASS"
	envESDB          = "MF_BOOTSTRAP_ES_DB"
	envInstanceName  = "MF_BOOTSTRAP_INSTANCE_NAME"
)

type config struct {
	logLevel     string
	dbConfig     postgres.Config
	clientTLS    bool
	caCerts      string
	httpPort     string
	serverCert   string
	serverKey    string
	baseURL      string
	thingsPrefix string
	usersURL     string
	esThingsURL  string
	esThingsPass string
	esThingsDB   string
	esURL        string
	esPass       string
	esDB         string
	instanceName string
}

func main() {
	cfg := loadConfig()

	logger, err := mflog.New(os.Stdout, cfg.logLevel)
	if err != nil {
		log.Fatalf(err.Error())
	}

	db := connectToDB(cfg.dbConfig, logger)
	defer db.Close()

	conn := connectToUsers(cfg, logger)
	defer conn.Close()

	thingsESConn := connectToRedis(cfg.esThingsURL, cfg.esThingsPass, cfg.esThingsDB, logger)
	defer thingsESConn.Close()

	esClient := connectToRedis(cfg.esURL, cfg.esPass, cfg.esDB, logger)
	defer esClient.Close()

	svc := newService(conn, db, logger, esClient, cfg)
	errs := make(chan error, 2)

	go startHTTPServer(svc, cfg, logger, errs)
	go subscribeToThingsES(svc, thingsESConn, cfg.instanceName, logger)

	go func() {
		c := make(chan os.Signal)
		signal.Notify(c, syscall.SIGINT)
		errs <- fmt.Errorf("%s", <-c)
	}()

	err = <-errs
	logger.Error(fmt.Sprintf("Bootstrap service terminated: %s", err))
}

func loadConfig() config {
	tls, err := strconv.ParseBool(mainflux.Env(envClientTLS, defClientTLS))
	if err != nil {
		tls = false
	}
	dbConfig := postgres.Config{
		Host:        mainflux.Env(envDBHost, defDBHost),
		Port:        mainflux.Env(envDBPort, defDBPort),
		User:        mainflux.Env(envDBUser, defDBUser),
		Pass:        mainflux.Env(envDBPass, defDBPass),
		Name:        mainflux.Env(envDBName, defDBName),
		SSLMode:     mainflux.Env(envDBSSLMode, defDBSSLMode),
		SSLCert:     mainflux.Env(envDBSSLCert, defDBSSLCert),
		SSLKey:      mainflux.Env(envDBSSLKey, defDBSSLKey),
		SSLRootCert: mainflux.Env(envDBSSLRootCert, defDBSSLRootCert),
	}

	return config{
		logLevel:     mainflux.Env(envLogLevel, defLogLevel),
		dbConfig:     dbConfig,
		clientTLS:    tls,
		caCerts:      mainflux.Env(envCACerts, defCACerts),
		httpPort:     mainflux.Env(envPort, defPort),
		serverCert:   mainflux.Env(envServerCert, defServerCert),
		serverKey:    mainflux.Env(envServerKey, defServerKey),
		baseURL:      mainflux.Env(envBaseURL, defBaseURL),
		thingsPrefix: mainflux.Env(envThingsPrefix, defThingsPrefix),
		usersURL:     mainflux.Env(envUsersURL, defUsersURL),
		esThingsURL:  mainflux.Env(envThingsESURL, defThingsESURL),
		esThingsPass: mainflux.Env(envThingsESPass, defThingsESPass),
		esThingsDB:   mainflux.Env(envThingsESDB, defThingsESDB),
		esURL:        mainflux.Env(envESURL, defESURL),
		esPass:       mainflux.Env(envESPass, defESPass),
		esDB:         mainflux.Env(envESDB, defESDB),
		instanceName: mainflux.Env(envInstanceName, defInstanceName),
	}
}

func connectToDB(cfg postgres.Config, logger mflog.Logger) *sqlx.DB {
	db, err := postgres.Connect(cfg)
	if err != nil {
		logger.Error(fmt.Sprintf("Failed to connect to postgres: %s", err))
		os.Exit(1)
	}
	return db
}

func connectToRedis(redisURL, redisPass, redisDB string, logger mflog.Logger) *r.Client {
	db, err := strconv.Atoi(redisDB)
	if err != nil {
		logger.Error(fmt.Sprintf("Failed to connect to redis: %s", err))
		os.Exit(1)
	}

	return r.NewClient(&r.Options{
		Addr:     redisURL,
		Password: redisPass,
		DB:       db,
	})
}

func newService(conn *grpc.ClientConn, db *sqlx.DB, logger mflog.Logger, esClient *r.Client, cfg config) bootstrap.Service {
	thingsRepo := postgres.NewConfigRepository(db, logger)

	config := mfsdk.Config{
		BaseURL:      cfg.baseURL,
		ThingsPrefix: cfg.thingsPrefix,
	}

	sdk := mfsdk.NewSDK(config)
	users := usersapi.NewClient(conn)

	svc := bootstrap.New(users, thingsRepo, sdk)
	svc = redisprod.NewEventStoreMiddleware(svc, esClient)
	svc = api.NewLoggingMiddleware(svc, logger)
	svc = api.MetricsMiddleware(
		svc,
		kitprometheus.NewCounterFrom(stdprometheus.CounterOpts{
			Namespace: "bootstrap",
			Subsystem: "api",
			Name:      "request_count",
			Help:      "Number of requests received.",
		}, []string{"method"}),
		kitprometheus.NewSummaryFrom(stdprometheus.SummaryOpts{
			Namespace: "bootstrap",
			Subsystem: "api",
			Name:      "request_latency_microseconds",
			Help:      "Total duration of requests in microseconds.",
		}, []string{"method"}),
	)
	return svc
}

func connectToUsers(cfg config, logger mflog.Logger) *grpc.ClientConn {
	var opts []grpc.DialOption
	if cfg.clientTLS {
		if cfg.caCerts != "" {
			tpc, err := credentials.NewClientTLSFromFile(cfg.caCerts, "")
			if err != nil {
				logger.Error(fmt.Sprintf("Failed to create tls credentials: %s", err))
				os.Exit(1)
			}
			opts = append(opts, grpc.WithTransportCredentials(tpc))
		}
	} else {
		opts = append(opts, grpc.WithInsecure())
		logger.Info("gRPC communication is not encrypted")
	}

	conn, err := grpc.Dial(cfg.usersURL, opts...)
	if err != nil {
		logger.Error(fmt.Sprintf("Failed to connect to users service: %s", err))
		os.Exit(1)
	}

	return conn
}

func startHTTPServer(svc bootstrap.Service, cfg config, logger mflog.Logger, errs chan error) {
	p := fmt.Sprintf(":%s", cfg.httpPort)
	if cfg.serverCert != "" || cfg.serverKey != "" {
		logger.Info(fmt.Sprintf("Bootstrap service started using https on port %s with cert %s key %s",
			cfg.httpPort, cfg.serverCert, cfg.serverKey))
		errs <- http.ListenAndServeTLS(p, cfg.serverCert, cfg.serverKey, api.MakeHandler(svc, bootstrap.NewConfigReader()))
		return
	}
	logger.Info(fmt.Sprintf("Bootstrap service started using http on port %s", cfg.httpPort))
	errs <- http.ListenAndServe(p, api.MakeHandler(svc, bootstrap.NewConfigReader()))
}

func subscribeToThingsES(svc bootstrap.Service, client *r.Client, consumer string, logger mflog.Logger) {
	eventStore := rediscons.NewEventStore(svc, client, consumer, logger)
	logger.Info("Subscribed to Redis Event Store")
	if err := eventStore.Subscribe("mainflux.things"); err != nil {
		logger.Warn(fmt.Sprintf("Botstrap service failed to subscribe to event sourcing: %s", err))
	}
}