main.go

package main

import (
	"context"
	"net"
	"net/http"
	"os"

	"github.com/Jingyii800/simplebank/api"
	db "github.com/Jingyii800/simplebank/db/sqlc"
	_ "github.com/Jingyii800/simplebank/doc/statik"
	"github.com/Jingyii800/simplebank/gapi"
	"github.com/Jingyii800/simplebank/mail"
	"github.com/Jingyii800/simplebank/pb"
	"github.com/Jingyii800/simplebank/util"
	"github.com/Jingyii800/simplebank/worker"
	"github.com/golang-migrate/migrate/v4"
	_ "github.com/golang-migrate/migrate/v4/database/postgres"
	_ "github.com/golang-migrate/migrate/v4/source/file"
	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
	"github.com/hibiken/asynq"
	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/rakyll/statik/fs"
	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
	"google.golang.org/grpc"
	"google.golang.org/grpc/reflection"
	"google.golang.org/protobuf/encoding/protojson"
)

func main() {
	config, err := util.LoadConfig(".")
	if err != nil {
		log.Fatal().Err(err).Msg("cannot load config")
	}

	if config.Environment == "development" {
		// for human-read friendly log
		log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
	}

	connPool, err := pgxpool.New(context.Background(), config.DBSource)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot connect to db")
	}

	// run DB migration
	runDBmigration(config.MigrationURL, config.DBSource)

	store := db.NewStore(connPool)

	// connect to redis
	redisOpt := asynq.RedisClientOpt{
		Addr: config.RedisAddress,
	}
	// create a task distributor
	taskDistributor := worker.NewRedisTaskDistributor(redisOpt)
	// process the task
	go runTaskProcessor(config, redisOpt, store)

	// run server
	go runGatewayServer(config, store, taskDistributor)
	runGrpcServer(config, store, taskDistributor)
}

func runDBmigration(migrationURL string, dbSource string) {
	migration, err := migrate.New(migrationURL, dbSource)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot create new migrate instance:")
	}
	if err = migration.Up(); err != nil && err != migrate.ErrNoChange {
		log.Fatal().Err(err).Msg("failed to run migrate up:")
	}

	log.Info().Msg("DB migrated successfully")
}

func runTaskProcessor(config util.Config, redisOpt asynq.RedisClientOpt, store db.Store) {
	mailer := mail.NewGmailSender(config.EmailSenderName, config.EmailSenderAddress, config.EmailSenderPassword)
	taskProcessor := worker.NewRedisTaskProcessor(redisOpt, store, mailer)
	log.Info().Msg("start task processor")
	err := taskProcessor.Start()
	if err != nil {
		log.Fatal().Err(err).Msg("failed to start task processor")
	}
}

func runGatewayServer(config util.Config, store db.Store, taskDistributor worker.TaskDistributor) {
	server, err := gapi.NewServer(config, store, taskDistributor)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot create server:")
	}

	// use proto names in JSON
	jsonOption := runtime.WithMarshalerOption(runtime.MIMEWildcard, &runtime.JSONPb{
		MarshalOptions: protojson.MarshalOptions{
			UseProtoNames: true,
		},
		UnmarshalOptions: protojson.UnmarshalOptions{
			DiscardUnknown: true,
		},
	})

	grpcMux := runtime.NewServeMux(jsonOption)

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel() // prevent unnecessary work

	err = pb.RegisterSimpleBankHandlerServer(ctx, grpcMux, server)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot register handler server")
	}

	mux := http.NewServeMux()
	mux.Handle("/", grpcMux)

	// open the UI
	// need to import the statik at the top
	// will read from server's memory instead of harddrive, so much faster
	statikFS, err := fs.New()
	if err != nil {
		log.Fatal().Err(err).Msg("cannot create statik fs")
	}
	swaggerHandler := http.StripPrefix("/swagger/", http.FileServer(statikFS))
	mux.Handle("/swagger/", swaggerHandler)
	// registers the handler for the given pattern

	// listen on specific port
	listener, err := net.Listen("tcp", config.HTTPServerAddress)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot create listener:")
	}
	log.Info().Msgf("start Http server at %s", listener.Addr().String())
	// logger middleware handler
	handler := gapi.HttpLogger(mux)
	// update mux to logger middleware handler
	err = http.Serve(listener, handler)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot start Http gateway server")
	}
}

func runGrpcServer(config util.Config, store db.Store, taskDistributor worker.TaskDistributor) {
	server, err := gapi.NewServer(config, store, taskDistributor)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot create server:")
	}
	// structured logs for grpc apis
	gprcLogger := grpc.UnaryInterceptor(gapi.GrpcLogger)
	// add a interceptor in grpc server
	grpcServer := grpc.NewServer(gprcLogger)

	pb.RegisterSimpleBankServer(grpcServer, server)
	// important step; like a self-documentation
	reflection.Register(grpcServer)
	// listen on specific port
	listener, err := net.Listen("tcp", config.GRPCServerAddress)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot create listener")
	}
	log.Info().Msgf("start gRPC server at %s", listener.Addr().String())
	err = grpcServer.Serve(listener)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot start gRPC server")
	}
}

func runGinServer(config util.Config, store db.Store) {
	server, err := api.NewServer(config, store)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot create server:")
	}

	err = server.Start(config.ServerAddress)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot start server")
	}
}