package main

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"reflect"
	"sync"
	"syscall"
	"time"

	"github.com/99designs/gqlgen/graphql/handler"
	"github.com/99designs/gqlgen/graphql/playground"
	"github.com/alecthomas/kong"
	"github.com/apex/log"
	"github.com/apex/log/handlers/json"
	"github.com/getsentry/sentry-go"
	sentryhttp "github.com/getsentry/sentry-go/http"
	"github.com/rs/cors"
	"github.com/sparetimecoders/goamqp"
	"gitlab.com/unboundsoftware/eventsourced/amqp"
	"gitlab.com/unboundsoftware/eventsourced/eventsourced"
	"gitlab.com/unboundsoftware/eventsourced/pg"

	"gitlab.com/unboundsoftware/schemas/cache"
	"gitlab.com/unboundsoftware/schemas/domain"
	"gitlab.com/unboundsoftware/schemas/graph"
	"gitlab.com/unboundsoftware/schemas/graph/generated"
	"gitlab.com/unboundsoftware/schemas/middleware"
	"gitlab.com/unboundsoftware/schemas/store"
)

type CLI struct {
	AmqpURL            string `name:"amqp-url" env:"AMQP_URL" help:"URL to use to connect to RabbitMQ" default:"amqp://user:password@localhost:5672/"`
	Port               int    `name:"port" env:"PORT" help:"Listen-port for GraphQL API" default:"8080"`
	APIKey             string `name:"api-key" env:"API_KEY" help:"The API-key that is required"`
	LogLevel           string `name:"log-level" env:"LOG_LEVEL" help:"The level of logging to use (debug, info, warn, error, fatal)" default:"info"`
	DatabaseURL        string `name:"postgres-url" env:"POSTGRES_URL" help:"URL to use to connect to Postgres" default:"postgres://postgres:postgres@:5432/schemas?sslmode=disable"`
	DatabaseDriverName string `name:"db-driver" env:"DB_DRIVER" help:"Driver to use to connect to db" default:"postgres"`
	SentryConfig
}

type SentryConfig struct {
	DSN         string `name:"sentry-dsn" env:"SENTRY_DSN" help:"Sentry dsn" default:""`
	Environment string `name:"sentry-environment" env:"SENTRY_ENVIRONMENT" help:"Sentry environment" default:"development"`
}

var buildVersion = "none"

const serviceName = "schemas"

func main() {
	var cli CLI
	_ = kong.Parse(&cli)
	log.SetHandler(json.New(os.Stdout))
	log.SetLevelFromString(cli.LogLevel)
	logger := log.WithField("service", serviceName)
	closeEvents := make(chan error)

	if err := start(
		closeEvents,
		logger,
		ConnectAMQP,
		cli,
	); err != nil {
		logger.WithError(err).Error("process error")
	}
}

func start(closeEvents chan error, logger *log.Entry, connectToAmqpFunc func(url string) (Connection, error), cli CLI) error {
	if err := setupSentry(logger, cli.SentryConfig); err != nil {
		return err
	}
	defer sentry.Flush(2 * time.Second)

	rootCtx, rootCancel := context.WithCancel(context.Background())
	defer rootCancel()

	db, err := store.SetupDB(cli.DatabaseDriverName, cli.DatabaseURL)
	if err != nil {
		return fmt.Errorf("failed to setup DB: %v", err)
	}

	eventStore, err := pg.New(
		rootCtx,
		db.DB,
		pg.WithEventTypes(
			&domain.SubGraphUpdated{},
		),
	)
	if err != nil {
		return fmt.Errorf("failed to create eventstore: %v", err)
	}
	publisher, err := goamqp.NewPublisher(
		goamqp.Route{
			Type: domain.SubGraphUpdated{},
			Key:  "SubGraph.Updated",
		},
	)
	if err != nil {
		return fmt.Errorf("failed to create publisher: %v", err)
	}
	eventPublisher, err := amqp.New(publisher)
	if err != nil {
		return fmt.Errorf("failed to create event publisher: %v", err)
	}
	conn, err := connectToAmqpFunc(cli.AmqpURL)
	if err != nil {
		return fmt.Errorf("failed to connect to AMQP: %v", err)
	}

	serviceCache := cache.New(logger)
	roots, err := eventStore.GetAggregateRoots(rootCtx, reflect.TypeOf(domain.SubGraph{}))
	if err != nil {
		return err
	}
	for _, root := range roots {
		subGraph := &domain.SubGraph{BaseAggregate: eventsourced.BaseAggregateFromString(root.String())}
		if _, err := eventsourced.NewHandler(rootCtx, subGraph, eventStore); err != nil {
			return err
		}
		_, err := serviceCache.Update(subGraph, nil)
		if err != nil {
			return err
		}
	}
	setups := []goamqp.Setup{
		goamqp.UseLogger(logger.Errorf),
		goamqp.CloseListener(closeEvents),
		goamqp.WithPrefetchLimit(20),
		goamqp.EventStreamPublisher(publisher),
		goamqp.TransientEventStreamConsumer("SubGraph.Updated", serviceCache.Update, domain.SubGraphUpdated{}),
	}
	if err := conn.Start(rootCtx, setups...); err != nil {
		return fmt.Errorf("failed to setup AMQP: %v", err)
	}

	defer func() { _ = conn.Close() }()

	logger.Info("Started")

	mux := http.NewServeMux()
	httpSrv := &http.Server{Addr: fmt.Sprintf(":%d", cli.Port), Handler: mux}

	wg := sync.WaitGroup{}

	sigint := make(chan os.Signal, 1)
	signal.Notify(sigint, os.Interrupt, syscall.SIGTERM)

	wg.Add(1)
	go func() {
		defer wg.Done()
		sig := <-sigint
		if sig != nil {
			// In case our shutdown logic is broken/incomplete we reset signal
			// handlers so next signal goes to go itself. Go is more aggressive when
			// shutting down goroutines
			signal.Reset(os.Interrupt, syscall.SIGTERM)
			logger.Info("Got shutdown signal..")
			rootCancel()
		}
	}()

	wg.Add(1)
	go func() {
		defer wg.Done()
		err := <-closeEvents
		if err != nil {
			logger.WithError(err).Error("received close from AMQP")
			rootCancel()
		}
	}()

	wg.Add(1)
	go func() {
		defer wg.Done()
		<-rootCtx.Done()

		if err := httpSrv.Close(); err != nil {
			logger.WithError(err).Error("close http server")
		}
		close(sigint)
		close(closeEvents)
	}()
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer rootCancel()

		resolver := &graph.Resolver{
			EventStore: eventStore,
			Publisher:  eventPublisher,
			Logger:     logger,
			Cache:      serviceCache,
		}

		config := generated.Config{
			Resolvers:  resolver,
			Complexity: generated.ComplexityRoot{},
		}
		apiKeyMiddleware := middleware.NewApiKey(cli.APIKey, logger)
		config.Directives.HasApiKey = apiKeyMiddleware.Directive
		srv := handler.NewDefaultServer(generated.NewExecutableSchema(
			config,
		))

		sentryHandler := sentryhttp.New(sentryhttp.Options{Repanic: true})
		mux.Handle("/", sentryHandler.HandleFunc(playground.Handler("GraphQL playground", "/query")))
		mux.Handle("/health", http.HandlerFunc(healthFunc))
		mux.Handle("/query", cors.AllowAll().Handler(sentryHandler.Handle(apiKeyMiddleware.Handler(srv))))

		logger.Infof("connect to http://localhost:%d/ for GraphQL playground", cli.Port)

		if err := httpSrv.ListenAndServe(); err != nil {
			logger.WithError(err).Error("listen http")
		}
	}()

	wg.Wait()

	return nil
}

func healthFunc(w http.ResponseWriter, _ *http.Request) {
	_, _ = w.Write([]byte("OK"))
}

func setupSentry(logger log.Interface, args SentryConfig) error {
	if args.Environment == "" {
		return fmt.Errorf("no Sentry environment supplied, exiting")
	}
	cfg := sentry.ClientOptions{
		Dsn:         args.DSN,
		Environment: args.Environment,
		Release:     fmt.Sprintf("%s-%s", serviceName, buildVersion),
	}
	switch args.Environment {
	case "development":
		cfg.Debug = true
		cfg.EnableTracing = false
		cfg.TracesSampleRate = 0.0
	case "production":
		if args.DSN == "" {
			return fmt.Errorf("no DSN supplied for non-dev environment, exiting")
		}
		cfg.Debug = false
		cfg.EnableTracing = true
		cfg.TracesSampleRate = 1.0
	default:
		return fmt.Errorf("illegal environment %s", args.Environment)
	}

	if err := sentry.Init(cfg); err != nil {
		return fmt.Errorf("sentry setup: %w", err)
	}
	logger.Infof("configured Sentry for env: %s", args.Environment)
	return nil
}

func ConnectAMQP(url string) (Connection, error) {
	return goamqp.NewFromURL(serviceName, url)
}

type Connection interface {
	Start(ctx context.Context, opts ...goamqp.Setup) error
	Close() error
}