package app

import (
	"context"
	"fmt"
	"net"
	"net/http"
	"os"
	"route256/comments/infra/config"
	"route256/comments/infra/db/postgres"
	"route256/comments/internal/app/server"
	"route256/comments/internal/domain/service"
	"time"

	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"google.golang.org/grpc/reflection"

	mw "route256/comments/infra/grpc/middleware"
	repository "route256/comments/infra/repository/sqlc"

	pb "route256/pkg/api/comments/v1"
)

type App struct {
	config     *config.Config
	controller *server.Server

	grpcServer *grpc.Server
	httpServer *http.Server
	gwConn     *grpc.ClientConn
}

func NewApp(configPath string) (*App, error) {
	c, err := config.LoadConfig(configPath)
	if err != nil {
		return nil, fmt.Errorf("unable to load config: %w", err)
	}

	log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
	zerolog.SetGlobalLevel(zerolog.InfoLevel)

	if c.Service.LogLevel != "" {
		level, logErr := zerolog.ParseLevel(c.Service.LogLevel)
		if logErr != nil {
			return nil, fmt.Errorf("unknown log level `%s` provided: %w", c.Service.LogLevel, logErr)
		}

		zerolog.SetGlobalLevel(level)
	}

	log.WithLevel(zerolog.GlobalLevel()).Msgf("using logging level=`%s`", zerolog.GlobalLevel().String())

	shards, err := getPostgresPools(c)
	if err != nil {
		return nil, err
	}

	repo := repository.NewCommentsRepository(shards[0], shards[1])

	service := service.NewCommentsService(repo, c.App.EditInterval)
	controller := server.NewServer(service)

	app := &App{
		config:     c,
		controller: controller,
	}

	return app, nil
}

func (app *App) Shutdown(ctx context.Context) (err error) {
	if app.httpServer != nil {
		err = app.httpServer.Shutdown(ctx)
		if err != nil {
			log.Error().Err(err).Msgf("failed http gateway server shutdown")
		}
	}

	done := make(chan struct{})
	if app.grpcServer != nil {
		go func() {
			app.grpcServer.GracefulStop()

			close(done)
		}()
	}

	select {
	case <-done:
	case <-ctx.Done():
		if app.grpcServer != nil {
			app.grpcServer.Stop()
		}
	}

	if app.gwConn != nil {
		err2 := app.gwConn.Close()

		if err2 != nil {
			err = err2

			log.Error().Err(err).Msgf("failed gateway connection close")
		}
	}

	return err
}

func (app *App) ListenAndServe(ctx context.Context) error {
	grpcAddr := fmt.Sprintf("%s:%s", app.config.Service.Host, app.config.Service.GRPCPort)
	l, err := net.Listen("tcp", grpcAddr)
	if err != nil {
		return err
	}

	app.grpcServer = grpc.NewServer(
		grpc.ChainUnaryInterceptor(
			mw.Logging,
			mw.Validate,
		),
	)
	reflection.Register(app.grpcServer)

	pb.RegisterCommentsServer(app.grpcServer, app.controller)

	go func() {
		if err = app.grpcServer.Serve(l); err != nil {
			log.Fatal().Err(err).Msg("failed to serve")
		}
	}()

	log.Info().Msgf("Serving grpc loms at grpc://%s", l.Addr())

	// Setup HTTP gateway

	conn, err := grpc.NewClient(
		grpcAddr,
		grpc.WithTransportCredentials(insecure.NewCredentials()),
	)
	if err != nil {
		return fmt.Errorf("grpc.NewClient: %w", err)
	}
	app.gwConn = conn

	gwmux := runtime.NewServeMux()
	if err = pb.RegisterCommentsHandler(ctx, gwmux, conn); err != nil {
		return fmt.Errorf("pb.RegisterLOMSHandler: %w", err)
	}

	root := http.NewServeMux()
	root.Handle("/metrics", promhttp.Handler())
	root.Handle("/", gwmux)

	app.httpServer = &http.Server{
		Addr:        fmt.Sprintf("%s:%s", app.config.Service.Host, app.config.Service.HTTPPort),
		Handler:     root,
		ReadTimeout: 10 * time.Second,
	}

	log.Info().Msgf("Serving http loms at http://%s", app.httpServer.Addr)

	return app.httpServer.ListenAndServe()
}

func getPostgresPools(c *config.Config) ([]*pgxpool.Pool, error) {
	conns := make([]string, len(c.DbShards))
	for i, shard := range c.DbShards {
		conns[i] = fmt.Sprintf(
			"postgresql://%s:%s@%s:%s/%s?sslmode=disable",
			shard.User,
			shard.Password,
			shard.Host,
			shard.Port,
			shard.DBName,
		)
	}

	pools, err := postgres.NewPools(context.Background(), conns...)
	if err != nil {
		return nil, err
	}

	return pools, nil
}