package serve

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	"gitea.dwysokinski.me/Kichiyaki/chizap"
	"gitea.dwysokinski.me/twhelp/sessions/cmd/sessions/internal"
	"gitea.dwysokinski.me/twhelp/sessions/internal/bundb"
	"gitea.dwysokinski.me/twhelp/sessions/internal/router/meta"
	"gitea.dwysokinski.me/twhelp/sessions/internal/router/rest"
	"gitea.dwysokinski.me/twhelp/sessions/internal/service"
	"github.com/kelseyhightower/envconfig"
	"github.com/uptrace/bun"
	"github.com/urfave/cli/v2"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
	"go.uber.org/zap"
)

const (
	defaultPort           = "9234"
	readTimeout           = 5 * time.Second
	readHeaderTimeout     = time.Second
	handlerTimeout        = time.Second
	writeTimeout          = 10 * time.Second
	idleTimeout           = 180 * time.Second
	serverShutdownTimeout = 10 * time.Second
	metaEndpointsPrefix   = "/_meta"
)

func New() *cli.Command {
	return &cli.Command{
		Name:  "serve",
		Usage: "Runs the http server",
		Action: func(c *cli.Context) error {
			logger := zap.L()

			db, err := internal.NewBunDB()
			if err != nil {
				return fmt.Errorf("internal.NewBunDB: %w", err)
			}
			defer func() {
				_ = db.Close()
			}()

			srv, err := newServer(logger, db)
			if err != nil {
				return fmt.Errorf("newServer: %w", err)
			}

			go runServer(srv, logger)
			defer func() {
				ctxShutdown, cancelShutdown := context.WithTimeout(c.Context, serverShutdownTimeout)
				defer cancelShutdown()
				_ = srv.Shutdown(ctxShutdown)
			}()
			logger.Info("Server is listening on the port "+defaultPort, zap.String("port", defaultPort))

			waitForSignal(c.Context)

			return nil
		},
	}
}

func newServer(logger *zap.Logger, db *bun.DB) (*http.Server, error) {
	apiCfg, err := newAPIConfig()
	if err != nil {
		return nil, fmt.Errorf("newAPIConfig: %w", err)
	}

	// repos
	userRepo := bundb.NewUser(db)
	apiKeyRepo := bundb.NewAPIKey(db)
	sessionRepo := bundb.NewSession(db)

	// services
	userSvc := service.NewUser(userRepo)
	apiKeySvc := service.NewAPIKey(apiKeyRepo, userSvc)
	sessionSvc := service.NewSession(sessionRepo, userSvc)

	// router
	r := chi.NewRouter()
	r.Use(getMiddlewares(logger)...)
	r.Mount(metaEndpointsPrefix, meta.New(bundb.NewChecker(db)))
	r.Mount("/api", rest.New(
		apiKeySvc,
		sessionSvc,
		rest.WithCORSConfig(rest.CORSConfig{
			Enabled:          apiCfg.CORSEnabled,
			AllowedOrigins:   apiCfg.CORSAllowedOrigins,
			AllowedMethods:   apiCfg.CORSAllowedMethods,
			AllowCredentials: apiCfg.CORSAllowCredentials,
			MaxAge:           int(apiCfg.CORSMaxAge),
		}),
		rest.WithSwaggerConfig(rest.SwaggerConfig{
			Enabled: apiCfg.SwaggerEnabled,
			Host:    apiCfg.SwaggerHost,
			Schemes: apiCfg.SwaggerSchemes,
		}),
	))

	return &http.Server{
		Addr:              ":" + defaultPort,
		Handler:           http.TimeoutHandler(r, handlerTimeout, "Timeout"),
		ReadTimeout:       readTimeout,
		ReadHeaderTimeout: readHeaderTimeout,
		WriteTimeout:      writeTimeout,
		IdleTimeout:       idleTimeout,
	}, nil
}

type apiConfig struct {
	SwaggerEnabled       bool     `envconfig:"SWAGGER_ENABLED" default:"false"`
	SwaggerHost          string   `envconfig:"SWAGGER_HOST" default:""`
	SwaggerSchemes       []string `envconfig:"SWAGGER_SCHEMES" default:"http,https"`
	CORSEnabled          bool     `envconfig:"CORS_ENABLED" default:"false"`
	CORSAllowedOrigins   []string `envconfig:"CORS_ALLOWED_ORIGINS" default:""`
	CORSAllowCredentials bool     `envconfig:"CORS_ALLOW_CREDENTIALS" default:"false"`
	CORSAllowedMethods   []string `envconfig:"CORS_ALLOWED_METHODS" default:"HEAD,GET,POST,PUT"`
	CORSMaxAge           uint32   `envconfig:"CORS_MAX_AGE" default:"300"`
}

func newAPIConfig() (apiConfig, error) {
	var cfg apiConfig
	if err := envconfig.Process("API", &cfg); err != nil {
		return apiConfig{}, fmt.Errorf("envconfig.Process: %w", err)
	}
	return cfg, nil
}

func getMiddlewares(logger *zap.Logger) chi.Middlewares {
	return chi.Middlewares{
		middleware.RealIP,
		chizap.Logger(logger, chizap.WithFilter(omitMetaEndpoints)),
		middleware.Recoverer,
	}
}

func runServer(srv *http.Server, logger *zap.Logger) {
	if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
		logger.Fatal("srv.ListenAndServe:" + err.Error())
	}
}

func waitForSignal(ctx context.Context) {
	ctx, stop := signal.NotifyContext(ctx, os.Interrupt, syscall.SIGTERM)
	defer stop()
	<-ctx.Done()
}

func omitMetaEndpoints(r *http.Request) bool {
	return !strings.HasPrefix(r.URL.Path, metaEndpointsPrefix)
}