package main

import (
	"RenewCMS/api"
	validator "RenewCMS/api/pkg/validator"
	"RenewCMS/internal/infrastructure/config"
	"context"
	"errors"
	"fmt"
	"log"
	"net"
	"net/http"
	"os"
	"os/signal"
	"slices"
	"syscall"
	"time"

	"github.com/joho/godotenv"
)

var version = "dev"

const (
	readHeaderTimeout = 10 * time.Second
	readTimeout       = 30 * time.Second
	writeTimeout      = 60 * time.Second
	idleTimeout       = 120 * time.Second
	shutdownTimeout   = 10 * time.Second
)

var possibleEnvFileLocations = []string{".env", "../.env"}

var requiredEnvVars = []string{
	"PUBLIC_URL",
	"JWT_SECRET",
	"SMTP_LOGIN",
	"SMTP_SENDER",
	"SMTP_PASSWORD",
	"SMTP_HOST",
	"SMTP_PORT",
}

var envDefaults = map[string]string{
	"ENVIRONMENT":                    "production",
	"PORT":                           "8080",
	"DB_FILE":                        "./data/renewcms.db",
	config.EnvDatabaseDriver:         config.DefaultDatabaseDriver,
	"DB_PORT":                        config.DefaultDatabasePort,
	"DB_TLS":                         config.DefaultDatabaseTLS,
	"DB_MAX_OPEN_CONNS":              config.DefaultMaxOpenConns,
	"DB_MAX_IDLE_CONNS":              config.DefaultMaxIdleConns,
	"DB_CONN_MAX_LIFETIME_SECONDS":   config.DefaultConnMaxLifetimeSeconds,
	"UPLOAD_DIR":                     "./data/uploads",
	"AUTH_RATE_LIMIT_MAX_ATTEMPTS":   "5",
	"AUTH_RATE_LIMIT_WINDOW_SECONDS": "60",
	"TRUSTED_PROXIES":                "",
	"UPDATE_FEED_URL":                "https://git.floriansylvain.fr",
	"RENEWCMS_CONTAINER":             "false",
}

const versionFlag = "--version"

func main() {
	if len(os.Args) == 2 && os.Args[1] == versionFlag {
		fmt.Println(version)
		return
	}
	if len(os.Args) > 1 {
		os.Exit(runCommand(os.Args[1:], os.Stdout, os.Stderr))
	}
	if err := run(); err != nil {
		log.Fatal(err)
	}
}

func run() error {
	initEnvVariables()

	settings, err := config.NewSettingsFromEnv()
	if err != nil {
		return err
	}
	settings.Version = version

	container, closeDb := api.InitContainer(settings)
	defer closeDatabase(closeDb)
	validator.InitValidator()

	server := newServer(api.InitRoutes(container, settings), settings)
	return serveUntilStopped(server, settings, container.RecordRunningInfoUseCase.Record, container.PurgeScheduler.Run)
}

func initEnvVariables() {
	loadEnvFile()
	applyEnvDefaults()
	ensureRequiredEnvVars()
}

func loadEnvFile() {
	for _, envLocation := range possibleEnvFileLocations {
		if godotenv.Load(envLocation) == nil {
			return
		}
	}
	log.Println("WARNING: Could not load any .env file")
}

func applyEnvDefaults() {
	for envVar, value := range envDefaults {
		if _, isSet := os.LookupEnv(envVar); !isSet {
			_ = os.Setenv(envVar, value)
		}
	}
}

func ensureRequiredEnvVars() {
	required := slices.Concat(requiredEnvVars, config.DatabaseRequiredEnvVars(os.Getenv(config.EnvDatabaseDriver)))
	if err := config.MissingEnvVarError(required, os.LookupEnv); err != nil {
		panic(err.Error())
	}
}

func closeDatabase(closeDb func() error) {
	if err := closeDb(); err != nil {
		log.Println("error closing database:", err)
	}
}

func newServer(handler http.Handler, settings config.Settings) *http.Server {
	return &http.Server{
		Addr:              ":" + settings.Port,
		Handler:           handler,
		ReadHeaderTimeout: readHeaderTimeout,
		ReadTimeout:       readTimeout,
		WriteTimeout:      writeTimeout,
		IdleTimeout:       idleTimeout,
	}
}

func serveUntilStopped(server *http.Server, settings config.Settings, recordRunning func() error, runScheduler func(context.Context)) error {
	stopSignal, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)

	schedulerDone := make(chan struct{})
	go func() {
		defer close(schedulerDone)
		runScheduler(stopSignal)
	}()
	defer func() {
		stop()
		<-schedulerDone
	}()

	serverErr := make(chan error, 1)
	go listen(server, serverErr, settings, recordRunning)

	select {
	case err := <-serverErr:
		return err
	case <-stopSignal.Done():
		return shutdown(server)
	}
}

func listen(server *http.Server, serverErr chan<- error, settings config.Settings, recordRunning func() error) {
	listener, err := net.Listen("tcp", server.Addr)
	if err != nil {
		serverErr <- err
		return
	}
	if err := recordRunning(); err != nil {
		log.Printf("WARNING: could not write the running-version file: %v", err)
	}
	log.Printf("RenewCMS %s (%s) listening on %s, public URL %s", version, settings.Environment, server.Addr, settings.PublicURL)
	err = server.Serve(listener)
	if errors.Is(err, http.ErrServerClosed) {
		err = nil
	}
	serverErr <- err
}

func shutdown(server *http.Server) error {
	log.Println("shutting down...")
	ctx, cancel := context.WithTimeout(context.Background(), shutdownTimeout)
	defer cancel()
	return server.Shutdown(ctx)
}