package main

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

	"mixmaker/backend/internal/adapter/httpapi"
	"mixmaker/backend/internal/adapter/postgres"
	"mixmaker/backend/internal/application"
	"mixmaker/backend/internal/realtime"
)

func main() {
	ctx := context.Background()
	databaseURL := required("DATABASE_URL")
	if len(os.Args) > 1 && os.Args[1] == "migrate" {
		dir := env("MIGRATIONS_DIR", "migrations")
		if err := postgres.Migrate(ctx, databaseURL, dir); err != nil {
			slog.Error("migration failed", "error", err)
			os.Exit(1)
		}
		slog.Info("migrations applied")
		return
	}

	store, err := postgres.Open(ctx, databaseURL)
	if err != nil {
		slog.Error("database connection failed", "error", err)
		os.Exit(1)
	}
	defer store.Close()
	hub := realtime.New()
	service := application.New(store, hub)
	cfg := httpapi.Config{
		DiscordClientID:     required("DISCORD_CLIENT_ID"),
		DiscordClientSecret: required("DISCORD_CLIENT_SECRET"),
		DiscordRedirectURL:  required("DISCORD_REDIRECT_URL"),
		FrontendURL:         env("FRONTEND_URL", "/"),
		CookieName:          env("SESSION_COOKIE_NAME", "mixmaker_session"),
		SecureCookies:       env("COOKIE_SECURE", "true") == "true",
		SessionTTL:          durationEnv("SESSION_TTL", 7*24*time.Hour),
		AdminDiscordIDs:     csvSet(os.Getenv("ADMIN_DISCORD_IDS")),
	}
	server := &http.Server{
		Addr:              env("HTTP_ADDR", ":8080"),
		Handler:           httpapi.New(service, store, hub, cfg),
		ReadHeaderTimeout: 5 * time.Second,
		IdleTimeout:       60 * time.Second,
	}
	go func() {
		slog.Info("API listening", "address", server.Addr)
		if err := server.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			slog.Error("server failed", "error", err)
			os.Exit(1)
		}
	}()
	stop, cancel := signal.NotifyContext(ctx, syscall.SIGINT, syscall.SIGTERM)
	defer cancel()
	<-stop.Done()
	shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer shutdownCancel()
	if err := server.Shutdown(shutdownCtx); err != nil {
		slog.Error("graceful shutdown failed", "error", err)
	}
}

func required(key string) string {
	value := os.Getenv(key)
	if value == "" {
		slog.Error("required environment variable missing", "key", key)
		os.Exit(2)
	}
	return value
}

func env(key, fallback string) string {
	if value := os.Getenv(key); value != "" {
		return value
	}
	return fallback
}

func csvSet(value string) map[string]bool {
	out := make(map[string]bool)
	for _, item := range strings.Split(value, ",") {
		if item = strings.TrimSpace(item); item != "" {
			out[item] = true
		}
	}
	return out
}

func durationEnv(key string, fallback time.Duration) time.Duration {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}
	parsed, err := time.ParseDuration(value)
	if err != nil || parsed <= 0 {
		slog.Error("invalid duration environment variable", "key", key, "value", value)
		os.Exit(2)
	}
	return parsed
}