package main

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

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
	"github.com/jackc/pgx/v5/pgxpool"
)

func main() {
	// Load configuration from environment
	port := getEnv("PORT", "8080")
	dbURL := getEnv("DATABASE_URL", "postgres://flowreader:flowreader@db:5432/flowreader?sslmode=disable")

	// Initialize database connection pool
	ctx := context.Background()
	pool, err := pgxpool.New(ctx, dbURL)
	if err != nil {
		log.Fatalf("Unable to create connection pool: %v", err)
	}
	defer pool.Close()

	// Verify database connection
	if err := pool.Ping(ctx); err != nil {
		log.Fatalf("Unable to ping database: %v", err)
	}
	log.Println("Connected to database")

	// Initialize router
	r := chi.NewRouter()

	// Middleware
	r.Use(middleware.Logger)
	r.Use(middleware.Recoverer)
	r.Use(middleware.RequestID)
	r.Use(middleware.RealIP)
	r.Use(middleware.Timeout(30 * time.Second))

	// Health check endpoint
	r.Get("/health", func(w http.ResponseWriter, r *http.Request) {
		// Check database connection
		if err := pool.Ping(r.Context()); err != nil {
			http.Error(w, "Database connection failed", http.StatusServiceUnavailable)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusOK)
		w.Write([]byte(`{"status":"ok","service":"flowreader"}`))
	})

	// API routes placeholder
	r.Route("/api/v1", func(r chi.Router) {
		r.Get("/", func(w http.ResponseWriter, r *http.Request) {
			w.Header().Set("Content-Type", "application/json")
			w.Write([]byte(`{"message":"FlowReader API v1"}`))
		})
	})

	// Create server
	srv := &http.Server{
		Addr:         ":" + port,
		Handler:      r,
		ReadTimeout:  15 * time.Second,
		WriteTimeout: 15 * time.Second,
		IdleTimeout:  60 * time.Second,
	}

	// Graceful shutdown
	go func() {
		log.Printf("Server starting on port %s", port)
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatalf("Server failed: %v", err)
		}
	}()

	// Wait for interrupt signal
	quit := make(chan os.Signal, 1)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
	<-quit

	log.Println("Shutting down server...")
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	if err := srv.Shutdown(ctx); err != nil {
		log.Fatalf("Server forced to shutdown: %v", err)
	}

	log.Println("Server exited properly")
}

// getEnv returns the value of an environment variable or a default value
func getEnv(key, defaultValue string) string {
	if value, exists := os.LookupEnv(key); exists {
		return value
	}
	return defaultValue
}