package main

import (
	"database/sql"
	"fmt"
	"log"
	"net/http"
	"os"

	"github.com/gorilla/mux"
	_ "github.com/lib/pq"
)

type URLShortener struct {
	DB *sql.DB
}

type URL struct {
	ID          int
	OriginalURL string
	ShortCode   string
	CreatedAt   string
	Visits      int
}

func main() {
	dbHost := getEnv("DB_HOST", "localhost")
	dbPort := getEnv("DB_PORT", "5432")
	dbUser := getEnv("DB_USER", "postgres")
	dbPassword := getEnv("DB_PASSWORD", "postgres")
	dbName := getEnv("DB_NAME", "urlshortener")

	connStr := fmt.Sprintf("host=%s port=%s user=%s password=%s dbname=%s sslmode=disable",
		dbHost, dbPort, dbUser, dbPassword, dbName)
	db, err := sql.Open("postgres", connStr)

	if err != nil {
		log.Fatalf("Failed to connect to the database: %v", err)
	}

	defer db.Close()

	err = db.Ping()
	if err != nil {
		log.Fatalf("Failed to ping the database: %v", err)
	}

	err = initializeDB(db)
	if err != nil {
		log.Fatalf("Failed to initialize the DB: %v", err)
	}

	shortener := &URLShortener{DB: db}

	router := mux.NewRouter()

	router.PathPrefix("/static/").Handler(http.StripPrefix("/static/", http.FileServer(http.Dir("./static"))))

	router.HandleFunc("/", shortener.homeHandler).Methods("GET")

	port := getEnv("PORT", "8080")
	log.Printf("Server starting on port http://localhost:%s", port)
	if err := http.ListenAndServe(":"+port, router); err != nil {
		log.Fatalf("Server failed to start: %v", err)
	}
}

func getEnv(key, fallback string) string {
	if value, exists := os.LookupEnv(key); exists {
		return value
	}
	return fallback
}

func initializeDB(db *sql.DB) error {
	_, err := db.Exec(`
	CREATE TABLE IF NOT EXISTS urls(
    id SERIAL PRIMARY KEY,
    original_url TEXT NOT NULL,
    short_code VARCHAR(10) UNIQUE NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    visits INTEGER DEFAULT 0
    )
`)
	return err
}

func (s *URLShortener) homeHandler(w http.ResponseWriter, r *http.Request) {
	http.ServeFile(w, r, "./templates/index.html")
}