// ExpenseFlow — AI-Powered Expense Tracker
//
// A production-ready, mobile-first Progressive Web App (PWA) that uses
// passwordless email OTP login, event-based expense tracking, AI receipt
// extraction (DeepSeek Vision), and event filing (CSV/PDF via email).
//
// Usage:
//   Copy .env.example to .env and fill in credentials, then:
//   go run main.go
//
// The server starts on the port specified by the PORT env var (default 8080).

package main

import (
	"log"
	"net/http"
	"os"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
	"github.com/joho/godotenv"

	"github.com/expenseflow/internal/auth"
	"github.com/expenseflow/internal/database"
	"github.com/expenseflow/internal/email"
	"github.com/expenseflow/internal/handlers"
)

func main() {
	// -----------------------------------------------------------------------
	// Configuration
	// -----------------------------------------------------------------------

	// Load environment variables from .env file (if present).
	if err := godotenv.Load(); err != nil {
		log.Printf("INFO  [%s] main: no .env file found, using system environment",
			time.Now().Format(time.RFC3339))
	}

	port := os.Getenv("PORT")
	if port == "" {
		port = "8080"
	}

	// SMTP configuration.
	smtpHost := os.Getenv("SMTP_HOST")
	smtpPort := os.Getenv("SMTP_PORT")
	smtpUser := os.Getenv("SMTP_USER")
	smtpPass := os.Getenv("SMTP_PASS")

	// DeepSeek API key is read directly by the ai package.
	_ = os.Getenv("DEEPSEEK_API_KEY")

	// -----------------------------------------------------------------------
	// Database
	// -----------------------------------------------------------------------

	db, err := database.Init()
	if err != nil {
		log.Fatalf("FATAL [%s] main: database init: %v", time.Now().Format(time.RFC3339), err)
	}
	defer db.Close()

	// -----------------------------------------------------------------------
	// Services
	// -----------------------------------------------------------------------

	sessionStore := auth.NewSessionStore()
	failureTracker := auth.NewFailureTracker()

	// Create the email sender only if SMTP credentials are configured.
	var emailSender *email.Sender
	if smtpHost != "" && smtpPort != "" && smtpUser != "" && smtpPass != "" {
		emailSender = email.NewSender(smtpHost, smtpPort, smtpUser, smtpPass, "post@2-4-h.app")
		log.Printf("INFO  [%s] main: SMTP sender configured (%s:%s)",
			time.Now().Format(time.RFC3339), smtpHost, smtpPort)
	} else {
		log.Printf("WARN  [%s] main: SMTP not configured — OTP emails will not be sent",
			time.Now().Format(time.RFC3339))
	}

	// -----------------------------------------------------------------------
	// Handlers
	// -----------------------------------------------------------------------

	authHandler := &handlers.AuthHandler{
		DB:             db,
		Sessions:       sessionStore,
		FailureTracker: failureTracker,
		EmailSender:    emailSender,
	}

	eventHandler := handlers.NewEventHandler(db)
	expenseHandler := handlers.NewExpenseHandler(db)
	fileHandler := &handlers.FileHandler{
		DB:          db,
		EmailSender: emailSender,
	}

	// -----------------------------------------------------------------------
	// Router
	// -----------------------------------------------------------------------

	r := chi.NewRouter()

	// Middleware.
	r.Use(middleware.Logger)
	r.Use(middleware.Recoverer)
	r.Use(middleware.RealIP)

	// PWA headers for service worker.
	r.Use(func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			if r.URL.Path == "/sw.js" {
				w.Header().Set("Service-Worker-Allowed", "/")
				w.Header().Set("Content-Type", "application/javascript")
			}
			next.ServeHTTP(w, r)
		})
	})

	// Static file serving.
	fileServer := http.FileServer(http.Dir("static"))
	r.Handle("/static/*", http.StripPrefix("/static/", fileServer))

	// Serve the manifest.json and sw.js from the root for PWA compliance.
	r.Get("/sw.js", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Service-Worker-Allowed", "/")
		w.Header().Set("Content-Type", "application/javascript")
		http.ServeFile(w, r, "static/sw.js")
	}))
	r.Get("/manifest.json", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		http.ServeFile(w, r, "static/manifest.json")
	}))

	// Serve uploaded receipt images.
	r.Get("/storage/*", http.StripPrefix("/storage/", http.FileServer(http.Dir("storage"))).ServeHTTP)

	// ---- Public routes (no auth required) ----

	r.Get("/", authHandler.LandingPage)
	r.Post("/request-otp", authHandler.RequestOTP)
	r.Post("/verify-otp", authHandler.VerifyOTP)

	// ---- Logout ----

	r.Post("/logout", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Delete the session cookie.
		http.SetCookie(w, &http.Cookie{
			Name:     "session_token",
			Value:    "",
			Path:     "/",
			HttpOnly: true,
			MaxAge:   -1,
		})
		w.Header().Set("HX-Redirect", "/")
		w.WriteHeader(http.StatusOK)
	}))

	// ---- Protected routes (auth required) ----

	r.Group(func(r chi.Router) {
		r.Use(authHandler.RequireAuth)

		// Events.
		r.Get("/dashboard", eventHandler.Dashboard)
		r.Post("/events", eventHandler.CreateEvent)
		r.Put("/events/{id}/reopen", eventHandler.ReopenEvent)
		r.Get("/events/{id}/expenses", eventHandler.ViewEventExpenses)

		// Expenses.
		r.Post("/expenses/upload", expenseHandler.UploadReceipt)
		r.Post("/expenses", expenseHandler.SaveExpense)

		// Filing.
		r.Post("/events/{id}/file", fileHandler.FileEvent)
	})

	// -----------------------------------------------------------------------
	// Startup
	// -----------------------------------------------------------------------

	addr := ":" + port
	log.Printf("INFO  [%s] main: ExpenseFlow server starting on %s",
		time.Now().Format(time.RFC3339), addr)
	log.Printf("INFO  [%s] main: open http://localhost%s in your browser",
		time.Now().Format(time.RFC3339), addr)

	if err := http.ListenAndServe(addr, r); err != nil {
		log.Fatalf("FATAL [%s] main: server error: %v", time.Now().Format(time.RFC3339), err)
	}
}