// SPDX-License-Identifier: AGPL-3.0-or-later

package main

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

	"kode.naiv.no/olemd/favoritter/internal/config"
	"kode.naiv.no/olemd/favoritter/internal/database"
	"kode.naiv.no/olemd/favoritter/internal/handler"
	"kode.naiv.no/olemd/favoritter/internal/handler/api"
	"kode.naiv.no/olemd/favoritter/internal/middleware"
	"kode.naiv.no/olemd/favoritter/internal/render"
	"kode.naiv.no/olemd/favoritter/internal/store"
)

var (
	version   = "dev"
	buildDate = "unknown"
)

func main() {
	// Handle flags and subcommands before starting the server.
	if len(os.Args) > 1 {
		switch os.Args[1] {
		case "-healthcheck":
			runHealthCheck()
			return
		case "-version":
			fmt.Printf("favoritter %s (built %s)\n", version, buildDate)
			return
		case "user":
			runUserCommand(os.Args[2:])
			return
		}
	}

	cfg := config.Load()

	// Set up structured logging.
	logLevel := slog.LevelInfo
	if cfg.DevMode {
		logLevel = slog.LevelDebug
	}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: logLevel}))
	slog.SetDefault(logger)

	slog.Info("starting favoritter", "version", version, "build_date", buildDate)

	// Open database and run migrations.
	db, err := database.Open(cfg.DBPath)
	if err != nil {
		slog.Error("failed to open database", "error", err)
		os.Exit(1)
	}
	defer db.Close()

	if err := database.Migrate(db); err != nil {
		slog.Error("failed to run migrations", "error", err)
		os.Exit(1)
	}

	// Initialize stores.
	users := store.NewUserStore(db)
	sessions := store.NewSessionStore(db)
	settings := store.NewSettingsStore(db)
	faves := store.NewFaveStore(db)
	tags := store.NewTagStore(db)
	signupRequests := store.NewSignupRequestStore(db)

	sessions.SetLifetime(cfg.SessionLifetime)

	// Ensure initial admin user exists.
	if err := users.EnsureAdmin(cfg.AdminUsername, cfg.AdminPassword); err != nil {
		slog.Error("failed to ensure admin user", "error", err)
		os.Exit(1)
	}

	// Initialize template renderer.
	renderer, err := render.New(cfg)
	if err != nil {
		slog.Error("failed to initialize templates", "error", err)
		os.Exit(1)
	}

	// Configure Argon2 parameters from config.
	store.Argon2Memory = cfg.Argon2Memory
	store.Argon2Time = cfg.Argon2Time
	store.Argon2Parallelism = cfg.Argon2Parallelism

	// Build the handler with all dependencies.
	h := handler.New(handler.Deps{
		Config:   cfg,
		Users:    users,
		Sessions: sessions,
		Settings: settings,
		Faves:          faves,
		Tags:           tags,
		SignupRequests: signupRequests,
		Renderer:       renderer,
	})

	// Register JSON API routes on the same mux.
	apiHandler := api.New(api.Deps{
		Config:   cfg,
		Users:    users,
		Sessions: sessions,
		Faves:    faves,
		Tags:     tags,
	})

	// Build the middleware chain.
	mux := h.Routes()
	apiHandler.Routes(mux)
	chain := middleware.Chain(
		mux,
		middleware.Recovery,
		middleware.SecurityHeaders,
		middleware.BasePath(cfg.BasePath),
		middleware.RealIP(cfg.TrustedProxies),
		middleware.RequestLogger,
		middleware.SessionLoader(sessions, users),
		middleware.CSRFProtection(cfg),
		middleware.MustResetPasswordGuard(cfg.BasePath),
	)

	srv := &http.Server{
		Addr:         cfg.Listen,
		Handler:      chain,
		ReadTimeout:  15 * time.Second,
		WriteTimeout: 30 * time.Second,
		IdleTimeout:  60 * time.Second,
	}

	// Start background cleanup goroutines.
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	go sessions.CleanupLoop(ctx, 1*time.Hour)
	go h.RateLimiterCleanupLoop(ctx, 5*time.Minute)

	// Start the server in a goroutine.
	errCh := make(chan error, 1)
	go func() {
		slog.Info("listening", "addr", cfg.Listen, "base_path", cfg.BasePath)
		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			errCh <- err
		}
	}()

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

	select {
	case sig := <-quit:
		slog.Info("shutting down", "signal", sig)
	case err := <-errCh:
		slog.Error("server error", "error", err)
	}

	// Graceful shutdown with 10-second timeout.
	cancel()
	shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer shutdownCancel()
	if err := srv.Shutdown(shutdownCtx); err != nil {
		slog.Error("shutdown error", "error", err)
	}

	slog.Info("stopped")
}

// runHealthCheck performs a health check by hitting the local health endpoint.
// It reads the configured listen address to determine the correct port.
func runHealthCheck() {
	cfg := config.Load()
	addr := cfg.Listen
	// If addr is just ":port", use localhost.
	if len(addr) > 0 && addr[0] == ':' {
		addr = "127.0.0.1" + addr
	}
	resp, err := http.Get("http://" + addr + cfg.BasePath + "/health")
	if err != nil {
		os.Exit(1)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		os.Exit(1)
	}
}