package cli

import (
	"fmt"
	"os"
	"os/exec"
	"os/signal"
	"syscall"

	"github.com/neutrino2211/at-rund/internal/atproto"
	"github.com/neutrino2211/at-rund/internal/config"
	"github.com/neutrino2211/at-rund/internal/server"
	"github.com/neutrino2211/at-rund/internal/vm"
	"github.com/spf13/cobra"
)

var (
	servePort      int
	serveDev       bool
	serveIsolation string
)

var serveCmd = &cobra.Command{
	Use:   "serve",
	Short: "Start the at-rund server",
	Long:  `Starts the HTTP server and initializes the execution backend.`,
	RunE:  runServe,
}

func init() {
	serveCmd.Flags().IntVarP(&servePort, "port", "p", 0, "port to listen on (default: from config)")
	serveCmd.Flags().BoolVar(&serveDev, "dev", false, "enable development mode (alias for --isolation=none)")
	serveCmd.Flags().StringVar(&serveIsolation, "isolation", "", "isolation backend: auto, none, container, firecracker")
}

func kvmAvailable() bool {
	_, err := os.Stat("/dev/kvm")
	return err == nil
}

func dockerAvailable() bool {
	cmd := exec.Command("docker", "info")
	return cmd.Run() == nil
}

func podmanAvailable() bool {
	cmd := exec.Command("podman", "info")
	return cmd.Run() == nil
}

func detectIsolation() string {
	if kvmAvailable() {
		return "firecracker"
	}
	if dockerAvailable() || podmanAvailable() {
		return "container"
	}
	return "none"
}

func runServe(cmd *cobra.Command, args []string) error {
	// Load config
	cfg, err := config.Load(cfgFile)
	if err != nil {
		return fmt.Errorf("failed to load config: %w", err)
	}

	// Override with flags
	if servePort != 0 {
		cfg.Port = servePort
	}
	if serveDev {
		cfg.Isolation = "none"
	}
	if serveIsolation != "" {
		cfg.Isolation = serveIsolation
	}

	// Auto-detect isolation if set to auto or empty
	if cfg.Isolation == "" || cfg.Isolation == "auto" {
		cfg.Isolation = detectIsolation()
	}

	fmt.Printf("at-rund starting...\n")
	fmt.Printf("  Port: %d\n", cfg.Port)
	fmt.Printf("  Isolation: %s\n", cfg.Isolation)
	if cfg.DID != "" {
		fmt.Printf("  DID: %s\n", cfg.DID)
	}

	// Initialize executor based on isolation mode
	var executor vm.Executor
	flakePath := vm.GetFlakePath()

	switch cfg.Isolation {
	case "none":
		fmt.Println("  Executor: Nix (direct execution, no isolation)")
		executor, err = vm.NewNixPool(flakePath)
		if err != nil {
			fmt.Println("\n  Nix is required. Install it with:")
			fmt.Println("    curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install")
			fmt.Println("")
			return fmt.Errorf("failed to initialize Nix executor: %w", err)
		}

	case "container":
		fmt.Println("  Executor: Container (namespace isolation)")
		executor, err = vm.NewContainerPool(flakePath)
		if err != nil {
			fmt.Println("\n  Docker or Podman is required for container isolation.")
			fmt.Println("  Install Docker: https://docs.docker.com/engine/install/")
			fmt.Println("  Or use --isolation=none for dev mode")
			fmt.Println("")
			return fmt.Errorf("failed to initialize Container executor: %w", err)
		}

	case "firecracker":
		fmt.Println("  Executor: Firecracker (VM isolation)")
		if !kvmAvailable() {
			return fmt.Errorf("firecracker requires KVM (/dev/kvm not accessible)")
		}
		executor, err = vm.NewFirecrackerPool(nil)
		if err != nil {
			return fmt.Errorf("failed to initialize Firecracker pool: %w", err)
		}

	default:
		return fmt.Errorf("unknown isolation mode: %s (valid: auto, none, container, firecracker)", cfg.Isolation)
	}
	defer executor.Shutdown()

	// Pre-warm if configured
	if cfg.Pool.PreWarm > 0 {
		fmt.Printf("  Pre-warming runtimes...\n")
		if err := executor.Warm(cfg.Pool.PreWarm); err != nil {
			fmt.Printf("  Warning: failed to pre-warm: %v\n", err)
		}
	}

	// Initialize bundle client
	bundleClient := atproto.NewBundleClient(cfg.BundlesDir(), cfg.DevMode)
	fmt.Println("  Bundle client: ready")

	// Start HTTP server
	srv := server.New(cfg, executor, bundleClient)

	// Handle shutdown gracefully
	sigCh := make(chan os.Signal, 1)
	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)

	errCh := make(chan error, 1)
	go func() {
		fmt.Printf("\nListening on http://localhost:%d\n", cfg.Port)
		errCh <- srv.ListenAndServe()
	}()

	select {
	case err := <-errCh:
		return err
	case sig := <-sigCh:
		fmt.Printf("\nReceived %s, shutting down...\n", sig)
		executor.Drain()
		return srv.Shutdown()
	}
}