// Copyright (c) 2026 Probo Inc <hello@probo.com>.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package main

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"os"
	"os/signal"
	"path/filepath"
	"runtime"
	"syscall"
	"time"

	"github.com/spf13/cobra"
	"go.gearno.de/kit/log"
	"go.probo.inc/probo/pkg/deviceagent"
	"go.probo.inc/probo/pkg/deviceagent/elevate"
	"go.probo.inc/probo/pkg/deviceagent/service"
	"go.probo.inc/probo/pkg/deviceagent/tray"
	"go.probo.inc/probo/pkg/deviceagent/update"

	// Side-effect import: registers per-OS posture checks.
	_ "go.probo.inc/probo/pkg/deviceagent/checks"
)

var version = "dev"

// restartExitCode signals the OS service supervisor that the agent
// process exited because its binary was replaced and needs to be
// restarted. The value matches sysexits.h's EX_TEMPFAIL and is
// whitelisted in the systemd unit so the unit does not enter the
// "failed" state on a normal self-update.
const restartExitCode = 75

func main() {
	// Best-effort cleanup of a previous-version binary left aside by
	// a Windows self-update. No-op on Unix.
	if exe, err := os.Executable(); err == nil {
		update.CleanupAfterRestart(exe)
	}

	if len(os.Args) == 2 {
		if _, _, err := deviceagent.ParseEnrollURL(os.Args[1]); err == nil {
			os.Args = []string{os.Args[0], "enroll-url", os.Args[1]}
		}
	}

	if err := newRootCmd().Execute(); err != nil {
		if errors.Is(err, deviceagent.ErrRestartRequired) {
			os.Exit(restartExitCode)
		}

		fmt.Fprintf(os.Stderr, "probo-agent: %s\n", err)
		os.Exit(1)
	}
}

func newRootCmd() *cobra.Command {
	root := &cobra.Command{
		Use:           "probo-agent",
		Short:         "Probo device posture agent",
		Long:          "probo-agent runs as a managed OS service, reporting device posture to Probo.",
		SilenceUsage:  true,
		SilenceErrors: true,
		Version:       version,
	}

	root.PersistentFlags().StringP("dir", "d", "", "agent config / keystore directory (defaults to platform-specific path)")

	root.AddCommand(newInstallCmd())
	root.AddCommand(newUninstallCmd())
	root.AddCommand(newRunCmd())
	root.AddCommand(newStatusCmd())
	root.AddCommand(newCollectCmd())
	root.AddCommand(newUpdateCmd())
	root.AddCommand(newEnrollURLCmd())
	registerPlatformCommands(root)

	return root
}

func newEnrollURLCmd() *cobra.Command {
	var preflight bool

	cmd := &cobra.Command{
		Use:    "enroll-url [url]",
		Hidden: true,
		Args:   cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			serverURL, enrollmentToken, err := deviceagent.ParseEnrollURL(args[0])
			if err != nil {
				return err
			}

			dir := resolveDir(cmd)

			if preflight {
				enrolled, err := deviceagent.IsEnrolled(deviceagent.EnrollmentRunDir(dir))
				if err != nil {
					return fmt.Errorf("cannot check enrollment state: %w", err)
				}

				return writeEnrollPreflight(cmd.OutOrStdout(), serverURL, enrollmentToken, dir, enrolled)
			}

			already, err := reportIfAlreadyEnrolled(dir)
			if err != nil {
				return err
			}

			if already {
				return nil
			}

			if runtime.GOOS == "darwin" {
				return fmt.Errorf(
					"macOS browser enrollment must use the signed Probo Agent.app " +
						"(probo:// deeplink); for CLI use: sudo probo-agent install " +
						"--server … --enrollment-token …",
				)
			}

			exePath, err := os.Executable()
			if err != nil {
				return fmt.Errorf("cannot resolve current executable path: %w", err)
			}

			if err := elevate.RunElevatedInstall(exePath, serverURL, enrollmentToken, dir); err != nil {
				return fmt.Errorf("cannot start elevated enrollment install: %w", err)
			}

			fmt.Println("Enrollment started.")

			return nil
		},
	}

	cmd.Flags().BoolVar(&preflight, "preflight", false, "validate enrollment URL and print JSON for the macOS URL handler")

	return cmd
}

type enrollPreflightResponse struct {
	Server          string `json:"server"`
	Token           string `json:"token"`
	AlreadyEnrolled bool   `json:"alreadyEnrolled"`
	ConfigDir       string `json:"configDir"`
}

func writeEnrollPreflight(
	w io.Writer,
	serverURL, enrollmentToken, dir string,
	alreadyEnrolled bool,
) error {
	payload := enrollPreflightResponse{
		Server:          serverURL,
		Token:           enrollmentToken,
		AlreadyEnrolled: alreadyEnrolled,
		ConfigDir:       dir,
	}

	out, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("cannot encode enrollment preflight response: %w", err)
	}

	if _, err := fmt.Fprintln(w, string(out)); err != nil {
		return fmt.Errorf("cannot write enrollment preflight response: %w", err)
	}

	return nil
}

// reportIfAlreadyEnrolled prints a success message and returns true when
// the local enrollment marker is already present. Deep-link retries must
// exit 0 so the macOS URL handler does not show "Enrollment failed".
func reportIfAlreadyEnrolled(dir string) (bool, error) {
	enrolled, err := deviceagent.IsEnrolled(deviceagent.EnrollmentRunDir(dir))
	if err != nil {
		return false, fmt.Errorf("cannot check enrollment state: %w", err)
	}

	if !enrolled {
		return false, nil
	}

	fmt.Println("Device is already enrolled.")

	return true, nil
}

// newUpdater returns an Updater scoped to the running binary, or nil
// when self-update cannot be performed (unresolvable binary path).
//
// dir is the agent state directory, used to host the Sigstore TUF
// metadata cache for cosign bundle verification.
func newUpdater(logger *log.Logger, dir string) *update.Updater {
	exePath, err := os.Executable()
	if err != nil || exePath == "" {
		return nil
	}

	return update.New(
		version,
		exePath,
		fmt.Sprintf("probo-agent/%s", version),
		filepath.Join(dir, "sigstore-cache"),
		logger,
	)
}

func resolveDir(cmd *cobra.Command) string {
	dir, _ := cmd.Flags().GetString("dir")
	if dir != "" {
		return dir
	}

	return deviceagent.DefaultConfigDir()
}

func newAgentLogger() *log.Logger {
	return log.NewLogger(
		log.WithName("probo-agent"),
		log.WithOutput(os.Stderr),
	)
}

func newInstallCmd() *cobra.Command {
	var (
		serverURL       string
		enrollmentToken string
		skipService     bool
		noAutoUpdate    bool
	)

	cmd := &cobra.Command{
		Use:   "install",
		Short: "Enroll this device and install the agent as a managed OS service",
		RunE: func(cmd *cobra.Command, args []string) error {
			if serverURL == "" {
				return errors.New("--server is required")
			}

			var err error

			serverURL, err = deviceagent.NormalizeServerURL(serverURL)
			if err != nil {
				return fmt.Errorf("invalid --server: %w", err)
			}

			if enrollmentToken == "" {
				if v := os.Getenv("PROBO_ENROLLMENT_TOKEN"); v != "" {
					enrollmentToken = v
				}
			}

			if enrollmentToken == "" {
				return errors.New("--enrollment-token (or PROBO_ENROLLMENT_TOKEN env var) is required")
			}

			dir := resolveDir(cmd)

			already, err := reportIfAlreadyEnrolled(dir)
			if err != nil {
				return err
			}

			if already {
				return nil
			}

			ctx, cancel := context.WithTimeout(cmd.Context(), 60*time.Second)
			defer cancel()

			client := deviceagent.NewClient(
				serverURL,
				"",
				fmt.Sprintf("probo-agent/%s", version),
			)

			apiKey, err := deviceagent.LoadOrExchangeAPIKey(ctx, dir, client, serverURL, enrollmentToken)
			if err != nil {
				return fmt.Errorf("cannot obtain device api key: %w", err)
			}

			agent := deviceagent.New(dir, version, newAgentLogger())

			resp, err := agent.ConfigureDevice(ctx, serverURL, apiKey)
			if err != nil {
				return fmt.Errorf("device configuration failed: %w", err)
			}

			fmt.Printf("Configured device %s (heartbeat %ds, posture %ds)\n",
				resp.DeviceID, resp.HeartbeatSeconds, resp.PostureSeconds)

			if noAutoUpdate {
				if err := persistAutoUpdate(dir, false); err != nil {
					return fmt.Errorf("cannot persist auto-update preference: %w", err)
				}

				fmt.Println("Auto-update disabled.")
			}

			if skipService {
				fmt.Println("Service installation skipped (--skip-service).")
				return nil
			}

			exePath, err := os.Executable()
			if err != nil {
				return fmt.Errorf("cannot resolve current executable path: %w", err)
			}

			if err := service.Install(
				service.Config{
					ExePath: exePath,
					Dir:     dir,
				},
			); err != nil {
				return clearEnrollmentMarkerOnSetupFailure(
					dir,
					fmt.Errorf("cannot install OS service: %w", err),
				)
			}

			fmt.Println("Service installed and started.")

			if err := registerTrayAutoStart(exePath, deviceagent.EnrollmentRunDir(dir)); err != nil {
				return clearEnrollmentMarkerOnSetupFailure(dir, err)
			}

			return nil
		},
	}

	cmd.Flags().StringVar(&serverURL, "server", "", "Probo server base URL (e.g. https://your-probo-host.example.com)")
	cmd.Flags().StringVar(&enrollmentToken, "enrollment-token", "", "one-shot enrollment token issued when the device was created")
	cmd.Flags().BoolVar(&skipService, "skip-service", false, "register the device but do not install the OS service")
	cmd.Flags().BoolVar(&noAutoUpdate, "no-auto-update", false, "disable automatic upgrades of the agent binary")

	return cmd
}

// clearEnrollmentMarkerOnSetupFailure drops the public enrollment marker
// so a later install can retry service/tray setup after ConfigureDevice
// already succeeded. Credentials, config, and any already-installed OS
// service are left in place; service.Install is idempotent on retry.
func clearEnrollmentMarkerOnSetupFailure(dir string, setupErr error) error {
	if clearErr := deviceagent.ClearEnrollmentMarker(deviceagent.EnrollmentRunDir(dir)); clearErr != nil {
		return fmt.Errorf("%w (also cannot clear enrollment marker: %v)", setupErr, clearErr)
	}

	return setupErr
}

// persistAutoUpdate flips the UpdatesDisabled flag in the agent's
// on-disk config without disturbing other fields.
func persistAutoUpdate(dir string, enabled bool) error {
	cfg, err := deviceagent.LoadConfig(dir)
	if err != nil {
		return err
	}

	cfg.UpdatesDisabled = !enabled

	return deviceagent.SaveConfig(dir, cfg)
}

func newUninstallCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "uninstall",
		Short: "Stop the service, unenroll this device, and remove local state",
		RunE: func(cmd *cobra.Command, args []string) error {
			dir := resolveDir(cmd)

			if runtime.GOOS == "darwin" && os.Geteuid() != 0 {
				return errors.New("macOS uninstall requires root; re-run as: sudo probo-agent uninstall")
			}

			ctx, cancel := context.WithTimeout(cmd.Context(), 30*time.Second)
			defer cancel()

			agent := deviceagent.New(dir, version, newAgentLogger())
			if err := agent.Unenroll(ctx); err != nil {
				fmt.Fprintf(os.Stderr, "warning: unenroll failed: %v\n", err)
			}

			if err := service.Uninstall(service.Config{Dir: dir}); err != nil {
				fmt.Fprintf(os.Stderr, "warning: service uninstall failed: %v\n", err)
			}

			if err := tray.UnregisterAutoStart(); err != nil {
				fmt.Fprintf(os.Stderr, "warning: tray uninstall failed: %v\n", err)
			}

			if err := deviceagent.RemoveLocalState(dir); err != nil {
				return fmt.Errorf("cannot remove agent state: %w", err)
			}

			fmt.Println("Uninstalled.")

			return nil
		},
	}
}

func newRunCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "run",
		Short: "Run the agent in the foreground (used by the OS service unit)",
		RunE: func(cmd *cobra.Command, args []string) error {
			dir := resolveDir(cmd)

			ctx, stop := signal.NotifyContext(cmd.Context(), syscall.SIGINT, syscall.SIGTERM)
			defer stop()

			logger := newAgentLogger()
			agent := deviceagent.New(dir, version, logger)
			agent.Updater = newUpdater(logger, dir)

			err := agent.Run(ctx)
			if errors.Is(err, context.Canceled) {
				return nil
			}

			return err
		},
	}
}

func newStatusCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "status",
		Short: "Print the agent's local state",
		RunE: func(cmd *cobra.Command, args []string) error {
			dir := resolveDir(cmd)

			cfg, err := deviceagent.LoadConfig(dir)
			if err != nil {
				return err
			}

			haveKey := true
			if _, err := deviceagent.LoadAPIKey(dir); err != nil {
				haveKey = false
			}

			fmt.Printf("Server URL:           %s\n", cfg.ServerURL)
			fmt.Printf("Device ID:            %s\n", cfg.DeviceID)
			fmt.Printf("Heartbeat interval:   %s\n", cfg.HeartbeatInterval)
			fmt.Printf("Posture interval:     %s\n", cfg.PostureInterval)
			fmt.Printf("Update interval:      %s\n", cfg.UpdateInterval)
			fmt.Printf("Auto-update enabled:  %v\n", !cfg.UpdatesDisabled)
			fmt.Printf("API key on disk:      %v\n", haveKey)
			fmt.Printf("Config directory:     %s\n", dir)

			return nil
		},
	}
}

func newCollectCmd() *cobra.Command {
	var (
		once     bool
		asJSON   bool
		printDir bool
	)

	cmd := &cobra.Command{
		Use:   "collect",
		Short: "Run the posture check set once and print results (no server push)",
		RunE: func(cmd *cobra.Command, args []string) error {
			dir := resolveDir(cmd)
			if printDir {
				fmt.Println(dir)
			}

			ctx, cancel := context.WithTimeout(cmd.Context(), 30*time.Second)
			defer cancel()

			agent := deviceagent.New(dir, version, newAgentLogger())
			results := agent.CollectOnce(ctx)

			if asJSON {
				return json.NewEncoder(os.Stdout).Encode(results)
			}

			for _, r := range results {
				fmt.Printf("%-20s %-15s %v\n", r.CheckKey, r.Status, r.Evidence)
			}

			return nil
		},
	}
	cmd.Flags().BoolVar(&once, "once", true, "(default true) run the check set once and exit")
	cmd.Flags().BoolVar(&asJSON, "json", false, "emit JSON instead of the human-readable table")
	cmd.Flags().BoolVar(&printDir, "print-dir", false, "print the resolved agent dir before the results")

	return cmd
}

func newUpdateCmd() *cobra.Command {
	var checkOnly bool

	cmd := &cobra.Command{
		Use:   "update",
		Short: "Check GitHub for a newer agent release and install it in place",
		RunE: func(cmd *cobra.Command, args []string) error {
			dir := resolveDir(cmd)
			logger := newAgentLogger()

			updater := newUpdater(logger, dir)
			if updater == nil {
				return errors.New("cannot resolve current executable path")
			}

			ctx, cancel := context.WithTimeout(cmd.Context(), 10*time.Minute)
			defer cancel()

			rel, err := updater.CheckLatest(ctx)
			if err != nil {
				if errors.Is(err, update.ErrNoUpdateAvailable) {
					fmt.Printf("probo-agent is up to date (version %s).\n", version)
					return nil
				}

				return fmt.Errorf("cannot check for updates: %w", err)
			}

			fmt.Printf("Update available: %s -> %s\n", version, rel.Version)

			if checkOnly {
				return nil
			}

			if err := updater.Apply(ctx, rel); err != nil {
				return fmt.Errorf("cannot apply update: %w", err)
			}

			fmt.Printf("Installed probo-agent %s. Restart the service to use it.\n", rel.Version)

			return nil
		},
	}

	cmd.Flags().BoolVar(&checkOnly, "check", false, "only print the available version, do not install it")

	return cmd
}