package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"log/slog"
	"os"
	"os/signal"
	"syscall"

	"gitea.dcglab.co.uk/steve/restic-manager/internal/agent/config"
	"gitea.dcglab.co.uk/steve/restic-manager/internal/agent/sysinfo"
	"gitea.dcglab.co.uk/steve/restic-manager/internal/agent/wsclient"
	"gitea.dcglab.co.uk/steve/restic-manager/internal/api"
)

var version = "dev"

func main() {
	if err := run(); err != nil {
		slog.Error("agent fatal", "err", err)
		os.Exit(1)
	}
}

func run() error {
	configPath := flag.String("config", config.DefaultPath(), "path to agent.yaml")
	enrollServer := flag.String("enroll-server", "", "server URL (used with -enroll-token to perform first-run enrollment)")
	enrollToken := flag.String("enroll-token", "", "one-time enrollment token (operator copies this from the UI)")
	showVersion := flag.Bool("version", false, "print version and exit")
	flag.Parse()

	if *showVersion {
		fmt.Println("restic-manager-agent", version)
		return nil
	}

	logger := slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelInfo}))
	slog.SetDefault(logger)

	cfg, err := config.Load(*configPath)
	if err != nil {
		return fmt.Errorf("config: %w", err)
	}

	// Enrollment mode: agent was started with -enroll-server -enroll-token.
	// On success we persist the credentials and exit (the install script
	// then starts the agent service). Avoiding a long-running process here
	// keeps the enrollment story restartable.
	if *enrollToken != "" {
		if *enrollServer == "" {
			return errors.New("enrollment: -enroll-server is required with -enroll-token")
		}
		return doEnroll(*enrollServer, *enrollToken, cfg, version)
	}

	if !cfg.Enrolled() {
		return fmt.Errorf("agent is not enrolled; run with -enroll-server and -enroll-token first (config %q)", *configPath)
	}

	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	snap, err := sysinfo.Collect(ctx, cfg.ResticPath)
	if err != nil {
		return fmt.Errorf("sysinfo: %w", err)
	}
	slog.Info("agent starting",
		"version", version,
		"host_id", cfg.HostID,
		"server", cfg.ServerURL,
		"restic_version", snap.ResticVersion,
		"protocol_version", snap.ProtocolVersion,
	)

	wsCfg := wsclient.Config{
		ServerURL:     cfg.ServerURL,
		AgentToken:    cfg.AgentToken,
		HostID:        cfg.HostID,
		CertPinSHA256: cfg.CertPinSHA256,
		HelloPayload: api.HelloPayload{
			ProtocolVersion: snap.ProtocolVersion,
			AgentVersion:    version,
			ResticVersion:   snap.ResticVersion,
			Hostname:        snap.Hostname,
			OS:              snap.OS,
			Arch:            snap.Arch,
		},
	}

	if err := wsclient.Run(ctx, wsCfg, dispatch); err != nil {
		return fmt.Errorf("ws run: %w", err)
	}
	slog.Info("agent shutting down")
	return nil
}

// dispatch handles server-pushed envelopes. Phase 1's first slice
// just logs; P1-19/20/21 wire command.run to the runner.
func dispatch(_ context.Context, env api.Envelope) error {
	switch env.Type {
	case api.MsgCommandRun:
		slog.Info("ws agent: command.run received (not yet implemented)", "id", env.ID)
	case api.MsgCommandCancel:
		slog.Info("ws agent: command.cancel received (not yet implemented)", "id", env.ID)
	case api.MsgScheduleSet:
		slog.Info("ws agent: schedule.set received (not yet implemented)", "id", env.ID)
	case api.MsgConfigUpdate:
		slog.Info("ws agent: config.update received (not yet implemented)", "id", env.ID)
	case api.MsgAgentUpdateAvail:
		slog.Info("ws agent: agent.update.available received (not yet implemented)", "id", env.ID)
	default:
		slog.Debug("ws agent: ignored message", "type", env.Type)
	}
	return nil
}

func doEnroll(serverURL, token string, cfg *config.Config, agentVersion string) error {
	ctx, cancel := context.WithTimeout(context.Background(), 60*1e9)
	defer cancel()

	snap, err := sysinfo.Collect(ctx, cfg.ResticPath)
	if err != nil {
		return fmt.Errorf("sysinfo: %w", err)
	}
	res, err := wsclient.Enroll(ctx, serverURL, wsclient.EnrollRequest{
		Token:         token,
		HostName:      snap.Hostname,
		OS:            snap.OS,
		Arch:          snap.Arch,
		AgentVersion:  agentVersion,
		ResticVersion: snap.ResticVersion,
	})
	if err != nil {
		return fmt.Errorf("enroll: %w", err)
	}
	cfg.ServerURL = serverURL
	cfg.HostID = res.HostID
	cfg.AgentToken = res.AgentToken
	cfg.CertPinSHA256 = res.CertPinSHA256
	if err := cfg.Save(); err != nil {
		return fmt.Errorf("save config: %w", err)
	}
	fmt.Fprintf(os.Stderr, "enrolled as host %s on %s\n", res.HostID, serverURL)
	return nil
}