package app

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"runtime"
	"time"

	"github.com/nats-io/nats.go"
	"github.com/vigilcyber/corrosion-companion/internal/files"
	"github.com/vigilcyber/corrosion-companion/internal/process"
	"github.com/vigilcyber/corrosion-companion/internal/update"
)

// DaemonConfig holds configuration for the daemon
type DaemonConfig struct {
	LicenseID         string
	HeartbeatInterval time.Duration
	SteamCMDPath      string
	GameServerPath    string
	GameServerArgs    string
	Version           string
}

// Daemon manages the companion agent's main operations
type Daemon struct {
	nc            *nats.Conn
	cfg           *DaemonConfig
	gameServer    *process.GameServer
	fileOps       *files.Operations
	updater       *update.Updater
	subscriptions []*nats.Subscription
}

// HeartbeatPayload represents the data sent in heartbeat messages
type HeartbeatPayload struct {
	Timestamp      string  `json:"timestamp"`
	Status         string  `json:"status"`
	ServerStatus   string  `json:"server_status"`
	UptimeSeconds  int64   `json:"uptime_seconds"`
	DiskFreeMB     int64   `json:"disk_free_mb"`
	CPUPercent     float64 `json:"cpu_percent"`
	LastUpdate     string  `json:"last_update"`
	PlayerCount    int     `json:"player_count"`
	Version        string  `json:"version"`
	OS             string  `json:"os"`
	Arch           string  `json:"arch"`
}

// NewDaemon creates a new daemon instance
func NewDaemon(nc *nats.Conn, cfg *DaemonConfig) (*Daemon, error) {
	gameServer := process.NewGameServer(cfg.GameServerPath, cfg.GameServerArgs)
	fileOps := files.NewOperations()
	updater := update.NewUpdater(cfg.Version)

	d := &Daemon{
		nc:         nc,
		cfg:        cfg,
		gameServer: gameServer,
		fileOps:    fileOps,
		updater:    updater,
	}

	return d, nil
}

// Run starts the daemon and blocks until context is cancelled
func (d *Daemon) Run(ctx context.Context) error {
	log.Println("Starting daemon subscriptions...")

	// Subscribe to server control commands
	if err := d.subscribeServerCommands(); err != nil {
		return fmt.Errorf("failed to subscribe to server commands: %w", err)
	}

	// Subscribe to file operations
	if err := d.subscribeFileOperations(); err != nil {
		return fmt.Errorf("failed to subscribe to file operations: %w", err)
	}

	// Subscribe to SteamCMD update commands
	if err := d.subscribeSteamUpdate(); err != nil {
		return fmt.Errorf("failed to subscribe to steam updates: %w", err)
	}

	// Subscribe to self-update commands
	if err := d.subscribeSelfUpdate(); err != nil {
		return fmt.Errorf("failed to subscribe to self-update: %w", err)
	}

	log.Println("All subscriptions active")

	// Start heartbeat ticker
	ticker := time.NewTicker(d.cfg.HeartbeatInterval)
	defer ticker.Stop()

	// Send initial heartbeat immediately
	d.publishHeartbeat()

	// Main event loop
	for {
		select {
		case <-ctx.Done():
			log.Println("Shutdown signal received, cleaning up...")
			d.cleanup()
			return nil
		case <-ticker.C:
			d.publishHeartbeat()
		}
	}
}

// subscribeServerCommands subscribes to server process control commands
func (d *Daemon) subscribeServerCommands() error {
	subject := fmt.Sprintf("corrosion.%s.cmd.server", d.cfg.LicenseID)

	sub, err := d.nc.Subscribe(subject, func(msg *nats.Msg) {
		var cmd struct {
			Action string `json:"action"`
		}

		if err := json.Unmarshal(msg.Data, &cmd); err != nil {
			log.Printf("Failed to parse server command: %v", err)
			d.respondError(msg, "invalid_command", err.Error())
			return
		}

		log.Printf("Received server command: %s", cmd.Action)

		var err error
		switch cmd.Action {
		case "start":
			err = d.gameServer.Start()
		case "stop":
			err = d.gameServer.Stop()
		case "restart":
			err = d.gameServer.Restart()
		default:
			err = fmt.Errorf("unknown action: %s", cmd.Action)
		}

		if err != nil {
			log.Printf("Server command failed: %v", err)
			d.respondError(msg, "command_failed", err.Error())
		} else {
			d.respondSuccess(msg, map[string]interface{}{
				"action": cmd.Action,
				"status": "success",
			})
		}
	})

	if err != nil {
		return err
	}

	d.subscriptions = append(d.subscriptions, sub)
	log.Printf("Subscribed to: %s", subject)
	return nil
}

// subscribeFileOperations subscribes to file operation commands
func (d *Daemon) subscribeFileOperations() error {
	subjects := []string{
		fmt.Sprintf("corrosion.%s.files.get", d.cfg.LicenseID),
		fmt.Sprintf("corrosion.%s.files.put", d.cfg.LicenseID),
		fmt.Sprintf("corrosion.%s.files.delete", d.cfg.LicenseID),
		fmt.Sprintf("corrosion.%s.files.list", d.cfg.LicenseID),
	}

	for _, subject := range subjects {
		sub, err := d.nc.Subscribe(subject, func(msg *nats.Msg) {
			d.handleFileOperation(msg)
		})

		if err != nil {
			return err
		}

		d.subscriptions = append(d.subscriptions, sub)
		log.Printf("Subscribed to: %s", subject)
	}

	return nil
}

// subscribeSteamUpdate subscribes to SteamCMD update commands
func (d *Daemon) subscribeSteamUpdate() error {
	subject := fmt.Sprintf("corrosion.%s.update.steam", d.cfg.LicenseID)

	sub, err := d.nc.Subscribe(subject, func(msg *nats.Msg) {
		var cmd struct {
			Validate bool `json:"validate"`
		}

		if err := json.Unmarshal(msg.Data, &cmd); err != nil {
			log.Printf("Failed to parse steam update command: %v", err)
			d.respondError(msg, "invalid_command", err.Error())
			return
		}

		log.Printf("Received SteamCMD update command (validate=%v)", cmd.Validate)

		steamCmd := process.NewSteamCMD(d.cfg.SteamCMDPath)
		err := steamCmd.UpdateRustServer(cmd.Validate)

		if err != nil {
			log.Printf("SteamCMD update failed: %v", err)
			d.respondError(msg, "update_failed", err.Error())
		} else {
			d.respondSuccess(msg, map[string]interface{}{
				"status":   "success",
				"validate": cmd.Validate,
			})
		}
	})

	if err != nil {
		return err
	}

	d.subscriptions = append(d.subscriptions, sub)
	log.Printf("Subscribed to: %s", subject)
	return nil
}

// subscribeSelfUpdate subscribes to companion agent self-update commands
func (d *Daemon) subscribeSelfUpdate() error {
	subject := fmt.Sprintf("corrosion.%s.update.companion", d.cfg.LicenseID)

	sub, err := d.nc.Subscribe(subject, func(msg *nats.Msg) {
		var cmd struct {
			DownloadURL string `json:"download_url"`
			Version     string `json:"version"`
		}

		if err := json.Unmarshal(msg.Data, &cmd); err != nil {
			log.Printf("Failed to parse self-update command: %v", err)
			d.respondError(msg, "invalid_command", err.Error())
			return
		}

		log.Printf("Received self-update command: version=%s", cmd.Version)

		err := d.updater.PerformUpdate(cmd.DownloadURL, cmd.Version)

		if err != nil {
			log.Printf("Self-update failed: %v", err)
			d.respondError(msg, "update_failed", err.Error())
		} else {
			d.respondSuccess(msg, map[string]interface{}{
				"status":  "success",
				"version": cmd.Version,
				"message": "Update downloaded, restart required",
			})
		}
	})

	if err != nil {
		return err
	}

	d.subscriptions = append(d.subscriptions, sub)
	log.Printf("Subscribed to: %s", subject)
	return nil
}

// handleFileOperation processes file operation requests
func (d *Daemon) handleFileOperation(msg *nats.Msg) {
	// Parse common fields
	var baseCmd struct {
		RequestID   string `json:"request_id"`
		Path        string `json:"path"`
		DownloadURL string `json:"download_url,omitempty"` // For put operations
	}

	if err := json.Unmarshal(msg.Data, &baseCmd); err != nil {
		log.Printf("Failed to parse file operation: %v", err)
		d.respondError(msg, "invalid_command", err.Error())
		return
	}

	var result interface{}
	var err error

	// Determine operation type from subject
	if contains(msg.Subject, ".files.get") {
		result, err = d.fileOps.Read(baseCmd.Path)
	} else if contains(msg.Subject, ".files.put") {
		err = d.fileOps.Write(baseCmd.Path, baseCmd.DownloadURL)
		result = map[string]string{"status": "written"}
	} else if contains(msg.Subject, ".files.delete") {
		err = d.fileOps.Delete(baseCmd.Path)
		result = map[string]string{"status": "deleted"}
	} else if contains(msg.Subject, ".files.list") {
		result, err = d.fileOps.List(baseCmd.Path)
	}

	responseSubject := fmt.Sprintf("corrosion.%s.files.response", d.cfg.LicenseID)

	if err != nil {
		log.Printf("File operation failed: %v", err)
		d.publishResponse(responseSubject, map[string]interface{}{
			"request_id": baseCmd.RequestID,
			"status":     "error",
			"error":      err.Error(),
		})
	} else {
		d.publishResponse(responseSubject, map[string]interface{}{
			"request_id": baseCmd.RequestID,
			"status":     "success",
			"data":       result,
		})
	}
}

// publishHeartbeat sends a heartbeat message to the cloud
func (d *Daemon) publishHeartbeat() {
	subject := fmt.Sprintf("corrosion.%s.companion.heartbeat", d.cfg.LicenseID)

	status := d.gameServer.Status()
	uptime := d.gameServer.Uptime()
	diskFree := getDiskFreeSpace(d.cfg.GameServerPath)

	payload := HeartbeatPayload{
		Timestamp:     time.Now().UTC().Format(time.RFC3339),
		Status:        "running",
		ServerStatus:  status,
		UptimeSeconds: int64(uptime.Seconds()),
		DiskFreeMB:    diskFree,
		CPUPercent:    0.0, // TODO: Implement CPU monitoring
		LastUpdate:    "", // TODO: Track last SteamCMD update
		PlayerCount:   0,  // Populated by plugin, not companion
		Version:       d.cfg.Version,
		OS:            runtime.GOOS,
		Arch:          runtime.GOARCH,
	}

	data, err := json.Marshal(payload)
	if err != nil {
		log.Printf("Failed to marshal heartbeat: %v", err)
		return
	}

	if err := d.nc.Publish(subject, data); err != nil {
		log.Printf("Failed to publish heartbeat: %v", err)
	}
}

// respondError sends an error response to a command
func (d *Daemon) respondError(msg *nats.Msg, code, message string) {
	response := map[string]interface{}{
		"status":  "error",
		"code":    code,
		"message": message,
	}

	data, _ := json.Marshal(response)
	if err := msg.Respond(data); err != nil {
		log.Printf("Failed to send error response: %v", err)
	}
}

// respondSuccess sends a success response to a command
func (d *Daemon) respondSuccess(msg *nats.Msg, payload interface{}) {
	data, _ := json.Marshal(payload)
	if err := msg.Respond(data); err != nil {
		log.Printf("Failed to send success response: %v", err)
	}
}

// publishResponse publishes a response to a specific subject
func (d *Daemon) publishResponse(subject string, payload interface{}) {
	data, _ := json.Marshal(payload)
	if err := d.nc.Publish(subject, data); err != nil {
		log.Printf("Failed to publish response: %v", err)
	}
}

// cleanup gracefully shuts down all daemon operations
func (d *Daemon) cleanup() {
	log.Println("Unsubscribing from all subjects...")
	for _, sub := range d.subscriptions {
		sub.Unsubscribe()
	}

	log.Println("Draining NATS connection...")
	d.nc.Drain()

	log.Println("Cleanup complete")
}

// Helper functions

func contains(s, substr string) bool {
	return len(s) >= len(substr) && s[len(s)-len(substr):] == substr ||
		   (len(s) > len(substr) && s[0:len(substr)] == substr) ||
		   (len(s) > 0 && len(substr) > 0 && findInString(s, substr))
}

func findInString(s, substr string) bool {
	for i := 0; i <= len(s)-len(substr); i++ {
		if s[i:i+len(substr)] == substr {
			return true
		}
	}
	return false
}

func getDiskFreeSpace(path string) int64 {
	// TODO: Implement actual disk space check
	// For now, return placeholder
	return 50000
}