package client

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"net/url"
	"sync"
	"time"

	"github.com/duffy/usb-server/internal/config"
	"github.com/duffy/usb-server/internal/protocol"
	"github.com/google/uuid"
	"github.com/gorilla/websocket"
)

// Client manages the connection to the relay server
type Client struct {
	cfg      *config.Config
	clientID string
	conn     *websocket.Conn
	mu       sync.Mutex

	// Event callbacks
	OnDeviceList    func(msg *protocol.DeviceList)
	OnDeviceGranted func(msg *protocol.DeviceGranted)
	OnDeviceDenied  func(msg *protocol.DeviceDenied)
	OnDeviceReleased func(msg *protocol.DeviceReleased)
	OnClientJoined  func(msg *protocol.ClientJoined)
	OnClientLeft    func(msg *protocol.ClientLeft)
	OnRequestDevice func(targetClient, fromClient, busID, requestID string)
	OnReleaseDevice func(busID, fromClient string)
	OnTunnelData    func(tunnelID string, data []byte)

	ctx    context.Context
	cancel context.CancelFunc
}

// NewClient creates a new client instance
func NewClient(cfg *config.Config) *Client {
	ctx, cancel := context.WithCancel(context.Background())
	return &Client{
		cfg:      cfg,
		clientID: uuid.New().String(),
		ctx:      ctx,
		cancel:   cancel,
	}
}

// ID returns the client ID
func (c *Client) ID() string {
	return c.clientID
}

// Config returns the client config
func (c *Client) Config() *config.Config {
	return c.cfg
}

// Connect establishes connection to the relay server
func (c *Client) Connect() error {
	u, err := url.Parse(c.cfg.RelayAddr)
	if err != nil {
		return fmt.Errorf("invalid relay address: %w", err)
	}

	// Ensure WebSocket scheme
	switch u.Scheme {
	case "ws", "wss":
		// ok
	case "http":
		u.Scheme = "ws"
	case "https":
		u.Scheme = "wss"
	default:
		u.Scheme = "ws"
	}

	if u.Path == "" {
		u.Path = "/ws"
	}

	log.Printf("[client] connecting to %s", u.String())

	conn, _, err := websocket.DefaultDialer.Dial(u.String(), nil)
	if err != nil {
		return fmt.Errorf("connecting to relay: %w", err)
	}

	c.mu.Lock()
	c.conn = conn
	c.mu.Unlock()

	// Send registration
	reg := &protocol.Register{
		Type:     protocol.MsgRegister,
		Hash:     c.cfg.Hash,
		Mode:     c.cfg.Mode,
		ClientID: c.clientID,
		Name:     c.cfg.Name,
	}

	if err := conn.WriteJSON(reg); err != nil {
		conn.Close()
		return fmt.Errorf("sending registration: %w", err)
	}

	log.Printf("[client] registered as %s (mode=%s, name=%s)", c.clientID, c.cfg.Mode, c.cfg.Name)

	return nil
}

// RunReadLoop reads messages from the relay and dispatches them
func (c *Client) RunReadLoop() error {
	for {
		select {
		case <-c.ctx.Done():
			return nil
		default:
		}

		msgType, data, err := c.conn.ReadMessage()
		if err != nil {
			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseNormalClosure) {
				return fmt.Errorf("read error: %w", err)
			}
			return nil
		}

		switch msgType {
		case websocket.TextMessage:
			c.handleTextMessage(data)
		case websocket.BinaryMessage:
			c.handleBinaryMessage(data)
		}
	}
}

// Run connects and runs the main loop with auto-reconnect
func (c *Client) Run() error {
	for {
		if err := c.Connect(); err != nil {
			log.Printf("[client] connection failed: %v, retrying in 5s...", err)
			select {
			case <-time.After(5 * time.Second):
				continue
			case <-c.ctx.Done():
				return nil
			}
		}

		err := c.RunReadLoop()
		if err != nil {
			log.Printf("[client] disconnected: %v, reconnecting in 5s...", err)
		} else {
			log.Printf("[client] disconnected, reconnecting in 5s...")
		}

		c.mu.Lock()
		if c.conn != nil {
			c.conn.Close()
			c.conn = nil
		}
		c.mu.Unlock()

		select {
		case <-time.After(5 * time.Second):
		case <-c.ctx.Done():
			return nil
		}
	}
}

// Close shuts down the client
func (c *Client) Close() {
	c.cancel()
	c.mu.Lock()
	if c.conn != nil {
		c.conn.Close()
	}
	c.mu.Unlock()
}

// SendJSON sends a JSON message to the relay
func (c *Client) SendJSON(v interface{}) error {
	c.mu.Lock()
	defer c.mu.Unlock()
	if c.conn == nil {
		return fmt.Errorf("not connected")
	}
	return c.conn.WriteJSON(v)
}

// SendBinary sends a binary message to the relay
func (c *Client) SendBinary(data []byte) error {
	c.mu.Lock()
	defer c.mu.Unlock()
	if c.conn == nil {
		return fmt.Errorf("not connected")
	}
	return c.conn.WriteMessage(websocket.BinaryMessage, data)
}

// SendTunnelData sends tunnel data with the tunnel ID prefix
func (c *Client) SendTunnelData(tunnelID string, data []byte) error {
	// Tunnel header: 16 bytes tunnel ID + payload
	msg := make([]byte, protocol.TunnelHeaderSize+len(data))
	copy(msg[:protocol.TunnelHeaderSize], tunnelID)
	copy(msg[protocol.TunnelHeaderSize:], data)
	return c.SendBinary(msg)
}

func (c *Client) handleTextMessage(data []byte) {
	var env protocol.Envelope
	if err := json.Unmarshal(data, &env); err != nil {
		return
	}

	switch env.Type {
	case protocol.MsgDeviceList:
		if c.OnDeviceList != nil {
			var msg protocol.DeviceList
			if json.Unmarshal(data, &msg) == nil {
				c.OnDeviceList(&msg)
			}
		}

	case protocol.MsgRequestDevice:
		if c.OnRequestDevice != nil {
			var msg struct {
				TargetClient string `json:"target_client"`
				FromClient   string `json:"from_client"`
				BusID        string `json:"bus_id"`
				RequestID    string `json:"request_id"`
			}
			if json.Unmarshal(data, &msg) == nil {
				c.OnRequestDevice(msg.TargetClient, msg.FromClient, msg.BusID, msg.RequestID)
			}
		}

	case protocol.MsgDeviceGranted:
		if c.OnDeviceGranted != nil {
			var msg protocol.DeviceGranted
			if json.Unmarshal(data, &msg) == nil {
				c.OnDeviceGranted(&msg)
			}
		}

	case protocol.MsgDeviceDenied:
		if c.OnDeviceDenied != nil {
			var msg protocol.DeviceDenied
			if json.Unmarshal(data, &msg) == nil {
				c.OnDeviceDenied(&msg)
			}
		}

	case protocol.MsgReleaseDevice:
		if c.OnReleaseDevice != nil {
			var msg struct {
				BusID      string `json:"bus_id"`
				FromClient string `json:"from_client"`
			}
			if json.Unmarshal(data, &msg) == nil {
				c.OnReleaseDevice(msg.BusID, msg.FromClient)
			}
		}

	case protocol.MsgDeviceReleased:
		if c.OnDeviceReleased != nil {
			var msg protocol.DeviceReleased
			if json.Unmarshal(data, &msg) == nil {
				c.OnDeviceReleased(&msg)
			}
		}

	case protocol.MsgClientJoined:
		if c.OnClientJoined != nil {
			var msg protocol.ClientJoined
			if json.Unmarshal(data, &msg) == nil {
				c.OnClientJoined(&msg)
			}
		}

	case protocol.MsgClientLeft:
		if c.OnClientLeft != nil {
			var msg protocol.ClientLeft
			if json.Unmarshal(data, &msg) == nil {
				c.OnClientLeft(&msg)
			}
		}

	case protocol.MsgPong:
		// ignore pong

	case protocol.MsgError:
		var msg protocol.ErrorMsg
		if json.Unmarshal(data, &msg) == nil {
			log.Printf("[client] error from relay: %s", msg.Message)
		}
	}
}

func (c *Client) handleBinaryMessage(data []byte) {
	if len(data) < protocol.TunnelHeaderSize {
		return
	}

	tunnelID := string(data[:protocol.TunnelHeaderSize])
	payload := data[protocol.TunnelHeaderSize:]

	if c.OnTunnelData != nil {
		c.OnTunnelData(tunnelID, payload)
	}
}