import asyncio
import serial_asyncio
import struct
import os
import sys
import serial
import signal
import traceback
from pymavlink import mavutil

# === 設定區 ===
SERIAL_PORT = 'COM15'  # 手動指定
SERIAL_BAUDRATE = 57600
UDP_REMOTE_IP = '127.0.0.1'
UDP_REMOTE_PORT = 14550
DEBUG_MODE = False
TARGET_ADDR64 = b'\x00\x00\x00\x00\x00\x00\xFF\xFF'  # 廣播

# === 工具函數 ===
def check_serial_port():
    try:
        ser = serial.Serial(SERIAL_PORT, SERIAL_BAUDRATE)
        ser.close()
        return True
    except serial.SerialException as e:
        print(f"錯誤：串口設備 {SERIAL_PORT} 被占用或無法訪問：{str(e)}")
        return False
    except Exception as e:
        print(f"錯誤：檢查串口時發生未知錯誤：{str(e)}")
        return False

def build_api_tx_frame(data: bytes, dest_addr64: bytes, frame_id=0x01) -> bytes:
    frame_type = 0x10
    dest_addr16 = b'\xFF\xFE'
    broadcast_radius = 0x00
    options = 0x00

    frame = struct.pack(">B", frame_type) + struct.pack(">B", frame_id)
    frame += dest_addr64 + dest_addr16
    frame += struct.pack(">BB", broadcast_radius, options) + data
    checksum = 0xFF - (sum(frame) & 0xFF)
    return b'\x7E' + struct.pack(">H", len(frame)) + frame + struct.pack("B", checksum)

# === Serial Protocol 實作 ===
class SerialToUDP(asyncio.Protocol):
    def __init__(self, udp_protocol):
        self.udp_protocol = udp_protocol
        self.buffer = bytearray()

    def connection_made(self, transport):
        self.transport = transport
        if hasattr(self.udp_protocol, 'set_serial_transport'):
            self.udp_protocol.set_serial_transport(self)
        print(f"Serial connection established on {SERIAL_PORT}")

    def data_received(self, data):
        self.buffer.extend(data)
        while True:
            if len(self.buffer) < 3:
                return
            if self.buffer[0] != 0x7E:
                self.buffer.pop(0)
                continue
            length = (self.buffer[1] << 8) | self.buffer[2]
            full_length = 3 + length + 1
            if len(self.buffer) < full_length:
                return
            frame = self.buffer[:full_length]
            del self.buffer[:full_length]
            if hasattr(self.udp_protocol, 'send_udp'):
                self.udp_protocol.send_udp(bytes(frame))

    def write_to_serial(self, data):
        try:
            api_frame = build_api_tx_frame(data, TARGET_ADDR64)
            pass
            self.transport.write(api_frame)
        except Exception as e:
            print(f"[TX Error] 無法封裝或傳送資料: {e}")

# === UDP Protocol 實作 ===
class UDPHandler(asyncio.DatagramProtocol):
    def __init__(self):
        self.serial_transport = None
        self.transport = None
        self.mav_decoder = mavutil.mavlink.MAVLink(None)

    def connection_made(self, transport):
        self.transport = transport
        print("UDP transport ready.")

    def set_serial_transport(self, serial_transport):
        self.serial_transport = serial_transport

    def datagram_received(self, data, addr):
        if self.serial_transport:
            self.serial_transport.write_to_serial(data)

    def send_udp(self, data):
        decoded_data = self.decapsulate_data(data)
        if decoded_data is None:
            pass
            return
        self.decode_mavlink_data(decoded_data)
        if self.transport:
            self.transport.sendto(decoded_data, (UDP_REMOTE_IP, UDP_REMOTE_PORT))

    def decapsulate_data(self, data):
        try:
            if not data or data[0] != 0x7E:
                return None
            length = (data[1] << 8) | data[2]
            if len(data) < length + 4:
                return None
            frame_type = data[3]
            if frame_type == 0x90:
                rf_data_start = 3 + 12
                return data[rf_data_start:3 + length]
            else:
                return None
        except Exception as e:
            print(f"[XBee 解封錯誤] {e}")
            return None

    def decode_mavlink_data(self, data):
        try:
            msg = self.mav_decoder.parse_char(data)
            if msg:
                if msg.get_type() == "HEARTBEAT":
                    pass  # 不輸出任何訊息
                else:
                    pass
        except Exception as e:
            print(f"[MAVLink Decode Error] {e}")

# === 主流程 ===
async def main():
    if not check_serial_port():
        print("程式終止：串口檢查失敗")
        return

    loop = asyncio.get_running_loop()
    if os.name != 'nt':  # Windows 不支援 add_signal_handler
        for sig in (signal.SIGINT, signal.SIGTERM):
            loop.add_signal_handler(sig, lambda: asyncio.create_task(shutdown(loop)))

    udp_handler = UDPHandler()

    try:
        udp_transport, _ = await loop.create_datagram_endpoint(
            lambda: udp_handler,
            local_addr=('0.0.0.0', 0)
        )
    except Exception as e:
        print(f"無法創建 UDP 端點：{str(e)}")
        return

    sock = udp_transport.get_extra_info('socket')
    print(f"UDP listening on {sock.getsockname()}")

    try:
        serial_proto = SerialToUDP(udp_handler)
        await serial_asyncio.create_serial_connection(
            loop, lambda: serial_proto, SERIAL_PORT, baudrate=SERIAL_BAUDRATE
        )
    except Exception as e:
        print(f"無法建立串口連接：{str(e)}")
        traceback.print_exc()
        udp_transport.close()
        return

    print("等待串口資料...")
    try:
        await asyncio.Future()
    except asyncio.CancelledError:
        pass

async def shutdown(loop):
    print("Shutting down...")
    tasks = [t for t in asyncio.all_tasks() if t is not asyncio.current_task()]
    for task in tasks:
        task.cancel()
    await asyncio.gather(*tasks, return_exceptions=True)
    loop.stop()

if __name__ == '__main__':
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        print("程式被使用者中斷")
    except Exception as e:
        print("程式執行錯誤：")
        traceback.print_exc()