srne-mqtt/srnemqtt/lib/feasycom_ble.py

# -*- coding: utf-8 -*-
import io
import queue
import time
from typing import TYPE_CHECKING, Optional, cast

from bluepy import btle

if TYPE_CHECKING:
    from _typeshed import ReadableBuffer, WriteableBuffer


WRITE_DEVICE = "0000ffd1-0000-1000-8000-00805f9b34fb"
READ_DEVICE = "0000fff1-0000-1000-8000-00805f9b34fb"


class BTLEUart(io.RawIOBase):
    mac: str
    write_endpoint: str
    read_endpoint: str
    timeout: float

    device: Optional[btle.Peripheral] = None
    _write_handle: Optional[btle.Characteristic] = None
    _read_handle: Optional[btle.Characteristic] = None
    delegate: "_QueueDelegate"
    _read_buffer: bytearray

    class _QueueDelegate(btle.DefaultDelegate):
        queue: queue.Queue
        handle: Optional[int]

        def __init__(self, queue, handle=None):
            self.queue = queue
            self.handle = handle

        def handleNotification(self, cHandle: int, data: bytes):
            # print("Notification:", cHandle, "sent data", binascii.b2a_hex(data))

            if self.handle is not None and cHandle != self.handle:
                return

            self.queue.put(data)

    def __init__(
        self,
        mac: str,
        write_endpoint: str = WRITE_DEVICE,
        read_endpoint: str = READ_DEVICE,
        timeout: float = 30,
    ):
        self.mac = mac
        self.write_endpoint = write_endpoint
        self.read_endpoint = read_endpoint
        self.timeout = timeout

        self.delegate = self._QueueDelegate(queue.Queue())
        self._read_buffer = bytearray()

        self._connect()

    def _ensure_connected(self):
        if self.device is None:
            self._connect()

    def _poll(self, timeout: float = 0.0001):
        self._ensure_connected()
        if TYPE_CHECKING:
            self.device = cast(btle.Peripheral, self.device)

        start = time.time()
        left = timeout - (time.time() - start)
        while self.device.waitForNotifications(max(left, 0) or 0.0001):
            left = timeout - (time.time() - start)
            if left < 0:
                break

    def _connect(self):
        try:
            del self.device
        except Exception:
            pass
        self.device = btle.Peripheral(self.mac).withDelegate(self.delegate)
        self._read_handle = self.device.getCharacteristics(uuid=self.read_endpoint)[0]
        # self.delegate.handle = self._read_handle.handle
        self._write_handle = self.device.getCharacteristics(uuid=self.write_endpoint)[0]
        # print("Handles:", self._read_handle.handle, self._write_handle.handle)

    def _read(self, num: Optional[int] = None, timeout: Optional[float] = None):
        self._ensure_connected()
        if TYPE_CHECKING:
            self.device = cast(btle.Peripheral, self.device)

        if timeout is None:
            timeout = self.timeout

        if num is None:
            start = time.time()
            while not len(self._read_buffer):
                left = timeout - (time.time() - start)
                if left < 0:
                    break
                self._poll()
                try:
                    self._read_buffer.extend(self.delegate.queue.get_nowait())
                except queue.Empty:
                    pass
            try:
                while True:
                    self._poll()
                    self._read_buffer.extend(self.delegate.queue.get_nowait())

            except queue.Empty:
                pass
        else:
            start = time.time()
            while len(self._read_buffer) < num:
                left = timeout - (time.time() - start)
                if left < 0:
                    break
                self._poll()
                try:
                    self._read_buffer.extend(self.delegate.queue.get_nowait())
                except queue.Empty:
                    pass

        if num is None:
            data = bytes(self._read_buffer.copy())
            self._read_buffer.clear()
        else:
            data = bytes(self._read_buffer[:num])
            del self._read_buffer[:num]
        return data or None

    def readinto(self, buffer: "WriteableBuffer") -> Optional[int]:
        data = self._read(len(buffer))

        if data is None:
            return None

        buffer[: len(data)] = data
        return len(data)

    def readall(self) -> bytes:
        return self._read()

    def read(
        self, size: Optional[int] = None, timeout: Optional[float] = None
    ) -> Optional[bytes]:
        if timeout:
            _timeout = self.timeout
            self.timeout = timeout

        if size is None:
            res = super().read()
        else:
            res = super().read(size)

        if timeout:
            self.timeout = _timeout
        return res

    def write(self, b: "ReadableBuffer") -> Optional[int]:
        self._ensure_connected()
        if TYPE_CHECKING:
            self.device = cast(btle.Peripheral, self.device)

        if self._write_handle is None:
            raise IOError("write_handle not open")
        self._write_handle.write(b, withResponse=True)
        return len(b)

    def __enter__(self):
        return self

    def __exit__(self, type, value, traceback):
        self.device.disconnect()
        del self.device

    def seekable(self) -> bool:
        return False

    def readable(self) -> bool:
        return True

    def writable(self) -> bool:
        return True