#
# Copyright (c) 2020 Michael Büsch <m@bues.ch>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#

import bleak
import asyncio

def make_uuid16(uuid):
    return f"0000{uuid:04x}-0000-1000-8000-00805f9b34fb"

class EnvsensorsError(Exception):
    pass

class EnvsensorsClient(object):
    uuid_pres = make_uuid16(0x2A6D)
    uuid_temp = make_uuid16(0x2A6E)
    uuid_hum = make_uuid16(0x2A6F)
    uuid_str = make_uuid16(0x2A3D)

    @staticmethod
    async def discover():
        try:
            for dev in await bleak.discover():
                if dev.name == "envsensors":
                    yield dev.address
        except bleak.BleakError as e:
            raise EnvsensorsError(str(e))

    def __init__(self, address):
        try:
            self.__address = address
            self.__client = bleak.BleakClient(address)
        except bleak.BleakError as e:
            raise EnvsensorsError(str(e))

    async def __aenter__(self):
        try:
            await self.__client.connect()
            return self
        except bleak.BleakError as e:
            raise EnvsensorsError(str(e))

    async def __aexit__(self, exc_type, exc_value, traceback):
        try:
            await self.__client.disconnect()
        except bleak.BleakError as e:
            raise EnvsensorsError(str(e))

    async def __getAttrInt(self, uuid):
        try:
            return int.from_bytes(await self.__client.read_gatt_char(uuid), "little")
        except bleak.BleakError as e:
            raise EnvsensorsError(str(e))

    async def __getAttrStr(self, uuid):
        try:
            return (await self.__client.read_gatt_char(uuid)).decode("UTF-8", "ignore")
        except bleak.BleakError as e:
            raise EnvsensorsError(str(e))

    async def dump(self):
        ret = []
        ret.append(f"Device {self.__address}")
        ret.append(f"    Temperature {await self.__getAttrInt(self.uuid_temp) * 1e-2 :.1f} °C")
        ret.append(f"    Humidity {await self.__getAttrInt(self.uuid_hum) * 1e-2 :.1f} %")
        ret.append(f"    {await self.__getAttrStr(self.uuid_str)}")
        ret.append(f"    Pressure {await self.__getAttrInt(self.uuid_pres) * 1e-3 :.1f} mBar")
        return "\n".join(ret)

# vim: ts=4 sw=4 expandtab