import asyncio
import json
import logging

class CommandError(Exception):
    pass

class Client:
    def __init__(self):
        self._reader = None
        self._writer = None
        self._command_lock = asyncio.Lock()

    async def connect(self, host='192.168.1.26', port=23, timeout=None):
        self._reader, self._writer = await asyncio.open_connection(host, port)
        await self._check_zero_limits()

    async def disconnect(self):
        self._writer.close()
        await self._writer.wait_closed()

    async def _check_zero_limits(self):
        pwm_report = await self.get_pwm()
        for pwm_channel in pwm_report:
            for limit in ["max_i_neg", "max_i_pos", "max_v"]:
                if pwm_channel[limit]["value"] == 0.0:
                    logging.warning("`{}` limit is set to zero on channel {}".format(limit, pwm_channel["channel"]))

    async def _read_line(self):
        # read 1 line
        chunk = await self._reader.readline()
        return chunk.decode('utf-8', errors='ignore')

    async def _command(self, *command):
        async with self._command_lock:
            self._writer.write(((" ".join(command)).strip() + "\n").encode('utf-8'))
            await self._writer.drain()

            line = await self._read_line()

        response = json.loads(line)
        logging.debug(f"{command}: {response}")
        if "error" in response:
            raise CommandError(response["error"])
        return response

    async def _get_conf(self, topic):
        result = [None, None]
        for item in await self._command(topic):
            result[int(item["channel"])] = item
        return result

    async def get_pwm(self):
        """Retrieve PWM limits for the TEC

        Example::
            [{'channel': 0,
              'center': 'vref',
              'i_set': {'max': 2.9802790335151985, 'value': -0.02002179650216762},
              'max_i_neg': {'max': 3.0, 'value': 3.0},
              'max_v': {'max': 5.988, 'value': 5.988},
              'max_i_pos': {'max': 3.0, 'value': 3.0}},
             {'channel': 1,
              'center': 'vref',
              'i_set': {'max': 2.9802790335151985, 'value': -0.02002179650216762},
              'max_i_neg': {'max': 3.0, 'value': 3.0},
              'max_v': {'max': 5.988, 'value': 5.988},
              'max_i_pos': {'max': 3.0, 'value': 3.0}}
            ]
        """
        return await self._get_conf("pwm")

    async def get_pid(self):
        """Retrieve PID control state

        Example::
            [{'channel': 0,
              'parameters': {
                  'kp': 10.0,
                  'ki': 0.02,
                  'kd': 0.0,
                  'output_min': 0.0,
                  'output_max': 3.0},
              'target': 37.0},
             {'channel': 1,
              'parameters': {
                  'kp': 10.0,
                  'ki': 0.02,
                  'kd': 0.0,
                  'output_min': 0.0,
                  'output_max': 3.0},
              'target': 36.5}]
        """
        return await self._get_conf("pid")

    async def get_steinhart_hart(self):
        """Retrieve Steinhart-Hart parameters for resistance to temperature conversion

        Example::
            [{'params': {'b': 3800.0, 'r0': 10000.0, 't0': 298.15}, 'channel': 0},
             {'params': {'b': 3800.0, 'r0': 10000.0, 't0': 298.15}, 'channel': 1}]
        """
        return await self._get_conf("s-h")

    async def get_postfilter(self):
        """Retrieve DAC postfilter configuration

        Example::
            [{'rate': None, 'channel': 0},
             {'rate': 21.25, 'channel': 1}]
        """
        return await self._get_conf("postfilter")

    async def report_mode(self):
        """Start reporting measurement values

        Example of yielded data::
            {'channel': 0,
             'time': 2302524,
             'adc': 0.6199188965423515,
             'sens': 6138.519310282602,
             'temperature': 36.87032392655527,
             'pid_engaged': True,
             'i_set': 2.0635816680889123,
             'vref': 1.494,
             'dac_value': 2.527790834044456,
             'dac_feedback': 2.523,
             'i_tec': 2.331,
             'tec_i': 2.0925,
             'tec_u_meas': 2.5340000000000003,
             'pid_output': 2.067581958092247}
        """
        await self._command("report mode", "on")

        while True:
            line = await self._read_line()
            if not line:
                break
            try:
                yield json.loads(line)
            except json.decoder.JSONDecodeError:
                pass

    async def set_param(self, topic, channel, field="", value=""):
        """Set configuration parameters

        Examples::
            tec.set_param("pwm", 0, "max_v", 2.0)
            tec.set_param("pid", 1, "output_max", 2.5)
            tec.set_param("s-h", 0, "t0", 20.0)
            tec.set_param("center", 0, "vref")
            tec.set_param("postfilter", 1, 21)

        See the firmware's README.md for a full list.
        """
        if type(value) is float:
            value = "{:f}".format(value)
        if type(value) is not str:
            value = str(value)
        await self._command(topic, str(channel), field, value)

    async def power_up(self, channel, target):
        """Start closed-loop mode"""
        await self.set_param("pid", channel, "target", value=target)
        await self.set_param("pwm", channel, "pid")

    async def save_config(self):
        """Save current configuration to EEPROM"""
        await self._command("save")

    async def load_config(self):
        """Load current configuration from EEPROM"""
        await self._command("load")

    async def hw_rev(self):
        """Get Thermostat hardware revision"""
        return await self._command("hwrev")

    async def fan(self):
        """Get Thermostat current fan settings"""
        return await self._command("fan")