"""Entry point to set up a temperature logging daemon."""

import argparse
import enum
import signal
import threading
import time
import typing as t

import attr
import toml

from . import http_writer
from . import logger
from . import reader

DEFAULT_INTERVAL_SECS = 60
MIN_INTERVAL_SECS = 5


def run(
    rd: reader.Reader,
    log: logger.BufferedLogger,
    writer: logger.RemoteWriter,
    interval: int = DEFAULT_INTERVAL_SECS,
) -> None:
    """Sets up and runs a logger daemon."""
    evt = threading.Event()
    signal.signal(signal.SIGTERM, lambda *args: evt.set())
    cycle = 0
    start = time.time()
    running = True
    log.start()
    try:
        while running:
            log.write(rd.read().as_dict())
            cycle += 1
            target = start + interval * cycle
            now = time.time()
            running = not evt.wait(max(target - now, MIN_INTERVAL_SECS))
    finally:
        log.close()


class SensorType(enum.Enum):
    BME280 = 'BME280'


_SENSOR_FACTORIES = {
    SensorType.BME280: reader.BME280Reader,
}


@attr.s(auto_attribs=True, frozen=True, slots=True)
class _Config:
    # The directory to store reading data in.
    directory: str
    # The URL to submit readings to.
    url: str
    # The type of sensor to read from.
    sensor: SensorType
    # The authentication preamble for the URL.
    auth: t.Dict[str, object]


def parse_config(config_file: str) -> _Config:
    with open(config_file, 'r') as infile:
        config = toml.load(infile)
    return _Config(
        directory=config['directory'],
        url=config['url'],
        sensor=SensorType(config['sensor']['type']),
        auth=config['auth'])


def main(args: t.Optional[t.Sequence[str]] = None) -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument('config_file', help='TOML file to load config from.')
    parsed = parser.parse_args(args)
    config = parse_config(parsed.config_file)
    writer = http_writer.HTTPWriter(config.url, config.auth)
    log = logger.BufferedLogger(config.directory, writer)

    try:
        factory = _SENSOR_FACTORIES[config.sensor]
    except KeyError:
        print(f'Invalid sensor type {config.sensor}.')
    rdr = factory()
    run(rdr, log, writer)


if __name__ == '__main__':
    main()