import re
import time
from threading import Thread

from backend.a_backend import ABackend
from msg.container import MsgContainer

_FILENAME_RE = re.compile(r'\d{4}_\d{2}_\d{2}_\d{2}_\d{2}_\d{2}_(.+)\.log$')
_CHUNK = 64


def source_id_from_path(path: str) -> str | None:
    m = _FILENAME_RE.search(path)
    return m.group(1) if m else None


class FileBackend(ABackend):
    def __init__(self, files: list[str], delay: float = 1.0):
        self._delay = max(0.0, min(10.0, delay))
        self._entries = [{'path': p, 'source_id': source_id_from_path(p), 'xcvr': None, 'file': None, 'thread': None}
                         for p in files]
        self._running = False

    @property
    def delay(self) -> float:
        return self._delay

    @delay.setter
    def delay(self, value: float):
        self._delay = max(0.0, min(10.0, value))

    def register_xcvr(self, xcvr):
        for e in self._entries:
            if e['source_id'] == xcvr.name.strip():
                e['xcvr'] = xcvr
                xcvr.on_register(self)
                return
        raise Exception(f"No log file found for source \"{xcvr.name}\"")

    def connect(self):
        for e in self._entries:
            e['file'] = open(e['path'], 'rb')

    def start(self):
        self._running = True
        for e in self._entries:
            e['thread'] = Thread(target=self._run, args=(e,), daemon=True)
            e['thread'].start()

    def stop(self):
        self._running = False
        for e in self._entries:
            if e['thread'] and e['thread'].is_alive():
                e['thread'].join(timeout=self._delay + 1.0)

    def join(self):
        for e in self._entries:
            if e['thread']:
                e['thread'].join()

    def disconnect(self):
        for e in self._entries:
            if e['file']:
                e['file'].close()
                e['file'] = None

    def _run(self, entry: dict):
        xcvr = entry['xcvr']
        f    = entry['file']
        while self._running:
            data = f.read(_CHUNK)
            if not data:
                break
            if xcvr:
                xcvr.on_recv(MsgContainer(data, xcvr))
            if self._delay > 0:
                time.sleep(self._delay)