"""Continuos serial frame reader (Live-mode source)"""
from __future__ import annotations
import logging
import threading
from typing import Callable

from pygui.backend.models.frame import Frame

log = logging.getLogger(__name__)

ParseLine = Callable[[str, int], Frame]

class StreamReader:
    
    def __init__(self, transport, parse_line: ParseLine,
                on_frame: Callable[[Frame], None],
                on_error: Callable[[Exception], None] | None = None ) -> None:
        self._transport = transport
        self._parse = parse_line
        self._on_frame = on_frame
        self._on_error = on_error or (lambda e: None)
        self._thread: threading.Thread | None = None
        self._stop = threading.Event()
        self._seq = 0
        self.error_count = 0
        
    def start(self) -> None:
        self._stop.clear()
        self._thread = threading.Thread(target=self._run, daemon = True)
        self._thread.start()

    def _run(self) -> None:
        try:
            while not self._stop.is_set():
                raw = self._transport.readline()
                if not raw:
                    continue
                text = raw.decode(errors="ignore").strip()
                if not text: 
                    continue
                try:
                    frame= self._parse(text, self._seq)
                    self._seq += 1
                    self._on_frame(frame)
                except Exception as exc:
                    self.error_count += 1
                    self._on_error(exc)
        finally:
            try:
                self._transport.close()
            except Exception:
                pass
            
    def stop(self) -> None:
        self._stop.set()
        if self._thread is not None and self._thread.is_alive():
            self._thread.join(timeout = 2.0)
            self._thread = None