"""Serial port monitor — read, display, and log ESP32 output."""

import threading
import time
from datetime import datetime
from pathlib import Path

from espmon.colors import info, err
from espmon.config import DEFAULT_BAUD, strip_ansi


class SerialMonitor:
    """Read a serial port, print to stdout with colors, log to file without ANSI."""

    def __init__(self, port: str, baud: int = DEFAULT_BAUD, log_path: Path = None):
        self.port = port
        self.baud = baud
        self.log_path = log_path
        self._stop = threading.Event()
        self._log_file = None

    def run(self) -> int:
        """Run the monitor (blocking). Returns exit code."""
        import serial

        try:
            # Open without toggling DTR/RTS to avoid resetting the ESP32
            ser = serial.Serial()
            ser.port = self.port
            ser.baudrate = self.baud
            ser.timeout = 0.5
            ser.dtr = False
            ser.rts = False
            ser.open()
        except serial.SerialException as e:
            err(f"Cannot open {self.port}: {e}")
            return 1

        if self.log_path:
            self.log_path.parent.mkdir(parents=True, exist_ok=True)
            self._log_file = open(self.log_path, 'a', encoding='utf-8')
            info(f"Logging to {self.log_path}")

        info(f"Monitoring {self.port} @ {self.baud} baud  (Ctrl+C to stop)")

        if self._log_file:
            self._log_file.write(
                f"# espmon session started {datetime.now().isoformat()}\n"
            )
            self._log_file.write(
                f"# port: {self.port}  baud: {self.baud}\n"
            )
            self._log_file.flush()

        buf = b""
        try:
            while not self._stop.is_set():
                try:
                    chunk = ser.read(256)
                except serial.SerialException:
                    if self._stop.is_set():
                        break
                    err(f"Serial read error on {self.port}")
                    time.sleep(0.5)
                    continue

                if not chunk:
                    continue

                buf += chunk
                while b"\n" in buf:
                    line_bytes, buf = buf.split(b"\n", 1)
                    line = line_bytes.decode("utf-8", errors="replace").rstrip("\r")

                    # stdout with original ANSI colors
                    print(line, flush=True)

                    # log file: timestamped, ANSI stripped
                    if self._log_file:
                        ts = datetime.now().strftime("%Y-%m-%dT%H:%M:%S.%f")[:-3]
                        clean = strip_ansi(line)
                        self._log_file.write(f"[{ts}] {clean}\n")
                        self._log_file.flush()

        except KeyboardInterrupt:
            pass
        finally:
            try:
                ser.close()
            except Exception:
                pass
            if self._log_file:
                self._log_file.write(
                    f"# espmon session ended {datetime.now().isoformat()}\n"
                )
                self._log_file.close()
            info("Monitor stopped")

        return 0

    def stop(self):
        """Signal the monitor to stop."""
        self._stop.set()