#!/usr/bin/env python3
"""Capture filament dryer CSV lines from serial into a file.

Designed for a Raspberry Pi attached to the dryer Nano over USB. The Arduino
still owns sensors and control; this script only records the csv,* stream.
"""

from __future__ import annotations

import argparse
import sys
import time
from datetime import datetime, timezone
from pathlib import Path

FALLBACK_HEADER = (
    "wall_time,ms,target_c,avg_c,min_c,max_c,spread_c,heatlim_pct,heater_pct,"
    "fan_pct,cutoff,failsafe,ch2_t,ch2_h,ch3_t,ch3_h,ch4_t,ch4_h,ch5_t,ch5_h"
)


def detect_serial_port() -> str | None:
    by_id = Path("/dev/serial/by-id")
    if by_id.is_dir():
        patterns = ("*Arduino*", "*arduino*", "*2341*", "*1a86*", "*CH340*", "*ch340*")
        for pattern in patterns:
            matches = sorted(by_id.glob(pattern))
            if matches:
                return str(matches[0])
    for candidate in ("/dev/ttyACM0", "/dev/ttyACM1", "/dev/ttyUSB0", "/dev/ttyUSB1"):
        if Path(candidate).exists():
            return candidate
    return None


def enable_dryer_logging(ser, retries: int = 3) -> None:
    for attempt in range(retries):
        ser.reset_input_buffer()
        ser.write(b"log on\n")
        ser.flush()
        deadline = time.monotonic() + 2.0
        while time.monotonic() < deadline:
            raw = ser.readline()
            if not raw:
                continue
            line = raw.decode("utf-8", errors="replace").strip()
            if line == "OK csv logging on" or line.startswith("csv_hdr,"):
                return
            if line.startswith("csv,"):
                return
            if line:
                print(line)
        time.sleep(0.5 * (attempt + 1))
    print("WARN: did not see 'OK csv logging on' — continuing anyway", file=sys.stderr)


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument(
        "-p",
        "--port",
        help="Serial port (default: auto-detect on Pi, else /dev/ttyUSB0)",
    )
    parser.add_argument("-b", "--baud", type=int, default=115200)
    parser.add_argument(
        "-o",
        "--output",
        type=Path,
        help="Output CSV file (default: logs/dryer_YYYYMMDD_HHMMSS.csv)",
    )
    parser.add_argument(
        "--log-dir",
        type=Path,
        default=Path("logs"),
        help="Directory for default timestamped log files",
    )
    parser.add_argument(
        "--auto-log-on",
        action=argparse.BooleanOptionalAction,
        default=True,
        help="Send 'log on' to the dryer after connect (default: on)",
    )
    args = parser.parse_args()

    port = args.port
    if port is None:
        port = detect_serial_port()
    if port is None:
        port = "/dev/ttyUSB0"
        print(
            f"WARN: no serial device found, using {port}",
            file=sys.stderr,
        )

    try:
        import serial
    except ImportError:
        print("Install pyserial: pip install pyserial", file=sys.stderr)
        return 1

    out = args.output
    if out is None:
        out = args.log_dir / f"dryer_{datetime.now():%Y%m%d_%H%M%S}.csv"
    out.parent.mkdir(parents=True, exist_ok=True)

    print(f"Logging {port} -> {out}", file=sys.stderr)
    if args.auto_log_on:
        print("Will send 'log on' after connect", file=sys.stderr)
    else:
        print("Send 'log on' to the dryer if CSV rows are not appearing", file=sys.stderr)

    header_written = False
    with serial.Serial(port, args.baud, timeout=1) as ser, out.open("w", encoding="utf-8") as fh:
        time.sleep(2.0)  # allow Nano reset after USB open
        if args.auto_log_on:
            enable_dryer_logging(ser)

        while True:
            try:
                raw = ser.readline()
            except KeyboardInterrupt:
                print("\nStopped.", file=sys.stderr)
                return 0

            if not raw:
                continue

            line = raw.decode("utf-8", errors="replace").strip()
            if not line.startswith("csv_hdr,") and not line.startswith("csv,"):
                if line:
                    print(line)
                continue

            if line.startswith("csv_hdr,"):
                device_header = line[len("csv_hdr,") :]
                fh.write("wall_time," + device_header + "\n")
                header_written = True
                fh.flush()
                continue

            if not header_written:
                fh.write(FALLBACK_HEADER + "\n")
                header_written = True

            wall_time = datetime.now(timezone.utc).isoformat(timespec="seconds")
            fh.write(wall_time + "," + line[len("csv,") :] + "\n")
            fh.flush()


if __name__ == "__main__":
    raise SystemExit(main())