#!/usr/bin/env python3
"""Filament dryer host tools — TUI dashboard and CSV logging.

  capture_csv.py                  TUI when run in a terminal (default)
  capture_csv.py tui              same
  capture_csv.py log              headless CSV capture (Pi systemd logger)
"""

from __future__ import annotations

import argparse
import re
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"
)

SENSOR_CHANNELS = [2, 3, 4, 5]

# If no bytes at all arrive for this long, treat the device as hung (e.g. an
# I2C bus lockup freezing the Arduino) rather than looping forever in silence.
DEFAULT_STALL_TIMEOUT_S = 20.0

_FAN_PCT_RE = re.compile(r"\((\d+)%\)")
_FAN_PWM_RE = re.compile(r"^(\d+)/")


def fan_pct_from_status(fan: str) -> int:
    match = _FAN_PCT_RE.search(fan)
    if match:
        return int(match.group(1))
    match = _FAN_PWM_RE.match(fan)
    if match:
        return (int(match.group(1)) * 100) // 255
    return 0


def target_c_from_status(target: str) -> str:
    if target.startswith("idle"):
        return "0.0"
    if target.endswith("C"):
        return target[:-1]
    return target


def build_csv_payload_from_status(data: dict, ms: int | None = None) -> str:
    if ms is None:
        ms = int(time.time() * 1000)

    sensors = {ch: (temp, hum) for ch, temp, hum in data.get("sensor_list", [])}
    parts = [
        str(ms),
        target_c_from_status(data["target"]),
        data["avg"],
        data["min"],
        data["max"],
        data["spread"],
        data["heatlim"],
        data["heater"],
        str(fan_pct_from_status(data.get("fan", "0"))),
        "1" if data.get("cutoff_active") == "YES" else "0",
        "1" if data.get("failsafe") == "YES" else "0",
    ]
    for ch in SENSOR_CHANNELS:
        if str(ch) in sensors:
            temp, hum = sensors[str(ch)]
            if temp == "ERR":
                parts.extend(["", ""])
            else:
                parts.extend([temp, hum])
        else:
            parts.extend(["", ""])
    return ",".join(parts)


class CsvSession:
    """Deferred CSV writer — no empty file until the first row lands."""

    def __init__(self, path: Path):
        self.path = path
        self._fh = None
        self._header_written = False
        self.row_count = 0

    def _ensure_open(self) -> None:
        if self._fh is None:
            self.path.parent.mkdir(parents=True, exist_ok=True)
            self._fh = self.path.open("w", encoding="utf-8")

    def _write_header(self) -> None:
        if not self._header_written:
            self._ensure_open()
            assert self._fh is not None
            self._fh.write(FALLBACK_HEADER + "\n")
            self._header_written = True

    def write_device_line(self, line: str) -> None:
        if line.startswith("csv_hdr,"):
            self._ensure_open()
            assert self._fh is not None
            device_header = line[len("csv_hdr,") :]
            self._fh.write("wall_time," + device_header + "\n")
            self._header_written = True
            self._fh.flush()
            return
        if not line.startswith("csv,"):
            return
        self._write_header()
        assert self._fh is not None
        wall_time = datetime.now(timezone.utc).isoformat(timespec="seconds")
        self._fh.write(wall_time + "," + line[len("csv,") :] + "\n")
        self._fh.flush()
        self.row_count += 1

    def write_status(self, data: dict) -> None:
        self._write_header()
        assert self._fh is not None
        wall_time = datetime.now(timezone.utc).isoformat(timespec="seconds")
        payload = build_csv_payload_from_status(data)
        self._fh.write(wall_time + "," + payload + "\n")
        self._fh.flush()
        self.row_count += 1

    def close(self) -> None:
        if self._fh is not None:
            self._fh.close()
            self._fh = None
        if self.row_count == 0 and self.path.exists():
            try:
                self.path.unlink()
            except OSError:
                pass


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 resolve_port(port: str | None) -> str:
    if port is not None:
        return port
    detected = detect_serial_port()
    if detected is not None:
        return detected
    fallback = "/dev/ttyUSB0"
    print(f"WARN: no serial device found, using {fallback}", file=sys.stderr)
    return fallback


def import_serial():
    try:
        import serial
    except ImportError:
        print("Install pyserial: pip install pyserial", file=sys.stderr)
        raise SystemExit(1) from None
    return serial


def open_serial(port: str, baud: int):
    serial = import_serial()
    ser = serial.Serial()
    ser.port = port
    ser.baudrate = baud
    ser.timeout = 0.1
    # DTR low: avoid resetting the Nano (CH340) on every reconnect.
    ser.dtr = False
    ser.rts = False
    ser.open()
    time.sleep(0.3)
    return ser


def decode_line(raw: bytes) -> str:
    return raw.decode("utf-8", errors="replace").strip()


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 = decode_line(raw)
            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 log_notice(message: str) -> None:
    stamp = datetime.now(timezone.utc).isoformat(timespec="seconds")
    print(f"{stamp} {message}", file=sys.stderr)


def cmd_log(args: argparse.Namespace) -> int:
    from dryer_tui import parse_status

    port = resolve_port(args.port)
    out = args.output
    if out is None:
        out = args.log_dir / f"dryer_{datetime.now():%Y%m%d_%H%M%S}.csv"

    stall_timeout = args.stall_timeout
    print(f"Logging {port} -> {out}", file=sys.stderr)
    if args.auto_log_on:
        print("Will send 'log on' after connect", file=sys.stderr)

    session = CsvSession(out)
    with open_serial(port, args.baud) as ser:
        if args.auto_log_on:
            enable_dryer_logging(ser)

        last_activity = time.monotonic()
        while True:
            try:
                raw = ser.readline()
            except KeyboardInterrupt:
                print(f"\nStopped ({session.row_count} rows).", file=sys.stderr)
                session.close()
                return 0
            except Exception as exc:
                log_notice(
                    f"ERROR: serial read failed ({exc}) — closing after "
                    f"{session.row_count} rows"
                )
                session.close()
                return 1

            if not raw:
                if time.monotonic() - last_activity >= stall_timeout:
                    log_notice(
                        f"WARN: no data from {port} for {stall_timeout:.0f}s — "
                        f"device likely hung (e.g. I2C bus lockup on the Arduino) "
                        f"— closing after {session.row_count} rows"
                    )
                    session.close()
                    return 1
                continue

            last_activity = time.monotonic()
            line = decode_line(raw)
            parsed = parse_status(line)
            if parsed:
                session.write_status(parsed)
                print(line)
                continue

            if line.startswith("csv_hdr,") or line.startswith("csv,"):
                session.write_device_line(line)
                continue

            if line:
                print(line)
    return 0


def cmd_tui(args: argparse.Namespace) -> int:
    from dryer_tui import run_tui

    return run_tui(args.port, args.baud, args.log_dir, args.auto_log_on)


def build_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(
        description="Filament dryer host tools (CSV logging and TUI).",
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog=(
            "Examples:\n"
            "  %(prog)s tui\n"
            "  %(prog)s log --log-dir logs\n"
            "  %(prog)s --log-dir logs    # legacy headless logger\n"
        ),
    )
    parser.add_argument("-p", "--port", help="Serial port (default: auto-detect)")
    parser.add_argument("-b", "--baud", type=int, default=115200)
    parser.add_argument("-o", "--output", type=Path, help="Output CSV file (log mode)")
    parser.add_argument("--log-dir", type=Path, default=Path("logs"), help="CSV log directory")
    parser.add_argument(
        "--auto-log-on",
        action=argparse.BooleanOptionalAction,
        default=True,
        help="Send 'log on' after connect in log mode (default: on)",
    )
    parser.add_argument(
        "--stall-timeout",
        type=float,
        default=DEFAULT_STALL_TIMEOUT_S,
        help=(
            "log mode: seconds without any data before treating the device as "
            f"hung and exiting (default: {DEFAULT_STALL_TIMEOUT_S:.0f})"
        ),
    )

    subparsers = parser.add_subparsers(dest="action")
    log_p = subparsers.add_parser("log", help="Headless CSV capture", add_help=False)
    log_p.add_argument("-p", "--port")
    log_p.add_argument("-b", "--baud", type=int, default=115200)
    log_p.add_argument("-o", "--output", type=Path)
    log_p.add_argument("--log-dir", type=Path, default=Path("logs"))
    log_p.add_argument("--auto-log-on", action=argparse.BooleanOptionalAction, default=True)
    log_p.add_argument("--stall-timeout", type=float, default=DEFAULT_STALL_TIMEOUT_S)

    tui_p = subparsers.add_parser("tui", help="Interactive curses dashboard")
    tui_p.add_argument("-p", "--port")
    tui_p.add_argument("-b", "--baud", type=int, default=115200)
    tui_p.add_argument("--log-dir", type=Path, default=Path("logs"))
    tui_p.add_argument(
        "--auto-log-on",
        action=argparse.BooleanOptionalAction,
        default=True,
        help="Start CSV logging when TUI opens (default: on)",
    )

    return parser


def main(argv: list[str] | None = None) -> int:
    argv = sys.argv[1:] if argv is None else list(argv)
    parser = build_parser()
    args = parser.parse_args(argv)

    if args.action == "tui":
        return cmd_tui(args)
    if args.action == "log":
        return cmd_log(args)
    # No subcommand: TUI in an interactive terminal, headless log otherwise (systemd).
    if sys.stdin.isatty() and sys.stdout.isatty():
        return cmd_tui(args)
    return cmd_log(args)


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