"""
api_layers/protocols/mark10.py

Mark-10 ASCII protocol layer (Series 5 primary, compatible with Series 4/3).

Commands (sent with CR terminator):
  ?   — request current reading
  Z   — zero the gauge
  U   — cycle units (lb → kgF → N → ozF → …)

Response format: "+0.1234 kgF" (sign, value, space, unit suffix)

Channels exposed:
  force      — current force reading (in instrument's selected unit)
  unit_code  — numeric index into UNITS list (lb=0, kgF=1, N=2, ozF=3)
"""

import math
import re
from typing import Dict, Optional

from api_layers.protocols.base_protocol import BaseProtocol


UNITS = ["lb", "kgF", "N", "ozF"]

_RESP_RE = re.compile(r"([+-]?\d+\.?\d*(?:[eE][+-]?\d+)?)\s*([a-zA-Z]*)")


class Mark10Layer(BaseProtocol):

    def __init__(
        self,
        port:          str,
        baud:          int   = 115200,
        poll_interval: float = 0.05,
        simulate:      bool  = True,
    ):
        super().__init__(port, baud, poll_interval, simulate)
        self._unit = "N"

    # ── Protocol ──────────────────────────────────────────────────────────

    def _poll(self) -> Dict[str, float]:
        try:
            self._ser.write(b"?\r")
            resp = self._ser.readline().decode(errors="replace").strip()
            return self._parse(resp)
        except Exception:
            return {}

    def _parse(self, resp: str) -> Dict[str, float]:
        m = _RESP_RE.search(resp)
        if not m:
            return {}
        val  = float(m.group(1))
        unit = m.group(2).strip() or self._unit
        if unit in UNITS:
            self._unit = unit
        return {
            "force":     val,
            "unit_code": float(UNITS.index(self._unit) if self._unit in UNITS else 2),
        }

    def _simulate(self, t: float) -> Dict[str, float]:
        cycle = t % 30.0
        ramp  = cycle * 6.67 if cycle < 15.0 else (30.0 - cycle) * 6.67
        return {
            "force":     ramp + math.sin(t * 10.0) * 0.3,
            "unit_code": float(UNITS.index("N")),
        }

    def write(self, channel_id: str, value) -> bool:
        cmd_map = {
            "zero":         b"Z\r",
            "cycle_units":  b"U\r",
        }
        cmd = cmd_map.get(channel_id)
        if cmd is None or not self._ser:
            return False
        try:
            self._ser.write(cmd)
            return True
        except Exception:
            return False

    # ── Convenience ───────────────────────────────────────────────────────

    def zero(self) -> None:
        if self._ser:
            self._ser.write(b"Z\r")

    def cycle_units(self) -> None:
        if self._ser:
            self._ser.write(b"U\r")