"""
OperationalModes: weather protection, heat shield, and harvest mode.

These override normal engine output at the P1/P2 priority level
in the CommandArbiter.  Each mode returns a dict that the arbiter
recognises as ``weather_override`` or ``harvest_active``.

Modes
-----
- **WindStow**: panels go flat (0°) when wind exceeds threshold.
- **HailStow**: panels go flat (0°) during hail events.
- **HeatShield**: maximum shading offset regardless of budget
  when air temperature AND CWSI exceed emergency thresholds.
- **HarvestMode**: panels park vertical (90°) for machine clearance.
  Activated/deactivated manually or by schedule.
"""

from __future__ import annotations

import logging
from dataclasses import dataclass
from datetime import date, datetime, time, timezone
from typing import Optional

from config.settings import (
    HEAT_SHIELD_CWSI,
    HEAT_SHIELD_TEMP_C,
    WIND_STOW_SPEED_MS,
)

logger = logging.getLogger(__name__)


# ---------------------------------------------------------------------------
# Mode results
# ---------------------------------------------------------------------------

@dataclass
class ModeOverride:
    """Result from an operational mode check."""

    active: bool
    mode: str               # "wind_stow" | "hail_stow" | "heat_shield" | "harvest"
    target_angle: float     # angle to command
    reason: str = ""
    bypass_budget: bool = False  # True → ignore energy budget
    bypass_hysteresis: bool = False  # True → skip hysteresis filter

    def to_weather_override(self) -> Optional[dict]:
        """Convert to the dict format CommandArbiter.arbitrate() expects."""
        if not self.active:
            return None
        return {
            "target_angle": self.target_angle,
            "reason": self.reason,
        }


# ---------------------------------------------------------------------------
# Individual mode checkers
# ---------------------------------------------------------------------------

def check_wind_stow(
    wind_speed_ms: float,
    threshold: float = WIND_STOW_SPEED_MS,
) -> ModeOverride:
    """Flat stow if wind exceeds threshold."""
    if wind_speed_ms >= threshold:
        return ModeOverride(
            active=True,
            mode="wind_stow",
            target_angle=0.0,
            reason=f"wind stow: {wind_speed_ms:.1f} m/s >= {threshold:.0f} m/s",
            bypass_budget=True,
            bypass_hysteresis=True,
        )
    return ModeOverride(active=False, mode="wind_stow", target_angle=0.0)


def check_hail_stow(hail_detected: bool) -> ModeOverride:
    """Flat stow during hail."""
    if hail_detected:
        return ModeOverride(
            active=True,
            mode="hail_stow",
            target_angle=0.0,
            reason="hail detected — flat stow",
            bypass_budget=True,
            bypass_hysteresis=True,
        )
    return ModeOverride(active=False, mode="hail_stow", target_angle=0.0)


def check_heat_shield(
    air_temp_c: float,
    cwsi: Optional[float] = None,
    temp_threshold: float = HEAT_SHIELD_TEMP_C,
    cwsi_threshold: float = HEAT_SHIELD_CWSI,
    max_offset_deg: float = 20.0,
    theta_astro: float = 0.0,
) -> ModeOverride:
    """Emergency heat shield: maximum shade offset regardless of budget.

    Activates when BOTH air temperature AND CWSI exceed their thresholds.
    If CWSI is unavailable, activates on temperature alone at +2°C above threshold.
    """
    temp_exceeded = air_temp_c >= temp_threshold

    if cwsi is not None:
        cwsi_exceeded = cwsi >= cwsi_threshold
        activate = temp_exceeded and cwsi_exceeded
        reason = (f"heat shield: T={air_temp_c:.1f}°C >= {temp_threshold:.0f}°C, "
                  f"CWSI={cwsi:.2f} >= {cwsi_threshold:.2f}")
    else:
        # Without CWSI, require a higher temperature
        activate = air_temp_c >= temp_threshold + 2.0
        reason = (f"heat shield (no CWSI): T={air_temp_c:.1f}°C >= "
                  f"{temp_threshold + 2.0:.0f}°C")

    if activate:
        return ModeOverride(
            active=True,
            mode="heat_shield",
            target_angle=theta_astro + max_offset_deg,
            reason=reason,
            bypass_budget=True,
            bypass_hysteresis=False,
        )
    return ModeOverride(active=False, mode="heat_shield", target_angle=0.0)


# ---------------------------------------------------------------------------
# Harvest mode
# ---------------------------------------------------------------------------

class HarvestMode:
    """Manages harvest parking state.

    Harvest mode is a manual toggle (operator activates it before
    sending machines into the vineyard).  Can also be scheduled.
    """

    def __init__(self):
        self._active = False
        self._scheduled_dates: list[date] = []

    def activate(self) -> None:
        self._active = True
        logger.info("Harvest mode ACTIVATED — panels will park vertical")

    def deactivate(self) -> None:
        self._active = False
        logger.info("Harvest mode DEACTIVATED — normal control resumed")

    def set_schedule(self, dates: list[date]) -> None:
        self._scheduled_dates = sorted(dates)
        logger.info("Harvest schedule set: %s", [str(d) for d in dates])

    def check(self, current_date: Optional[date] = None) -> ModeOverride:
        today = current_date or date.today()
        active = self._active or today in self._scheduled_dates
        if active:
            return ModeOverride(
                active=True,
                mode="harvest",
                target_angle=90.0,
                reason="harvest mode — panels parked vertical for machine clearance",
                bypass_budget=True,
                bypass_hysteresis=True,
            )
        return ModeOverride(active=False, mode="harvest", target_angle=0.0)


# ---------------------------------------------------------------------------
# Composite checker
# ---------------------------------------------------------------------------

class OperationalModeChecker:
    """Run all mode checks in priority order.

    Returns the highest-priority active mode, or None if all clear.

    Priority: wind_stow > hail_stow > harvest > heat_shield
    """

    def __init__(self):
        self.harvest = HarvestMode()

    def check_all(
        self,
        wind_speed_ms: Optional[float] = None,
        hail_detected: bool = False,
        air_temp_c: Optional[float] = None,
        cwsi: Optional[float] = None,
        theta_astro: float = 0.0,
        current_date: Optional[date] = None,
    ) -> Optional[ModeOverride]:
        """Check all operational modes in priority order.

        Returns the first active override, or None.
        """
        # P1a: Wind stow
        if wind_speed_ms is not None:
            result = check_wind_stow(wind_speed_ms)
            if result.active:
                logger.warning("Mode override: %s", result.reason)
                return result

        # P1b: Hail stow
        if hail_detected:
            result = check_hail_stow(True)
            if result.active:
                logger.warning("Mode override: %s", result.reason)
                return result

        # P2: Harvest
        harvest_result = self.harvest.check(current_date)
        if harvest_result.active:
            logger.info("Mode override: %s", harvest_result.reason)
            return harvest_result

        # Heat shield (lower priority than harvest — don't shade
        # while machines are in the vineyard)
        if air_temp_c is not None:
            result = check_heat_shield(
                air_temp_c=air_temp_c,
                cwsi=cwsi,
                theta_astro=theta_astro,
            )
            if result.active:
                logger.warning("Mode override: %s", result.reason)
                return result

        return None