"""Steam generator and turbine performance models."""

from __future__ import annotations

from dataclasses import dataclass
import logging

from . import constants
from .state import CoolantLoopState, TurbineState

LOGGER = logging.getLogger(__name__)


@dataclass
class SteamGenerator:
    drum_volume_m3: float = 200.0

    def steam_enthalpy(self, loop: CoolantLoopState) -> float:
        base = 2_700.0  # kJ/kg saturated steam
        quality_adjustment = 500.0 * loop.steam_quality
        return base + quality_adjustment


@dataclass
class Turbine:
    generator_efficiency: float = constants.GENERATOR_EFFICIENCY
    mechanical_efficiency: float = constants.STEAM_TURBINE_EFFICIENCY
    rated_output_mw: float = 400.0  # cap per unit electrical output

    def step(
        self,
        loop: CoolantLoopState,
        state: TurbineState,
        steam_power_mw: float = 0.0,
    ) -> None:
        enthalpy = 2_700.0 + loop.steam_quality * 600.0
        mass_flow = loop.mass_flow_rate * 0.6
        available_power = max(steam_power_mw, (enthalpy * mass_flow / 1_000.0) / 1_000.0)
        shaft_power_mw = available_power * self.mechanical_efficiency
        electrical = shaft_power_mw * self.generator_efficiency
        if electrical > self.rated_output_mw:
            electrical = self.rated_output_mw
            shaft_power_mw = electrical / max(1e-6, self.generator_efficiency)
        condenser_temp = max(305.0, loop.temperature_in - 20.0)
        state.steam_enthalpy = enthalpy
        state.shaft_power_mw = shaft_power_mw
        state.electrical_output_mw = electrical
        state.condenser_temperature = condenser_temp
        LOGGER.debug(
            "Turbine output: shaft=%.1fMW electrical=%.1fMW condenser=%.1fK",
            shaft_power_mw,
            electrical,
            condenser_temp,
        )