import random
import math
from bots.base import BaseBot


class ChillerBot(BaseBot):
    """Water-cooled chiller plant — supplies chilled water to CRAC/CRAH units."""

    interval = 60

    RATED_COOLING_KW  = 300.0    # total cooling capacity
    DESIGN_FLOW_GPM   = 600.0    # nominal chilled water flow
    CHW_SETPOINT      = 7.0      # chilled water supply setpoint (°C)
    CW_RETURN_DESIGN  = 35.0     # condenser water return design temp (°C)

    def __init__(self, site_id: str, chiller_id: str) -> None:
        super().__init__()
        self.site_id    = site_id
        self.chiller_id = chiller_id
        self._fault     = False
        self._run_hours = 8_000 + random.randint(0, 2_000)

    def get_topic(self) -> str:
        return f"bms/{self.site_id}/cooling/chiller/{self.chiller_id}"

    def set_scenario(self, name: str | None) -> None:
        super().set_scenario(name)
        self._fault = (name == "CHILLER_FAULT")

    def get_payload(self) -> dict:
        hour_inc = self.interval / 3_600
        self._run_hours += hour_inc

        if self._fault:
            return {
                "state":                "fault",
                "chw_supply_c":         None,
                "chw_return_c":         None,
                "chw_delta_c":          None,
                "flow_gpm":             0,
                "cooling_load_kw":      0,
                "cooling_load_pct":     0,
                "cop":                  0,
                "compressor_load_pct":  0,
                "condenser_pressure_bar": None,
                "evaporator_pressure_bar": None,
                "cw_supply_c":          None,
                "cw_return_c":          None,
                "run_hours":            round(self._run_hours, 1),
            }

        # Normal operation
        load_pct    = 55.0 + random.gauss(0, 5.0)
        load_pct    = max(20.0, min(100.0, load_pct))
        load_kw     = self.RATED_COOLING_KW * load_pct / 100.0

        # CHW temperatures — supply held near setpoint, return rises with load
        chw_supply  = self.CHW_SETPOINT + random.gauss(0, 0.15)
        chw_delta   = 5.0 + (load_pct / 100.0) * 3.0 + random.gauss(0, 0.2)
        chw_return  = chw_supply + chw_delta

        # Condenser water
        cw_return   = self.CW_RETURN_DESIGN - 3.0 + (load_pct / 100.0) * 4.0 + random.gauss(0, 0.5)
        cw_supply   = cw_return - 5.0 + random.gauss(0, 0.3)

        # Flow — slight variation from design
        flow_gpm    = self.DESIGN_FLOW_GPM * (0.92 + random.gauss(0, 0.01))

        # Refrigerant pressures (R134a-like)
        evap_p      = 3.0  + (chw_supply / 10.0) + random.gauss(0, 0.05)
        cond_p      = 12.0 + (cw_return  / 10.0) + random.gauss(0, 0.1)

        # COP
        comp_load   = load_pct * 0.9 + random.gauss(0, 1.0)
        comp_power  = (comp_load / 100.0) * (load_kw / 4.5)   # ~4.5 COP design
        cop         = load_kw / comp_power if comp_power > 0 else 0.0

        return {
            "state":                  "online",
            "chw_supply_c":           round(chw_supply, 2),
            "chw_return_c":           round(chw_return, 2),
            "chw_delta_c":            round(chw_delta, 2),
            "flow_gpm":               round(flow_gpm, 0),
            "cooling_load_kw":        round(load_kw, 1),
            "cooling_load_pct":       round(load_pct, 1),
            "cop":                    round(cop, 2),
            "compressor_load_pct":    round(comp_load, 1),
            "condenser_pressure_bar": round(cond_p, 2),
            "evaporator_pressure_bar": round(evap_p, 2),
            "cw_supply_c":            round(cw_supply, 2),
            "cw_return_c":            round(cw_return, 2),
            "run_hours":              round(self._run_hours, 1),
        }