"""CryoSim — Cryogenic Pump Hardware Prototyping Simulator.

Quick start:
    from cryosim import predict
    result = predict(hardware="old_icv", Pexit=350, speed=0.65)
    print(result)
"""

__version__ = "0.1.0"

from dataclasses import dataclass
from typing import Optional, Dict, Any

import numpy as np


@dataclass
class CycleResult:
    """Result of a single pump cycle simulation."""
    mdot_kgpm: float          # Discharge flow rate [kg/min]
    mass_eff: float           # Mass inflow efficiency [0-1]
    Tc_peak_K: float          # Peak chamber temperature [K]
    pc_peak_barg: float       # Peak chamber pressure [barg]
    DCV_ct_s: float           # DCV closure time [s]
    ICV_open_frac: float      # Max ICV opening fraction [0-1]
    cpu_s: float              # Simulation wall time [s]
    steps: int                # Adaptive timesteps used
    kWh_retract: float        # Retract stroke work [kWh/kg]
    kWh_extend: float         # Extend stroke work [kWh/kg]
    tcycle_s: float           # Cycle period [s]
    hardware_name: str        # Config name used
    Pexit_barg: float         # Exit pressure [barg]
    speed_f: float            # Speed fraction [0-1]
    backflow_warning: bool = False    # True if raw mdot was negative (clamped to 0)
    raw_out: Optional[np.ndarray] = None
    raw_history: Optional[Dict[str, Any]] = None

    def __repr__(self) -> str:
        warn = " BACKFLOW!" if self.backflow_warning else ""
        return (
            f"CycleResult(mdot={self.mdot_kgpm:.4f} kg/min, "
            f"eff={self.mass_eff:.1%}, "
            f"Tc_peak={self.Tc_peak_K:.1f} K, "
            f"pc_peak={self.pc_peak_barg:.1f} barg, "
            f"steps={self.steps}, "
            f"cpu={self.cpu_s:.2f}s{warn})"
        )


def predict(
    hardware: str,
    Pexit: float,
    speed: float,
    Ptank: float = 7.0,
    Psat: float = 2.0,
    flash_eff: float = 0.0,
) -> CycleResult:
    """Run a single pump cycle simulation.

    Args:
        hardware: Config name ("old_icv", "new_icv", "calibrated_lh2")
                  or absolute path to a YAML file.
        Pexit: Discharge pressure target [barg].
        speed: Speed fraction [0-1].
        Ptank: Inlet tank pressure [barg]. Default 7.0.
        Psat: Saturation pressure [barg]. Default 2.0.
        flash_eff: Thermal mass film boiling efficiency [0-1]. Default 0.0.

    Returns:
        CycleResult with all simulation outputs.

    Raises:
        ValueError: If inputs are outside valid physical ranges.
    """
    if Pexit < 0:
        raise ValueError(f"Pexit must be non-negative, got {Pexit}")
    if not 0.0 < speed <= 1.5:
        raise ValueError(f"speed must be in (0, 1.5], got {speed}")
    if Ptank < 0:
        raise ValueError(f"Ptank must be non-negative, got {Ptank}")

    from cryosim.hardware.config import load_config
    from cryosim.engine.fast import ICV_open

    cfg = load_config(hardware)
    engine_args = cfg.to_engine_args()

    out, hist = ICV_open(
        Pexit_barg=Pexit,
        speed_f=speed,
        Ptank_barg=Ptank,
        Psat_barg=Psat,
        flash_eff=flash_eff,
        **engine_args,
    )

    raw_mdot = hist["mdot_kgpm"]
    _backflow = raw_mdot < 0.0
    mdot_clamped = max(0.0, raw_mdot)

    return CycleResult(
        mdot_kgpm=mdot_clamped,
        mass_eff=float(out[1, 0]),
        Tc_peak_K=float(np.max(hist["Tc_K"])),
        pc_peak_barg=float(np.max(hist["pc"])),
        DCV_ct_s=float(out[2, 0]),
        ICV_open_frac=float(out[4, 0]),
        cpu_s=float(out[0, 0]),
        steps=hist["steps"],
        kWh_retract=hist["kWh_retract"],
        kWh_extend=hist["kWh_extend"],
        tcycle_s=hist["tcycle_s"],
        hardware_name=cfg.name,
        Pexit_barg=Pexit,
        speed_f=speed,
        backflow_warning=_backflow,
        raw_out=out,
        raw_history=hist,
    )


from cryosim.results import FillResult, FillTimeResult
from cryosim.optimization.optimizer import (
    optimize, multi_start_optimize, differential_evolution_optimize,
)
from cryosim.optimization.design_optimizer import design_optimize


def fill(
    hardware: str,
    target_bar: float,
    speed: float,
    tank_volume_L: float = 50.0,
    max_time_s: float = 1800.0,
    Ptank: float = 7.0,
    Psat: float = 2.0,
    T_inlet_K: float = 55.0,
    system_loss_kgmin: float = 0.02,
    **kwargs,
) -> FillResult:
    """Simulate a complete fill cycle.

    Args:
        hardware: Config name ("old_icv", "new_icv", etc.).
        target_bar: Target discharge pressure [bar].
        speed: Speed fraction [0-1].
        tank_volume_L: Receiver tank volume [liters].
        max_time_s: Maximum simulation time [s].
        Ptank: Inlet tank pressure [barg].
        Psat: Saturation pressure [barg].
        T_inlet_K: Inlet fluid temperature [K].
        system_loss_kgmin: Combined system losses (blowby + heat leak + valve
            leakage) expressed as equivalent mass flow [kg/min]. When net pump
            flow drops below this threshold the fill is considered stalled,
            because the pump can no longer overcome parasitic losses.
            Default 0.02 kg/min.
        **kwargs: Accepts deprecated ``stall_threshold_kgmin`` for backward
            compatibility (mapped to ``system_loss_kgmin``).

    Returns:
        FillResult with fill profile, stall detection, timing.

    Raises:
        ValueError: If inputs are outside valid physical ranges.
    """
    # Backward compatibility: accept old parameter name
    if "stall_threshold_kgmin" in kwargs:
        system_loss_kgmin = kwargs.pop("stall_threshold_kgmin")
    if kwargs:
        raise TypeError(f"Unexpected keyword arguments: {list(kwargs.keys())}")

    if not 0.0 < speed <= 1.5:
        raise ValueError(f"speed must be in (0, 1.5], got {speed}")
    if Ptank < 0:
        raise ValueError(f"Ptank must be non-negative, got {Ptank}")
    if target_bar <= 0:
        raise ValueError(f"target_bar must be positive, got {target_bar}")
    if tank_volume_L <= 0:
        raise ValueError(f"tank_volume_L must be positive, got {tank_volume_L}")

    from cryosim.fill_sim.simulator import FillSimulator

    sim = FillSimulator(
        hardware=hardware, speed=speed, tank_volume_L=tank_volume_L,
        Ptank=Ptank, Psat=Psat, T_inlet_K=T_inlet_K,
        system_loss_kgmin=system_loss_kgmin,
    )
    return sim.run(target_bar=target_bar, max_time_s=max_time_s)


def stall_pressure(
    hardware: str,
    speed: float,
    Ptank: float = 7.0,
    Psat: float = 2.0,
    threshold_kgmin: float = 0.05,
) -> float:
    """Find the maximum achievable discharge pressure for a hardware config.

    Uses the pre-computed flow curve to find where flow drops below threshold.

    Returns:
        Stall pressure [barg].
    """
    from cryosim.fill_sim.flow_curve import FlowCurve

    fc = FlowCurve.build(
        hardware=hardware, speed=speed, n_points=30,
        P_min=50.0, P_max=950.0, Ptank=Ptank, Psat=Psat,
    )
    return fc.find_stall(threshold_kgmin=threshold_kgmin)


def cliff_pressure(
    hardware: str,
    speed: float,
    Ptank: float = 7.0,
    Psat: float = 2.0,
) -> Optional["CliffResult"]:
    """Detect the flow cliff for a hardware config at a given speed.

    The flow cliff is the narrow pressure band (typically ~5 bar wide) where
    pump flow drops by 50%+ due to the discharge check valve dynamics.
    Knowing the cliff location is critical for fill strategy — the pump
    transitions from bulk filling to trickle-charge above the cliff.

    Args:
        hardware: Config name ("old_icv", "new_icv", etc.).
        speed: Speed fraction [0-1].
        Ptank: Inlet tank pressure [barg].
        Psat: Saturation pressure [barg].

    Returns:
        CliffResult with cliff boundaries and flow drop info,
        or None if no significant cliff detected.
    """
    from cryosim.fill_sim.flow_curve import FlowCurve, CliffResult  # noqa: F811

    fc = FlowCurve.build(
        hardware=hardware, speed=speed, n_points=30,
        P_min=50.0, P_max=950.0, Ptank=Ptank, Psat=Psat,
        adaptive=True,
    )
    return fc.find_cliff()


def fill_time(
    hardware: str,
    target_bar: float,
    speed: float,
    tank_volume_L: float = 50.0,
    Ptank: float = 7.0,
    Psat: float = 2.0,
    T_inlet_K: float = 55.0,
) -> 'FillTimeResult':
    """Estimate fill time to reach a target pressure.

    Returns:
        FillTimeResult with structured info about whether target was reached,
        and why it wasn't if unreachable. Supports float() for backward compat.
    """
    from cryosim.results import FillTimeResult as _FTR

    result = fill(
        hardware=hardware, target_bar=target_bar, speed=speed,
        tank_volume_L=tank_volume_L, Ptank=Ptank, Psat=Psat,
        T_inlet_K=T_inlet_K,
    )
    if result.reached_target:
        return _FTR(
            time_s=result.fill_time_s, reachable=True,
            stall_pressure_bar=None, reason="Target reached")
    elif result.stalled:
        return _FTR(
            time_s=None, reachable=False,
            stall_pressure_bar=result.stall_pressure_bar,
            reason=f"Pump stalled at {result.stall_pressure_bar:.0f} bar (flow below system loss threshold)")
    else:
        return _FTR(
            time_s=None, reachable=False,
            stall_pressure_bar=result.peak_pressure_bar,
            reason=f"Timeout: reached {result.peak_pressure_bar:.0f} bar in {result.fill_time_s:.0f}s")


def calibrate(
    hardware: str,
    fills: list,
    maxiter: int = 200,
):
    """Calibrate engine parameters against measured fill data.

    Args:
        hardware: Base hardware config to start from.
        fills: List of fill dicts, each with keys:
            Pexit_barg, speed_f, Ptank_barg, Psat_barg, measured_mdot_kgpm
        maxiter: Maximum L-BFGS-B iterations.

    Returns:
        CalibrationResult with fitted params, RMSE, and export methods.
    """
    from cryosim.calibration.engine import Calibrator

    cal = Calibrator(hardware=hardware, fills=fills, maxiter=maxiter)
    return cal.run()


@dataclass
class UncertainPrediction:
    """Prediction with uncertainty bounds."""
    result: CycleResult           # The point estimate
    mdot_bounds: 'UncertaintyBands'   # Bounds on mass flow
    envelope_status: str          # VALIDATED/EXTRAPOLATING/OUTSIDE_RANGE


def predict_with_uncertainty(
    hardware: str,
    Pexit: float,
    speed: float,
    Ptank: float = 7.0,
    Psat: float = 2.0,
) -> UncertainPrediction:
    """Run prediction with uncertainty bounds.

    Returns the standard CycleResult plus uncertainty bands
    computed from calibration residuals and extrapolation penalties.
    """
    from cryosim.validation.uncertainty import ResidualModel, UncertaintyBands
    from cryosim.validation.envelope import check_envelope

    result = predict(hardware=hardware, Pexit=Pexit, speed=speed, Ptank=Ptank, Psat=Psat)

    model = ResidualModel()
    bounds = model.predict_bounds(result.mdot_kgpm, Pexit, speed)

    envelope = check_envelope(Pexit, speed)

    return UncertainPrediction(
        result=result,
        mdot_bounds=bounds,
        envelope_status=envelope.status,
    )


def sensitivity(hardware="old_icv", speed=0.65, Pexit=350.0, **kwargs):
    """Run parameter sensitivity analysis. Returns SensitivityResult."""
    from cryosim.optimization.sensitivity import run_sensitivity
    return run_sensitivity(hardware=hardware, speed=speed, Pexit=Pexit, **kwargs)


def sweep(hardware, param_name, values, speed=0.65, Pexit=350.0, metric="mdot_kgpm", **kwargs):
    """Sweep one parameter across values, returning metric at each point."""
    from cryosim.optimization.sweep import sweep_1d
    return sweep_1d(hardware=hardware, param_name=param_name, values=values,
                    speed=speed, Pexit=Pexit, metric=metric, **kwargs)


def __getattr__(name):
    if name == "CliffResult":
        from cryosim.fill_sim.flow_curve import CliffResult
        return CliffResult
    raise AttributeError(f"module 'cryosim' has no attribute {name!r}")


__all__ = [
    "predict", "CycleResult",
    "predict_with_uncertainty", "UncertainPrediction",
    "fill", "stall_pressure", "fill_time", "FillResult", "FillTimeResult",
    "cliff_pressure", "CliffResult",
    "calibrate",
    "sensitivity", "sweep", "optimize",
    "multi_start_optimize", "differential_evolution_optimize",
    "design_optimize",
    "__version__",
]