# src/cryo_tank/main.py
"""
Entry point for the cryogenic LN2 tank simulation.

Run from project root:
    python3 src/cryo_tank/main.py
"""
import os
import sys

_HERE = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, os.path.dirname(_HERE))

from cryo_tank.config import (
    V_TOTAL, H_TANK, P_WORKING, T_INIT, ULLAGE_FRACTION,
    MDOT_IN_LN2, T_IN_LN2, MDOT_OUT_LN2, T_IN_HE,
    H_CONV_SURFACE, T_ENV, A_TOTAL,
    T_END, RTOL, ATOL, OUTPUT_DIR,
)
from cryo_tank.tank_model import CryoTank
from cryo_tank.heat_leak import MLIHeatLeak
from cryo_tank.solver import run
from cryo_tank.output import (
    save_history, plot_temperatures, plot_liquid_level,
    plot_he_flow, plot_heat_fluxes, plot_pressure,
)


def main():
    os.makedirs(OUTPUT_DIR, exist_ok=True)

    # --- Assemble ---
    heat_leak = MLIHeatLeak(A_total=A_TOTAL, q_mli=1.0)
    tank = CryoTank(
        V_total=V_TOTAL, H_tank=H_TANK,
        P_work=P_WORKING,
        T_init=T_INIT, ullage_fraction=ULLAGE_FRACTION,
        mdot_in_ln2=MDOT_IN_LN2, T_in_ln2=T_IN_LN2,
        mdot_out_ln2=MDOT_OUT_LN2,
        T_in_he=T_IN_HE,
        h_conv=H_CONV_SURFACE, T_env=T_ENV,
        heat_leak_model=heat_leak,
    )

    y0 = tank.initial_state()
    info0 = tank.derive(y0)
    print(f"Initial state:")
    print(f"  m_liq = {y0[0]:.2f} kg")
    print(f"  T_liq = {info0['T_liq']:.2f} K, T_ull = {info0['T_ull']:.2f} K")
    print(f"  fill_fraction = {info0['fill_fraction']:.1%}")
    print(f"  m_He = {info0['m_He']*1000:.2f} g")
    print(f"  P_N2 = {info0['P_N2']/1e6:.4f} MPa, P_He = {info0['P_He']/1e6:.4f} MPa")
    print(f"Running to t_end = {T_END:.0f} s ...")
    print()

    # --- Run ---
    history = run(tank, t_end=T_END, rtol=RTOL, atol=ATOL)

    n_steps = len(history['t'])
    t_final = history['t'][-1]
    print(f"Simulation complete: {n_steps} output points, t_final = {t_final:.1f} s")
    print(f"  T_liq: {history['T_liq'][0]:.2f} -> {history['T_liq'][-1]:.2f} K")
    print(f"  T_ull: {history['T_ull'][0]:.2f} -> {history['T_ull'][-1]:.2f} K")
    print(f"  fill_fraction: {history['fill_fraction'][0]:.1%} -> {history['fill_fraction'][-1]:.1%}")
    print(f"  m_He: {history['m_He'][0]*1000:.2f} -> {history['m_He'][-1]*1000:.2f} g")
    print(f"  T_out (LN2 outlet) = T_liq = {history['T_liq'][-1]:.2f} K")

    # --- Output ---
    save_history(history, os.path.join(OUTPUT_DIR, "cryo_tank_history.npz"))
    plot_temperatures(history, os.path.join(OUTPUT_DIR, "cryo_tank_temperatures.png"))
    plot_liquid_level(history, os.path.join(OUTPUT_DIR, "cryo_tank_level.png"))
    plot_he_flow(history, os.path.join(OUTPUT_DIR, "cryo_tank_he_flow.png"))
    plot_heat_fluxes(history, os.path.join(OUTPUT_DIR, "cryo_tank_heat.png"))
    plot_pressure(history, os.path.join(OUTPUT_DIR, "cryo_tank_pressure.png"))

    print(f"\nOutputs written to {OUTPUT_DIR}/")


if __name__ == "__main__":
    main()