"""
COST-231 Hata model (extension of Okumura-Hata).

Valid for:
- Frequency: 1500-2000 MHz
- Distance: 1-20 km

Better for LTE bands than original Okumura-Hata.
"""

import math
from app.propagation.base import PropagationModel, PropagationInput, PropagationOutput


class Cost231HataModel(PropagationModel):

    @property
    def name(self) -> str:
        return "COST-231-Hata"

    @property
    def frequency_range(self) -> tuple:
        return (1500, 2000)

    @property
    def distance_range(self) -> tuple:
        return (100, 20000)

    def calculate(self, input: PropagationInput) -> PropagationOutput:
        f = input.frequency_mhz
        d = max(input.distance_m / 1000, 0.1)
        hb = max(input.tx_height_m, 1.0)
        hm = max(input.rx_height_m, 1.0)

        # Mobile antenna correction (medium city)
        a_hm = (1.1 * math.log10(f) - 0.7) * hm - (1.56 * math.log10(f) - 0.8)

        # Metropolitan center correction
        C_m = 3 if input.environment == "urban" else 0

        L = (
            46.3
            + 33.9 * math.log10(f)
            - 13.82 * math.log10(hb)
            - a_hm
            + (44.9 - 6.55 * math.log10(hb)) * math.log10(d)
            + C_m
        )

        return PropagationOutput(
            path_loss_db=L,
            model_name=self.name,
            is_los=False,
            breakdown={
                "base_loss": 46.3,
                "frequency_term": 33.9 * math.log10(f),
                "height_gain": -13.82 * math.log10(hb),
                "mobile_correction": -a_hm,
                "distance_term": (44.9 - 6.55 * math.log10(hb)) * math.log10(d),
                "metro_correction": C_m,
            },
        )