"""
Okumura-Hata empirical propagation model.

Valid for:
- Frequency: 150-1500 MHz
- Distance: 1-20 km
- TX height: 30-200 m
- RX height: 1-10 m

Reference: Hata (1980), "Empirical Formula for Propagation Loss
           in Land Mobile Radio Services"
"""

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


class OkumuraHataModel(PropagationModel):

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

    @property
    def frequency_range(self) -> tuple:
        return (150, 1500)

    @property
    def distance_range(self) -> tuple:
        return (100, 20000)  # Extended to 100m minimum for practical use

    def calculate(self, input: PropagationInput) -> PropagationOutput:
        f = input.frequency_mhz
        d = max(input.distance_m / 1000, 0.1)  # km, min 100m
        hb = max(input.tx_height_m, 1.0)
        hm = max(input.rx_height_m, 1.0)

        # Mobile antenna height correction factor
        if input.environment == "urban" and f >= 400:
            # Large city
            a_hm = 3.2 * (math.log10(11.75 * hm) ** 2) - 4.97
        else:
            # Medium/small city
            a_hm = (1.1 * math.log10(f) - 0.7) * hm - (1.56 * math.log10(f) - 0.8)

        # Basic path loss (urban)
        L_urban = (
            69.55
            + 26.16 * math.log10(f)
            - 13.82 * math.log10(hb)
            - a_hm
            + (44.9 - 6.55 * math.log10(hb)) * math.log10(d)
        )

        # Environment correction
        if input.environment == "suburban":
            L = L_urban - 2 * (math.log10(f / 28) ** 2) - 5.4
        elif input.environment == "rural":
            L = L_urban - 4.78 * (math.log10(f) ** 2) + 18.33 * math.log10(f) - 35.94
        elif input.environment == "open":
            L = L_urban - 4.78 * (math.log10(f) ** 2) + 18.33 * math.log10(f) - 40.94
        else:
            L = L_urban

        return PropagationOutput(
            path_loss_db=L,
            model_name=self.name,
            is_los=False,
            breakdown={
                "basic_loss": L_urban,
                "environment_correction": L - L_urban,
                "antenna_correction": a_hm,
            },
        )