"""
Free Space Path Loss (FSPL) model.

Used as baseline and for LOS conditions.
FSPL = 20*log10(d) + 20*log10(f) + 32.45
where d in km, f in MHz
"""

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


class FreeSpaceModel(PropagationModel):
    """Free Space Path Loss — theoretical minimum propagation loss."""

    @property
    def name(self) -> str:
        return "Free-Space"

    @property
    def frequency_range(self) -> tuple:
        return (1, 100000)

    @property
    def distance_range(self) -> tuple:
        return (1, 1000000)  # 1m to 1000km

    def calculate(self, input: PropagationInput) -> PropagationOutput:
        d_km = max(input.distance_m / 1000, 0.001)
        f = input.frequency_mhz

        L = 20 * math.log10(d_km) + 20 * math.log10(f) + 32.45

        return PropagationOutput(
            path_loss_db=L,
            model_name=self.name,
            is_los=True,
            breakdown={
                "distance_loss": 20 * math.log10(d_km),
                "frequency_loss": 20 * math.log10(f),
                "constant": 32.45,
            },
        )