"""
Longley-Rice Irregular Terrain Model (ITM).

Best for:
- VHF/UHF over irregular terrain
- Point-to-point links
- Distances 1-2000 km

Note: This is a simplified area-mode version.
Full implementation requires terrain profile data.

Reference: NTIA Report 82-100
"""

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


class LongleyRiceModel(PropagationModel):

    @property
    def name(self) -> str:
        return "Longley-Rice"

    @property
    def frequency_range(self) -> tuple:
        return (20, 20000)  # 20 MHz to 20 GHz

    @property
    def distance_range(self) -> tuple:
        return (1000, 2000000)  # 1-2000 km

    def calculate(self, input: PropagationInput) -> PropagationOutput:
        """
        Simplified Longley-Rice (area mode).

        For proper implementation, use splat! or NTIA ITM reference.
        """
        f = input.frequency_mhz
        d = max(input.distance_m / 1000, 1.0)
        h1 = max(input.tx_height_m, 1.0)
        h2 = max(input.rx_height_m, 1.0)

        # Terrain irregularity parameter (simplified)
        delta_h = input.terrain_roughness_m or 90  # Default: rolling hills

        # Free space loss
        L_fs = 32.45 + 20 * math.log10(d) + 20 * math.log10(f)

        # Terrain clutter loss (simplified)
        if delta_h < 10:
            L_terrain = 0  # Flat
        elif delta_h < 50:
            L_terrain = 5  # Gently rolling
        elif delta_h < 150:
            L_terrain = 10  # Rolling hills
        else:
            L_terrain = 15  # Mountains

        # Height gain
        h_eff = h1 + h2
        height_gain = 10 * math.log10(h_eff / 20) if h_eff > 20 else 0

        L = L_fs + L_terrain - height_gain

        return PropagationOutput(
            path_loss_db=L,
            model_name=self.name,
            is_los=delta_h < 10 and d < 10,
            breakdown={
                "free_space_loss": L_fs,
                "terrain_loss": L_terrain,
                "height_gain": height_gain,
            },
        )