"""
Unit tests for line-of-sight and Fresnel zone calculations.
"""

import sys
import os
import math

sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', '..'))

from app.geometry.los import fresnel_radius, check_los_terrain


def freq_to_wavelength(freq_mhz):
    return 300.0 / freq_mhz


class TestFresnelRadius:
    def test_positive_result(self):
        r = fresnel_radius(500, 500, freq_to_wavelength(1800))
        assert r > 0

    def test_symmetric(self):
        wl = freq_to_wavelength(900)
        r1 = fresnel_radius(300, 700, wl)
        r2 = fresnel_radius(700, 300, wl)
        assert abs(r1 - r2) < 0.001

    def test_lower_freq_larger_radius(self):
        r_high = fresnel_radius(500, 500, freq_to_wavelength(1800))
        r_low = fresnel_radius(500, 500, freq_to_wavelength(900))
        assert r_low > r_high

    def test_center_is_maximum(self):
        """Fresnel radius is largest at the midpoint of the path."""
        wl = freq_to_wavelength(900)
        r_center = fresnel_radius(500, 500, wl)
        r_offset = fresnel_radius(200, 800, wl)
        assert r_center > r_offset

    def test_known_value(self):
        """First Fresnel zone radius at midpoint of 1km path at 1GHz ~ 8.66m."""
        # F1 = sqrt(lambda * d1 * d2 / (d1+d2))
        # lambda = 0.3m at 1000MHz, d1=d2=500m
        # F1 = sqrt(0.3 * 500 * 500 / 1000) = sqrt(75) ~ 8.66m
        r = fresnel_radius(500, 500, freq_to_wavelength(1000))
        assert 8.0 < r < 9.5

    def test_zero_distance(self):
        r = fresnel_radius(0, 500, freq_to_wavelength(900))
        assert r == 0.0


class TestCheckLosTerrain:
    def test_flat_terrain_has_los(self):
        profile = [
            {"elevation": 100, "distance": 0},
            {"elevation": 100, "distance": 250},
            {"elevation": 100, "distance": 500},
            {"elevation": 100, "distance": 750},
            {"elevation": 100, "distance": 1000},
        ]
        result = check_los_terrain(profile, tx_height=30, rx_height=1.5)
        assert result["has_los"] is True
        assert result["clearance"] > 0

    def test_hill_blocks_los(self):
        profile = [
            {"elevation": 100, "distance": 0},
            {"elevation": 100, "distance": 250},
            {"elevation": 200, "distance": 500},  # 100m hill
            {"elevation": 100, "distance": 750},
            {"elevation": 100, "distance": 1000},
        ]
        result = check_los_terrain(profile, tx_height=10, rx_height=1.5)
        assert result["has_los"] is False
        assert result["blocked_at"] is not None

    def test_empty_profile(self):
        result = check_los_terrain([], tx_height=30, rx_height=1.5)
        assert result["has_los"] is True

    def test_high_antenna_clears_hill(self):
        profile = [
            {"elevation": 100, "distance": 0},
            {"elevation": 110, "distance": 500},
            {"elevation": 100, "distance": 1000},
        ]
        # TX at 150m (100+50), RX at 101.5m. LOS at 500m ≈ 125.75m, terrain=110m → clear
        result = check_los_terrain(profile, tx_height=50, rx_height=1.5)
        assert result["has_los"] is True


if __name__ == "__main__":
    for cls in [TestFresnelRadius, TestCheckLosTerrain]:
        instance = cls()
        for method_name in [m for m in dir(instance) if m.startswith("test_")]:
            try:
                getattr(instance, method_name)()
                print(f"  PASS  {cls.__name__}.{method_name}")
            except Exception as e:
                print(f"  FAIL  {cls.__name__}.{method_name}: {e}")
    print("\nAll tests completed.")