"""
Unit tests for line-segment intersection calculations.

These require NumPy, so use __main__ block with conditional import.
"""

import sys
import os

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

import numpy as np
from app.geometry.intersection import line_segments_intersect_batch


class TestLineSegmentIntersect:
    def test_crossing_lines(self):
        """Two crossing segments should intersect."""
        # Line from (0,0)→(1,1) and (0,1)→(1,0)
        result = line_segments_intersect_batch(
            p1=np.array([0.0, 0.0]),
            p2=np.array([1.0, 1.0]),
            seg_starts=np.array([[0.0, 1.0]]),
            seg_ends=np.array([[1.0, 0.0]]),
        )
        assert result[0] == True

    def test_parallel_lines(self):
        """Parallel lines should not intersect."""
        result = line_segments_intersect_batch(
            p1=np.array([0.0, 0.0]),
            p2=np.array([1.0, 0.0]),
            seg_starts=np.array([[0.0, 1.0]]),
            seg_ends=np.array([[1.0, 1.0]]),
        )
        assert result[0] == False

    def test_non_crossing(self):
        """Segments that don't reach each other."""
        result = line_segments_intersect_batch(
            p1=np.array([0.0, 0.0]),
            p2=np.array([0.5, 0.5]),
            seg_starts=np.array([[0.8, 0.0]]),
            seg_ends=np.array([[0.8, 1.0]]),
        )
        assert result[0] == False

    def test_multiple_segments(self):
        """Batch test with multiple segments."""
        result = line_segments_intersect_batch(
            p1=np.array([0.0, 0.0]),
            p2=np.array([1.0, 1.0]),
            seg_starts=np.array([
                [0.0, 1.0],   # crosses
                [2.0, 0.0],   # doesn't cross
                [0.5, 0.0],   # crosses
            ]),
            seg_ends=np.array([
                [1.0, 0.0],   # crosses
                [2.0, 1.0],   # doesn't cross
                [0.5, 1.0],   # crosses
            ]),
        )
        assert result[0] == True
        assert result[1] == False
        assert result[2] == True


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