test_drip_engine.py

"""
Unit tests for drip_engine module.
"""

import pytest
import math
from shapely.geometry import Polygon, LineString
from drip_engine import (
    parse_geofence_to_polygon,
    validate_polygon,
    polygon_area_hectares,
    generate_drip_layout,
    estimate_bom,
    design_summary,
    DripLayoutError,
    latlon_to_utm,
)


class TestParseGeofence:
    """Test geofence parsing."""

    def test_parse_valid_rectangle(self):
        """Parse valid rectangular polygon."""
        geofence = "0,0;100,0;100,100;0,100"
        poly = parse_geofence_to_polygon(geofence)
        assert poly.is_valid
        assert len(list(poly.exterior.coords)) == 5  # 4 + closing point

    def test_parse_triangle(self):
        """Parse valid triangle."""
        geofence = "0,0;100,0;50,100"
        poly = parse_geofence_to_polygon(geofence)
        assert poly.is_valid
        assert poly.area > 0

    def test_parse_with_whitespace(self):
        """Handle extra whitespace."""
        geofence = "  0, 0 ; 100 , 0 ; 100 , 100 ; 0 , 100  "
        poly = parse_geofence_to_polygon(geofence)
        assert poly.is_valid

    def test_parse_invalid_format(self):
        """Reject invalid format."""
        with pytest.raises(DripLayoutError):
            parse_geofence_to_polygon("0,0;100")  # Missing y coord

    def test_parse_too_few_points(self):
        """Reject polygon with < 3 points."""
        with pytest.raises(DripLayoutError):
            parse_geofence_to_polygon("0,0;100,100")  # Only 2 points

    def test_parse_zero_area(self):
        """Reject collinear points (zero area)."""
        with pytest.raises(DripLayoutError):
            parse_geofence_to_polygon("0,0;50,50;100,100")  # Collinear

    def test_parse_float_coordinates(self):
        """Parse float coordinates."""
        geofence = "0.5,0.5;100.5,0.5;100.5,100.5;0.5,100.5"
        poly = parse_geofence_to_polygon(geofence)
        assert poly.is_valid


class TestValidatePolygon:
    """Test polygon validation."""

    def test_validate_valid_rectangle(self):
        """Validate a valid rectangle."""
        poly = Polygon([(0, 0), (100, 0), (100, 100), (0, 100)])
        is_valid, msg = validate_polygon(poly)
        assert is_valid
        assert msg == "Valid"

    def test_validate_self_intersecting(self):
        """Reject self-intersecting polygon."""
        # Bowtie shape: self-intersecting
        poly = Polygon([(0, 0), (100, 100), (100, 0), (0, 100)])
        is_valid, msg = validate_polygon(poly)
        assert not is_valid

    def test_validate_too_small(self):
        """Reject polygon with tiny area."""
        poly = Polygon([(0, 0), (0.1, 0), (0.1, 0.1), (0, 0.1)])
        is_valid, msg = validate_polygon(poly)
        assert not is_valid
        assert "too small" in msg.lower()


class TestAreaCalculation:
    """Test area calculation in hectares."""

    def test_area_100x100_meters(self):
        """100m x 100m = 1 hectare."""
        poly_utm = Polygon([(0, 0), (100, 0), (100, 100), (0, 100)])
        area_ha = polygon_area_hectares(poly_utm)
        assert abs(area_ha - 1.0) < 0.01

    def test_area_50x50_meters(self):
        """50m x 50m = 0.25 hectares."""
        poly_utm = Polygon([(0, 0), (50, 0), (50, 50), (0, 50)])
        area_ha = polygon_area_hectares(poly_utm)
        assert abs(area_ha - 0.25) < 0.01

    def test_area_large_field(self):
        """Large field: 500m x 200m = 10 hectares."""
        poly_utm = Polygon([(0, 0), (500, 0), (500, 200), (0, 200)])
        area_ha = polygon_area_hectares(poly_utm)
        assert abs(area_ha - 10.0) < 0.01


class TestDripLayout:
    """Test drip layout generation."""

    def test_generate_layout_rectangle(self):
        """Generate layout for a rectangular field."""
        # 100m x 50m field (0.5 ha)
        poly_utm = Polygon([(0, 0), (100, 0), (100, 50), (0, 50)])

        design = generate_drip_layout(
            poly_utm, crop="generic", headland_buffer_m=0
        )

        assert design["farm_area_ha"] > 0
        assert design["total_main_length_m"] > 0
        assert len(design["laterals"]) > 0
        assert design["total_drip_tape_m"] > 0
        assert design["emitter_count"] > 0

    def test_generate_layout_with_headland(self):
        """Headland buffer reduces area and pipe length."""
        poly_utm = Polygon([(0, 0), (100, 0), (100, 100), (0, 100)])

        design_no_buffer = generate_drip_layout(
            poly_utm, crop="generic", headland_buffer_m=0
        )
        design_with_buffer = generate_drip_layout(
            poly_utm, crop="generic", headland_buffer_m=5
        )

        # Area should be smaller with buffer
        assert design_with_buffer["farm_area_ha"] < design_no_buffer["farm_area_ha"]
        # Total pipe should be less
        assert (
            design_with_buffer["total_drip_tape_m"]
            < design_no_buffer["total_drip_tape_m"]
        )

    def test_generate_layout_crop_tomato(self):
        """Tomato has tighter spacing than orchard."""
        poly_utm = Polygon([(0, 0), (200, 0), (200, 100), (0, 100)])

        design_tomato = generate_drip_layout(
            poly_utm, crop="tomato", headland_buffer_m=0
        )
        design_orchard = generate_drip_layout(
            poly_utm, crop="orchard", headland_buffer_m=0
        )

        # Tomato should have tighter spacing (more laterals, more tape)
        assert design_tomato["total_drip_tape_m"] > design_orchard["total_drip_tape_m"]

    def test_generate_layout_override_spacing(self):
        """Override lateral spacing parameter."""
        poly_utm = Polygon([(0, 0), (200, 0), (200, 100), (0, 100)])

        design_default = generate_drip_layout(
            poly_utm, crop="generic", headland_buffer_m=0
        )
        design_tight = generate_drip_layout(
            poly_utm, crop="generic", headland_buffer_m=0, override_spacing_m=0.5
        )
        design_loose = generate_drip_layout(
            poly_utm, crop="generic", headland_buffer_m=0, override_spacing_m=2.0
        )

        # Tighter spacing = more tape
        assert design_tight["total_drip_tape_m"] > design_loose["total_drip_tape_m"]

    def test_generate_layout_irregular_polygon(self):
        """L-shaped field should still generate layout."""
        # L-shape: rectangle + extension
        poly_utm = Polygon(
            [
                (0, 0),
                (100, 0),
                (100, 100),
                (50, 100),
                (50, 50),
                (0, 50),
            ]
        )

        design = generate_drip_layout(poly_utm, crop="generic", headland_buffer_m=0)

        assert design["farm_area_ha"] > 0
        assert len(design["laterals"]) > 0

    def test_headland_too_large_raises_error(self):
        """Headland larger than field dimensions should raise error."""
        poly_utm = Polygon([(0, 0), (10, 0), (10, 10), (0, 10)])

        with pytest.raises(DripLayoutError):
            generate_drip_layout(
                poly_utm, crop="generic", headland_buffer_m=20
            )  # Larger than field


class TestBOM:
    """Test bill of materials estimation."""

    def test_bom_calculation(self):
        """BOM should have all required fields."""
        poly_utm = Polygon([(0, 0), (100, 0), (100, 100), (0, 100)])
        design = generate_drip_layout(poly_utm, crop="generic", headland_buffer_m=0)

        bom = estimate_bom(design, unit="inr")

        assert "main_line_16mm_m" in bom
        assert "drip_tape_16mm_m" in bom
        assert "inline_emitters" in bom
        assert "total_cost_inr" in bom or "total_cost" in bom
        assert bom.get("total_cost_inr", bom.get("total_cost")) > 0
        assert bom["currency"] == "INR"

    def test_bom_cost_breakdown(self):
        """Total cost should equal sum of components."""
        poly_utm = Polygon([(0, 0), (200, 0), (200, 100), (0, 100)])
        design = generate_drip_layout(poly_utm, crop="generic", headland_buffer_m=0)

        bom = estimate_bom(design, unit="inr")

        total = bom["cost_main"] + bom["cost_drip_tape"] + bom["cost_emitters"] + bom["cost_valves"]
        total_cost = bom.get("total_cost_inr", bom.get("total_cost"))
        assert abs(total_cost - total) < 0.01

    def test_bom_metric_mode(self):
        """Metric mode should not include costs."""
        poly_utm = Polygon([(0, 0), (100, 0), (100, 100), (0, 100)])
        design = generate_drip_layout(poly_utm, crop="generic", headland_buffer_m=0)

        bom = estimate_bom(design, unit="metric")

        assert "total_cost_usd" not in bom
        assert "main_line_16mm_m" in bom


class TestDesignSummary:
    """Test human-readable design summary."""

    def test_summary_format(self):
        """Summary should contain key metrics."""
        poly_utm = Polygon([(0, 0), (100, 0), (100, 100), (0, 100)])
        design = generate_drip_layout(poly_utm, crop="tomato", headland_buffer_m=1.0)
        bom = estimate_bom(design, unit="usd")

        summary = design_summary(design, bom)

        assert "Drip Irrigation Design Summary" in summary
        assert "Farm Area" in summary
        assert "Crop" in summary
        assert "Tomato" in summary
        assert "Main Line Length" in summary
        assert "Total Cost" in summary


class TestEdgeCases:
    """Test edge cases and boundary conditions."""

    def test_very_small_polygon(self):
        """Small polygon (1m x 1m) should still work."""
        poly_utm = Polygon([(0, 0), (1, 0), (1, 1), (0, 1)])
        design = generate_drip_layout(poly_utm, crop="generic", headland_buffer_m=0)
        assert design["farm_area_ha"] > 0

    def test_long_thin_polygon(self):
        """Long, thin field (strip) should still work."""
        poly_utm = Polygon([(0, 0), (1000, 0), (1000, 5), (0, 5)])
        design = generate_drip_layout(poly_utm, crop="generic", headland_buffer_m=0)
        assert len(design["laterals"]) > 0

    def test_triangle_polygon(self):
        """Triangular field should work."""
        poly_utm = Polygon([(0, 0), (100, 0), (50, 100)])
        design = generate_drip_layout(poly_utm, crop="generic", headland_buffer_m=0)
        assert design["farm_area_ha"] > 0


if __name__ == "__main__":
    pytest.main([__file__, "-v"])