package geospatial

import (
	"math"
	"testing"
)

func TestHaversineDistance(t *testing.T) {
	calc := NewDistanceCalculator(DefaultConfig())

	tests := []struct {
		name      string
		p1        Point
		p2        Point
		wantDist  float64
		tolerance float64
	}{
		{
			name:      "Same point",
			p1:        Point{Latitude: 52.5200, Longitude: 13.4050}, // Berlin
			p2:        Point{Latitude: 52.5200, Longitude: 13.4050},
			wantDist:  0.0,
			tolerance: 0.001,
		},
		{
			name:      "Berlin to Munich",
			p1:        Point{Latitude: 52.5200, Longitude: 13.4050}, // Berlin
			p2:        Point{Latitude: 48.1351, Longitude: 11.5820}, // Munich
			wantDist:  504.0,                                        // Approximately 504 km
			tolerance: 5.0,
		},
		{
			name:      "Short distance",
			p1:        Point{Latitude: 52.5200, Longitude: 13.4050},
			p2:        Point{Latitude: 52.5300, Longitude: 13.4150},
			wantDist:  1.3, // Approximately 1.3 km
			tolerance: 0.1,
		},
		{
			name:      "Cross equator",
			p1:        Point{Latitude: 10.0, Longitude: 0.0},
			p2:        Point{Latitude: -10.0, Longitude: 0.0},
			wantDist:  2220.0, // Approximately 2220 km
			tolerance: 10.0,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, err := calc.HaversineDistance(tt.p1, tt.p2)
			if err != nil {
				t.Fatalf("HaversineDistance() error = %v", err)
			}

			if math.Abs(got-tt.wantDist) > tt.tolerance {
				t.Errorf("HaversineDistance() = %v, want %v (tolerance: %v)", got, tt.wantDist, tt.tolerance)
			}
		})
	}
}

func TestHaversineDistance_InvalidPoints(t *testing.T) {
	calc := NewDistanceCalculator(DefaultConfig())

	tests := []struct {
		name string
		p1   Point
		p2   Point
	}{
		{
			name: "Invalid latitude - too high",
			p1:   Point{Latitude: 91.0, Longitude: 0.0},
			p2:   Point{Latitude: 52.5200, Longitude: 13.4050},
		},
		{
			name: "Invalid latitude - too low",
			p1:   Point{Latitude: -91.0, Longitude: 0.0},
			p2:   Point{Latitude: 52.5200, Longitude: 13.4050},
		},
		{
			name: "Invalid longitude - too high",
			p1:   Point{Latitude: 52.5200, Longitude: 181.0},
			p2:   Point{Latitude: 52.5200, Longitude: 13.4050},
		},
		{
			name: "Invalid longitude - too low",
			p1:   Point{Latitude: 52.5200, Longitude: -181.0},
			p2:   Point{Latitude: 52.5200, Longitude: 13.4050},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			_, err := calc.HaversineDistance(tt.p1, tt.p2)
			if err == nil {
				t.Error("HaversineDistance() expected error for invalid point")
			}
		})
	}
}

func TestVincentyDistance(t *testing.T) {
	config := DefaultConfig()
	config.UseEllipsoidalModel = true
	calc := NewDistanceCalculator(config)

	tests := []struct {
		name      string
		p1        Point
		p2        Point
		wantDist  float64
		tolerance float64
	}{
		{
			name:      "Same point",
			p1:        Point{Latitude: 52.5200, Longitude: 13.4050},
			p2:        Point{Latitude: 52.5200, Longitude: 13.4050},
			wantDist:  0.0,
			tolerance: 0.001,
		},
		{
			name:      "Berlin to Munich",
			p1:        Point{Latitude: 52.5200, Longitude: 13.4050}, // Berlin
			p2:        Point{Latitude: 48.1351, Longitude: 11.5820}, // Munich
			wantDist:  504.0,                                        // Approximately 504 km
			tolerance: 5.0,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, err := calc.VincentyDistance(tt.p1, tt.p2)
			if err != nil {
				t.Fatalf("VincentyDistance() error = %v", err)
			}

			if math.Abs(got-tt.wantDist) > tt.tolerance {
				t.Errorf("VincentyDistance() = %v, want %v (tolerance: %v)", got, tt.wantDist, tt.tolerance)
			}
		})
	}
}

func TestCalculateDistance(t *testing.T) {
	tests := []struct {
		name      string
		method    string
		p1        Point
		p2        Point
		wantDist  float64
		tolerance float64
	}{
		{
			name:      "Haversine method",
			method:    "haversine",
			p1:        Point{Latitude: 52.5200, Longitude: 13.4050},
			p2:        Point{Latitude: 52.5300, Longitude: 13.4150},
			wantDist:  1.3,
			tolerance: 0.1,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			config := DefaultConfig()
			config.DefaultDistanceMethod = tt.method
			calc := NewDistanceCalculator(config)

			impl := calc.(*DistanceCalculatorImpl)
			got, err := impl.CalculateDistance(tt.p1, tt.p2)
			if err != nil {
				t.Fatalf("CalculateDistance() error = %v", err)
			}

			if math.Abs(got-tt.wantDist) > tt.tolerance {
				t.Errorf("CalculateDistance() = %v, want %v (tolerance: %v)", got, tt.wantDist, tt.tolerance)
			}
		})
	}
}