package geospatial

import (
	"math"
	"testing"
)

func TestCalculateBearing(t *testing.T) {
	calc := NewBearingCalculator(DefaultConfig())

	tests := []struct {
		name        string
		from        Point
		to          Point
		wantBearing float64
		tolerance   float64
	}{
		{
			name:        "North",
			from:        Point{Latitude: 52.5200, Longitude: 13.4050},
			to:          Point{Latitude: 52.5300, Longitude: 13.4050},
			wantBearing: 0.0, // North
			tolerance:   5.0,
		},
		{
			name:        "East",
			from:        Point{Latitude: 52.5200, Longitude: 13.4050},
			to:          Point{Latitude: 52.5200, Longitude: 13.4150},
			wantBearing: 90.0, // East
			tolerance:   5.0,
		},
		{
			name:        "South",
			from:        Point{Latitude: 52.5200, Longitude: 13.4050},
			to:          Point{Latitude: 52.5100, Longitude: 13.4050},
			wantBearing: 180.0, // South
			tolerance:   5.0,
		},
		{
			name:        "West",
			from:        Point{Latitude: 52.5200, Longitude: 13.4050},
			to:          Point{Latitude: 52.5200, Longitude: 13.3950},
			wantBearing: 270.0, // West
			tolerance:   5.0,
		},
	}

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

			// Normalize bearing difference
			diff := math.Abs(got - tt.wantBearing)
			if diff > 180 {
				diff = 360 - diff
			}

			if diff > tt.tolerance {
				t.Errorf("CalculateBearing() = %v, want %v (tolerance: %v)", got, tt.wantBearing, tt.tolerance)
			}
		})
	}
}

func TestCalculateBearingRadians(t *testing.T) {
	calc := NewBearingCalculator(DefaultConfig())

	from := Point{Latitude: 52.5200, Longitude: 13.4050}
	to := Point{Latitude: 52.5300, Longitude: 13.4150}

	gotRad, err := calc.CalculateBearingRadians(from, to)
	if err != nil {
		t.Fatalf("CalculateBearingRadians() error = %v", err)
	}

	gotDeg, err := calc.CalculateBearing(from, to)
	if err != nil {
		t.Fatalf("CalculateBearing() error = %v", err)
	}

	expectedRad := gotDeg * math.Pi / 180

	if math.Abs(gotRad-expectedRad) > 0.01 {
		t.Errorf("CalculateBearingRadians() = %v, expected %v (from degrees)", gotRad, expectedRad)
	}
}

func TestCalculateMidpoint(t *testing.T) {
	calc := NewBearingCalculator(DefaultConfig())

	tests := []struct {
		name      string
		p1        Point
		p2        Point
		wantLat   float64
		wantLon   float64
		tolerance float64
	}{
		{
			name:      "Simple midpoint",
			p1:        Point{Latitude: 50.0, Longitude: 10.0},
			p2:        Point{Latitude: 52.0, Longitude: 12.0},
			wantLat:   51.0,
			wantLon:   11.0,
			tolerance: 0.1,
		},
	}

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

			if math.Abs(got.Latitude-tt.wantLat) > tt.tolerance {
				t.Errorf("CalculateMidpoint() Latitude = %v, want %v", got.Latitude, tt.wantLat)
			}
			if math.Abs(got.Longitude-tt.wantLon) > tt.tolerance {
				t.Errorf("CalculateMidpoint() Longitude = %v, want %v", got.Longitude, tt.wantLon)
			}
		})
	}
}

func TestCalculateDestination(t *testing.T) {
	calc := NewBearingCalculator(DefaultConfig())

	origin := Point{Latitude: 52.5200, Longitude: 13.4050}
	bearing := 45.0  // Northeast
	distance := 10.0 // 10 km

	dest, err := calc.CalculateDestination(origin, bearing, distance)
	if err != nil {
		t.Fatalf("CalculateDestination() error = %v", err)
	}

	// Verify the destination is approximately northeast of origin
	if dest.Latitude <= origin.Latitude {
		t.Error("CalculateDestination() destination should be north of origin")
	}
	if dest.Longitude <= origin.Longitude {
		t.Error("CalculateDestination() destination should be east of origin")
	}

	// Verify distance is approximately correct
	distCalc := NewDistanceCalculator(DefaultConfig())
	actualDist, err := distCalc.HaversineDistance(origin, dest)
	if err != nil {
		t.Fatalf("HaversineDistance() error = %v", err)
	}

	if math.Abs(actualDist-distance) > 0.5 {
		t.Errorf("CalculateDestination() distance = %v, want %v", actualDist, distance)
	}
}