package position_test

import (
	"math"
	"testing"

	"git.wtrh.nl/patterns/gopatterns/pkg/position"
	"git.wtrh.nl/patterns/gopatterns/pkg/vector"
	"github.com/stretchr/testify/require"
)

func TestPosition_Direction(t *testing.T) {
	t.Parallel()

	type testCase struct {
		A, B           position.Position
		ExpA2B, ExpB2A float64
	}

	testCases := []testCase{
		{
			A: position.Position{
				Vector:   vector.Vector{X: 0, Y: 0},
				Rotation: math.Pi / 4,
			},
			B: position.Position{
				Vector:   vector.Vector{X: 2, Y: 0},
				Rotation: 3 * math.Pi / 4,
			},
			ExpA2B: -math.Pi / 4,
			ExpB2A: math.Pi / 4,
		},
		{
			A: position.Position{
				Vector:   vector.Vector{X: 0, Y: 1},
				Rotation: math.Pi,
			},
			B: position.Position{
				Vector:   vector.Vector{X: 1, Y: 0},
				Rotation: -math.Pi / 2,
			},
			ExpA2B: 3 * math.Pi / 4,
			ExpB2A: -3 * math.Pi / 4,
		},
	}

	for _, test := range testCases {
		actA2B := test.A.Direction(test.B)
		require.InDelta(t, test.ExpA2B, actA2B, 1e-12)

		actB2A := test.B.Direction(test.A)
		require.InDelta(t, test.ExpB2A, actB2A, 1e-12)
	}
}

func TestPosition_Add(t *testing.T) {
	t.Parallel()

	tests := map[string]struct {
		p, q position.Position
		want position.Position
	}{
		"straight angle": {
			p: position.Position{
				Vector:   vector.Vector{X: 1, Y: 0},
				Rotation: math.Pi / 2,
			},
			q: position.Position{
				Vector:   vector.Vector{X: 1, Y: 0},
				Rotation: 0,
			},
			want: position.Position{
				Vector:   vector.Vector{X: 1, Y: 1},
				Rotation: math.Pi / 2,
			},
		},
		"3-4-5 triangle": {
			p: position.Position{
				Vector:   vector.Vector{X: -2, Y: 0},
				Rotation: math.Atan2(3, 4),
			},
			q: position.Position{
				Vector:   vector.Vector{X: 5, Y: 0},
				Rotation: -math.Atan2(3, 4),
			},
			want: position.Position{
				Vector:   vector.Vector{X: 2, Y: 3},
				Rotation: 0,
			},
		},
	}

	for name, tt := range tests {
		t.Run(name, func(t *testing.T) {
			t.Parallel()

			require.Equal(t, tt.want, tt.p.Add(tt.q))
		})
	}
}