package world

import (
	"testing"

	"github.com/stretchr/testify/require"
)

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

	// World 10 units => 10000 fixed.
	worldW := 10 * SCALE
	worldH := 10 * SCALE

	// Tie-case along X: 1 -> 6 is exactly half world apart (dx = +5000).
	// Deterministic rule chooses negative delta representation (wrap is applied).
	l := Line{
		X1: 1 * SCALE, Y1: 5 * SCALE,
		X2: 6 * SCALE, Y2: 5 * SCALE,
	}

	segs := torusShortestLineSegments(l, worldW, worldH)

	// Expect two horizontal segments:
	// [6000..10000] and [0..1000] at y=5000.
	require.Len(t, segs, 2)

	// Direction is deterministic and follows the chosen negative-delta representation.
	require.Equal(t, lineSeg{x1: 1000, y1: 5000, x2: 0, y2: 5000}, segs[0])
	require.Equal(t, lineSeg{x1: 10000, y1: 5000, x2: 6000, y2: 5000}, segs[1])
}

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

	w := NewWorld(10, 10)
	w.resetGrid(2 * SCALE)

	// Tie-case along X: 1 -> 6 in world of 10.
	_, err := w.AddLine(1, 5, 6, 5)
	require.NoError(t, err)
	for _, obj := range w.objects {
		w.indexObject(obj)
	}

	params := RenderParams{
		ViewportWidthPx:  10,
		ViewportHeightPx: 10,
		MarginXPx:        0,
		MarginYPx:        0,
		CameraXWorldFp:   5 * SCALE,
		CameraYWorldFp:   5 * SCALE,
		CameraZoom:       1.0,
		Options: &RenderOptions{
			DisableWrapScroll: true,
			Layers:            []RenderLayer{RenderLayerLines},
		},
	}

	d := &fakePrimitiveDrawer{}
	require.NoError(t, w.Render(d, params))

	lines := d.CommandsByName("AddLine")
	require.Len(t, lines, 1)

	// At zoom=1 and margin=0, world==canvas, so pixels equal world units.
	require.Equal(t, []float64{1, 5, 6, 5}, lines[0].Args)
}