package world

import (
	"testing"

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

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

	cx, cy := PivotZoomCameraNoWrap(
		50*SCALE, 60*SCALE,
		100, 80,
		50, 40, // cursor at center
		SCALE, 2*SCALE,
	)
	require.Equal(t, 50*SCALE, cx)
	require.Equal(t, 60*SCALE, cy)
}

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

	// viewport 100px, cursor at x=100 (right edge), center is 50 => offX=50px
	// zoom 1->2 halves worldPerPx, so camera must move towards the cursor to keep the same world point.
	cx0 := 50 * SCALE

	cx, _ := PivotZoomCameraNoWrap(
		cx0, 50*SCALE,
		100, 100,
		100, 50,
		SCALE, 2*SCALE,
	)
	require.Greater(t, cx, cx0)
}

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

	cx0 := 50 * SCALE

	cx, _ := PivotZoomCameraNoWrap(
		cx0, 50*SCALE,
		100, 100,
		0, 50,
		SCALE, 2*SCALE,
	)
	require.Less(t, cx, cx0)
}