2 files changed, 95 insertions, 0 deletions
diff --git a/pkg/field/step.go b/pkg/field/step.go
new file mode 100644
index 0000000..50147d2
--- /dev/null
+++ b/pkg/field/step.go
@@ -0,0 +1,20 @@
+package field
+
+func (f Field) Step(x, y, dx, dy int) (int, int) {
+	x2, y2 := x+dx, y+dy
+	if f.IsIn(x2, y2) {
+		return x2, y2
+	}
+	// We are stepping outside, we need to wrap the Lahey-space
+	for {
+		x2, y2 := x-dx, y-dy
+		if !f.IsIn(x2, y2) {
+			return x, y
+		}
+		x, y = x2, y2
+	}
+}
+
+func (f Field) IsIn(x, y int) bool {
+	return x >= f.x && x < f.x+f.lx && y >= f.y && y < f.y+f.ly
+}
diff --git a/pkg/field/step_test.go b/pkg/field/step_test.go
new file mode 100644
index 0000000..f7da366
--- /dev/null
+++ b/pkg/field/step_test.go
@@ -0,0 +1,75 @@
+package field
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestStep(t *testing.T) {
+	// Test cases
+	testCases := []struct {
+		name  string
+		input string
+		x     int
+		y     int
+		dx    int
+		dy    int
+		ex    int // expectedX
+		ey    int
+	}{
+		{"minimal0", "test_data/minimal.b98", 0, 0, 0, 0, 0, 0},
+		{"minimal1", "test_data/minimal.b98", 0, 0, 1, 0, 0, 0},
+		{"hello0", "test_data/hello.b98", 3, 0, 0, 0, 3, 0},
+		{"hello1", "test_data/hello.b98", 3, 0, 1, 0, 4, 0},
+		{"dna0", "test_data/dna.b98", 3, 3, 2, 1, 5, 4},
+		{"dna1", "test_data/dna.b98", 6, 1, 1, 1, 5, 0},
+		{"dna2", "test_data/dna.b98", 1, 4, -2, 2, 5, 0},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			file, err := os.Open(tc.input)
+			require.NoError(t, err, "Failed to open file")
+			defer file.Close()
+			field, err := LoadFile(file)
+			x, y := field.Step(tc.x, tc.y, tc.dx, tc.dy)
+			require.NoError(t, err)
+			require.Equal(t, tc.ex, x, "Invalid x value")
+			require.Equal(t, tc.ey, y, "Invalid y value")
+		})
+	}
+}
+
+func TestIsIn(t *testing.T) {
+	// Test cases
+	testCases := []struct {
+		name     string
+		input    string
+		inputX   int
+		inputY   int
+		expected bool
+	}{
+		{"minimal0,0", "test_data/minimal.b98", 0, 0, true},
+		{"minimal-1,0", "test_data/minimal.b98", -1, 0, false},
+		{"minimal1,0", "test_data/minimal.b98", 1, 0, false},
+		{"minimal0,-1", "test_data/minimal.b98", 0, -1, false},
+		{"minimal0,1", "test_data/minimal.b98", 0, 1, false},
+		{"hello3,0", "test_data/hello.b98", 3, 0, true},
+		{"hello3,1", "test_data/hello.b98", 3, 1, false},
+		{"factorial0,1", "test_data/factorial.b98", 0, 1, true},
+		{"factorial14,1", "test_data/factorial.b98", 14, 1, true},
+		{"factorial15,1", "test_data/factorial.b98", 15, 1, false},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			file, err := os.Open(tc.input)
+			require.NoError(t, err, "Failed to open file")
+			defer file.Close()
+			field, err := LoadFile(file)
+			valid := field.IsIn(tc.inputX, tc.inputY)
+			require.NoError(t, err)
+			require.Equal(t, tc.expected, valid, "Invalid value")
+		})
+	}
+}