feat: solve day 1 part 1

cmd/01/dial/dial.go

@@ -0,0 +1,48 @@
+// Package dial provides a model for representing a dial
+package dial
+
+import (
+	"github.com/StevanFreeborn/advent-of-code-2025/cmd/01/direction"
+	"github.com/StevanFreeborn/advent-of-code-2025/cmd/01/instruction"
+)
+
+type Dial interface {
+	Value() int
+	Turn(instruction instruction.Instruction)
+}
+
+type dial struct {
+	value int
+}
+
+func New() Dial {
+	return &dial{
+		value: 50,
+	}
+}
+
+func (d *dial) Value() int {
+	return d.value
+}
+
+func (d *dial) Turn(instruction instruction.Instruction) {
+	if instruction.Direction() == direction.Left {
+		d.value -= instruction.Distance()
+
+		for d.value < 0 {
+			d.value += 100
+		}
+
+		return
+	}
+
+	if instruction.Direction() == direction.Right {
+		d.value += instruction.Distance()
+
+		for d.value > 99 {
+			d.value -= 100
+		}
+
+		return
+	}
+}

cmd/01/dial/dial_test.go

@@ -0,0 +1,78 @@
+package dial_test
+
+import (
+	"testing"
+
+	"github.com/StevanFreeborn/advent-of-code-2025/cmd/01/dial"
+	"github.com/StevanFreeborn/advent-of-code-2025/cmd/01/instruction"
+)
+
+func TestNew(t *testing.T) {
+	expectedStartingValue := 50
+	result := dial.New()
+
+	if result.Value() != expectedStartingValue {
+		t.Errorf("got unexpected beginning value. expected %d but got %d", expectedStartingValue, result.Value())
+	}
+}
+
+type TurnTestCase struct {
+	Instruction       instruction.Instruction
+	ExpectedDialValue int
+}
+
+func TestTurn(t *testing.T) {
+	testCases := []TurnTestCase{
+		{
+			Instruction:       instruction.FromParts("L", 68),
+			ExpectedDialValue: 82,
+		},
+		{
+			Instruction:       instruction.FromParts("L", 30),
+			ExpectedDialValue: 52,
+		},
+		{
+			Instruction:       instruction.FromParts("R", 48),
+			ExpectedDialValue: 0,
+		},
+		{
+			Instruction:       instruction.FromParts("L", 5),
+			ExpectedDialValue: 95,
+		},
+		{
+			Instruction:       instruction.FromParts("R", 60),
+			ExpectedDialValue: 55,
+		},
+		{
+			Instruction:       instruction.FromParts("L", 55),
+			ExpectedDialValue: 0,
+		},
+		{
+			Instruction:       instruction.FromParts("L", 1),
+			ExpectedDialValue: 99,
+		},
+		{
+			Instruction:       instruction.FromParts("L", 99),
+			ExpectedDialValue: 0,
+		},
+		{
+			Instruction:       instruction.FromParts("R", 14),
+			ExpectedDialValue: 14,
+		},
+		{
+			Instruction:       instruction.FromParts("L", 82),
+			ExpectedDialValue: 32,
+		},
+	}
+
+	dial := dial.New()
+
+	for i, testCase := range testCases {
+
+		dial.Turn(testCase.Instruction)
+
+		if dial.Value() != testCase.ExpectedDialValue {
+			t.Errorf("%d: got dial value %d, but expected dial value %d", i, dial.Value(), testCase.ExpectedDialValue)
+		}
+	}
+}