added implementation in GO lang

internal/modes/calculator.go

@@ -0,0 +1,235 @@
+package modes
+
+import (
+	"fmt"
+	"image/color"
+	"math"
+	"strconv"
+	"strings"
+
+	"github.com/hajimehoshi/ebiten/v2"
+
+	"kidskeyboard/internal/ui"
+)
+
+type CalculatorMode struct {
+	ctx      Context
+	display  string
+	acc      float64
+	op       string
+	newEntry bool
+	err      bool
+}
+
+func NewCalculatorMode(ctx Context) *CalculatorMode {
+	return &CalculatorMode{ctx: ctx, display: "0", newEntry: true}
+}
+
+func (m *CalculatorMode) Name() string { return "CTRL+F4 Calculator" }
+func (m *CalculatorMode) OnEnter()     {}
+func (m *CalculatorMode) OnLeave()     {}
+func (m *CalculatorMode) Update()      {}
+
+func (m *CalculatorMode) HandleInput() {
+	handled := false
+	valid := false
+	chars := ebiten.AppendInputChars(nil)
+
+	for _, r := range chars {
+		handled = true
+		if m.handleChar(r) {
+			valid = true
+		}
+	}
+
+	for _, key := range justPressedKeys() {
+		switch {
+		case key == ebiten.KeyDelete:
+			handled = true
+			m.clear()
+			valid = true
+		case key == ebiten.KeyBackspace:
+			handled = true
+			m.backspace()
+			valid = true
+		case key == ebiten.KeyEnter || key == ebiten.KeyNumpadEnter:
+			handled = true
+			m.equals()
+			valid = true
+		case isNumpadOperatorKey(key) && len(chars) == 0:
+			handled = true
+			m.operator(operatorForKey(key))
+			valid = true
+		default:
+			if childKey(key) && len(chars) == 0 {
+				handled = true
+			}
+		}
+	}
+
+	if valid {
+		m.ctx.Audio.PlayBeep()
+	} else if handled {
+		m.ctx.Audio.PlayError()
+	}
+}
+
+func (m *CalculatorMode) handleChar(r rune) bool {
+	switch {
+	case r >= '0' && r <= '9':
+		m.digit(string(r))
+		return true
+	case r == '+' || r == '-' || r == '*' || r == '/':
+		m.operator(string(r))
+		return true
+	case r == 'c' || r == 'C':
+		m.clear()
+		return true
+	default:
+		return false
+	}
+}
+
+func (m *CalculatorMode) Draw(screen *ebiten.Image) {
+	screen.Fill(color.Black)
+	w, h := screen.Bounds().Dx(), screen.Bounds().Dy()
+	ui.Text(screen, "CTRL+F4", 20, 20, color.White, 2)
+
+	panelW := float32(min(float64(w)*0.78, 620))
+	keySize := panelW / 4
+	startX := (float32(w) - panelW) / 2
+	startY := float32(h)/2 - keySize*1.9
+	displayH := keySize * 0.72
+
+	ui.Rect(screen, startX, startY-displayH-16, panelW, displayH, color.NRGBA{R: 20, G: 20, B: 20, A: 255})
+	ui.RectOutline(screen, startX, startY-displayH-16, panelW, displayH, 2, color.White)
+	scale := 4.0
+	if len(m.display) > 12 {
+		scale = 3
+	}
+	ui.CenteredText(screen, m.display, int(startX+panelW/2), int(startY-displayH/2-16), color.White, scale)
+
+	keys := [][]string{
+		{"7", "8", "9", "/"},
+		{"4", "5", "6", "*"},
+		{"1", "2", "3", "-"},
+		{"C", "0", "=", "+"},
+	}
+	for r, row := range keys {
+		for c, label := range row {
+			x := startX + float32(c)*keySize
+			y := startY + float32(r)*keySize
+			ui.Rect(screen, x+4, y+4, keySize-8, keySize-8, color.NRGBA{R: 28, G: 28, B: 28, A: 255})
+			ui.RectOutline(screen, x+4, y+4, keySize-8, keySize-8, 2, color.White)
+			ui.CenteredText(screen, label, int(x+keySize/2), int(y+keySize/2), color.White, 4)
+		}
+	}
+}
+
+func (m *CalculatorMode) digit(d string) {
+	if m.err || m.newEntry || m.display == "0" {
+		m.display = d
+		m.newEntry = false
+		m.err = false
+		return
+	}
+	if len(m.display) < 16 {
+		m.display += d
+	}
+}
+
+func (m *CalculatorMode) operator(op string) {
+	if m.err {
+		return
+	}
+	if m.op != "" && !m.newEntry {
+		m.equals()
+	}
+	m.acc = m.value()
+	m.op = op
+	m.newEntry = true
+}
+
+func (m *CalculatorMode) equals() {
+	if m.err || m.op == "" {
+		m.newEntry = true
+		return
+	}
+	right := m.value()
+	var result float64
+	switch m.op {
+	case "+":
+		result = m.acc + right
+	case "-":
+		result = m.acc - right
+	case "*":
+		result = m.acc * right
+	case "/":
+		if right == 0 {
+			m.display = "DIV 0"
+			m.err = true
+			m.op = ""
+			m.newEntry = true
+			return
+		}
+		result = m.acc / right
+	}
+	m.display = formatNumber(result)
+	m.acc = result
+	m.op = ""
+	m.newEntry = true
+}
+
+func (m *CalculatorMode) backspace() {
+	if m.err || m.newEntry || len(m.display) <= 1 {
+		m.display = "0"
+		m.err = false
+		m.newEntry = true
+		return
+	}
+	m.display = m.display[:len(m.display)-1]
+}
+
+func (m *CalculatorMode) clear() {
+	m.display = "0"
+	m.acc = 0
+	m.op = ""
+	m.err = false
+	m.newEntry = true
+}
+
+func (m *CalculatorMode) value() float64 {
+	v, _ := strconv.ParseFloat(m.display, 64)
+	return v
+}
+
+func formatNumber(v float64) string {
+	if math.Abs(v-math.Round(v)) < 0.0000001 {
+		return fmt.Sprintf("%.0f", v)
+	}
+	return strings.TrimRight(strings.TrimRight(fmt.Sprintf("%.6f", v), "0"), ".")
+}
+
+func isNumpadOperatorKey(key ebiten.Key) bool {
+	switch key {
+	case ebiten.KeyNumpadAdd, ebiten.KeyNumpadSubtract, ebiten.KeyNumpadMultiply, ebiten.KeyNumpadDivide:
+		return true
+	default:
+		return false
+	}
+}
+
+func operatorForKey(key ebiten.Key) string {
+	switch key {
+	case ebiten.KeyNumpadAdd:
+		return "+"
+	case ebiten.KeyNumpadSubtract:
+		return "-"
+	case ebiten.KeyNumpadMultiply:
+		return "*"
+	case ebiten.KeyNumpadDivide:
+		return "/"
+	default:
+		return ""
+	}
+}