Initial commit

lib/calculator_logic.dart

@@ -0,0 +1,96 @@
+class CalculatorLogic {
+  String _display = '0';
+  double _firstOperand = 0;
+  String _operator = '';
+  bool _waitingForSecondOperand = false;
+
+  String get display => _display;
+
+  void inputDigit(String digit) {
+    if (_waitingForSecondOperand) {
+      _display = digit;
+      _waitingForSecondOperand = false;
+    } else {
+      _display = _display == '0' ? digit : _display + digit;
+    }
+  }
+
+  void inputDecimal() {
+    if (_waitingForSecondOperand) {
+      _display = '0.';
+      _waitingForSecondOperand = false;
+      return;
+    }
+    if (!_display.contains('.')) {
+      _display += '.';
+    }
+  }
+
+  void inputOperator(String op) {
+    final current = double.parse(_display);
+
+    if (_operator.isNotEmpty && !_waitingForSecondOperand) {
+      _firstOperand = _calculate(_firstOperand, current, _operator);
+      _display = _formatResult(_firstOperand);
+    } else {
+      _firstOperand = current;
+    }
+
+    _operator = op;
+    _waitingForSecondOperand = true;
+  }
+
+  void calculate() {
+    if (_operator.isEmpty) return;
+
+    final secondOperand = double.parse(_display);
+    final result = _calculate(_firstOperand, secondOperand, _operator);
+    _display = _formatResult(result);
+    _firstOperand = result;
+    _operator = '';
+    _waitingForSecondOperand = true;
+  }
+
+  void clear() {
+    _display = '0';
+    _firstOperand = 0;
+    _operator = '';
+    _waitingForSecondOperand = false;
+  }
+
+  void toggleSign() {
+    final value = double.parse(_display);
+    _display = _formatResult(-value);
+  }
+
+  void percent() {
+    final value = double.parse(_display);
+    _display = _formatResult(value / 100);
+  }
+
+  double _calculate(double a, double b, String op) {
+    switch (op) {
+      case '+':
+        return a + b;
+      case '-':
+        return a - b;
+      case '*':
+        return a * b;
+      case '/':
+        if (b == 0) return double.infinity;
+        return a / b;
+      default:
+        return b;
+    }
+  }
+
+  String _formatResult(double value) {
+    if (value.isInfinite || value.isNaN) {
+      return value.toString();
+    }
+    if (value == value.toInt().toDouble()) {
+      return value.toInt().toString();
+    }
+    return value.toString();
+  }
+}

lib/main.dart

@@ -0,0 +1,159 @@
+import 'package:flutter/material.dart';
+import 'calculator_logic.dart';
+
+void main() {
+  runApp(const KalkulatorApp());
+}
+
+class KalkulatorApp extends StatelessWidget {
+  const KalkulatorApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Kalkulator',
+      theme: ThemeData(
+        colorScheme: ColorScheme.fromSeed(
+          seedColor: Colors.blueGrey,
+          brightness: Brightness.dark,
+        ),
+        useMaterial3: true,
+      ),
+      home: const CalculatorScreen(),
+    );
+  }
+}
+
+class CalculatorScreen extends StatefulWidget {
+  const CalculatorScreen({super.key});
+
+  @override
+  State<CalculatorScreen> createState() => _CalculatorScreenState();
+}
+
+class _CalculatorScreenState extends State<CalculatorScreen> {
+  final _logic = CalculatorLogic();
+
+  void _onPressed(String label) {
+    setState(() {
+      switch (label) {
+        case 'C':
+          _logic.clear();
+        case '+/-':
+          _logic.toggleSign();
+        case '%':
+          _logic.percent();
+        case '=':
+          _logic.calculate();
+        case '.':
+          _logic.inputDecimal();
+        case '+' || '-' || '*' || '/':
+          _logic.inputOperator(label);
+        default:
+          _logic.inputDigit(label);
+      }
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      backgroundColor: Colors.black,
+      body: SafeArea(
+        child: Column(
+          children: [
+            Expanded(
+              child: Container(
+                alignment: Alignment.bottomRight,
+                padding: const EdgeInsets.all(24),
+                child: Text(
+                  _logic.display,
+                  style: const TextStyle(
+                    fontSize: 64,
+                    fontWeight: FontWeight.w300,
+                    color: Colors.white,
+                  ),
+                  maxLines: 1,
+                  overflow: TextOverflow.ellipsis,
+                ),
+              ),
+            ),
+            _buildButtonRow(['C', '+/-', '%', '/']),
+            _buildButtonRow(['7', '8', '9', '*']),
+            _buildButtonRow(['4', '5', '6', '-']),
+            _buildButtonRow(['1', '2', '3', '+']),
+            _buildButtonRow(['0', '.', '=']),
+            const SizedBox(height: 8),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildButtonRow(List<String> labels) {
+    return Padding(
+      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
+      child: Row(
+        children: labels.map((label) {
+          final isWide = label == '0' && labels.length == 3;
+          return Expanded(
+            flex: isWide ? 2 : 1,
+            child: Padding(
+              padding: const EdgeInsets.all(4),
+              child: _CalcButton(
+                label: label,
+                onPressed: () => _onPressed(label),
+                color: _buttonColor(label),
+                textColor: _textColor(label),
+              ),
+            ),
+          );
+        }).toList(),
+      ),
+    );
+  }
+
+  Color _buttonColor(String label) {
+    if (['+', '-', '*', '/', '='].contains(label)) return Colors.orange;
+    if (['C', '+/-', '%'].contains(label)) return Colors.grey.shade700;
+    return Colors.grey.shade900;
+  }
+
+  Color _textColor(String label) {
+    if (['C', '+/-', '%'].contains(label)) return Colors.black;
+    return Colors.white;
+  }
+}
+
+class _CalcButton extends StatelessWidget {
+  final String label;
+  final VoidCallback onPressed;
+  final Color color;
+  final Color textColor;
+
+  const _CalcButton({
+    required this.label,
+    required this.onPressed,
+    required this.color,
+    required this.textColor,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return ElevatedButton(
+      onPressed: onPressed,
+      style: ElevatedButton.styleFrom(
+        backgroundColor: color,
+        foregroundColor: textColor,
+        padding: const EdgeInsets.all(20),
+        shape: RoundedRectangleBorder(
+          borderRadius: BorderRadius.circular(16),
+        ),
+      ),
+      child: Text(
+        label,
+        style: const TextStyle(fontSize: 28, fontWeight: FontWeight.w400),
+      ),
+    );
+  }
+}