const fs = require('fs');
const path = require('path');
const assert = require('assert');

// --- Mock Bangle.js environment ---
let mock_display_str = "";
let mock_ui_callbacks = {};

// Mock 'g' (graphics)
global.g = {
  _col: 0,
  _bg: 0,
  _font: "6x8",
  _font_size: 1,
  clear: () => {},
  clearRect: () => {},
  setColor: (c) => { global.g._col = c; return global.g; },
  setBgColor: (c) => { global.g._bg = c; return global.g; },
  fillRect: () => {},
  setFont: function(font, size) {
    if (font && font.includes(":")) {
      const parts = font.split(":");
      this._font = parts[0];
      this._font_size = parseInt(parts[1], 10);
    } else {
      this._font = font;
      if (size) this._font_size = size;
    }
    return this;
  },
  setFontAlign: () => {},
  stringWidth: (s) => s.length * 8 * (global.g._font_size || 1), // simple approximation
  getWidth: () => 176,
  getHeight: () => 176,
  drawString: (s) => { mock_display_str = String(s); },
  getFontHeight: () => 8 * (global.g._font_size || 1)
};

global.Graphics = {};

// Mock 'process'
global.process = {
  env: { HWVERSION: 2 } // Simulate Bangle.js 2
};

// Mock 'Bangle'
global.Bangle = {
  setUI: (callbacks) => { mock_ui_callbacks = callbacks; },
  http: () => new Promise(resolve => resolve({resp: "{}"})),
  buzz: () => {},
};

// Mock 'load' (to exit app)
global.load = () => {};

// --- End Mock ---


// --- Load calculator app ---
const calculatorCode = fs.readFileSync(path.join(__dirname, 'calculator.app.js'), 'utf8');
(function(require) {
  eval(calculatorCode);
})((name) => {
  if (name === "FontDylex7x13") {
    return { add: () => {} };
  }
  return require(name);
});
// --- End Load ---


// --- Test Framework ---
const test_suite = [];
let tests_passed = 0;
let tests_failed = 0;

function test(name, fn) {
  test_suite.push({ name, fn });
}

function runTests() {
  test_suite.forEach(t => {
    // Reset state before each test
    buttonPress('R'); // C
    buttonPress('R'); // AC
    if (mock_display_str !== '0') {
      console.error(`[FAIL] ${t.name} - Failed to reset state. Display is: "${mock_display_str}"`);
      tests_failed++;
      return;
    }

    try {
      t.fn();
      console.log(`[PASS] ${t.name}`);
      tests_passed++;
    } catch (e) {
      console.error(`[FAIL] ${t.name}`);
      console.error(e);
      tests_failed++;
    }
  });

  console.log(`\nTests finished. Passed: ${tests_passed}, Failed: ${tests_failed}.`);
  if (tests_failed > 0) {
    process.exit(1);
  }
}

function press(buttons) {
  for (const button of buttons) {
    buttonPress(button);
  }
}

function checkDisplay(expected, message) {
  assert.strictEqual(mock_display_str, String(expected), message);
}
// --- End Test Framework ---


// --- Test Cases ---

test('Addition', () => {
  press('1+2=');
  checkDisplay('3');
});

test('Subtraction', () => {
  press('9-5=');
  checkDisplay('4');
});

test('Multiplication', () => {
  press('3*4=');
  checkDisplay('12');
});

test('Division', () => {
  press('10/2=');
  checkDisplay('5');
});

test('Chained operations (no precedence)', () => {
  press('2+3*4='); // (2+3)*4 = 20
  checkDisplay('20');
});

test('Decimal numbers', () => {
  press('1.5+2.5=');
  checkDisplay('4');
});

test('Clear and All Clear', () => {
  press('123+');
  checkDisplay('123');
  press('R'); // Clear
  checkDisplay('0');
  press('456');
  checkDisplay('456');
  press('=');
  checkDisplay('579'); // 123 + 456
  press('R'); // Clear
  checkDisplay('0');
  buttonPress('R'); // All Clear
  press('+1=');
  checkDisplay('1');
});


test('Negative result', () => {
  press('5-10=');
  checkDisplay('-5');
});

test('Negative input', () => {
  press('5*');
  press('2');
  press('N'); // make it -2
  press('=');
  checkDisplay('-10');
});

test('Division by zero', () => {
  press('5/0=');
  checkDisplay('INF');
});

test('Percentage', () => {
  press('200*5%=');
  checkDisplay('10');
});

test('Square root', () => {
  press('16');
  press('r');
  checkDisplay('4');
  press('='); // pressing equals after unary op
  checkDisplay('4');
});

test('Square', () => {
  press('5');
  press('s');
  checkDisplay('25');
  press('=');
  checkDisplay('25');
});

test('Inverse', () => {
  press('4');
  press('i');
  checkDisplay('0.25');
});

test('Backspace', () => {
  press('123B');
  checkDisplay('12');
  press('B');
  checkDisplay('1');
  press('B');
  checkDisplay('0');
  press('B');
  checkDisplay('0');
});

test('Repeated equals', () => {
  press('2+3=');
  checkDisplay('5');
  press('=');
  checkDisplay('8');
  press('=');
  checkDisplay('11');
});

test('Operator change', () => {
  press('10+-*/2=');
  checkDisplay('5'); // 10/2=5
});

test('Long number with separators', () => {
  press('1234567');
  checkDisplay('1,234,567');
});

test('Sine (deg)', () => {
  press('30');
  press('sin');
  checkDisplay('0.5');
  press('R'); press('R');
  press('90');
  press('sin');
  checkDisplay('1');
  press('R'); press('R');
  press('180');
  press('sin');
  checkDisplay('0');
});

test('Cosine (deg)', () => {
  press('60');
  press('cos');
  checkDisplay('0.5');
  press('R'); press('R');
  press('0');
  press('cos');
  checkDisplay('1');
  press('R'); press('R');
  press('90');
  press('cos');
  checkDisplay('0');
});

test('Angle mode switch to radians and back', () => {
    press('angleMode'); // now rad
    // The buttonPress function doesn't return the state, but we can check the object it modifies
    assert.strictEqual(scientificOperators.angleMode.val, 'rad');
    press('angleMode'); // back to deg
    assert.strictEqual(scientificOperators.angleMode.val, 'deg');
});


// Run all the defined tests
runTests();