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

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

// Mock 'g' (graphics)
global.g = {
  _col: 0,
  _bg: 0,
  _font: "6x8",
  _font_size: 1,
  clear: () => { drawn_since_clear = false; },
  clearRect: () => { drawn_since_clear = false; },
  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 * 4.7 * (global.g._font_size || 1), // approximation to match watch
  getWidth: () => 176,
  getHeight: () => 176,
  drawString: (s) => {
    if (!drawn_since_clear) {
      mock_display_str = String(s);
      drawn_since_clear = true;
    }
  },
  getFontHeight: () => 8 * (global.g._font_size || 1)
};

global.Graphics = {};

// Mock Bangle.js-specific process.env properties
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 ---
// We wrap the app code in a function that returns the buttonPress function,
// so we can capture it and use it in our tests.
const calculatorCode = fs.readFileSync(path.join(__dirname, 'calculator.app.js'), 'utf8');
const wrappedCode = `(function(require) { ${calculatorCode}; return { buttonPress, scientificOperators }; })`;
const getAppFns = eval(wrappedCode);
const { buttonPress, scientificOperators } = getAppFns((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) {
  let expectedStr = String(expected);
  if (expected === Infinity) {
    expectedStr = 'INF';
  } else if (expected === -Infinity) {
    expectedStr = '-INF';
  }

  // attempt a numeric comparison for float-related issues
  const expectedNum = parseFloat(expectedStr.replace(/,/g, ''));
  let actualStrForParsing = mock_display_str.replace(/,/g, '');
  if (actualStrForParsing.endsWith('...')) {
    actualStrForParsing = actualStrForParsing.slice(0, -3);
  }
  const actualNum = parseFloat(actualStrForParsing);

  if (!isNaN(expectedNum) && !isNaN(actualNum)) {
    if (expectedNum === actualNum) return; // Handles Infinity and exact matches
    const tolerance = 1e-4; // Increased tolerance for float comparisons
    if (Math.abs(expectedNum - actualNum) < tolerance) {
      return; // Close enough for floating point
    }
  }

  // Fallback for strings, formatted numbers, or failed float checks
  assert.strictEqual(mock_display_str, expectedStr, message);
}
// --- End Test Framework ---


// --- Test Cases ---

const testNumbers = [
  0, 1, -1, 5, -5, 0.5, -0.5, 123, -123, 1.23, -1.23,
  1234567, -1234567, 99999999, -99999999,
  1e-6, -1e-6, Math.PI, Math.E
];

// Helper to press a number, handling negatives
function pressNumber(n) {
  const s = String(n);
  if (s.startsWith('-')) {
    press(s.substring(1));
    buttonPress('N');
  } else {
    press(s);
  }
}

// --- Generated Tests: Binary Operations ---
const binaryOps = {
  '+': (a, b) => a + b,
  '-': (a, b) => a - b,
  '*': (a, b) => a * b,
  '/': (a, b) => a / b,
};

for (const op in binaryOps) {
  for (const a of testNumbers) {
    for (const b of testNumbers) {
      if (op === '/' && b === 0) {
        test(`Binary Edge Case: ${a} / 0`, () => {
          pressNumber(a);
          buttonPress('/');
          pressNumber(0);
          buttonPress('=');
          checkDisplay(a === 0 ? NaN : (a > 0 ? Infinity : -Infinity));
        });
        continue;
      }

      test(`Binary: ${a} ${op} ${b}`, () => {
        pressNumber(a);
        buttonPress(op);
        pressNumber(b);
        buttonPress('=');
        const expected = binaryOps[op](a, b);
        checkDisplay(expected);
      });
    }
  }
}

// --- Generated Tests: Unary Operations ---
const unaryOps = {
  'r': { name: 'sqrt', fn: Math.sqrt },
  's': { name: 'x^2', fn: (a) => a * a },
  'i': { name: '1/x', fn: (a) => 1 / a },
  '%': { name: '%', fn: (a) => a / 100 },
};

for (const op in unaryOps) {
  for (const a of testNumbers) {
    if (op === 'r' && a < 0) {
      test(`Unary Edge Case: sqrt(${a})`, () => {
        pressNumber(a);
        buttonPress('r');
        checkDisplay(NaN);
      });
      continue;
    }

    test(`Unary: ${unaryOps[op].name}(${a})`, () => {
      pressNumber(a);
      buttonPress(op);
      const expected = unaryOps[op].fn(a);
      checkDisplay(expected);
    });
  }
}

// --- Generated Tests: Chaining Operations ---
// To keep runtime sane, we'll pick a smaller subset for chaining
const chainNumbers = [0, 1, -5, 0.5, 10, 123];
const chainOps = ['+', '-', '*', '/'];

for (const a of chainNumbers) {
  for (const b of chainNumbers) {
    for (const c of chainNumbers) {
      for (const op1 of chainOps) {
        for (const op2 of chainOps) {
          test(`Chaining: ${a} ${op1} ${b} ${op2} ${c}`, () => {
            pressNumber(a);
            buttonPress(op1);
            pressNumber(b);
            buttonPress(op2); // This will execute the first operation
            pressNumber(c);
            buttonPress('='); // This will execute the second operation
            // Calculator does sequential evaluation: (a op1 b) op2 c
            const expected = binaryOps[op2](binaryOps[op1](a, b), c);
            checkDisplay(expected);
          });
        }
      }
    }
  }
}

// --- Generated Tests: Trigonometry ---
const trigOps = {
  'sin': { fn: Math.sin, name: 'sin' },
  'cos': { fn: Math.cos, name: 'cos' },
  'tan': { fn: Math.tan, name: 'tan' },
};
const trigAngles = [0, 30, 45, 60, 90, 180, 270, 360, Math.PI/6, Math.PI/4, Math.PI/2, Math.PI, 3*Math.PI/2, 2*Math.PI];

// Test in DEG mode (default)
for (const op in trigOps) {
  for (const angle of trigAngles) {
    test(`Trig (deg): ${trigOps[op].name}(${angle})`, () => {
      pressNumber(angle);
      buttonPress(op);
      const expected = trigOps[op].fn(angle * Math.PI / 180);
      checkDisplay(expected);
    });
  }
}

// Test in RAD mode
test('Switch to RAD mode', () => {
  buttonPress('angleMode');
  assert.strictEqual(scientificOperators.angleMode.val, 'rad');
});

for (const op in trigOps) {
  for (const angle of trigAngles) {
    // tan(pi/2) is Infinity, which the calculator can handle
    if (op === 'tan' && (Math.abs(angle - Math.PI/2) < 1e-9 || Math.abs(angle - 3*Math.PI/2) < 1e-9)) {
       test(`Trig Edge Case (rad): tan(${angle})`, () => {
        pressNumber(angle);
        buttonPress('tan');
        checkDisplay(Infinity);
      });
      continue;
    }
    test(`Trig (rad): ${trigOps[op].name}(${angle})`, () => {
      pressNumber(angle);
      buttonPress(op);
      const expected = trigOps[op].fn(angle);
      checkDisplay(expected);
    });
  }
}

test('Switch back to DEG mode for subsequent tests', () => {
  buttonPress('angleMode');
  assert.strictEqual(scientificOperators.angleMode.val, 'deg');
});


// --- Specific Functionality Tests ---

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('Backspace', () => {
  press('123.45B');
  checkDisplay('123.4');
  press('BB');
  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');
  press('R'); press('R');
  press('10-2=');
  checkDisplay('8');
  press('=');
  checkDisplay('6');
});

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

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

// Run all the defined tests
runTests();