const cache = new Map();

function memoize(fn) {
  return function(...args) {
    const key = JSON.stringify(args);
    if (cache.has(key)) {
      return cache.get(key);
    }
    const result = fn(...args);
    cache.set(key, result);
    return result;
  };
}

const fibonacci = memoize((n) => {
  if (n <= 1) return n;
  return fibonacci(n - 1) + fibonacci(n - 2);
});

console.log(fibonacci(5));
console.log(cache.size);

const obj = {
  data: ['x', 'y', 'z'],
  *[Symbol.iterator]() {
    for (let i = this.data.length - 1; i >= 0; i--) {
      yield this.data[i].toUpperCase();
    }
  }
};

const result = [];
for (const item of obj) {
  result.push(item);
  if (result.length === 2) break;
}

console.log(result.join('-'));

function asyncQuiz() {
  return new Promise((resolve) => {
    setTimeout(() => resolve('Hello'), 1000);
  });
}

async function runAsyncQuiz() {
  const result = await asyncQuiz();
  console.log(result);
}

runAsyncQuiz();
console.log('World');

let a = 1;
let b = new Number(1);
let c = '1';

console.log(a == b);
console.log(a === b);
console.log(b == c);

const x = 5;
const y = 10;

const result = `${x + y}`;
const nested = `Value: ${`${x}` + `${y}`}`;
const expr = `${x}${y}`;

console.log(result);
console.log(nested);
console.log(expr);
console.log(typeof result);

const wm = new WeakMap();
const obj1 = { name: 'first' };
const obj2 = { name: 'second' };

wm.set(obj1, 'value1');
wm.set(obj2, 'value2');

const keys = [];
for (let key of wm) {
  keys.push(key);
}

console.log(keys.length);
console.log(wm.has(obj1));
console.log(wm.get(obj2));

console.log(sum);

const obj = { a: 1, b: 2, c: 3 };
Object.defineProperty(obj, 'd', { 
  value: 4, 
  enumerable: false 
});

const entries = Object.entries(obj);
const keys = Object.keys(obj);
const values = Object.values(obj);

console.log(entries.length + keys.length + values.length);

function* reverseGenerator(arr) {
  for (let i = arr.length - 1; i >= 0; i--) {
    yield arr[i];
  }
}

const result = [...reverseGenerator([1, 2, 3, 4, 5])].join('');

console.log(result);

console.log('1');

setTimeout(() => console.log('2'), 0);

Promise.resolve().then(() => console.log('3'));

queueMicrotask(() => console.log('4'));

setTimeout(() => {
  console.log('5');
  Promise.resolve().then(() => console.log('6'));
}, 0);

console.log('7');

function createCounter() {
  let count = 0;
  return {
    increment() {
      count++;
      return count;
    },
    getCount() {
      return count;
    }
  };
}

const counter = createCounter();

console.log(counter.increment());
console.log(counter.getCount());
console.log(counter.increment());
console.log(counter.getCount());

const obj = { a: 1, b: 2, c: 3 };
const result = Object.values(obj).reduce((acc, curr) => acc * curr, 1);
console.log(result);

console.log(1);

setTimeout(() => {
  console.log(2);
}, 100);

setTimeout(() => {
  console.log(3);
}, 0);

Promise.resolve().then(() => {
  console.log(4);
}).then(() => {
  console.log(5);
});

console.log(6);

const data = [1, 2, 3, 4, 5];

const result = data.reduce((acc, val) => acc.concat(Array.from({ length: val }, (_, index) => val + index)), []);

console.log(result);

function createSymbolDemo() {
  const obj = {};
  
  const sym1 = Symbol('description');
  const sym2 = Symbol('description');
  const sym3 = Symbol.for('shared');
  const sym4 = Symbol.for('shared');
  
  obj[sym1] = 'Value 1';
  obj[sym2] = 'Value 2';
  obj[sym3] = 'Value 3';
  obj[sym4] = 'Value 4';
  
  console.log(Object.keys(obj).length, sym1 === sym2, sym3 === sym4, obj[sym3]);
}

createSymbolDemo();

const obj = {
  [Symbol('a')]: 'hidden',
  [Symbol.for('b')]: 'registered',
  c: 'normal'
};

const symbols = Object.getOwnPropertySymbols(obj);
const keys = Object.keys(obj);
const allProps = Reflect.ownKeys(obj);

console.log(symbols.length, keys.length, allProps.length);

const user = {
  name: 'Sarah',
  age: 25,
  greet() {
    return `Hello, I'm ${this.name}`;
  }
};

const keys = Object.keys(user);
const values = Object.values(user);
const entries = Object.entries(user);

console.log(keys.length);
console.log(values.includes('Sarah'));
console.log(entries[2][0]);

const data = [1, 2, 3, 4, 5];

const result = data.reduce((acc, val) => acc.concat(Array.from({ length: val }, (_, index) => val + index)), []);

console.log(result);

const user = {
  name: 'Sarah',
  profile: {
    settings: {
      theme: 'dark'
    }
  }
};

const config = {
  name: 'John',
  profile: null
};

console.log(user.profile?.settings?.theme);
console.log(config.profile?.settings?.theme);
console.log(user.profile?.preferences?.language);
console.log(config.profile?.settings?.theme ?? 'light');

const original = {
  name: 'Sarah',
  hobbies: ['reading', 'coding'],
  address: { city: 'Portland', zip: 97201 }
};

const shallow = { ...original };
const deep = JSON.parse(JSON.stringify(original));

shallow.name = 'Emma';
shallow.hobbies.push('hiking');
shallow.address.city = 'Seattle';

deep.hobbies.push('swimming');
deep.address.zip = 98101;

console.log(original.hobbies.length, original.address.city);

const target = { name: 'Sarah', age: 25 };
const handler = {
  get(obj, prop) {
    if (prop in obj) {
      return obj[prop].toString().toUpperCase();
    }
    return `Property ${prop} not found`;
  },
  set(obj, prop, value) {
    obj[prop] = value * 2;
    return true;
  }
};
const proxy = new Proxy(target, handler);
proxy.salary = 50000;
console.log(proxy.name);
console.log(proxy.age);
console.log(proxy.salary);
console.log(proxy.city);

function testScope() {
  var x = 'outer';
  let y = 'outer';
  
  if (true) {
    var x = 'inner';
    let y = 'inner';
    console.log(x, y);
  }
  
  console.log(x, y);
}

testScope();