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// Custom Mapped Types Example
// This demonstrates the concept of custom mapped types in JavaScript

// Define a Product object
const product = {
  id: 1,
  name: "Laptop",
  price: 999.99,
  inStock: true
};

// Simulate StringifyProperties<T> mapped type
function stringifyProperties(obj) {
  const result = {};
  
  for (const key in obj) {
    // Convert each property to a string
    result[key] = String(obj[key]);
  }
  
  return result;
}

// Simulate Validator<T> mapped type
function createProductValidator() {
  return {
    id: (id) => id > 0,
    name: (name) => name.length > 0,
    price: (price) => price >= 0,
    inStock: (inStock) => typeof inStock === "boolean"
  };
}

// Examples
const stringProduct = stringifyProperties(product);
console.log("StringifyProperties<Product>:");
console.log(stringProduct);
console.log("Types of properties:");
for (const key in stringProduct) {
  console.log(`${key}: ${typeof stringProduct[key]}`);
}

// Example of invalid data
console.log("\nInvalid data validation:");
console.log(`negative id valid: ${productValidator.id(-1)}`);
console.log(`empty name valid: ${productValidator.name("")}`);
console.log(`negative price valid: ${productValidator.price(-10)}`);
console.log(`non-boolean inStock valid: ${productValidator.inStock("yes")}`);

StringifyProperties:
{ id: '1', name: 'Laptop', price: '999.99', inStock: 'true' }
Types of properties:
id: string
name: string
price: string
inStock: string

Validator:
Validation results:
id valid: true
name valid: true
price valid: true
inStock valid: true

Invalid data validation:
negative id valid: false
empty name valid: false
negative price valid: false
non-boolean inStock valid: false