Builder

class SQLQuery {
  private selectClause: string = '';
  private fromClause: string = '';
  private whereConditions: string[] = [];
  private orderByClause: string = '';
  private limitClause: string = '';

  toString(): string {
    let query = this.selectClause + ' ' + this.fromClause;
    
    if (this.whereConditions.length > 0) {
      query += ' WHERE ' + this.whereConditions.join(' AND ');
    }
    
    if (this.orderByClause) {
      query += ' ' + this.orderByClause;
    }
    
    if (this.limitClause) {
      query += ' ' + this.limitClause;
    }
    
    return query;
  }
}

class QueryBuilder {
  private query: SQLQuery;

  constructor() {
    this.query = new SQLQuery();
  }

  select(...columns: string[]): this {
    this.query['selectClause'] = `SELECT ${columns.join(', ')}`;
    return this;
  }

  from(table: string): this {
    this.query['fromClause'] = `FROM ${table}`;
    return this;
  }

  where(condition: string): this {
    this.query['whereConditions'].push(condition);
    return this;
  }

  orderBy(column: string, direction: 'ASC' | 'DESC' = 'ASC'): this {
    this.query['orderByClause'] = `ORDER BY ${column} ${direction}`;
    return this;
  }

  limit(count: number): this {
    this.query['limitClause'] = `LIMIT ${count}`;
    return this;
  }

  build(): SQLQuery {
    return this.query;
  }
}

// Utilizzo
const query = new QueryBuilder()
  .select('name', 'email', 'age')
  .from('users')
  .where('age > 18')
  .where('active = true')
  .orderBy('name', 'ASC')
  .limit(10)
  .build();

console.log(query.toString());
// SELECT name, email, age FROM users WHERE age > 18 AND active = true ORDER BY name ASC LIMIT 10

class Hamburger {
  constructor(
    public bun: string,
    public patty: string,
    public cheese?: string,
    public toppings: string[] = [],
    public sauces: string[] = []
  ) {}

  describe(): string {
    let description = `${this.bun} bun with ${this.patty} patty`;
    if (this.cheese) description += `, ${this.cheese} cheese`;
    if (this.toppings.length) description += `, toppings: ${this.toppings.join(', ')}`;
    if (this.sauces.length) description += `, sauces: ${this.sauces.join(', ')}`;
    return description;
  }
}

class HamburgerBuilder {
  private bun: string = 'regular';
  private patty: string = 'beef';
  private cheese?: string;
  private toppings: string[] = [];
  private sauces: string[] = [];

  setBun(bun: string): this {
    this.bun = bun;
    return this;
  }

  setPatty(patty: string): this {
    this.patty = patty;
    return this;
  }

  addCheese(cheese: string): this {
    this.cheese = cheese;
    return this;
  }

  addTopping(topping: string): this {
    this.toppings.push(topping);
    return this;
  }

  addSauce(sauce: string): this {
    this.sauces.push(sauce);
    return this;
  }

  build(): Hamburger {
    return new Hamburger(
      this.bun,
      this.patty,
      this.cheese,
      this.toppings,
      this.sauces
    );
  }
}

// Utilizzo
const burger = new HamburgerBuilder()
  .setBun('sesame')
  .setPatty('chicken')
  .addCheese('cheddar')
  .addTopping('lettuce')
  .addTopping('tomato')
  .addTopping('onion')
  .addSauce('mayo')
  .addSauce('ketchup')
  .build();

console.log(burger.describe());