/**
 * Email Value Object
 *
 * Represents a validated email address.
 * Value objects are immutable and enforce validation rules.
 *
 * Domain invariants enforced:
 * - Email must be valid format
 * - Email is normalized (lowercase, trimmed)
 *
 * @layer Domain
 */

/**
 * Email Value Object
 *
 * Immutable representation of a validated email address.
 */
export class Email {
  private readonly value: string;

  private constructor(email: string) {
    this.value = this.normalize(email);
    this.validate();
  }

  /**
   * Creates a new Email instance
   *
   * @param email - Email address string
   * @returns Email value object
   * @throws Error if email is invalid
   */
  static create(email: string): Email {
    return new Email(email);
  }

  /**
   * Normalizes email address
   *
   * @param email - Raw email string
   * @returns Normalized email (lowercase, trimmed)
   */
  private normalize(email: string): string {
    return email.toLowerCase().trim();
  }

  /**
   * Validates email format
   *
   * @throws Error if email is invalid
   */
  private validate(): void {
    if (!this.value || this.value.length === 0) {
      throw new Error('Email cannot be empty');
    }

    // Basic email format validation
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    if (!emailRegex.test(this.value)) {
      throw new Error(`Invalid email format: ${this.value}`);
    }

    // Additional validations
    if (this.value.length > 254) {
      throw new Error('Email too long (max 254 characters)');
    }

    const [localPart, domain] = this.value.split('@');

    if (localPart.length > 64) {
      throw new Error('Email local part too long (max 64 characters)');
    }

    if (domain.length > 253) {
      throw new Error('Email domain too long (max 253 characters)');
    }
  }

  /**
   * Gets email address string
   *
   * @returns Email address
   */
  getValue(): string {
    return this.value;
  }

  /**
   * Gets domain part of email
   *
   * @returns Domain (e.g., "example.com" from "user@example.com")
   */
  getDomain(): string {
    return this.value.split('@')[1];
  }

  /**
   * Gets local part of email
   *
   * @returns Local part (e.g., "user" from "user@example.com")
   */
  getLocalPart(): string {
    return this.value.split('@')[0];
  }

  /**
   * Checks if email belongs to a specific domain
   *
   * @param domain - Domain to check
   * @returns true if email domain matches
   */
  hasDomain(domain: string): boolean {
    return this.getDomain() === domain.toLowerCase();
  }

  /**
   * Checks equality with another Email
   *
   * @param other - Email to compare
   * @returns true if emails are equal
   */
  equals(other: Email): boolean {
    return this.value === other.value;
  }

  /**
   * Converts to string
   *
   * @returns Email address string
   */
  toString(): string {
    return this.value;
  }

  /**
   * Converts to JSON
   *
   * @returns Email address string
   */
  toJSON(): string {
    return this.value;
  }
}