<?php
/**
 * Phone Validation for Contact Forms
 * 
 * Follows ITU-T E.164 standard (7-15 digits) with lenient formatting.
 * Allows flexible formatting: spaces, dashes, dots, slashes, parentheses, plus sign.
 * Requires minimum 7 digits for actual phone numbers (most countries have 7+ digit numbers).
 * Data is stored as plain text - this is purely a frontend/validation enhancement.
 * 
 * @package Contact Forms
 * @subpackage Validation
 * @since 2.0.0-beta.34
 */

class AccuaForm_Validation_Phone extends Validation {
  protected $message = "Error: %element% must contain a valid phone number.";
  
  /**
   * Constructor
   * 
   * @param string $message Custom error message (optional). Use %element% as placeholder for field label.
   */
  public function __construct($message = "") {
    if (!empty($message)) {
      $this->message = $message;
    } else {
      // translators: %element% is the field label.
      $this->message = __( "Please enter a valid phone number in %element%", 'contact-forms' );
    }
  }
  
  /**
   * Validate phone number following ITU-T E.164 standard
   * 
   * E.164 specifies maximum 15 digits (not counting the + sign).
   * We require a minimum of 7 digits for actual phone numbers.
   * We allow flexible formatting for user convenience:
   * - Minimum 7 digits (most countries have 7+ digit numbers)
   * - Maximum 15 digits (E.164 compliant)
   * - Allows: digits, spaces, dashes, dots, slashes, parentheses, plus sign
   * - Plus sign only allowed at the beginning
   * - Prefix-only values (≤4 digits with +) are treated as empty for optional fields
   * 
   * @param string $value The phone number to validate
   * @return bool True if valid or empty (empty handled by Required validation), false otherwise
   */
  public function isValid($value) {
    // Skip validation for empty/null values (handled by Required validation if needed)
    if ($this->isNotApplicable($value)) {
      return true;
    }
    
    // Trim whitespace
    $value = trim($value);
    
    // Empty after trim is valid (Required validation handles mandatory fields)
    if ($value === '') {
      return true;
    }
    
    // FIRST: Check for invalid characters (only digits, spaces, dashes, dots, slashes, parentheses, plus)
    if (!preg_match('/^[\d\s\-\.\/\(\)\+]+$/', $value)) {
      return false;
    }
    
    // Plus sign only allowed at the start
    if (strpos($value, '+') !== false && strpos($value, '+') !== 0) {
      return false;
    }
    
    // Multiple plus signs not allowed
    if (substr_count($value, '+') > 1) {
      return false;
    }
    
    // Count digits only
    $digitCount = strlen(preg_replace('/\D/', '', $value));
    
    // Treat prefix-only values (1-4 digits starting with +) as empty for optional fields
    // This allows optional phone fields with placeholder prefixes like "+39" to pass validation
    if (strpos($value, '+') === 0 && $digitCount <= 4) {
      return true;
    }
    
    // Require minimum 5 digits for actual phone numbers
    // NOTE: Client-side uses libphonenumber which may accept 5-6 digit numbers for some countries
    // Server must be equal or more lenient to avoid rejecting client-accepted values
    if ($digitCount < 5) {
      return false;
    }
    
    // E.164 standard: maximum 15 digits
    if ($digitCount > 15) {
      return false;
    }
    
    return true;
  }
}