<?php
/** Per-question email domain policy. @package AccessibleForms */
namespace AccessibleForms;

if ( ! defined( 'ABSPATH' ) ) {
	exit();
}

class EmailDomains {
	const MODES = array( 'any', 'work', 'allow', 'deny' );
	const FREE_PROVIDERS = array(
		'aol.com', 'gmail.com', 'googlemail.com', 'hotmail.com', 'icloud.com',
		'live.com', 'mail.com', 'me.com', 'msn.com', 'outlook.com', 'proton.me',
		'protonmail.com', 'yahoo.com', 'yandex.com', 'ymail.com', 'zoho.com',
	);

	/** Keep settings on the field, with a linked issue for an unusable rule. */
	public static function sanitize( array $field, $index ) {
		$mode = $field['email_domain_mode'] ?? 'any';
		if ( 'any' === $mode ) {
			return array( array(), array() );
		}
		if ( ! in_array( $mode, self::MODES, true ) ) {
			return array( array(), array( Schema::issue( __( 'Choose an email domain rule.', 'accessible-forms-by-accessible-org' ), null, $index, 'email_domain_mode' ) ) );
		}
		$key = 'work' === $mode ? 'free_email_domains' : 'email_domains';
		$list = $field[ $key ] ?? ( 'work' === $mode ? self::FREE_PROVIDERS : '' );
		$items = is_array( $list ) ? $list : preg_split( '/[\s,]+/', FormOptions::text( $list, 26000 ), -1, PREG_SPLIT_NO_EMPTY );
		$domains = array();
		$valid = count( $items ) <= 100;
		foreach ( array_slice( $items, 0, 100 ) as $item ) {
			$domain = is_string( $item ) ? strtolower( trim( $item ) ) : '';
			if ( ! self::valid( $domain ) ) {
				$valid = false;
				continue;
			}
			$domains[] = $domain;
		}
		$issues = $valid && $domains ? array() : array(
			Schema::issue( __( 'Enter 1 to 100 domains such as example.org, one per line. Use only the part after @.', 'accessible-forms-by-accessible-org' ), null, $index, $key ),
		);
		return array( array( 'email_domain_mode' => $mode, $key => array_values( array_unique( $domains ) ) ), $issues );
	}

	private static function valid( $domain ) {
		return strlen( $domain ) <= 253 && (bool) preg_match( '/^(?:[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?$/D', $domain );
	}

	/** A visible instruction, also used as the error when a valid address is refused. */
	public static function instruction( array $field ) {
		switch ( $field['email_domain_mode'] ?? 'any' ) {
			case 'work':
				return __( 'Enter a work email address, such as you@your-company.com.', 'accessible-forms-by-accessible-org' );
			case 'allow':
				$domains = (array) ( $field['email_domains'] ?? array() );
				if ( 1 === count( $domains ) ) {
					return sprintf(
						/* translators: %s: an allowed email domain, including the @. */
						__( 'Enter an email address ending in %s.', 'accessible-forms-by-accessible-org' ), '@' . reset( $domains )
					);
				}
				if ( $domains ) {
					$examples = implode( ', ', array_map( static function ( $domain ) { return '@' . $domain; }, array_slice( $domains, 0, 3 ) ) );
					return sprintf(
						/* translators: %s: examples of allowed email domains. */
						__( 'Use an approved email domain such as %s.', 'accessible-forms-by-accessible-org' ), $examples
					);
				}
				return __( 'Enter an email address from an organization approved for this form.', 'accessible-forms-by-accessible-org' );
			case 'deny':
				return __( 'Use an email address from a different domain.', 'accessible-forms-by-accessible-org' );
		}
		return '';
	}

	public static function allows( array $field, $address ) {
		$mode = $field['email_domain_mode'] ?? 'any';
		if ( 'any' === $mode ) {
			return true;
		}
		$list = 'work' === $mode ? ( $field['free_email_domains'] ?? self::FREE_PROVIDERS ) : ( $field['email_domains'] ?? array() );
		$match = in_array( strtolower( substr( strrchr( $address, '@' ), 1 ) ), (array) $list, true );
		return 'allow' === $mode ? $match : ! $match;
	}
}