<?php
/**
 * Validator.
 *
 * @package HostKhata
 */

namespace HostKhata\Security;

defined( 'ABSPATH' ) || exit;

use HostKhata\Support\Date;

/**
 * Rule based validation of already sanitised input.
 *
 * Rules are pipe separated strings per field, for example
 * `required|email|max_length:190`. Supported rules: required, string, int,
 * numeric, bool, email, url, date, domain, min, max, min_length, max_length, in.
 * Empty values pass every rule except `required`.
 *
 * @since 0.1.0
 */
final class Validator {

	/**
	 * Validates data against rules.
	 *
	 * @since 0.1.0
	 *
	 * @param array<string, mixed>  $data  Input data.
	 * @param array<string, string> $rules Rules per field.
	 * @return ValidationResult
	 */
	public function validate( array $data, array $rules ): ValidationResult {
		$result = new ValidationResult();

		foreach ( $rules as $field => $rule_string ) {
			$value = $data[ $field ] ?? null;

			foreach ( explode( '|', $rule_string ) as $rule ) {
				$parts = explode( ':', $rule, 2 );
				$name  = $parts[0];
				$arg   = $parts[1] ?? '';

				$message = $this->check( $name, $arg, $value );

				if ( null !== $message ) {
					$result->add( (string) $field, $message );
					break;
				}
			}
		}

		return $result;
	}

	/**
	 * Tells whether a string is a valid domain name (ASCII or punycode).
	 *
	 * @since 0.1.0
	 *
	 * @param string $domain Domain name.
	 * @return bool
	 */
	public static function is_domain( string $domain ): bool {
		if ( strlen( $domain ) > 253 || false === strpos( $domain, '.' ) ) {
			return false;
		}

		return 1 === preg_match( '/^(?=.{1,253}$)(?:(?!-)[a-z0-9-]{1,63}(?<!-)\.)+[a-z][a-z0-9-]{1,62}$/i', $domain );
	}

	/**
	 * Applies one rule.
	 *
	 * @param string $name  Rule name.
	 * @param string $arg   Rule argument.
	 * @param mixed  $value Value.
	 * @return string|null Error message, or null when the rule passes.
	 */
	private function check( string $name, string $arg, $value ): ?string {
		$empty = null === $value || '' === $value || array() === $value;

		if ( 'required' === $name ) {
			return $empty ? __( 'This field is required.', 'hostkhata' ) : null;
		}

		if ( $empty ) {
			return null;
		}

		switch ( $name ) {
			case 'string':
				return is_string( $value ) ? null : __( 'Enter text.', 'hostkhata' );
			case 'int':
				return false !== filter_var( $value, FILTER_VALIDATE_INT ) ? null : __( 'Enter a whole number.', 'hostkhata' );
			case 'numeric':
				return is_numeric( $value ) ? null : __( 'Enter a number.', 'hostkhata' );
			case 'bool':
				return is_bool( $value ) || in_array( $value, array( 0, 1, '0', '1' ), true ) ? null : __( 'Choose yes or no.', 'hostkhata' );
			case 'email':
				return false !== filter_var( $value, FILTER_VALIDATE_EMAIL ) ? null : __( 'Enter a valid email address.', 'hostkhata' );
			case 'url':
				return false !== filter_var( $value, FILTER_VALIDATE_URL ) ? null : __( 'Enter a valid URL.', 'hostkhata' );
			case 'date':
				return is_string( $value ) && Date::is_valid_date( $value ) ? null : __( 'Enter a valid date.', 'hostkhata' );
			case 'domain':
				return is_string( $value ) && self::is_domain( $value ) ? null : __( 'Enter a valid domain name.', 'hostkhata' );
			case 'min':
				return is_numeric( $value ) && $value >= (float) $arg
					? null
					/* translators: %s: minimum number. */
					: sprintf( __( 'Must be at least %s.', 'hostkhata' ), $arg );
			case 'max':
				return is_numeric( $value ) && $value <= (float) $arg
					? null
					/* translators: %s: maximum number. */
					: sprintf( __( 'Must be at most %s.', 'hostkhata' ), $arg );
			case 'min_length':
				return is_string( $value ) && mb_strlen( $value ) >= (int) $arg
					? null
					/* translators: %s: minimum number of characters. */
					: sprintf( __( 'Must be at least %s characters.', 'hostkhata' ), $arg );
			case 'max_length':
				return is_string( $value ) && mb_strlen( $value ) <= (int) $arg
					? null
					/* translators: %s: maximum number of characters. */
					: sprintf( __( 'Must be at most %s characters.', 'hostkhata' ), $arg );
			case 'in':
				return in_array( (string) $value, explode( ',', $arg ), true ) ? null : __( 'Choose one of the allowed values.', 'hostkhata' );
		}

		return null;
	}
}