<?php
/**
 * Registration form fields.
 *
 * @package Aslansheed\OTP
 */

namespace Aslansheed\OTP\Auth;

use Aslansheed\OTP\Core\Crypto;
use Aslansheed\OTP\Core\Options;
use WP_Error;

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

/**
 * Decides which extra details a new user is asked for, checks them, and
 * stores them. Each field is hidden, optional or required, set by the admin.
 */
final class Register_Fields {

	const META_NATIONAL_ID       = 'aslansheed_national_id';
	const META_NATIONAL_ID_INDEX = 'aslansheed_national_id_idx';
	const META_POSTAL_CODE       = 'aslansheed_postal_code';
	const META_BIRTH_DATE        = 'aslansheed_birth_date';
	const META_EMAIL_VERIFIED    = 'aslansheed_email_verified';

	/**
	 * Settings key of each field.
	 *
	 * @return array<string, string>
	 */
	private static function setting_keys() {
		return array(
			'name'             => 'forms.register_name',
			'first_name'       => 'forms.field_first_name',
			'last_name'        => 'forms.field_last_name',
			'email'            => 'forms.field_email',
			'username'         => 'forms.field_username',
			'password'         => 'forms.register_password',
			'password_confirm' => 'forms.field_password_confirm',
			'national_id'      => 'forms.field_national_id',
			'postal_code'      => 'forms.field_postal_code',
			'birth_date'       => 'forms.field_birth_date',
		);
	}

	/**
	 * Returns the fields to show, with their mode, for a type of identifier.
	 *
	 * The email field is only asked when the visitor registers with a phone
	 * number. The confirmation field only appears together with the password.
	 *
	 * @param string $type Identifier type: "phone" or "email".
	 * @return array<string, string> Field name to "optional" or "required".
	 */
	public static function for_type( $type ) {
		$fields = array();

		foreach ( self::setting_keys() as $name => $key ) {
			$mode = (string) Options::get( $key );

			if ( 'optional' !== $mode && 'required' !== $mode ) {
				continue;
			}

			if ( 'email' === $name && 'phone' !== $type ) {
				continue;
			}

			$fields[ $name ] = $mode;
		}

		if ( ! isset( $fields['password'] ) ) {
			unset( $fields['password_confirm'] );
		}

		if ( Options::get( 'forms.terms_required' ) ) {
			$fields['terms'] = 'required';
		}

		return $fields;
	}

	/**
	 * Validates submitted details and returns the clean values.
	 *
	 * @param string $type Identifier type.
	 * @param array  $data Submitted values.
	 * @return array|WP_Error
	 */
	public static function validate( $type, array $data ) {
		$fields = self::for_type( $type );
		$clean  = array();

		foreach ( array( 'name', 'first_name', 'last_name', 'email', 'username', 'national_id', 'postal_code', 'birth_date' ) as $name ) {
			$value = isset( $fields[ $name ], $data[ $name ] ) ? trim( (string) $data[ $name ] ) : '';

			if ( '' === $value ) {
				if ( isset( $fields[ $name ] ) && 'required' === $fields[ $name ] ) {
					return self::required_error( $name );
				}

				continue;
			}

			$checked = self::check( $name, $value );

			if ( is_wp_error( $checked ) ) {
				return $checked;
			}

			$clean[ $name ] = $checked;
		}

		$password = isset( $fields['password'], $data['password'] ) ? (string) $data['password'] : '';

		if ( '' === $password && isset( $fields['password'] ) && 'required' === $fields['password'] ) {
			return new WP_Error( 'aslansheed_password_weak', __( 'Please choose a password.', 'aslansheed-login' ) );
		}

		if ( '' !== $password ) {
			if ( strlen( $password ) < (int) Options::get( 'forms.password_min_length' ) ) {
				return new WP_Error(
					'aslansheed_password_weak',
					sprintf(
						/* translators: %d: minimum number of characters. */
						__( 'Please choose a password with at least %d characters.', 'aslansheed-login' ),
						(int) Options::get( 'forms.password_min_length' )
					)
				);
			}

			if ( isset( $fields['password_confirm'] ) && ( ! isset( $data['password_confirm'] ) || (string) $data['password_confirm'] !== $password ) ) {
				return new WP_Error( 'aslansheed_password_mismatch', __( 'The two passwords do not match.', 'aslansheed-login' ) );
			}

			$clean['password'] = $password;
		}

		$custom = Custom_Fields::validate( $type, isset( $data['custom'] ) ? $data['custom'] : array() );

		if ( is_wp_error( $custom ) ) {
			return $custom;
		}

		if ( array() !== $custom ) {
			$clean['custom'] = $custom;
		}

		if ( isset( $fields['terms'] ) && empty( $data['terms'] ) ) {
			return new WP_Error( 'aslansheed_terms_required', __( 'Please accept the terms to continue.', 'aslansheed-login' ) );
		}

		return $clean;
	}

	/**
	 * Stores the details that live in user meta.
	 *
	 * @param int   $user_id User id.
	 * @param array $clean   Values from validate().
	 * @return void
	 */
	public static function save_meta( $user_id, array $clean ) {
		if ( isset( $clean['national_id'] ) ) {
			update_user_meta( $user_id, self::META_NATIONAL_ID, Crypto::encrypt( $clean['national_id'] ) );
			update_user_meta( $user_id, self::META_NATIONAL_ID_INDEX, Crypto::hmac( 'national_id|' . $clean['national_id'] ) );
		}

		if ( isset( $clean['postal_code'] ) ) {
			update_user_meta( $user_id, self::META_POSTAL_CODE, $clean['postal_code'] );
		}

		if ( isset( $clean['birth_date'] ) ) {
			update_user_meta( $user_id, self::META_BIRTH_DATE, $clean['birth_date'] );
		}

		if ( isset( $clean['custom'] ) && is_array( $clean['custom'] ) ) {
			Custom_Fields::save( $user_id, $clean['custom'] );
		}
	}

	/**
	 * Returns the national ID of a user, or an empty string.
	 *
	 * @param int $user_id User id.
	 * @return string
	 */
	public static function national_id( $user_id ) {
		$plain = Crypto::decrypt( (string) get_user_meta( $user_id, self::META_NATIONAL_ID, true ) );

		return is_string( $plain ) ? $plain : '';
	}

	/**
	 * Checks the Iranian national code: 10 digits, not one repeated digit, and a valid check digit.
	 *
	 * @param string $code Digits only.
	 * @return bool
	 */
	public static function is_valid_national_id( $code ) {
		if ( ! preg_match( '/^\d{10}$/', $code ) || preg_match( '/^(\d)\1{9}$/', $code ) ) {
			return false;
		}

		$sum = 0;

		for ( $i = 0; $i < 9; $i++ ) {
			$sum += (int) $code[ $i ] * ( 10 - $i );
		}

		$remainder = $sum % 11;
		$check     = $remainder < 2 ? $remainder : 11 - $remainder;

		return (int) $code[9] === $check;
	}

	/**
	 * Validates one field and returns its clean value.
	 *
	 * @param string $name  Field name.
	 * @param string $value Trimmed raw value.
	 * @return string|WP_Error
	 */
	private static function check( $name, $value ) {
		switch ( $name ) {
			case 'name':
			case 'first_name':
			case 'last_name':
				return substr( sanitize_text_field( $value ), 0, 100 );

			case 'email':
				$email = strtolower( sanitize_email( $value ) );

				if ( '' === $email || ! is_email( $email ) ) {
					return new WP_Error( 'aslansheed_email_invalid', __( 'Please enter a valid email address.', 'aslansheed-login' ) );
				}

				if ( email_exists( $email ) ) {
					return new WP_Error( 'aslansheed_email_taken', __( 'This email address is already used by another account.', 'aslansheed-login' ) );
				}

				return $email;

			case 'username':
				$login = sanitize_user( $value, true );

				if ( '' === $login || strlen( $login ) < 3 || strlen( $login ) > 60 || ! validate_username( $login ) ) {
					return new WP_Error( 'aslansheed_username_invalid', __( 'Please choose a username of 3 to 60 letters, digits, dots or dashes.', 'aslansheed-login' ) );
				}

				if ( username_exists( $login ) ) {
					return new WP_Error( 'aslansheed_username_taken', __( 'This username is already taken.', 'aslansheed-login' ) );
				}

				return $login;

			case 'national_id':
				$code = Phone_Normalizer::ascii_digits( $value );

				if ( ! self::is_valid_national_id( $code ) ) {
					return new WP_Error( 'aslansheed_national_invalid', __( 'The national ID is not valid.', 'aslansheed-login' ) );
				}

				if ( Options::get( 'forms.national_id_unique' ) && self::national_id_taken( $code ) ) {
					return new WP_Error( 'aslansheed_national_taken', __( 'This national ID is already registered.', 'aslansheed-login' ) );
				}

				return $code;

			case 'postal_code':
				$code = Phone_Normalizer::ascii_digits( $value );

				if ( ! preg_match( '/^\d{10}$/', $code ) || preg_match( '/^(\d)\1{9}$/', $code ) ) {
					return new WP_Error( 'aslansheed_postal_invalid', __( 'The postal code must be 10 digits.', 'aslansheed-login' ) );
				}

				return $code;

			default:
				return self::check_date( Phone_Normalizer::ascii_digits( $value ) );
		}
	}

	/**
	 * Accepts a Gregorian date written as YYYY-MM-DD that exists and is not in the future.
	 *
	 * The form converts Jalali dates to Gregorian before it submits them.
	 *
	 * @param string $value Date string.
	 * @return string|WP_Error
	 */
	private static function check_date( $value ) {
		$invalid = new WP_Error( 'aslansheed_date_invalid', __( 'Please enter a valid date.', 'aslansheed-login' ) );

		if ( ! preg_match( '/^(\d{4})-(\d{2})-(\d{2})$/', $value, $m ) || ! checkdate( (int) $m[2], (int) $m[3], (int) $m[1] ) || (int) $m[1] < 1900 ) {
			return $invalid;
		}

		if ( $value > gmdate( 'Y-m-d' ) ) {
			return $invalid;
		}

		return $value;
	}

	/**
	 * Tells whether a national ID is already used by a user.
	 *
	 * @param string $code Digits.
	 * @return bool
	 */
	private static function national_id_taken( $code ) {
		$users = get_users(
			array(
				'meta_key'   => self::META_NATIONAL_ID_INDEX, // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key -- Indexed lookup of one hash.
				'meta_value' => Crypto::hmac( 'national_id|' . $code ), // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_value -- Indexed lookup of one hash.
				'number'     => 1,
				'fields'     => 'ID',
			)
		);

		return array() !== $users;
	}

	/**
	 * Builds the error for an empty required field.
	 *
	 * @param string $name Field name.
	 * @return WP_Error
	 */
	private static function required_error( $name ) {
		$labels = array(
			'name'        => __( 'a display name', 'aslansheed-login' ),
			'first_name'  => __( 'your first name', 'aslansheed-login' ),
			'last_name'   => __( 'your last name', 'aslansheed-login' ),
			'email'       => __( 'your email address', 'aslansheed-login' ),
			'username'    => __( 'a username', 'aslansheed-login' ),
			'national_id' => __( 'your national ID', 'aslansheed-login' ),
			'postal_code' => __( 'your postal code', 'aslansheed-login' ),
			'birth_date'  => __( 'your birth date', 'aslansheed-login' ),
		);

		return new WP_Error(
			'name' === $name ? 'aslansheed_name_required' : 'aslansheed_field_required',
			sprintf(
				/* translators: %s: what the visitor must enter, for example "your first name". */
				__( 'Please enter %s.', 'aslansheed-login' ),
				isset( $labels[ $name ] ) ? $labels[ $name ] : $name
			)
		);
	}
}