<?php
/**
 * Server-side client of the Jsonpage API. The API key never leaves the server.
 *
 * Every method answers with plain arrays and never throws: when the API does not
 * answer, the caller gets status "error" and carries on (degraded mode).
 *
 * @package Jsonpage
 */

defined( 'ABSPATH' ) || exit;

class Jsonpage_Client {

	/**
	 * Is an API key configured?
	 *
	 * @return bool
	 */
	public static function has_key() {
		return '' !== (string) jsonpage_setting( 'api_key' );
	}

	/**
	 * Calls the API.
	 *
	 * @param string $path    Path under the base URL, such as /autocomplete.
	 * @param array  $query   Query arguments.
	 * @param int    $timeout Seconds.
	 * @return array{ok:bool,http:int,data:?array}
	 */
	private static function request( $path, $query, $timeout ) {
		$failure = array(
			'ok'   => false,
			'http' => 0,
			'data' => null,
		);
		// After a network failure or a server error, do not wait for the API again for a minute:
		// the shop keeps its normal speed and the checkout is never slowed down (degraded mode).
		if ( ! self::has_key() || get_transient( 'jsonpage_down' ) ) {
			return $failure;
		}
		$url      = add_query_arg( $query, rtrim( JSONPAGE_API_BASE, '/' ) . $path );
		$response = wp_remote_get(
			$url,
			array(
				'timeout'     => $timeout,
				'redirection' => 0,
				'headers'     => array(
					'X-API-Key'  => (string) jsonpage_setting( 'api_key' ),
					'Accept'     => 'application/json',
					'User-Agent' => 'Jsonpage-WordPress/' . JSONPAGE_VERSION,
				),
			)
		);
		if ( is_wp_error( $response ) ) {
			set_transient( 'jsonpage_down', 1, MINUTE_IN_SECONDS );
			return $failure;
		}
		$http = (int) wp_remote_retrieve_response_code( $response );
		if ( $http >= 500 ) {
			set_transient( 'jsonpage_down', 1, MINUTE_IN_SECONDS );
		}
		$data = json_decode( wp_remote_retrieve_body( $response ), true );
		if ( 401 === $http || 403 === $http ) {
			// Shown once in the admin so that the shop owner learns about a wrong or revoked key.
			set_transient( 'jsonpage_key_rejected', 1, HOUR_IN_SECONDS );
		} elseif ( 200 === $http ) {
			delete_transient( 'jsonpage_key_rejected' );
		}
		return array(
			'ok'   => 200 === $http && is_array( $data ),
			'http' => $http,
			'data' => is_array( $data ) ? $data : null,
		);
	}

	/**
	 * Suggestions while the customer types.
	 *
	 * @param string   $q         Text typed, at least 3 characters.
	 * @param string[] $countries Country codes.
	 * @return array|null List of suggestions, or null when the API is not available.
	 */
	public static function autocomplete( $q, $countries ) {
		$status = 'allow' === jsonpage_setting( 'closed' ) || 'warn' === jsonpage_setting( 'closed' ) ? 'any' : 'active';
		$key    = 'jsonpage_ac_' . md5( strtolower( $q ) . '|' . implode( ',', $countries ) . '|' . $status );
		$cached = get_transient( $key );
		if ( is_array( $cached ) ) {
			return $cached;
		}
		$answer = self::request(
			'/autocomplete',
			array(
				'q'       => $q,
				'country' => implode( ',', $countries ),
				'status'  => $status,
				'limit'   => 8,
			),
			5
		);
		if ( ! $answer['ok'] || ! isset( $answer['data']['data'] ) || ! is_array( $answer['data']['data'] ) ) {
			return null;
		}
		$out = array();
		foreach ( $answer['data']['data'] as $row ) {
			if ( ! is_array( $row ) || empty( $row['id'] ) ) {
				continue;
			}
			$out[] = array(
				'id'          => (string) $row['id'],
				'name'        => isset( $row['name'] ) ? (string) $row['name'] : '',
				'status'      => isset( $row['status'] ) ? (string) $row['status'] : 'unknown',
				'postal_code' => isset( $row['postal_code'] ) ? (string) $row['postal_code'] : '',
				'city'        => isset( $row['city'] ) ? (string) $row['city'] : '',
				'kind'        => isset( $row['kind'] ) ? (string) $row['kind'] : 'company',
			);
		}
		set_transient( $key, $out, 10 * MINUTE_IN_SECONDS );
		return $out;
	}

	/**
	 * Company record (name, address, VAT number) from its global identifier.
	 *
	 * @param string $id Identifier such as FR-552032534.
	 * @return array|null Record, or null when the API is not available.
	 */
	public static function company( $id ) {
		if ( ! preg_match( '/^[A-Z]{2}-[A-Za-z0-9]{3,20}$/', $id ) ) {
			return null;
		}
		$key    = 'jsonpage_co_' . md5( $id );
		$cached = get_transient( $key );
		if ( is_array( $cached ) ) {
			return $cached;
		}
		$answer = self::request( '/companies/' . rawurlencode( $id ), array( 'include' => 'address,vat' ), 5 );
		if ( ! $answer['ok'] || ! isset( $answer['data']['data'] ) || ! is_array( $answer['data']['data'] ) ) {
			return null;
		}
		$c       = $answer['data']['data'];
		$address = isset( $c['address'] ) && is_array( $c['address'] ) ? $c['address'] : array();
		$vat     = isset( $c['vat'] ) && is_array( $c['vat'] ) ? $c['vat'] : array();
		$out     = array(
			'id'          => isset( $c['id'] ) ? (string) $c['id'] : $id,
			'country'     => isset( $c['country'] ) ? (string) $c['country'] : '',
			'registry_id' => isset( $c['registry_id'] ) ? (string) $c['registry_id'] : '',
			'name'        => isset( $c['name'] ) ? (string) $c['name'] : '',
			'status'      => isset( $c['status'] ) ? (string) $c['status'] : 'unknown',
			'address'     => array(
				'line'        => isset( $address['line'] ) ? (string) $address['line'] : '',
				'postal_code' => isset( $address['postal_code'] ) ? (string) $address['postal_code'] : '',
				'city'        => isset( $address['city'] ) ? (string) $address['city'] : '',
				'country'     => isset( $address['country'] ) ? (string) $address['country'] : '',
			),
			'vat'         => array(
				'number' => isset( $vat['number'] ) ? (string) $vat['number'] : '',
				'status' => isset( $vat['status'] ) ? (string) $vat['status'] : '',
			),
		);
		set_transient( $key, $out, DAY_IN_SECONDS );
		return $out;
	}

	/**
	 * Checks a VAT number. The result is cached for 24 hours.
	 *
	 * Status:
	 *  valid       the number is registered (the order can be exempted).
	 *  invalid     the number is malformed or not registered.
	 *  pending     the check is not finished yet.
	 *  unverified  the check cannot be made (country not served, register unavailable).
	 *  error       the API did not answer: degraded mode, nothing is blocked.
	 *
	 * @param string $vat Number typed by the customer.
	 * @return array{status:string,number:string,closed:bool,checked_at:int,cached:bool}
	 */
	public static function verify_vat( $vat ) {
		$number = jsonpage_normalize_vat( $vat );
		$result = array(
			'status'     => 'error',
			'number'     => $number,
			'closed'     => false,
			'checked_at' => time(),
			'cached'     => false,
		);
		if ( '' === $number ) {
			$result['status'] = 'unverified';
			return $result;
		}
		static $memo = array();
		if ( isset( $memo[ $number ] ) ) {
			return $memo[ $number ];
		}
		$key    = 'jsonpage_v_' . md5( $number );
		$cached = get_transient( $key );
		if ( is_array( $cached ) && isset( $cached['status'] ) ) {
			$cached['cached'] = true;
			$memo[ $number ]  = $cached;
			return $cached;
		}
		$answer = self::request( '/validate', array( 'vat' => $number ), 4 );
		if ( ! $answer['ok'] || ! isset( $answer['data']['data'] ) || ! is_array( $answer['data']['data'] ) ) {
			return $result;
		}
		$data   = $answer['data']['data'];
		$checks = array();
		foreach ( isset( $data['checks'] ) && is_array( $data['checks'] ) ? $data['checks'] : array() as $check ) {
			if ( is_array( $check ) && isset( $check['code'] ) ) {
				$checks[ $check['code'] ] = $check;
			}
		}
		$status = 'unverified';
		if ( isset( $checks['vat_format'] ) && empty( $checks['vat_format']['ok'] ) ) {
			$status = 'invalid';
		} elseif ( isset( $checks['vat_country_supported'] ) && empty( $checks['vat_country_supported']['ok'] ) ) {
			$status = 'unverified';
		} elseif ( isset( $checks['vat_registered'] ) ) {
			$value = isset( $checks['vat_registered']['value'] ) ? $checks['vat_registered']['value'] : '';
			if ( 'valid' === $value && ! empty( $checks['vat_registered']['ok'] ) ) {
				$status = 'valid';
			} elseif ( 'invalid' === $value || empty( $checks['vat_registered']['ok'] ) ) {
				$status = 'invalid';
			} elseif ( 'pending' === $value ) {
				$status = 'pending';
			}
		}
		$closed = ( isset( $checks['company_active'] ) && empty( $checks['company_active']['ok'] ) )
			|| ( isset( $data['company']['status'] ) && 'closed' === $data['company']['status'] );

		$result['status'] = $status;
		$result['closed'] = (bool) $closed;
		if ( 'pending' !== $status ) {
			set_transient( $key, $result, 'unverified' === $status ? HOUR_IN_SECONDS : DAY_IN_SECONDS );
			$memo[ $number ] = $result;
		}
		return $result;
	}
}