<?php
/**
 * Talks to the Clientager service. All calls run on the server; the site token never reaches the browser.
 *
 * @package Clientager
 */

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

/**
 * Thin wrapper around wp_remote_request for the Clientager API.
 */
class Clientager_Api {

	const OPT_TOKEN       = 'clientager_token';
	const OPT_SITE_ID     = 'clientager_site_id';
	const OPT_LAST_STATUS = 'clientager_last_status';
	const STATUS_CACHE    = 'clientager_status';

	/**
	 * Base URL of the API (filterable for testing).
	 *
	 * @return string
	 */
	public static function base() {
		return untrailingslashit( apply_filters( 'clientager_api_base', CLIENTAGER_API ) );
	}

	/**
	 * The saved site token, or an empty string when not connected.
	 *
	 * @return string
	 */
	public static function token() {
		return (string) get_option( self::OPT_TOKEN, '' );
	}

	/**
	 * Saves the site token without autoloading it.
	 *
	 * @param string $token Token from the server.
	 */
	public static function save_token( $token ) {
		delete_option( self::OPT_TOKEN );
		add_option( self::OPT_TOKEN, sanitize_text_field( $token ), '', false );
		self::clear_status();
	}

	/**
	 * Forgets the connection.
	 */
	public static function forget() {
		delete_option( self::OPT_TOKEN );
		delete_option( self::OPT_LAST_STATUS );
		self::clear_status();
	}

	/**
	 * A random id for this WordPress site, created once.
	 *
	 * @return string
	 */
	public static function site_id() {
		$id = (string) get_option( self::OPT_SITE_ID, '' );
		if ( ! $id ) {
			$id = wp_generate_uuid4();
			add_option( self::OPT_SITE_ID, $id, '', false );
		}
		return $id;
	}

	/**
	 * Sends one request.
	 *
	 * @param string     $method HTTP method.
	 * @param string     $path   Path after the base, e.g. "/status".
	 * @param array|null $body   JSON body.
	 * @param array      $opts   timeout (seconds), blocking (bool), auth (bool).
	 * @return array { ok, status, data, error, code }
	 */
	public static function request( $method, $path, $body = null, $opts = array() ) {
		$opts    = wp_parse_args(
			$opts,
			array(
				'timeout'  => 15,
				'blocking' => true,
				'auth'     => true,
			)
		);
		// Time zone and locale are only used to show local prices before a billing country is saved.
		$headers = array(
			'Accept'                => 'application/json',
			'X-Clientager-Site'     => self::site_id(),
			'X-Clientager-Timezone' => wp_timezone_string(),
			'X-Clientager-Locale'   => get_locale(),
		);
		if ( $opts['auth'] ) {
			$token = self::token();
			if ( ! $token ) {
				return self::fail( 0, __( 'Connect your Clientager account first.', 'clientager' ), 'not_connected' );
			}
			$headers['Authorization'] = 'Bearer ' . $token;
		}
		$args = array(
			'method'     => $method,
			'timeout'    => $opts['timeout'],
			'blocking'   => $opts['blocking'],
			'headers'    => $headers,
			'user-agent' => 'Clientager-WordPress/' . CLIENTAGER_VERSION . '; ' . home_url( '/' ),
		);
		if ( null !== $body ) {
			$args['headers']['Content-Type'] = 'application/json';
			$args['body']                    = wp_json_encode( $body );
		}
		$res = wp_remote_request( self::base() . $path, $args );
		if ( ! $opts['blocking'] ) {
			return array(
				'ok'     => true,
				'status' => 0,
				'data'   => array(),
				'error'  => '',
				'code'   => '',
			);
		}
		if ( is_wp_error( $res ) ) {
			return self::fail( 0, __( 'Could not reach Clientager. Please try again in a moment.', 'clientager' ), 'network' );
		}
		$status = (int) wp_remote_retrieve_response_code( $res );
		$data   = json_decode( wp_remote_retrieve_body( $res ), true );
		$data   = is_array( $data ) ? $data : array();
		if ( $status >= 200 && $status < 300 ) {
			return array(
				'ok'     => true,
				'status' => $status,
				'data'   => $data,
				'error'  => '',
				'code'   => '',
			);
		}
		$code = isset( $data['code'] ) ? sanitize_key( $data['code'] ) : '';
		if ( 401 === $status && 'bad_token' === $code ) {
			self::forget();
		}
		$msg = isset( $data['error'] ) ? sanitize_text_field( $data['error'] ) : __( 'Something went wrong. Please try again.', 'clientager' );
		$out = self::fail( $status, $msg, $code );
		$out['data'] = $data;
		return $out;
	}

	/**
	 * Error result.
	 *
	 * @param int    $status HTTP status.
	 * @param string $error  Message.
	 * @param string $code   Machine code.
	 * @return array
	 */
	private static function fail( $status, $error, $code ) {
		return array(
			'ok'     => false,
			'status' => $status,
			'data'   => array(),
			'error'  => $error,
			'code'   => $code,
		);
	}

	/**
	 * Account status. Fresh from the server, or cached for 10 minutes when $cached is true.
	 * When the server cannot be reached, the last good answer is used for up to 24 hours.
	 *
	 * @param bool $cached Use the 10-minute cache.
	 * @return array|null Status, or null when not connected.
	 */
	public static function status( $cached = false ) {
		if ( ! self::token() ) {
			return null;
		}
		if ( $cached ) {
			$hit = get_transient( self::STATUS_CACHE );
			if ( is_array( $hit ) ) {
				return $hit;
			}
		}
		$res = self::request( 'GET', '/status', null, array( 'timeout' => $cached ? 3 : 10 ) );
		if ( $res['ok'] ) {
			set_transient( self::STATUS_CACHE, $res['data'], 10 * MINUTE_IN_SECONDS );
			update_option(
				self::OPT_LAST_STATUS,
				array(
					'at'     => time(),
					'status' => $res['data'],
				),
				false
			);
			return $res['data'];
		}
		if ( in_array( $res['code'], array( 'bad_token', 'blocked', 'not_connected' ), true ) ) {
			self::clear_status();
			return 'blocked' === $res['code'] ? array( 'blocked' => true ) : null;
		}
		$last = get_option( self::OPT_LAST_STATUS );
		if ( is_array( $last ) && isset( $last['at'], $last['status'] ) && time() - (int) $last['at'] < DAY_IN_SECONDS ) {
			// Retry in a minute rather than on every page view.
			set_transient( self::STATUS_CACHE, $last['status'], MINUTE_IN_SECONDS );
			return $last['status'];
		}
		return $cached ? null : array( 'unreachable' => true );
	}

	/**
	 * Drops the cached status so the next read asks the server.
	 */
	public static function clear_status() {
		delete_transient( self::STATUS_CACHE );
	}
}