<?php
	/**
	 * @package     Freemius
	 * @copyright   Copyright (c) 2015, Freemius, Inc.
	 * @license     https://www.gnu.org/licenses/gpl-3.0.html GNU General Public License Version 3
	 * @since       1.0.4
	 */

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

	/**
	 * Class FS_Api
	 *
	 * Wraps Freemius API SDK to handle:
	 *      1. Clock sync.
	 *      2. Fallback to HTTP when HTTPS fails.
	 *      3. Adds caching layer to GET requests.
	 *      4. Adds consistency for failed requests by using last cached version.
	 */
	class FS_Api {
		/**
		 * @var FS_Api[]
		 */
		private static $_instances = array();

		/**
		 * @var FS_Option_Manager Freemius options, options-manager.
		 */
		private static $_options;

		/**
		 * @var FS_Cache_Manager API Caching layer
		 */
		private static $_cache;

		/**
		 * @var int Clock diff in seconds between current server to API server.
		 */
		private static $_clock_diff;

		/**
		 * @var Freemius_Api_WordPress
		 */
		private $_api;

		/**
		 * @var string
		 */
		private $_slug;

		/**
		 * @var FS_Logger
		 * @since 1.0.4
		 */
		private $_logger;

        /**
         * @author Leo Fajardo (@leorw)
         * @since 2.3.0
         *
         * @var string
         */
        private $_sdk_version;

        /**
         * @author Leo Fajardo (@leorw)
         * @since 2.5.0
         *
         * @var string
         */
        private $_url;

        /**
		 * @param string      $slug
		 * @param string      $scope      'app', 'developer', 'user' or 'install'.
		 * @param number      $id         Element's id.
		 * @param string      $public_key Public key.
		 * @param bool        $is_sandbox
		 * @param bool|string $secret_key Element's secret key.
		 * @param null|string $sdk_version
		 * @param null|string $url
		 *
		 * @return FS_Api
		 */
		static function instance(
		    $slug,
            $scope,
            $id,
            $public_key,
            $is_sandbox,
            $secret_key = false,
            $sdk_version = null,
            $url = null
        ) {
			$identifier = md5( $slug . $scope . $id . $public_key . ( is_string( $secret_key ) ? $secret_key : '' ) . json_encode( $is_sandbox ) );

			if ( ! isset( self::$_instances[ $identifier ] ) ) {
				self::_init();

				self::$_instances[ $identifier ] = new FS_Api( $slug, $scope, $id, $public_key, $secret_key, $is_sandbox, $sdk_version, $url );
			}

			return self::$_instances[ $identifier ];
		}

		private static function _init() {
			if ( isset( self::$_options ) ) {
				return;
			}

			if ( ! class_exists( 'Freemius_Api_WordPress' ) ) {
				require_once WP_FS__DIR_SDK . '/FreemiusWordPress.php';
			}

			self::$_options = FS_Option_Manager::get_manager( WP_FS__OPTIONS_OPTION_NAME, true, true );
			self::$_cache   = FS_Cache_Manager::get_manager( WP_FS__API_CACHE_OPTION_NAME );

			self::$_clock_diff = self::$_options->get_option( 'api_clock_diff', 0 );
			Freemius_Api_WordPress::SetClockDiff( self::$_clock_diff );

			if ( self::$_options->get_option( 'api_force_http', false ) ) {
				Freemius_Api_WordPress::SetHttp();
			}
		}

		/**
		 * @param string      $slug
		 * @param string      $scope      'app', 'developer', 'user' or 'install'.
		 * @param number      $id         Element's id.
		 * @param string      $public_key Public key.
		 * @param bool|string $secret_key Element's secret key.
		 * @param bool        $is_sandbox
		 * @param null|string $sdk_version
		 * @param null|string $url
		 */
		private function __construct(
		    $slug,
            $scope,
            $id,
            $public_key,
            $secret_key,
            $is_sandbox,
            $sdk_version,
            $url
        ) {
			$this->_api = new Freemius_Api_WordPress( $scope, $id, $public_key, $secret_key, $is_sandbox );

			$this->_slug        = $slug;
			$this->_sdk_version = $sdk_version;
			$this->_url         = $url;
			$this->_logger      = FS_Logger::get_logger( WP_FS__SLUG . '_' . $slug . '_api', WP_FS__DEBUG_SDK, WP_FS__ECHO_DEBUG_SDK );
		}

		/**
		 * Find clock diff between server and API server, and store the diff locally.
		 *
		 * @param bool|int $diff
		 *
		 * @return bool|int False if clock diff didn't change, otherwise returns the clock diff in seconds.
		 */
		private function _sync_clock_diff( $diff = false ) {
			$this->_logger->entrance();

			// Sync clock and store.
			$new_clock_diff = ( false === $diff ) ?
				Freemius_Api_WordPress::FindClockDiff() :
				$diff;

			if ( $new_clock_diff === self::$_clock_diff ) {
				return false;
			}

			self::$_clock_diff = $new_clock_diff;

			// Update API clock's diff.
			Freemius_Api_WordPress::SetClockDiff( self::$_clock_diff );

			// Store new clock diff in storage.
			self::$_options->set_option( 'api_clock_diff', self::$_clock_diff, true );

			return $new_clock_diff;
		}

		/**
		 * Override API call to enable retry with servers' clock auto sync method.
		 *
		 * @param string $path
		 * @param string $method
		 * @param array  $params
		 * @param bool   $retry Is in retry or first call attempt.
		 *
		 * @return array|mixed|string|void
		 */
		private function _call( $path, $method = 'GET', $params = array(), $retry = false ) {
            $this->_logger->entrance( $method . ':' . $path );

            if ( self::is_temporary_down() ) {
                $result = $this->get_temporary_unavailable_error();
            } else {
                /**
                 * @since 2.3.0 Include the SDK version with all API requests that going through the API manager. IMPORTANT: Only pass the SDK version if the caller didn't include it yet.
                 */
                if ( ! empty( $this->_sdk_version ) ) {
                    if ( false === strpos( $path, 'sdk_version=' ) &&
                         ! isset( $params['sdk_version'] )
                    ) {
                        // Always add the sdk_version param in the querystring. DO NOT INCLUDE IT IN THE BODY PARAMS, OTHERWISE, IT MAY LEAD TO AN UNEXPECTED PARAMS PARSING IN CASES WHERE THE $params IS A REGULAR NON-ASSOCIATIVE ARRAY.
                        $path = add_query_arg( 'sdk_version', $this->_sdk_version, $path );
                    }
                }

                /**
                 * @since 2.5.0 Include the site's URL, if available, in all API requests that are going through the API manager.
                 */
                if ( ! empty( $this->_url ) ) {
                    if ( false === strpos( $path, 'url=' ) &&
                         ! isset( $params['url'] )
                    ) {
                        $path = add_query_arg( 'url', $this->_url, $path );
                    }
                }

                $result = $this->_api->Api( $path, $method, $params );

                if ( null !== $result &&
                     isset( $result->error ) &&
                     isset( $result->error->code ) &&
                     'request_expired' === $result->error->code
                ) {
                    if ( ! $retry ) {
                        $diff = isset( $result->error->timestamp ) ?
                            ( time() - strtotime( $result->error->timestamp ) ) :
                            false;

                        // Try to sync clock diff.
                        if ( false !== $this->_sync_clock_diff( $diff ) ) {
                            // Retry call with new synced clock.
                            return $this->_call( $path, $method, $params, true );
                        }
                    }
                }
            }

            if ( $this->_logger->is_on() && self::is_api_error( $result ) ) {
                // Log API errors.
                $this->_logger->api_error( $result );
            }

            return $result;
        }

		/**
		 * Override API call to wrap it in servers' clock sync method.
		 *
		 * @param string $path
		 * @param string $method
		 * @param array  $params
		 *
		 * @return array|mixed|string|void
		 * @throws Freemius_Exception
		 */
		function call( $path, $method = 'GET', $params = array() ) {
			return $this->_call( $path, $method, $params );
		}

		/**
		 * Get API request URL signed via query string.
		 *
		 * @param string $path
		 *
		 * @return string
		 */
		function get_signed_url( $path ) {
			return $this->_api->GetSignedUrl( $path );
		}

		/**
		 * @param string $path
		 * @param bool   $flush
		 * @param int    $expiration (optional) Time until expiration in seconds from now, defaults to 24 hours
		 *
		 * @return stdClass|mixed
		 */
		function get( $path = '/', $flush = false, $expiration = WP_FS__TIME_24_HOURS_IN_SEC ) {
			$this->_logger->entrance( $path );

			$cache_key = $this->get_cache_key( $path );

			// Always flush during development.
			if ( WP_FS__DEV_MODE || $this->_api->IsSandbox() ) {
				$flush = true;
			}

			$cached_result = self::$_cache->get( $cache_key );

			if ( $flush || ! self::$_cache->has_valid( $cache_key, $expiration ) ) {
				$result = $this->call( $path );

				if ( ! is_object( $result ) || isset( $result->error ) ) {
					// Api returned an error.
					if ( is_object( $cached_result ) &&
					     ! isset( $cached_result->error )
					) {
						// If there was an error during a newer data fetch,
						// fallback to older data version.
						$result = $cached_result;

						if ( $this->_logger->is_on() ) {
							$this->_logger->warn( 'Fallback to cached API result: ' . var_export( $cached_result, true ) );
						}
					} else {
					    if ( is_object( $result ) && isset( $result->error->http ) && 404 == $result->error->http ) {
                            /**
                             * If the response code is 404, cache the result for half of the `$expiration`.
                             *
                             * @author Leo Fajardo (@leorw)
                             * @since 2.2.4
                             */
					        $expiration /= 2;
                        } else {
                            // If no older data version and the response code is not 404, return result without
                            // caching the error.
                            return $result;
                        }
					}
				}

				self::$_cache->set( $cache_key, $result, $expiration );

				$cached_result = $result;
			} else {
				$this->_logger->log( 'Using cached API result.' );
			}

			return $cached_result;
		}

		/**
		 * Check if there's a cached version of the API request.
		 *
		 * @author Vova Feldman (@svovaf)
		 * @since  1.2.1
		 *