<?php
/**
 * Updater class.
 *
 * @since 1.0.0
 *
 * @package TGM Updater
 * @author  Thomas Griffin
 *
 * TGM Updater is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * any later version.
 *
 * TGM Updater is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with TGM Updater. If not, see <http://www.gnu.org/licenses/>.
 */
class TGM_Updater {

	/**
	 * Plugin name.
	 *
	 * @since 1.0.0
	 *
	 * @var bool|string
	 */
	public $plugin_name = false;

	/**
	 * Plugin slug.
	 *
	 * @since 1.0.0
	 *
	 * @var bool|string
	 */
	public $plugin_slug = false;

	/**
	 * Plugin path.
	 *
	 * @since 1.0.0
	 *
	 * @var bool|string
	 */
	public $plugin_path = false;

	/**
	 * URL of the plugin.
	 *
	 * @since 1.0.0
	 *
	 * @var bool|string
	 */
	public $plugin_url = false;

	/**
	 * Remote URL for getting plugin updates.
	 *
	 * @since 1.0.0
	 *
	 * @var bool|string
	 */
	public $remote_url = false;

	/**
	 * Version number of the plugin.
	 *
	 * @since 1.0.0
	 *
	 * @var bool|int
	 */
	public $version = false;

	/**
	 * License key for the plugin.
	 *
	 * @since 1.0.0
	 *
	 * @var bool|string
	 */
	public $key = false;

	/**
	 * Holds the update data returned from the API.
	 *
	 * @since 1.0.0
	 *
	 * @var bool|object
	 */
	public $update = false;

	/**
	 * Holds the plugin info details for the update.
	 *
	 * @since 1.0.0
	 *
	 * @var bool|object
	 */
	public $info = false;

	/**
	 * Primary class constructor.
	 *
	 * @since 1.0.0
	 *
	 * @param array $config Array of updater config args.
	 */
	public function __construct( array $config ) {

		// Set class properties.
		$accepted_args = array(
			'plugin_name',
			'plugin_slug',
			'plugin_path',
			'plugin_url',
			'remote_url',
			'version',
			'key'
		);
		foreach ( $accepted_args as $arg ) {
			$this->$arg = $config[$arg];
		}

		// If the user cannot update plugins, stop processing here.
		if ( ! current_user_can( 'update_plugins' ) ) {
			return;
		}

		// Load the updater hooks and filters.
		add_filter( 'pre_set_site_transient_update_plugins', array( $this, 'update_plugins_filter' ), 100 );
		add_filter( 'pre_set_transient_update_plugins', array( $this, 'update_plugins_filter' ), 100 );
		add_filter( 'http_request_args', array( $this, 'http_request_args' ), 10, 2 );
		add_filter( 'plugins_api', array( $this, 'plugins_api' ), 100, 3 );

	}

	/**
	 * Infuse plugin update details when WordPress runs its update checker.
	 *
	 * @since 1.0.0
	 *
	 * @param object $value  The WordPress update object.
	 * @return object $value Amended WordPress update object on success, default if object is empty.
	 */
	public function update_plugins_filter( $value ) {

		// If no update object exists, return early.
		if ( empty( $value ) ) {
			return $value;
		}

		// Run update check by pinging the external API. If it fails, return the default update object.
		if ( ! $this->update ) {
			$this->update = $this->perform_remote_request( 'get-plugin-update', array( 'tgm-updater-plugin' => $this->plugin_slug ) );
			if ( ! $this->update || ! empty( $this->update->error ) ) {
				$this->update = false;
				return $value;
			}
		}

		global $wp_version;

		// Check WP version
		if ( version_compare( $wp_version, $this->update->wp_version, '<' ) ) {
			return $value;
		}

		// Infuse the update object with our data if the version from the remote API is newer.
		if ( isset( $this->update->new_version ) && version_compare( $this->version, $this->update->new_version, '<' ) ) {
			// The $plugin_update object contains new_version, package, slug and last_update keys.
			$value->response[$this->plugin_path] = $this->update;
		}

		// Return the update object.
		return $value;

	}

	/**
	 * Disables SSL verification to prevent download package failures.
	 *
	 * @since 1.0.0
	 *
	 * @param array $args  Array of request args.
	 * @param string $url  The URL to be pinged.
	 * @return array $args Amended array of request args.
	 */
	public function http_request_args( $args, $url ) {

		// If this is an SSL request and we are performing an upgrade routine, disable SSL verification.
		if ( strpos( $url, 'https://' ) !== false && strpos( $url, 'tgm-updater-action=get-plugin-update' ) ) {
			$args['sslverify'] = false;
		}

		return $args;

	}

	/**
	 * Filters the plugins_api function to get our own custom plugin information
	 * from our private repo.
	 *
	 * @since 1.0.0
	 *
	 * @param object $api    The original plugins_api object.
	 * @param string $action The action sent by plugins_api.
	 * @param array $args    Additional args to send to plugins_api.
	 * @return object $api   New stdClass with plugin information on success, default response on failure.
	 */
	public function plugins_api( $api, $action = '', $args = null ) {

		$plugin = ( 'plugin_information' == $action ) && isset( $args->slug ) && ( $this->plugin_slug == $args->slug );

		// If our plugin matches the request, set our own plugin data, else return the default response.
		if ( $plugin ) {
			return $this->set_plugins_api( $api );
		} else {
			return $api;
		}

	}

	/**
	 * Pings a remote API to retrieve plugin information for WordPress to display.
	 *
	 * @since 1.0.0
	 *
	 * @param object $default_api The default API object.
	 * @return object $api        Return custom plugin information to plugins_api.
	 */
	public function set_plugins_api( $default_api ) {

		// Perform the remote request to retrieve our plugin information. If it fails, return the default object.
		if ( ! $this->info ) {
			$this->info = $this->perform_remote_request( 'get-plugin-info', array( 'tgm-updater-plugin' => $this->plugin_slug ) );
			if ( ! $this->info || ! empty( $this->info->error ) ) {
				$this->info = false;
				return $default_api;
			}
		}

		// Create a new stdClass object and populate it with our plugin information.
		$api                        = new stdClass;
		$api->name                  = isset( $this->info->name )           ? $this->info->name           : '';
		$api->slug                  = isset( $this->info->slug )           ? $this->info->slug           : '';
		$api->version               = isset( $this->info->version )        ? $this->info->version        : '';
		$api->author                = isset( $this->info->author )         ? $this->info->author         : '';
		$api->author_profile        = isset( $this->info->author_profile ) ? $this->info->author_profile : '';
		$api->requires              = isset( $this->info->requires )       ? $this->info->requires       : '';
		$api->tested                = isset( $this->info->tested )         ? $this->info->tested         : '';
		$api->last_updated          = isset( $this->info->last_updated )   ? $this->info->last_updated   : '';
		$api->homepage              = isset( $this->info->homepage )       ? $this->info->homepage       : '';
		$api->sections['changelog'] = isset( $this->info->changelog )      ? $this->info->changelog      : '';
		$api->download_link         = isset( $this->info->download_link )  ? $this->info->download_link  : '';

		// Return the new API object with our custom data.
		return $api;

	}

	/**
	 * Queries the remote URL via wp_remote_post and returns a json decoded response.
	 *
	 * @since 1.0.0
	 *
	 * @param string $action        The name of the $_POST action var.
	 * @param array $body           The content to retrieve from the remote URL.
	 * @param array $headers        The headers to send to the remote URL.
	 * @param string $return_format The format for returning content from the remote URL.
	 * @return string|bool          Json decoded response on success, false on failure.
	 */
	public function perform_remote_request( $action, $body = array(), $headers = array(), $return_format = 'json' ) {

		// Build the body of the request.
		$body = wp_parse_args(
			$body,
			array(
				'tgm-updater-action'     => $action,
				'tgm-updater-key'        => $this->key,
				'tgm-updater-wp-version' => get_bloginfo( 'version' ),
				'tgm-updater-referer'    => site_url()
			)
		);
		$body = http_build_query( $body, '', '&' );

		// Build the headers of the request.
		$headers = wp_parse_args(
			$headers,
			array(
				'Content-Type'   => 'application/x-www-form-urlencoded',
				'Content-Length' => strlen( $body )
			)
		);

		// Setup variable for wp_remote_post.
		$post = array(
			'headers' => $headers,
			'body'    => $body
		);

		// Perform the query and retrieve the response.
		$response      = wp_remote_post( esc_url_raw( $this->remote_url ), $post );
		$response_code = wp_remote_retrieve_response_code( $response );
		$response_body = wp_remote_retrieve_body( $response );

		// Bail out early if there are any errors.
		if ( 200 != $response_code || is_wp_error( $response_body ) ) {
			return false;
		}

		// Return the json decoded content.
		return json_decode( $response_body );

	}

}
