<?php

namespace WPMailSMTP;

use Plugin_Upgrader;
use WP_Error;
use WPMailSMTP\Admin\PluginsInstallSkin;
use WPMailSMTP\Helpers\Helpers;

/**
 * WP Mail SMTP Connect.
 *
 * WP Mail SMTP Connect is our service that makes it easy for non-techy users to
 * upgrade to Pro version without having to manually install Pro plugin.
 *
 * @since 2.6.0
 */
class Connect {

	/**
	 * Query parameter marking a return URL as coming back from an upgrade.
	 *
	 * @since 4.10.0
	 *
	 * @var string
	 */
	const UPGRADED_QUERY_ARG = 'wp_mail_smtp_upgraded';

	/**
	 * The only plugin the Connect flow installs and activates.
	 *
	 * @since 4.10.1
	 *
	 * @var string
	 */
	private const PRO_PLUGIN_BASENAME = 'wp-mail-smtp-pro/wp_mail_smtp.php';

	/**
	 * The host the Pro package is downloaded from.
	 *
	 * @since 4.10.1
	 *
	 * @var string
	 */
	private const DOWNLOAD_HOST = 'wpmailsmtpapi.com';

	/**
	 * Hooks.
	 *
	 * @since 2.6.0
	 */
	public function hooks() {

		add_action( 'wp_ajax_wp_mail_smtp_connect_url', [ $this, 'ajax_generate_url' ] );
		add_action( 'wp_ajax_nopriv_wp_mail_smtp_connect_process', [ $this, 'process' ] );
	}

	/**
	 * Generate and return WP Mail SMTP Connect URL.
	 *
	 * @since 2.6.0
	 *
	 * @param string $key        The license key.
	 * @param string $oth        The One-time hash.
	 * @param string $redirect   The redirect URL.
	 *
	 * @return bool|string
	 */
	public static function generate_url( $key, $oth = '', $redirect = '' ) {

		if ( empty( $key ) || wp_mail_smtp()->is_pro() ) {
			return false;
		}

		$oth        = ! empty( $oth ) ? $oth : hash( 'sha512', wp_rand() );
		$hashed_oth = hash_hmac( 'sha512', $oth, wp_salt() );

		$redirect = ! empty( $redirect ) ? $redirect : wp_mail_smtp()->get_admin()->get_admin_page_url();

		set_transient( 'wp_mail_smtp_connect_token', $oth, HOUR_IN_SECONDS );
		update_option( 'wp_mail_smtp_connect', $key );

		return add_query_arg(
			[
				'key'      => $key,
				'oth'      => $hashed_oth,
				'endpoint' => admin_url( 'admin-ajax.php' ),
				'version'  => WPMS_PLUGIN_VER,
				'siteurl'  => admin_url(),
				'homeurl'  => wp_mail_smtp()->get_license_site_url()->derive(),
				'redirect' => rawurldecode( base64_encode( $redirect ) ), // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode
				'v'        => 2,
			],
			'https://upgrade.wpmailsmtp.com'
		);
	}

	/**
	 * AJAX callback to generate and return the WP Mail SMTP Connect URL.
	 *
	 * @since 2.6.0
	 */
	public function ajax_generate_url() { //phpcs:ignore Generic.Metrics.CyclomaticComplexity.TooHigh

		if ( check_ajax_referer( 'wp-mail-smtp-admin', 'nonce', false ) === false ) {
			wp_send_json_error( esc_html__( 'Your session expired. Please reload the page and try again.', 'wp-mail-smtp' ) );
		}

		// Check for permissions.
		if ( ! current_user_can( 'install_plugins' ) ) {
			wp_send_json_error( esc_html__( 'You are not allowed to install plugins.', 'wp-mail-smtp' ) );
		}

		// A license key is an md5 hash, so sanitize_key cannot mangle it.
		$key = ! empty( $_POST['key'] ) ? sanitize_key( wp_unslash( $_POST['key'] ) ) : '';

		if ( empty( $key ) ) {
			wp_send_json_error( esc_html__( 'Please enter your license key to connect.', 'wp-mail-smtp' ) );
		}

		if ( ! $this->is_valid_key_format( $key ) ) {
			wp_send_json_error( esc_html__( 'License key format is not valid.', 'wp-mail-smtp' ) );
		}

		if ( wp_mail_smtp()->is_pro() ) {
			wp_send_json_error( esc_html__( 'Only the Lite version can be upgraded.', 'wp-mail-smtp' ) );
		}

		$return_url = $this->get_return_url();

		// Verify pro version is not installed.
		$active = activate_plugin( 'wp-mail-smtp-pro/wp_mail_smtp.php', false, false, true );

		if ( ! is_wp_error( $active ) ) {

			// Deactivate Lite.
			deactivate_plugins( plugin_basename( WPMS_PLUGIN_FILE ) );

			wp_send_json_success( [ 'url' => $return_url ] );
		}

		$url = self::generate_url( $key, '', $return_url );

		if ( empty( $url ) ) {
			wp_send_json_error( esc_html__( 'There was an error while generating an upgrade URL. Please try again.', 'wp-mail-smtp' ) );
		}

		wp_send_json_success( [ 'url' => $url ] );
	}

	/**
	 * Where the upgrade service sends the browser back to once it is done.
	 *
	 * @since 4.10.0
	 *
	 * @return string A marked URL on this site.
	 */
	private function get_return_url() {

		// The value travels to the service as a query parameter, so an unvalidated one
		// would turn the upgrade page into an open redirect.
		// phpcs:ignore WordPress.Security.NonceVerification.Missing -- ajax_generate_url() verifies the nonce before calling this.
		$requested = ! empty( $_POST['redirect'] ) ? esc_url_raw( wp_unslash( $_POST['redirect'] ) ) : '';
		$fallback  = wp_mail_smtp()->get_admin()->get_admin_page_url();

		$url = empty( $requested ) ? $fallback : wp_validate_redirect( $requested, $fallback );

		return add_query_arg( self::UPGRADED_QUERY_ARG, '1', $url );
	}

	/**
	 * Whether the key is a 32-char MD5 hex string.
	 *
	 * @since 4.10.0
	 *
	 * @param string $key License key.
	 *
	 * @return bool
	 */
	private function is_valid_key_format( $key ) {

		return (bool) preg_match( '/^[a-f0-9]{32}$/i', $key );
	}

	/**
	 * AJAX callback to process WP Mail SMTP Connect.
	 *
	 * @since 2.6.0
	 */
	public function process() { // phpcs:ignore Generic.Metrics.CyclomaticComplexity.MaxExceeded, WPForms.PHP.HooksMethod.InvalidPlaceForAddingHooks

		$error = esc_html__( 'There was an error while installing an upgrade. Please download the plugin from wpmailsmtp.com and install it manually.', 'wp-mail-smtp' );

		// Verify params present (oth & download link).
		$post_oth = ! empty( $_REQUEST['oth'] ) ? sanitize_text_field( wp_unslash( $_REQUEST['oth'] ) ) : ''; // phpcs:ignore WordPress.Security.NonceVerification
		$post_url = ! empty( $_REQUEST['file'] ) ? esc_url_raw( wp_unslash( $_REQUEST['file'] ) ) : ''; // phpcs:ignore WordPress.Security.NonceVerification

		if ( empty( $post_oth ) || empty( $post_url ) || ! $this->is_valid_download_url( $post_url ) ) {
			wp_send_json_error( $error );
		}

		// Verify oth.
		$oth = get_transient( 'wp_mail_smtp_connect_token' );

		if ( empty( $oth ) ) {
			wp_send_json_error( $error );
		}

		if ( hash_hmac( 'sha512', $oth, wp_salt() ) !== $post_oth ) {
			wp_send_json_error( $error );
		}

		// Delete so cannot replay.
		delete_transient( 'wp_mail_smtp_connect_token' );

		// Set the current screen to avoid undefined notices.
		set_current_screen( 'toplevel_page_wp-mail-smtp' );

		// Prepare variables.
		$url = esc_url_raw( wp_mail_smtp()->get_admin()->get_admin_page_url() );

		// Verify pro not activated.
		if ( wp_mail_smtp()->is_pro() ) {
			wp_send_json_success( esc_html__( 'Plugin installed & activated.', 'wp-mail-smtp' ) );
		}

		// Verify pro not installed.
		$active = activate_plugin( 'wp-mail-smtp-pro/wp_mail_smtp.php', $url, false, true );

		if ( ! is_wp_error( $active ) ) {
			deactivate_plugins( plugin_basename( WPMS_PLUGIN_FILE ) );
			wp_send_json_success( esc_html__( 'Plugin installed & activated.', 'wp-mail-smtp' ) );
		}

		/*
		 * The `request_filesystem_credentials` function will output a credentials form in case of failure.
		 * We don't want that, since it will break AJAX response. So just hide output with a buffer.
		 */
		ob_start();
		// phpcs:ignore WPForms.Formatting.EmptyLineAfterAssigmentVariables.AddEmptyLine
		$creds = request_filesystem_credentials( $url, '', false, false, null );
		ob_end_clean();

		// Check for file system permissions.
		$perm_error = esc_html__( 'There was an error while installing an upgrade. Please check file system permissions and try again. Also, you can download the plugin from wpmailsmtp.com and install it manually.', 'wp-mail-smtp' );

		if ( false === $creds || ! WP_Filesystem( $creds ) ) {
			wp_send_json_error( $perm_error );
		}

		/*
		 * We do not need any extra credentials if we have gotten this far, so let's install the plugin.
		 */

		// Do not allow WordPress to search/download translations, as this will break JS output.
		remove_action( 'upgrader_process_complete', array( 'Language_Pack_Upgrader', 'async_upgrade' ), 20 );

		// Import the plugin upgrader.
		Helpers::include_plugin_upgrader();

		// Create the plugin upgrader with our custom skin.
		$installer = new Plugin_Upgrader( new PluginsInstallSkin() );

		// Error check.
		if ( ! method_exists( $installer, 'install' ) ) {
			wp_send_json_error( $error );
		}

		// Check license key.
		$key = get_option( 'wp_mail_smtp_connect', false );
		delete_option( 'wp_mail_smtp_connect' );

		if ( empty( $key ) ) {
			wp_send_json_error(
				new WP_Error(
					'403',
					esc_html__( 'There was an error while installing an upgrade. Please try again.', 'wp-mail-smtp' )
				)
			);
		}

		$installer->install( $post_url );

		// Flush the cache and return the newly installed plugin basename.
		wp_cache_flush();

		$plugin_basename = $installer->plugin_info();

		if ( $plugin_basename !== self::PRO_PLUGIN_BASENAME ) {
			// Not delete_plugins(): it would run the package's uninstall code.
			if ( is_array( $installer->result ) && ! empty( $installer->result['destination'] ) ) {
				$installer->clear_destination( $installer->result['destination'] );
			}

			wp_send_json_error( $error );
		}

		// Deactivate the lite version first.
		deactivate_plugins( plugin_basename( WPMS_PLUGIN_FILE ) );

		// Activate the plugin silently.
		$activated = activate_plugin( $plugin_basename, '', false, true );

		if ( ! is_wp_error( $activated ) ) {

			// Save the license data, since it was verified on the connect page.
			$options = Options::init();
			$all_opt = $options->get_all_raw();

			$all_opt['license']['key']              = $key;
			$all_opt['license']['type']             = 'pro';
			$all_opt['license']['is_expired']       = false;
			$all_opt['license']['is_disabled']      = false;
			$all_opt['license']['is_invalid']       = false;
			$all_opt['license']['is_limit_reached'] = false;

			// The connect page activated the license against the URL the upgrade link sent,
			// so pin that same one: this flow never runs an activation of its own.
			$all_opt['license']['site_url']           = wp_mail_smtp()->get_license_site_url()->derive();
			$all_opt['license']['site_url_pinned_at'] = time();

			$options->set( $all_opt, false, true );

			wp_send_json_success( esc_html__( 'Plugin installed & activated.', 'wp-mail-smtp' ) );
		} else {
			// Reactivate the lite plugin if pro activation failed.
			activate_plugin( plugin_basename( WPMS_PLUGIN_FILE ), '', false, true );
			wp_send_json_error( esc_html__( 'Pro version installed but needs to be activated on the Plugins page.', 'wp-mail-smtp' ) );
		}
	}

	/**
	 * Whether a package URL points at the Pro download host over HTTPS.
	 *
	 * @since 4.10.1
	 *
	 * @param string $url Package URL.
	 *
	 * @return bool
	 */
	private function is_valid_download_url( $url ) {

		$parts = wp_parse_url( $url );

		$is_valid = ! empty( $parts['scheme'] ) &&
			! empty( $parts['host'] ) &&
			strtolower( $parts['scheme'] ) === 'https' &&
			strtolower( $parts['host'] ) === self::DOWNLOAD_HOST;

		/**
		 * Filters whether the Connect flow accepts a package URL.
		 *
		 * @since 4.10.1
		 *
		 * @param bool   $is_valid Whether the URL is on the Pro download host over HTTPS.
		 * @param string $url      Package URL.
		 */
		return (bool) apply_filters( 'wp_mail_smtp_connect_is_valid_download_url', $is_valid, $url );
	}

	/**
	 * Enqueue the connect JS file.
	 *
	 * @since      2.6.0
	 * @deprecated {VERSION}
	 */
	public function enqueue_scripts() {

		_deprecated_function( __METHOD__, '4.10.0' );
	}
}