<?php
/**
 * Install, upgrade and deactivate routines.
 *
 * The plugin only ever creates and changes its own two tables. Core tables are never altered.
 *
 * @package LinkTender
 */

defined( 'ABSPATH' ) || exit;

/**
 * Table management.
 */
class LinkTender_Install {

	const DB_OPTION = 'linktender_db_version';

	const STARTED_OPTION = 'linktender_checking_started';

	const NETWORK_OPTION = 'linktender_network_install';

	const NETWORK_HOOK = 'linktender_network_install';

	const SITE_BATCH = 100;

	/**
	 * Links table name.
	 *
	 * @return string
	 */
	public static function links_table() {
		global $wpdb;
		return $wpdb->prefix . 'linktender_links';
	}

	/**
	 * Instances (where a link appears) table name.
	 *
	 * @return string
	 */
	public static function instances_table() {
		global $wpdb;
		return $wpdb->prefix . 'linktender_instances';
	}

	/**
	 * Activation hook.
	 *
	 * Activation only creates the plugin's tables and stores the schema version. It prints
	 * nothing, makes no HTTP requests, schedules no events and does not start link checking:
	 * checks begin only after an administrator clicks "Start checking links" on the LinkTender
	 * screen (see LinkTender_Install::start_checking()).
	 *
	 * On multisite, network activation sets up every site of the network, in batches of
	 * self::SITE_BATCH. If a very large network cannot be finished within the time budget,
	 * each remaining site creates its tables the first time its dashboard is opened
	 * (maybe_upgrade on admin_init). Nothing is scheduled for this.
	 *
	 * @param bool $network_wide Network activation.
	 * @return void
	 */
	public static function activate( $network_wide = false ) {
		if ( is_multisite() && $network_wide ) {
			delete_site_option( self::NETWORK_OPTION );
			self::install_network( 0 );
			return;
		}
		self::install_site();
	}

	/**
	 * Sets up sites of the current network, starting at the given offset.
	 *
	 * Sites are read with get_sites() in batches of self::SITE_BATCH, ordered by ID, until
	 * no more are returned or the time budget is used up. There is no upper limit on the
	 * number of sites; sites not reached set themselves up on their first admin page load.
	 *
	 * @param int $offset Number of sites already processed.
	 * @return bool True when every site was processed.
	 */
	public static function install_network( $offset = 0 ) {
		$start = microtime( true );
		/**
		 * Filters the seconds network activation may spend before the rest continues in the background.
		 *
		 * @param int $seconds Seconds.
		 */
		$budget = (int) apply_filters( 'linktender_network_install_budget', 20 );
		$offset = max( 0, (int) $offset );

		do {
			$ids = self::site_ids( $offset, get_current_network_id() );
			foreach ( $ids as $site_id ) {
				switch_to_blog( $site_id );
				self::install_site();
				restore_current_blog();
			}
			$offset += count( $ids );
			if ( count( $ids ) < self::SITE_BATCH ) {
				delete_site_option( self::NETWORK_OPTION );
				return true;
			}
		} while ( microtime( true ) - $start < $budget );

		// Very large network: the remaining sites are set up on their first admin page load.
		return false;
	}

	/**
	 * Handles a background event left by version 1.0.3 or 1.1.0 (which continued very large
	 * network activations in the background). Newer versions no longer schedule it.
	 *
	 * @return void
	 */
	public static function continue_network_install() {
		$offset = get_site_option( self::NETWORK_OPTION, false );
		delete_site_option( self::NETWORK_OPTION );
		if ( false === $offset || ! is_multisite() ) {
			return;
		}
		self::install_network( (int) $offset );
	}

	/**
	 * One batch of site IDs, oldest first.
	 *
	 * @param int      $offset     Offset.
	 * @param int|null $network_id Network ID, or null for all networks.
	 * @return int[]
	 */
	public static function site_ids( $offset, $network_id = null ) {
		$args = array(
			'fields'                 => 'ids',
			'number'                 => self::SITE_BATCH,
			'offset'                 => max( 0, (int) $offset ),
			'orderby'                => 'id',
			'order'                  => 'ASC',
			'update_site_meta_cache' => false,
		);
		if ( null !== $network_id ) {
			$args['network_id'] = (int) $network_id;
		}
		return array_map( 'intval', get_sites( $args ) );
	}

	/**
	 * Creates the tables on the current site. Silent and offline: no output, no HTTP requests,
	 * no scheduled events. Link checking is not started here.
	 *
	 * @return void
	 */
	public static function install_site() {
		$installed = (int) get_option( self::DB_OPTION, 0 );
		self::create_tables();
		if ( $installed < LINKTENDER_DB_VERSION ) {
			self::migrate( $installed );
			update_option( self::DB_OPTION, LINKTENDER_DB_VERSION );
		}
	}

	/**
	 * Whether the plugin's tables exist on the current site (schema version stored).
	 *
	 * @return bool
	 */
	public static function is_installed() {
		return (int) get_option( self::DB_OPTION, 0 ) >= 1;
	}

	/**
	 * Whether an administrator has started link checking on this site.
	 *
	 * @return bool
	 */
	public static function checking_started() {
		return (bool) get_option( self::STARTED_OPTION, false );
	}

	/**
	 * Starts link checking on the current site after an administrator asked for it:
	 * records the choice, queues the first content scan and schedules background batches.
	 *
	 * @return void
	 */
	public static function start_checking() {
		self::maybe_upgrade();
		if ( ! self::checking_started() ) {
			update_option(
				self::STARTED_OPTION,
				array(
					'time' => time(),
					'user' => get_current_user_id(),
				),
				false
			);
		}
		// Content may have changed while checking was stopped, so start with a fresh scan.
		if ( ! LinkTender_Scanner::is_running() ) {
			LinkTender_Scanner::request_full_scan();
		}
		LinkTender_Queue::schedule();
	}

	/**
	 * Deactivation hook: removes scheduled events and stops checking. Data is kept until
	 * uninstall. After re-activation nothing runs until an administrator clicks Start again.
	 *
	 * @param bool $network_wide Network deactivation.
	 * @return void
	 */
	public static function deactivate( $network_wide = false ) {
		if ( is_multisite() && $network_wide ) {
			wp_clear_scheduled_hook( self::NETWORK_HOOK );
			delete_site_option( self::NETWORK_OPTION );
			$offset = 0;
			do {
				$ids = self::site_ids( $offset, get_current_network_id() );
				foreach ( $ids as $site_id ) {
					switch_to_blog( $site_id );
					self::stop_site();
					restore_current_blog();
				}
				$found   = count( $ids );
				$offset += $found;
			} while ( self::SITE_BATCH === $found );
			return;
		}
		self::stop_site();
	}

	/**
	 * Stops checking on the current site: no scheduled events, consent to check is cleared.
	 *
	 * @return void
	 */
	private static function stop_site() {
		LinkTender_Queue::unschedule();
		delete_option( self::STARTED_OPTION );
		delete_option( LinkTender_Scanner::PENDING_OPTION );
	}

	/**
	 * Adds the plugin's tables to the list core drops when a multisite site is deleted.
	 *
	 * @param string[] $tables Table names.
	 * @return string[]
	 */
	public static function drop_site_tables( $tables ) {
		$tables[] = self::links_table();
		$tables[] = self::instances_table();
		return $tables;
	}

	/**
	 * Runs table migrations when the stored version is older than the code.
	 *
	 * Migrations use dbDelta on the plugin's own small tables only. dbDelta never drops
	 * columns, so an interrupted or repeated upgrade is harmless.
	 *
	 * @return void
	 */
	public static function maybe_upgrade() {
		$installed = (int) get_option( self::DB_OPTION, 0 );
		if ( $installed >= LINKTENDER_DB_VERSION ) {
			return;
		}

		// Avoid two requests upgrading at once.
		if ( get_transient( 'linktender_upgrading' ) ) {
			return;
		}
		set_transient( 'linktender_upgrading', 1, MINUTE_IN_SECONDS );

		self::create_tables();
		self::migrate( $installed );
		update_option( self::DB_OPTION, LINKTENDER_DB_VERSION );

		delete_transient( 'linktender_upgrading' );
	}

	/**
	 * Data migrations between schema versions.
	 *
	 * @param int $installed Previously installed schema version (0 for new installs).
	 * @return void
	 */
	private static function migrate( $installed ) {
		// 1.0.0–1.0.2 started checking on activation. Sites that already ran it keep running.
		if ( $installed >= 1 && $installed < 2 && false === get_option( self::STARTED_OPTION, false ) && false !== get_option( LinkTender_Scanner::STATE_OPTION, false ) ) {
			update_option(
				self::STARTED_OPTION,
				array(
					'time' => time(),
					'user' => 0,
				),
				false
			);
		}

		// 1.1.0 also indexes comments and shortcode attributes: re-scan sites where checking already runs.
		if ( $installed >= 1 && $installed < 3 && self::checking_started() ) {
			LinkTender_Scanner::request_full_scan();
		}

		/**
		 * Fires after the plugin's tables were created or upgraded.
		 *
		 * @param int $installed Previously installed schema version (0 for new installs).
		 */
		do_action( 'linktender_db_upgraded', $installed );
	}

	/**
	 * Creates or updates the tables with dbDelta.
	 *
	 * @return void
	 */
	private static function create_tables() {
		global $wpdb;
		require_once ABSPATH . 'wp-admin/includes/upgrade.php';

		$charset   = $wpdb->get_charset_collate();
		$links     = self::links_table();
		$instances = self::instances_table();

		$tables = array();

		$tables[] = "CREATE TABLE {$links} (
  id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  url text NOT NULL,
  url_hash char(40) NOT NULL,
  host varchar(191) NOT NULL DEFAULT '',
  status varchar(20) NOT NULL DEFAULT 'pending',
  http_code smallint(5) unsigned NOT NULL DEFAULT 0,
  error_code varchar(30) NOT NULL DEFAULT '',
  message varchar(255) NOT NULL DEFAULT '',
  final_url text NULL,
  redirect_count tinyint(3) unsigned NOT NULL DEFAULT 0,
  response_ms int(10) unsigned NOT NULL DEFAULT 0,
  check_count int(10) unsigned NOT NULL DEFAULT 0,
  fail_count smallint(5) unsigned NOT NULL DEFAULT 0,
  first_failure datetime NULL DEFAULT NULL,
  last_checked datetime NULL DEFAULT NULL,
  next_check datetime NOT NULL DEFAULT '2000-01-01 00:00:00',
  dismissed tinyint(1) unsigned NOT NULL DEFAULT 0,
  created_at datetime NOT NULL DEFAULT '2000-01-01 00:00:00',
  PRIMARY KEY  (id),
  UNIQUE KEY url_hash (url_hash),
  KEY status (status),
  KEY next_check (next_check),
  KEY host (host)
) {$charset};";

		$tables[] = "CREATE TABLE {$instances} (
  id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  link_id bigint(20) unsigned NOT NULL,
  source_type varchar(20) NOT NULL,
  source_id bigint(20) unsigned NOT NULL DEFAULT 0,
  source_field varchar(191) NOT NULL DEFAULT '',
  element varchar(20) NOT NULL DEFAULT 'a',
  anchor varchar(255) NOT NULL DEFAULT '',
  raw_url text NOT NULL,
  PRIMARY KEY  (id),
  KEY link_id (link_id),
  KEY source (source_type,source_id)
) {$charset};";

		dbDelta( $tables );
	}
}