<?php
namespace FPCA;

defined( 'ABSPATH' ) || exit;

/**
 * Handles plugin activation, deactivation, and DB upgrades.
 *
 * @package FPCA
 */
class Activator {

	/**
	 * Sentinel for "option not present", distinct from any stored value.
	 */
	private const MISSING = '__fpca_missing__';

	/**
	 * Options that must never be autoloaded: secrets and unbounded blobs that
	 * would otherwise be read into memory on every single request.
	 */
	private const NO_AUTOLOAD_OPTIONS = [
		'fpca_gsc_tokens',
		'fpca_gsc_properties_list',
	];

	public static function activate(): void {
		self::create_tables();
		self::set_default_options();
	}

	/**
	 * Stop all scheduled work, but leave every trace of the user's data alone.
	 *
	 * Deactivation is not uninstallation: options, post meta and both custom
	 * tables are deliberately untouched here, so reactivating restores the plugin
	 * exactly as it was. The only thing that must not survive is scheduled work —
	 * a deactivated plugin whose cron events still fire is an orphaned-event flag
	 * in WordPress.org review, and the handlers no longer exist to run anyway.
	 *
	 * wp_unschedule_hook() rather than wp_clear_scheduled_hook(), matching
	 * uninstall.php: the latter only removes events whose arguments match the
	 * ones passed, so it would leave every fpca_rescore_post event behind —
	 * those are always scheduled with a post ID argument.
	 */
	public static function deactivate(): void {
		wp_unschedule_hook( 'fpca_check_overdue' );
		wp_unschedule_hook( 'fpca_weekly_rescore' );
		wp_unschedule_hook( 'fpca_rescore_post' );
	}

	/**
	 * Run if stored DB version doesn't match current plugin version.
	 *
	 * Guarded by a short-lived transient lock so two concurrent requests
	 * can't both run dbDelta() against the same tables.
	 */
	public static function maybe_upgrade(): void {
		if ( get_option( 'fpca_db_version' ) === FPCA_VERSION ) {
			return;
		}

		// Bail if another request is already migrating.
		if ( ! self::acquire_upgrade_lock() ) {
			return;
		}

		self::create_tables();

		// Seed any options introduced since the stored version. add_option() is
		// a no-op for keys that already exist, so this never clobbers settings.
		self::set_default_options();

		update_option( 'fpca_db_version', FPCA_VERSION );

		delete_transient( 'fpca_upgrading' );
	}

	/**
	 * Claim the migration lock. Returns false if another request holds it.
	 */
	private static function acquire_upgrade_lock(): bool {
		if ( get_transient( 'fpca_upgrading' ) ) {
			return false;
		}

		set_transient( 'fpca_upgrading', 1, 5 * MINUTE_IN_SECONDS );

		return true;
	}

	/**
	 * Create or migrate the plugin tables.
	 *
	 * Note: the CREATE TABLE statements must NOT use IF NOT EXISTS. dbDelta()
	 * extracts the table name with the regex /CREATE TABLE ([^ ]*)/, so
	 * "IF NOT EXISTS" makes it capture the literal string "IF", after which it
	 * fails to DESCRIBE the table and skips all column/index diffing. Without
	 * this, schema changes never reach existing installs.
	 *
	 * Note also: column types must be lowercase. Only WordPress 6.9 lowercases
	 * the declared type before comparing it to DESCRIBE's output; 6.0 to 6.8
	 * compare verbatim, and MySQL reports types lowercase. An uppercase
	 * declaration therefore made every column look changed on those versions,
	 * so dbDelta rewrote both tables on every upgrade. Core's own schema.php
	 * declares types lowercase for the same reason.
	 */
	private static function create_tables(): void {
		global $wpdb;
		$charset = $wpdb->get_charset_collate();

		// The two CREATE TABLE statements below are the only place in the plugin
		// that still interpolates a table name instead of using prepare()'s %i.
		// dbDelta() parses the literal SQL text — it extracts the table name
		// with its own regex and diffs the column list — so a prepared
		// statement, or a backtick-quoted identifier from %i, would defeat it.
		// Both names are built from $wpdb->prefix and a literal; no input
		// reaches them.

		$sql = "CREATE TABLE {$wpdb->prefix}fpca_posts (
			id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
			post_id bigint(20) unsigned NOT NULL,
			freshness_score tinyint(3) unsigned DEFAULT NULL,
			sub_scores text,
			scored_at datetime DEFAULT NULL,
			ai_reasoning text,
			assigned_to bigint(20) unsigned DEFAULT NULL,
			assigned_at datetime DEFAULT NULL,
			status varchar(32) DEFAULT 'unreviewed',
			notes text,
			gsc_clicks int(11) DEFAULT NULL,
			gsc_impressions int(11) DEFAULT NULL,
			gsc_position float DEFAULT NULL,
			gsc_ctr float DEFAULT NULL,
			gsc_synced_at datetime DEFAULT NULL,
			created_at datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
			updated_at datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
			PRIMARY KEY  (id),
			UNIQUE KEY post_id (post_id),
			KEY status (status),
			KEY freshness_score (freshness_score)
		) $charset;";

		$sql_assignments = "CREATE TABLE {$wpdb->prefix}fpca_assignments (
			id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
			post_id bigint(20) unsigned NOT NULL,
			user_id bigint(20) unsigned NOT NULL,
			assigned_by bigint(20) unsigned NOT NULL,
			assigned_at datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
			PRIMARY KEY  (id),
			UNIQUE KEY unique_post_user (post_id, user_id)
		) $charset;";

		require_once ABSPATH . 'wp-admin/includes/upgrade.php';
		dbDelta( $sql );
		dbDelta( $sql_assignments );
	}

	private static function set_default_options(): void {
		$defaults = [
			'fpca_db_version'          => FPCA_VERSION,
			'fpca_gsc_connected'       => false,
			'fpca_gsc_property'        => '',
			'fpca_gsc_tokens'          => '',
			'fpca_gsc_properties_list' => '',
			'fpca_decay_threshold'     => 180,
			'fpca_tracked_post_types'  => [ 'post', 'page' ],
			'fpca_weight_age'          => 25,
			'fpca_weight_refs'         => 40,
			'fpca_weight_depth'        => 35,
			'fpca_flag_threshold'      => 50,
			'fpca_overdue_days'        => 7,
			'fpca_auto_rescore'        => false,
			'fpca_acf_autodetect'      => 1,
			'fpca_extra_fields'        => '',
			'fpca_scoring_ack'         => 0,
		];

		foreach ( $defaults as $key => $value ) {
			// Use a sentinel rather than `false === get_option()`, which is also
			// true for options legitimately storing the value false.
			if ( self::MISSING !== get_option( $key, self::MISSING ) ) {
				continue;
			}

			$autoload = ! in_array( $key, self::NO_AUTOLOAD_OPTIONS, true );

			add_option( $key, $value, '', $autoload );
		}
	}
}