<?php
/**
 * Database management for activity log.
 *
 * @package ActivityLog404
 */

namespace ActivityLog404;

/**
 * Manages the activity log database table.
 */
class Database {

	/**
	 * The database table name (unprefixed).
	 */
	const TABLE_NAME = 'ops_activity_log';

	/**
	 * Current schema version. Bump when the table definition changes.
	 *
	 * 2: `import_source` / `import_id` and a unique key over them and the
	 * timestamp, for rows brought in by the history importer (#21,
	 * Import\Importer). NULL on every row the plugin logged itself; MySQL
	 * lets a unique key hold any number of NULLs, so the key constrains
	 * imported rows only -- one row per source row, which is what makes a
	 * re-run of an import idempotent. The timestamp is part of it because a
	 * source's ids restart when its log is cleared.
	 *
	 * 3: the request context (#7, Context\RequestContext): `country` (ISO
	 * 3166-1 alpha-2) and `city` from the owner's own geolocation database,
	 * and `device_class`, `browser`, `os` parsed from the user agent. All
	 * NULL where nothing was known -- every row written before 3, imported
	 * rows, WP-CLI and cron. The user-agent string itself has no column.
	 * No index: the filters on them run inside the log's own timestamp
	 * ordering, and the login check reads them through `user_id`.
	 *
	 * 4: the tamper-evident chain (Chain\Seal): `chain_prev`, `chain_content`
	 * and `chain_hash` (hex HMAC-SHA256, NULL on rows the chain does not
	 * cover: imported history, and an event stored unsealed rather than
	 * lost), and `chain_redacted`, set when a privacy erasure blanked the
	 * row. `chain_prev` is UNIQUE: that is how two requests logging at once
	 * cannot both extend the chain from the same row (Chain\Sealer).
	 */
	const SCHEMA_VERSION = '4';

	/**
	 * Option key storing the installed schema version.
	 */
	const SCHEMA_OPTION = 'ops_activity_log_schema_version';

	/**
	 * Ensure the table exists and matches the current schema.
	 *
	 * Runs on plugins_loaded: activation hooks do not re-fire on redeploys of
	 * an already-active plugin, so a version-gated check here is what actually
	 * guarantees the table exists on live sites (and makes future schema
	 * upgrades safe). The activation hook still calls create_table directly —
	 * belt and suspenders.
	 */
	public static function maybe_upgrade(): void {
		if ( get_option( self::SCHEMA_OPTION ) === self::SCHEMA_VERSION ) {
			return;
		}

		self::create_table();
		update_option( self::SCHEMA_OPTION, self::SCHEMA_VERSION );
	}

	/**
	 * Create or update the activity log table via dbDelta.
	 */
	public static function create_table(): void {
		global $wpdb;
		$table_name      = self::get_table_name();
		$charset_collate = $wpdb->get_charset_collate();

		$sql = "CREATE TABLE $table_name (
			id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
			timestamp datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
			user_id bigint(20) unsigned DEFAULT NULL,
			user_email varchar(100) DEFAULT NULL,
			ip_address varchar(45) DEFAULT NULL,
			event_type varchar(50) NOT NULL,
			object_type varchar(50) DEFAULT NULL,
			object_id bigint(20) unsigned DEFAULT NULL,
			summary text,
			details longtext,
			import_source varchar(20) DEFAULT NULL,
			import_id bigint(20) unsigned DEFAULT NULL,
			country char(2) DEFAULT NULL,
			city varchar(80) DEFAULT NULL,
			device_class varchar(10) DEFAULT NULL,
			browser varchar(40) DEFAULT NULL,
			os varchar(40) DEFAULT NULL,
			chain_prev char(64) DEFAULT NULL,
			chain_content char(64) DEFAULT NULL,
			chain_hash char(64) DEFAULT NULL,
			chain_redacted tinyint(1) unsigned NOT NULL DEFAULT 0,
			PRIMARY KEY  (id),
			KEY timestamp (timestamp),
			KEY user_id (user_id),
			KEY event_type (event_type),
			KEY object_type (object_type),
			UNIQUE KEY import_ref (import_source,import_id,timestamp),
			UNIQUE KEY chain_prev (chain_prev)
		) $charset_collate;";

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

	/**
	 * Drop the activity log table.
	 */
	public static function drop_table(): void {
		global $wpdb;
		$table_name = self::get_table_name();
		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		$wpdb->query( "DROP TABLE IF EXISTS $table_name;" );
		// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		delete_option( self::SCHEMA_OPTION );
	}

	/**
	 * Get the full table name with prefix.
	 */
	public static function get_table_name(): string {
		global $wpdb;
		return $wpdb->prefix . self::TABLE_NAME;
	}
}