<?php
/**
 * @package PlugixaCrm
 */

declare( strict_types = 1 );

namespace PlugixaCrm\Modules\Stream;

use PlugixaCrm\Core\Database\Schema as Db;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Who is following what.
 *
 * The entries themselves live in `notes`, which the Notes module owns — see its Schema for why the
 * stream grew into that table rather than beside it. This module owns only the subscription, which
 * is the part Notes has no opinion about.
 *
 * NO UNIQUE KEY on (entity_type, entity_id, user_id), for the reason the soft-delete trap teaches:
 * rows here are soft-deleted like everything else, so a trashed subscription would keep the key
 * taken and re-following a record you had unfollowed would fail its INSERT silently — leaving a
 * Follow button that does nothing, for ever, for that one user on that one record. Uniqueness among
 * LIVE rows is the service's job.
 */
final class Schema {

	/**
	 * @return string[]
	 */
	public static function tables(): array {
		return array( 'stream_subscriptions' );
	}

	/**
	 * @return array<string, string> What dbDelta changed. Empty on a settled schema.
	 */
	public static function install(): array {
		$charset = Db::charset();

		$changes = Db::delta( self::subscriptions( $charset ) );

		Db::ensure_innodb( ...self::tables() );

		return $changes;
	}

	/**
	 * @param string $charset Charset/collate clause.
	 */
	private static function subscriptions( string $charset ): string {
		$table = Db::table( 'stream_subscriptions' );

		return "CREATE TABLE {$table} (
			id bigint(20) unsigned NOT NULL auto_increment,
			entity_type varchar(50) NOT NULL default '',
			entity_id bigint(20) unsigned NOT NULL default 0,
			user_id bigint(20) unsigned NOT NULL default 0,
			created_by bigint(20) unsigned default NULL,
			modified_by bigint(20) unsigned default NULL,
			created_at datetime default NULL,
			modified_at datetime default NULL,
			deleted_at datetime default NULL,
			PRIMARY KEY  (id),
			KEY entity (entity_type,entity_id),
			KEY user_id (user_id),
			KEY entity_user (entity_type,entity_id,user_id),
			KEY deleted_at (deleted_at)
		) {$charset};";
	}
}