<?php
/**
 * Daily bounded reconciliation of catalog vs open revisions.
 *
 * @package Kayvandra\MarginBeacon
 */

declare(strict_types=1);

namespace Kayvandra\MarginBeacon\Application\Provenance;

use Kayvandra\MarginBeacon\Infrastructure\Persistence\OperationalEventsRepository;
use Kayvandra\MarginBeacon\Infrastructure\Persistence\PriceRevisionRepository;
use Kayvandra\MarginBeacon\Infrastructure\Scheduler\SchedulerInterface;
use Kayvandra\MarginBeacon\Infrastructure\Scheduler\SchedulerResult;
use Kayvandra\MarginBeacon\Support\Constants;

/**
 * Detects direct-DB / unknown catalog drift and marks gap_detected.
 */
final class PriceRevisionReconciler {

	const BATCH_SIZE    = 40;
	const OPTION_CURSOR = 'aksmb_price_reconcile_cursor';

	/**
	 * @var SchedulerInterface|null
	 */
	private $scheduler;

	/**
	 * @param SchedulerInterface|null $scheduler Scheduler.
	 */
	public function __construct( $scheduler = null ) {
		$this->scheduler = $scheduler;
	}

	/**
	 * @param int $batch Batch index.
	 * @return array{checked:int,changed:int,done:bool}
	 */
	public function run_batch( $batch = 0 ) {
		global $wpdb;

		$cursor = (int) get_option( self::OPTION_CURSOR, 0 );
		$writer = new PriceRevisionWriter();
		$repo   = new PriceRevisionRepository();

		$ids = $wpdb->get_col(
			$wpdb->prepare(
				"SELECT ID FROM {$wpdb->posts}
				WHERE post_type IN ('product','product_variation')
				AND post_status IN ('publish','private')
				AND ID > %d
				ORDER BY ID ASC
				LIMIT %d",
				$cursor,
				self::BATCH_SIZE
			)
		);

		$checked = 0;
		$changed = 0;
		foreach ( (array) $ids as $id ) {
			$id     = (int) $id;
			$cursor = $id;
			++$checked;
			if ( ! function_exists( 'wc_get_product' ) ) {
				break;
			}
			$product = wc_get_product( $id );
			if ( ! $product ) {
				continue;
			}

			$is_variation = $product->is_type( 'variation' );
			$variation_id = $is_variation ? (int) $product->get_id() : 0;
			$product_id   = $is_variation ? (int) $product->get_parent_id() : (int) $product->get_id();
			$snapshot     = $writer->snapshot_from_product( $product );
			$hash         = $writer->revision_hash( $product_id, $variation_id, $snapshot );
			$open         = $repo->get_open( $product_id, $variation_id );

			if ( $open && $open['price_revision_hash'] === $hash ) {
				continue;
			}

			// Drift without going through supported hooks → gap_detected.
			$result = $writer->observe_product( $product, 'reconciliation', 'gap_detected' );
			if ( ! empty( $result['changed'] ) ) {
				++$changed;
			}
		}

		update_option( self::OPTION_CURSOR, $cursor, false );

		$done = empty( $ids ) || count( $ids ) < self::BATCH_SIZE;
		if ( $done ) {
			update_option( self::OPTION_CURSOR, 0, false ); // reset for next day.
			update_option( 'aksmb_price_reconcile_done_gmt', gmdate( 'Y-m-d H:i:s' ), false );
			return array(
				'checked'               => $checked,
				'changed'               => $changed,
				'done'                  => true,
				'continuation_enqueued' => false,
				'continuation_error'    => null,
			);
		}

		$continuation_enqueued = false;
		$continuation_error    = null;
		if ( $this->scheduler ) {
			$action_id = $this->scheduler->enqueue(
				Constants::ACTION_RECONCILE_PRICE_REVISIONS,
				array( 'batch' => (int) $batch + 1 ),
				Constants::SCHEDULER_GROUP,
				null,
				'reconcile_' . ( (int) $batch + 1 )
			);
			if ( SchedulerResult::is_enqueued( $action_id ) ) {
				$continuation_enqueued = true;
			} else {
				$continuation_error = 'scheduler_enqueue_failed';
				update_option(
					'aksmb_price_reconcile_continuation_failed',
					array(
						'batch'  => (int) $batch + 1,
						'at_gmt' => gmdate( 'Y-m-d H:i:s' ),
						'error'  => $continuation_error,
					),
					false
				);
				$this->record_continuation_event(
					'price_reconcile',
					(string) ( (int) $batch + 1 ),
					array( 'batch' => (int) $batch + 1 ),
					$continuation_error
				);
			}
		} else {
			$continuation_error = 'scheduler_unavailable';
		}

		return array(
			'checked'               => $checked,
			'changed'               => $changed,
			'done'                  => false,
			'continuation_enqueued' => $continuation_enqueued,
			'continuation_error'    => $continuation_error,
		);
	}

	/**
	 * Best-effort operational event when WPDB is available.
	 *
	 * @param string              $ref_type Ref type.
	 * @param string              $ref_id   Ref id.
	 * @param array<string,mixed> $context  Context.
	 * @param string              $error    Error code.
	 * @return void
	 */
	private function record_continuation_event( $ref_type, $ref_id, array $context, $error ) {
		global $wpdb;
		if ( ! isset( $wpdb ) || ! is_object( $wpdb ) || ! method_exists( $wpdb, 'insert' ) ) {
			return;
		}
		( new OperationalEventsRepository() )->record(
			$ref_type,
			$ref_id,
			'running',
			'continuation_failed',
			$context,
			$error
		);
	}
}