<?php
/**
 * The enriched products list.
 *
 * @package CortexCommerce
 */

namespace CortexCommerce\Sync;

use CortexCommerce\Settings\Flavor;
use CortexCommerce\Settings\Options;
use CortexCommerce\Support\Log;
use CortexCommerce\Support\SignedClient;

defined( 'ABSPATH' ) || exit;

/**
 * POST /webhooks/woo/enriched: the products CortexCommerce has enriched, one page at a time. Follows StatsApi: short
 * timeout, response type-checked, a failure remembered for a minute. A good page is cached for 60 seconds by its
 * filter values; a finished sync throws the cache away.
 */
final class EnrichedApi {

	const PATH = '/webhooks/woo/enriched';

	/**
	 * Without a field filter the backend answers from its index; with one it reads every candidate, so it gets longer.
	 */
	const TIMEOUT       = 5;
	const FIELD_TIMEOUT = 15;
	const TTL           = 60;
	const FAILURE_TTL   = 60;

	const FIELDS   = array( 'title', 'description', 'short_description', 'tags', 'seo_title', 'meta_description', 'image_alts', 'new_image' );
	const STATUSES = array( 'live', 'approved', 'waiting' );

	/**
	 * @param array<string, mixed> $query Any of q, status, field, page, per_page; empty ones are left out.
	 * @return array{total: int, page: int, per_page: int, products: array<int, array{product_id: string, status: string, fields: array<int, string>, title: string, updated_at: string, preview_image_url: string}>}|null
	 */
	public static function fetch( array $query ): ?array {
		if ( ! Options::is_connected() ) {
			return null;
		}
		$request = self::request( $query );
		$key     = self::cache_key( $request );
		$cached  = self::parse( get_transient( $key ) );
		if ( null !== $cached ) {
			return $cached;
		}
		$marker = isset( $request['field'] ) ? Options::ENRICHED_FIELD_FAILED_TRANSIENT : Options::ENRICHED_FAILED_TRANSIENT;
		if ( false !== get_transient( $marker ) ) {
			return null;
		}
		$timeout  = isset( $request['field'] ) ? self::FIELD_TIMEOUT : self::TIMEOUT;
		$response = SignedClient::post( self::PATH, SignedClient::body( $request ), $timeout );
		if ( ! $response->ok() ) {
			Log::warning( sprintf( 'Products list: CortexCommerce did not give the list (%s).', $response->describe() ) );
			set_transient( $marker, 1, self::FAILURE_TTL );
			return null;
		}
		$list = self::parse( $response->json );
		if ( null === $list ) {
			Log::error( 'Products list: CortexCommerce answered the list request with an unexpected body.' );
			set_transient( $marker, 1, self::FAILURE_TTL );
			return null;
		}
		set_transient( $key, $list, self::TTL );
		return $list;
	}

	/**
	 * Throws away every cached list and the status panel's numbers, so the next look asks CortexCommerce again.
	 */
	public static function flush(): void {
		update_option( Options::ENRICHED_GENERATION, self::generation() + 1, false );
		delete_transient( Options::ENRICHED_FAILED_TRANSIENT );
		delete_transient( Options::ENRICHED_FIELD_FAILED_TRANSIENT );
		delete_transient( Options::STATS_TRANSIENT );
	}

	private static function generation(): int {
		return (int) get_option( Options::ENRICHED_GENERATION, 0 );
	}

	/**
	 * @param array<string, mixed> $request Filters actually sent.
	 */
	private static function cache_key( array $request ): string {
		return Flavor::OPTION_PREFIX . 'enriched_' . self::generation() . '_' . md5( (string) wp_json_encode( $request ) );
	}

	/**
	 * @param array<string, mixed> $query Raw filters.
	 * @return array<string, mixed>
	 */
	private static function request( array $query ): array {
		$request = array();
		foreach ( array( 'q', 'status', 'field', 'page', 'per_page' ) as $key ) {
			if ( isset( $query[ $key ] ) && '' !== $query[ $key ] && 0 !== $query[ $key ] ) {
				$request[ $key ] = $query[ $key ];
			}
		}
		return $request;
	}

	/**
	 * @param mixed $raw Decoded body or cached value.
	 * @return array{total: int, page: int, per_page: int, products: array<int, array{product_id: string, status: string, fields: array<int, string>, title: string, updated_at: string, preview_image_url: string}>}|null
	 */
	private static function parse( $raw ): ?array {
		if ( ! is_array( $raw ) || ! isset( $raw['products'] ) || ! is_array( $raw['products'] ) ) {
			return null;
		}
		foreach ( array( 'total', 'page', 'per_page' ) as $key ) {
			if ( ! isset( $raw[ $key ] ) || ! is_int( $raw[ $key ] ) || $raw[ $key ] < 0 ) {
				return null;
			}
		}
		$products = array();
		foreach ( $raw['products'] as $row ) {
			$product = self::parse_row( $row );
			if ( null !== $product ) {
				$products[] = $product;
			}
		}
		$dropped = count( $raw['products'] ) - count( $products );
		if ( $dropped > 0 ) {
			Log::warning( sprintf( 'Products list: %d rows from CortexCommerce were left out because they were malformed.', $dropped ) );
		}
		return array(
			'total'    => $raw['total'],
			'page'     => $raw['page'],
			'per_page' => $raw['per_page'],
			'products' => $products,
		);
	}

	/**
	 * @param mixed $row One row of the body.
	 * @return array{product_id: string, status: string, fields: array<int, string>, title: string, updated_at: string, preview_image_url: string}|null
	 */
	private static function parse_row( $row ): ?array {
		if ( ! is_array( $row ) || ! isset( $row['product_id'], $row['status'] ) || ! is_string( $row['product_id'] ) || '' === $row['product_id'] || ! in_array( $row['status'], self::STATUSES, true ) ) {
			return null;
		}
		$fields = array();
		if ( isset( $row['fields'] ) && is_array( $row['fields'] ) ) {
			foreach ( $row['fields'] as $field ) {
				if ( is_string( $field ) && in_array( $field, self::FIELDS, true ) && ! in_array( $field, $fields, true ) ) {
					$fields[] = $field;
				}
			}
		}
		$preview = isset( $row['preview_image_url'] ) && is_string( $row['preview_image_url'] ) ? $row['preview_image_url'] : '';
		return array(
			'product_id'        => $row['product_id'],
			'status'            => $row['status'],
			'fields'            => $fields,
			'title'             => isset( $row['title'] ) && is_string( $row['title'] ) ? $row['title'] : '',
			'updated_at'        => isset( $row['updated_at'] ) && is_string( $row['updated_at'] ) ? $row['updated_at'] : '',
			'preview_image_url' => 0 === strpos( $preview, 'https://' ) ? $preview : '',
		);
	}
}