<?php
/**
 * Supplies observed search-query evidence to AI-O Content Pal's Content Audit.
 *
 * This is a transitional read-only adapter over Optimiser's legacy GSC store.
 * It must disappear from the evidence chain as soon as an external Search Ops
 * implementation becomes authoritative, otherwise frozen legacy rows could be
 * presented indefinitely as current evidence after provider polling moves.
 *
 * @package AI_O_Optimiser
 */

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

final class AI_O_Optimiser_Content_Pal_Performance_Signals {

	/** Cap the rows pulled into memory in one read; above this, read per page. */
	const MAX_ROWS = 5000;

	/** Content Pal reads at most 60 queries per page; stay under that. */
	const MAX_QUERIES_PER_PAGE = 60;

	/** @var array<string,array<int,array>> page_hash => query rows. */
	private static $by_page = array();

	/**
	 * @var bool|null Null until the first lookup decides how to read the store:
	 *                true when the whole current period fitted in one read,
	 *                false when pages are looked up individually.
	 */
	private static $read_whole_period = null;

	/** Register only while Optimiser still owns traditional search evidence. */
	public static function boot() {
		if ( ! self::content_pal_available() || self::external_search_ops_authoritative() ) {
			return;
		}
		add_filter( 'bcp_content_audit_performance_signals', array( __CLASS__, 'supply' ), 10, 3 );
	}

	/**
	 * Answer Content Pal's request for one page's observed search performance.
	 *
	 * Re-check authority at supply time as a defensive boundary: boot ordering or
	 * a test/plugin changing the manifest later in the request must never make
	 * legacy rows win over the authoritative Search Ops store.
	 *
	 * @param array  $signals Signals collected so far.
	 * @param int    $post_id Post being audited.
	 * @param string $url     Public URL of that post.
	 * @return array Signals, with Search Console query evidence merged in.
	 */
	public static function supply( $signals, $post_id, $url ) {
		$signals = is_array( $signals ) ? $signals : array();
		if ( self::external_search_ops_authoritative() ) {
			return $signals;
		}

		$url = (string) $url;
		if ( '' === $url ) {
			$url = (string) get_permalink( (int) $post_id );
		}
		if ( '' === $url ) {
			return $signals;
		}

		$rows = self::rows_for_url( $url );
		if ( ! $rows ) {
			return $signals;
		}

		$queries = array();
		foreach ( $rows as $row ) {
			$queries[] = array(
				'query'       => (string) $row['query_text'],
				'clicks'      => (float) $row['clicks'],
				'impressions' => (float) $row['impressions'],
				'position'    => (float) $row['position'],
			);
		}

		$signals['search_console'] = array(
			'source'  => 'ai-o-optimiser',
			'period'  => 'current',
			'queries' => $queries,
		);

		return $signals;
	}

	/**
	 * Look up the queries recorded against one URL.
	 *
	 * @param string $url Page URL.
	 * @return array<int,array>
	 */
	private static function rows_for_url( $url ) {
		if ( ! self::store_available() ) {
			return array();
		}

		$hash = hash( 'sha256', untrailingslashit( esc_url_raw( $url ) ) );

		if ( null === self::$read_whole_period ) {
			self::$read_whole_period = AI_O_Optimiser_GSC_DB::count( 'current' ) <= self::MAX_ROWS;
			if ( self::$read_whole_period ) {
				self::index_rows( AI_O_Optimiser_GSC_DB::top_rows( 'current', self::MAX_ROWS ) );
			}
		}

		if ( ! self::$read_whole_period && ! array_key_exists( $hash, self::$by_page ) ) {
			self::$by_page[ $hash ] = array();
			self::index_rows( AI_O_Optimiser_GSC_DB::rows_for_page( 'current', $hash, self::MAX_QUERIES_PER_PAGE ) );
		}

		return isset( self::$by_page[ $hash ] ) ? self::$by_page[ $hash ] : array();
	}

	/** @param mixed $rows Store rows, highest impressions first. */
	private static function index_rows( $rows ) {
		foreach ( is_array( $rows ) ? $rows : array() as $row ) {
			if ( empty( $row['page_hash'] ) || ! isset( $row['query_text'] ) ) {
				continue;
			}
			$page = (string) $row['page_hash'];
			if ( isset( self::$by_page[ $page ] ) && count( self::$by_page[ $page ] ) >= self::MAX_QUERIES_PER_PAGE ) {
				continue;
			}
			self::$by_page[ $page ][] = $row;
		}
	}

	/** Make sure the legacy Search Console store class is loaded. */
	private static function store_available() {
		if ( ! class_exists( 'AI_O_Optimiser_GSC_DB' ) && defined( 'AI_O_Optimiser_PLUGIN_DIR' ) ) {
			$file = AI_O_Optimiser_PLUGIN_DIR . 'includes/class-ai-o-optimiser-gsc-db.php';
			if ( is_readable( $file ) ) {
				require_once $file;
			}
		}
		return class_exists( 'AI_O_Optimiser_GSC_DB' );
	}

	/** Read the public ownership contract without coupling to Content Pal classes. */
	private static function external_search_ops_authoritative() {
		if ( ! class_exists( 'AI_O_Optimiser_Search_Ops_Ownership' ) && defined( 'AI_O_Optimiser_PLUGIN_DIR' ) ) {
			$file = AI_O_Optimiser_PLUGIN_DIR . 'includes/class-ai-o-optimiser-search-ops-ownership.php';
			if ( is_readable( $file ) ) {
				require_once $file;
			}
		}
		return class_exists( 'AI_O_Optimiser_Search_Ops_Ownership' )
			&& AI_O_Optimiser_Search_Ops_Ownership::external_authoritative();
	}

	/** Detect an installed AI-O Content Pal. */
	private static function content_pal_available() {
		return class_exists( 'BCP_Config' ) || class_exists( 'BCP_Plugin' ) || defined( 'BCP_MENU_SLUG' );
	}
}