<?php

namespace WPDeveloper\BetterDocsPro\Core;

/**
 * Action Scheduler aggregation (Advanced Analytics v1.0).
 *
 * A recurring 15-minute job drains unprocessed rows from
 * {prefix}betterdocs_analytics_events and rolls 'view' events up into
 * {prefix}betterdocs_analytics_daily.
 *
 * Idempotent by design: for each "dirty" (post, kb, lang, day) group it
 * RECOMPUTES the totals from all of that group's events and SETs the daily row
 * (via INSERT ... ON DUPLICATE KEY UPDATE on the uniq_post_day key), rather than
 * incrementing. A re-run can never double-count, and COUNT(DISTINCT session_hash)
 * gives a correct unique count. The Free betterdocs_analytics table is left
 * untouched — Free maintains it directly, so there is no dual-write here.
 */
class AnalyticsAggregator {
	const HOOK  = 'betterdocs_analytics_aggregate';
	const BATCH = 1000;

	public function __construct() {
		add_action( 'init', [ $this, 'maybe_schedule' ] );
		add_action( self::HOOK, [ $this, 'run' ] );
	}

	/**
	 * Schedule the recurring rollup once (every 15 minutes).
	 */
	public function maybe_schedule() {
		if ( ! function_exists( 'as_schedule_recurring_action' ) || ! function_exists( 'as_next_scheduled_action' ) ) {
			return;
		}
		if ( false === as_next_scheduled_action( self::HOOK ) ) {
			as_schedule_recurring_action( time() + MINUTE_IN_SECONDS, 15 * MINUTE_IN_SECONDS, self::HOOK, [], 'betterdocs' );
		}
	}

	/**
	 * Drain a batch of unprocessed view events into the daily rollup.
	 */
	public function run() {
		global $wpdb;

		$events = $wpdb->prefix . 'betterdocs_analytics_events';
		$daily  = $wpdb->prefix . 'betterdocs_analytics_daily';

		$rows = $wpdb->get_results(
			$wpdb->prepare(
				"SELECT id, object_id, kb_id, lang, DATE( created_at ) AS d
				FROM {$wpdb->prefix}betterdocs_analytics_events
				WHERE processed = 0 AND event_type IN ( 'view', 'scroll' )
				ORDER BY id ASC
				LIMIT %d",
				self::BATCH
			)
		);

		if ( empty( $rows ) ) {
			return;
		}

		$ids    = [];
		$groups = [];
		foreach ( $rows as $r ) {
			$ids[] = (int) $r->id;
			// Key the dirty group; lang may be '' which is fine.
			$groups[ $r->object_id . '|' . $r->kb_id . '|' . $r->lang . '|' . $r->d ] = [
				'post_id' => (int) $r->object_id,
				'kb_id'   => (int) $r->kb_id,
				'lang'    => (string) $r->lang,
				'date'    => $r->d
			];
		}

		foreach ( $groups as $g ) {
			$views_agg = $wpdb->get_row(
				$wpdb->prepare(
					"SELECT COUNT(*) AS views, COUNT( DISTINCT session_hash ) AS unique_views
					FROM {$wpdb->prefix}betterdocs_analytics_events
					WHERE event_type = 'view' AND object_id = %d AND kb_id = %d AND lang = %s AND DATE( created_at ) = %s",
					$g['post_id'],
					$g['kb_id'],
					$g['lang'],
					$g['date']
				)
			);

			$scroll_agg = $wpdb->get_row(
				$wpdb->prepare(
					"SELECT
						AVG( CAST( JSON_EXTRACT( payload, '$.depth' ) AS DECIMAL(6,2) ) ) AS avg_depth,
						SUM( CASE WHEN CAST( JSON_EXTRACT( payload, '$.depth' ) AS UNSIGNED ) >= 90 THEN 1 ELSE 0 END ) AS completions
					FROM {$wpdb->prefix}betterdocs_analytics_events
					WHERE event_type = 'scroll' AND object_id = %d AND kb_id = %d AND lang = %s AND DATE( created_at ) = %s",
					$g['post_id'],
					$g['kb_id'],
					$g['lang'],
					$g['date']
				)
			);

			$wpdb->query(
				$wpdb->prepare(
					"INSERT INTO {$wpdb->prefix}betterdocs_analytics_daily
						( post_id, kb_id, lang, stat_date, views, unique_views, avg_scroll_depth, reading_completions )
					VALUES ( %d, %d, %s, %s, %d, %d, %f, %d )
					ON DUPLICATE KEY UPDATE
						views = VALUES( views ),
						unique_views = VALUES( unique_views ),
						avg_scroll_depth = VALUES( avg_scroll_depth ),
						reading_completions = VALUES( reading_completions )",
					$g['post_id'],
					$g['kb_id'],
					$g['lang'],
					$g['date'],
					$views_agg ? (int) $views_agg->views : 0,
					$views_agg ? (int) $views_agg->unique_views : 0,
					$scroll_agg && $scroll_agg->avg_depth !== null ? (float) $scroll_agg->avg_depth : 0,
					$scroll_agg ? (int) $scroll_agg->completions : 0
				)
			);
		}

		$placeholders = implode( ',', array_fill( 0, count( $ids ), '%d' ) );
		$wpdb->query(
			$wpdb->prepare(
				"UPDATE {$wpdb->prefix}betterdocs_analytics_events SET processed = 1 WHERE id IN ( {$placeholders} )",
				$ids
			)
		);

		// Drain pattern: if the batch was full there may be more — run again now.
		if ( count( $rows ) >= self::BATCH && function_exists( 'as_enqueue_async_action' ) ) {
			as_enqueue_async_action( self::HOOK, [], 'betterdocs' );
		}
	}
}