<?php
/**
 * Analytics recording + aggregate queries.
 *
 * @package AccordionFaq
 */

namespace AccordionFaq\Analytics;

defined( 'ABSPATH' ) || exit;

use AccordionFaq\Setup\PostType;

/**
 * Class Tracker
 */
class Tracker {

	const META_VIEWS = '_afaq_views';
	const META_UP    = '_afaq_up';
	const META_DOWN  = '_afaq_down';

	/**
	 * Increment the daily events table.
	 *
	 * @param int    $faq_id FAQ post ID.
	 * @param string $type   view|up|down.
	 * @return void
	 */
	private static function bump_daily( $faq_id, $type ) {
		global $wpdb;
		$table = Database::table();
		$day   = gmdate( 'Y-m-d' );
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery -- writing to the plugin's own analytics table has no WordPress API alternative; the cache is invalidated below.
		$wpdb->query(
			$wpdb->prepare(
				'INSERT INTO %i (faq_id, event_type, event_day, hits) VALUES (%d, %s, %s, 1)
				 ON DUPLICATE KEY UPDATE hits = hits + 1',
				$table,
				$faq_id,
				$type,
				$day
			)
		);

		// New event data invalidates the cached totals/trend aggregates.
		wp_cache_delete( 'last_changed', Database::CACHE_GROUP );
	}

	/**
	 * Guard: is this FAQ id valid & published?
	 *
	 * @param int $faq_id ID.
	 * @return bool
	 */
	private static function valid( $faq_id ) {
		return $faq_id > 0 && PostType::POST_TYPE === get_post_type( $faq_id ) && 'publish' === get_post_status( $faq_id );
	}

	/**
	 * Record a view (once per visitor per FAQ per 6h).
	 *
	 * @param int    $faq_id FAQ ID.
	 * @param string $token  Client fingerprint (hashed).
	 * @return int New view count, or -1 on invalid.
	 */
	public static function record_view( $faq_id, $token = '' ) {
		$faq_id = absint( $faq_id );
		if ( ! self::valid( $faq_id ) ) {
			return -1;
		}
		$key = 'afaq_v_' . md5( $faq_id . '|' . $token . '|' . self::client_ip() );
		if ( get_transient( $key ) ) {
			return (int) get_post_meta( $faq_id, self::META_VIEWS, true );
		}
		set_transient( $key, 1, 6 * HOUR_IN_SECONDS );

		$count = (int) get_post_meta( $faq_id, self::META_VIEWS, true ) + 1;
		update_post_meta( $faq_id, self::META_VIEWS, $count );
		self::bump_daily( $faq_id, 'view' );
		return $count;
	}

	/**
	 * Record a helpful/unhelpful vote (once per visitor per FAQ per 30 days).
	 *
	 * @param int    $faq_id FAQ ID.
	 * @param string $dir    up|down.
	 * @param string $token  Client fingerprint.
	 * @return array|null [ up, down ] or null on invalid/duplicate.
	 */
	public static function record_vote( $faq_id, $dir, $token = '' ) {
		$faq_id = absint( $faq_id );
		$dir    = ( 'down' === $dir ) ? 'down' : 'up';
		if ( ! self::valid( $faq_id ) ) {
			return null;
		}
		$key = 'afaq_vote_' . md5( $faq_id . '|' . $token . '|' . self::client_ip() );
		if ( get_transient( $key ) ) {
			return null;
		}
		set_transient( $key, $dir, 30 * DAY_IN_SECONDS );

		$meta  = ( 'up' === $dir ) ? self::META_UP : self::META_DOWN;
		$count = (int) get_post_meta( $faq_id, $meta, true ) + 1;
		update_post_meta( $faq_id, $meta, $count );
		self::bump_daily( $faq_id, $dir );

		return array(
			'up'   => (int) get_post_meta( $faq_id, self::META_UP, true ),
			'down' => (int) get_post_meta( $faq_id, self::META_DOWN, true ),
		);
	}

	/**
	 * Hashed client IP for rate limiting (never stored raw).
	 *
	 * @return string
	 */
	private static function client_ip() {
		$ip = isset( $_SERVER['REMOTE_ADDR'] ) ? sanitize_text_field( wp_unslash( $_SERVER['REMOTE_ADDR'] ) ) : '';
		return md5( $ip );
	}

	/* ------------------------------------------------------------------ */
	/* Reporting                                                           */
	/* ------------------------------------------------------------------ */

	/**
	 * Global totals.
	 *
	 * @return array
	 */
	public static function totals() {
		$last_changed = wp_cache_get_last_changed( Database::CACHE_GROUP );
		$cache_key    = 'totals:' . $last_changed;
		$cached       = wp_cache_get( $cache_key, Database::CACHE_GROUP );
		if ( false !== $cached ) {
			return $cached;
		}

		global $wpdb;
		$table = Database::table();
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery -- reading the plugin's own analytics table has no WordPress API alternative; results are object-cached above.
		$rows = $wpdb->get_results(
			$wpdb->prepare( 'SELECT event_type, SUM(hits) AS total FROM %i GROUP BY event_type', $table ),
			ARRAY_A
		);
		$out = array(
			'view' => 0,
			'up'   => 0,
			'down' => 0,
		);
		foreach ( (array) $rows as $row ) {
			if ( isset( $out[ $row['event_type'] ] ) ) {
				$out[ $row['event_type'] ] = (int) $row['total'];
			}
		}

		wp_cache_set( $cache_key, $out, Database::CACHE_GROUP, HOUR_IN_SECONDS );
		return $out;
	}

	/**
	 * Daily trend series for the last N days.
	 *
	 * @param string $type view|up|down.
	 * @param int    $days Days back.
	 * @return array<string,int> day => hits.
	 */
	public static function trend( $type = 'view', $days = 30 ) {
		$last_changed = wp_cache_get_last_changed( Database::CACHE_GROUP );
		$cache_key    = 'trend:' . $type . ':' . (int) $days . ':' . $last_changed;
		$cached       = wp_cache_get( $cache_key, Database::CACHE_GROUP );
		if ( false !== $cached ) {
			return $cached;
		}

		global $wpdb;
		$table = Database::table();
		$since = gmdate( 'Y-m-d', time() - ( $days * DAY_IN_SECONDS ) );
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery -- reading the plugin's own analytics table has no WordPress API alternative; results are object-cached above.
		$rows = $wpdb->get_results(
			$wpdb->prepare(
				'SELECT event_day, SUM(hits) AS hits FROM %i WHERE event_type = %s AND event_day >= %s GROUP BY event_day ORDER BY event_day ASC',
				$table,
				$type,
				$since
			),
			ARRAY_A
		);
		$series = array();
		for ( $i = $days - 1; $i >= 0; $i-- ) {
			$series[ gmdate( 'Y-m-d', time() - ( $i * DAY_IN_SECONDS ) ) ] = 0;
		}
		foreach ( (array) $rows as $row ) {
			$series[ $row['event_day'] ] = (int) $row['hits'];
		}

		wp_cache_set( $cache_key, $series, Database::CACHE_GROUP, HOUR_IN_SECONDS );
		return $series;
	}

	/**
	 * Top FAQs by a meta measure.
	 *
	 * @param string $meta  Meta key.
	 * @param int    $limit Rows.
	 * @return array[] [ id, title, value ].
	 */
	public static function top( $meta = self::META_VIEWS, $limit = 8 ) {
		$q = new \WP_Query(
			array(
				'post_type'      => PostType::POST_TYPE,
				'post_status'    => 'publish',
				'posts_per_page' => (int) $limit,
				'orderby'        => 'meta_value_num',
				'meta_key'       => $meta, // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key
				'order'          => 'DESC',
				'no_found_rows'  => true,
			)
		);
		$out = array();
		foreach ( $q->posts as $post ) {
			$val = (int) get_post_meta( $post->ID, $meta, true );
			if ( $val <= 0 ) {
				continue;
			}
			$out[] = array(
				'id'    => $post->ID,
				'title' => get_the_title( $post ),
				'value' => $val,
			);
		}
		wp_reset_postdata();
		return $out;
	}
}