<?php
namespace QWSpeedCache\Cache;

defined( 'ABSPATH' ) || exit;

/**
 * Page-cache hit and miss counters.
 */
class Stats {

	const OPTION = 'qwsc_cache_stats';

	public function __construct() {
		add_action( 'qwsc_cache_stat_hit', array( $this, 'hit' ) );
		add_action( 'qwsc_cache_stat_miss', array( $this, 'miss' ) );
		add_action( 'admin_post_qwsc_reset_cache_stats', array( $this, 'reset' ) );
	}

	/**
	 * @return array{hits:int,misses:int,updated:int}
	 */
	public static function get() {
		$d = get_option( self::OPTION, array() );
		return array(
			'hits'    => isset( $d['hits'] ) ? (int) $d['hits'] : 0,
			'misses'  => isset( $d['misses'] ) ? (int) $d['misses'] : 0,
			'updated' => isset( $d['updated'] ) ? (int) $d['updated'] : 0,
		);
	}

	public function hit() {
		self::bump( 'hits' );
	}

	public function miss() {
		self::bump( 'misses' );
	}

	/**
	 * @param string $key hits|misses.
	 */
	private static function bump( $key ) {
		$d = self::get();
		$d[ $key ] = (int) $d[ $key ] + 1;
		$d['updated'] = time();
		update_option( self::OPTION, $d, false );
	}

	public function reset() {
		check_admin_referer( 'qwsc_reset_cache_stats' );
		if ( ! current_user_can( 'manage_options' ) ) {
			wp_die( esc_html__( 'Unauthorized', 'qw-optimize' ), '', array( 'response' => 403 ) );
		}
		delete_option( self::OPTION );
		wp_safe_redirect( admin_url( 'admin.php?page=qw-speed-cache' ) );
		exit;
	}

	/**
	 * @return float 0-100
	 */
	public static function hit_rate() {
		$d = self::get();
		$t = $d['hits'] + $d['misses'];
		if ( $t <= 0 ) {
			return 0.0;
		}
		return round( 100 * $d['hits'] / $t, 1 );
	}
}