<?php
namespace QWSpeedCache\Stats;

defined( 'ABSPATH' ) || exit;

/**
 * Dashboard metrics and diagnostics snapshot.
 */
class Metrics {

	/**
	 * @return array<string,mixed>
	 */
	public static function snapshot() {
		$settings = \QWSpeedCache\Plugin::instance()->get_all_settings();
		$cache_files = 0;
		$cache_bytes = 0;
		$html_files  = 0;
		$dir = defined( 'QWSC_CACHE_DIR' ) ? QWSC_CACHE_DIR : '';
		if ( $dir && is_dir( $dir ) ) {
			$it = new \RecursiveIteratorIterator(
				new \RecursiveDirectoryIterator( $dir, \FilesystemIterator::SKIP_DOTS )
			);
			foreach ( $it as $file ) {
				if ( $file->isFile() ) {
					++$cache_files;
					$cache_bytes += $file->getSize();
					if ( 'html' === $file->getExtension() ) {
						++$html_files;
					}
				}
			}
		}
		$log = Logger::all();
		$purges = 0;
		foreach ( $log as $row ) {
			if ( isset( $row['type'] ) && 'purge' === $row['type'] ) {
				++$purges;
			}
		}
		$warmup = 0;
		if ( class_exists( '\\QWSpeedCache\\Preload\\Queue' ) ) {
			$warmup = count( \QWSpeedCache\Preload\Queue::get() );
		}
		$opcode = array();
		if ( class_exists( '\\QWSpeedCache\\Diagnostics\\Opcode' ) ) {
			$opcode = \QWSpeedCache\Diagnostics\Opcode::status();
		}
		$last_purge = (int) get_option( 'qwsc_last_purge_at', 0 );
		$conflicts  = array();
		if ( class_exists( '\\QWSpeedCache\\Safety\\ConflictDetector' ) ) {
			$conflicts = \QWSpeedCache\Safety\ConflictDetector::active_conflicts();
		}
		$adv = array( 'installed' => false, 'ours' => false, 'wp_cache' => false );
		if ( class_exists( '\\QWSpeedCache\\Cache\\AdvancedCache' ) ) {
			$adv = \QWSpeedCache\Cache\AdvancedCache::status();
		}
		return array(
			'version'            => defined( 'QWSC_VERSION' ) ? QWSC_VERSION : '',
			'page_cache'         => ! empty( $settings['page_cache_enabled'] ) || ! empty( $settings['cache_enabled'] ),
			'cache_files'        => $cache_files,
			'cache_html_files'   => $html_files,
			'cache_bytes'        => $cache_bytes,
			'cache_lifespan'     => (int) ( $settings['cache_lifespan'] ?? 10 ),
			'purge_events'       => $purges,
			'last_purge_at'      => $last_purge,
			'last_purge_human'   => $last_purge ? self::human_ago( $last_purge ) : '',
			'preload_queue'      => $warmup,
			'multisite'          => is_multisite(),
			'opcode'             => $opcode,
			'conflicts'          => $conflicts,
			'advanced_cache'     => $adv,
			'test_mode'          => ! empty( $settings['test_mode'] ),
			'delay_js'           => ( \QWSpeedCache\Free\Extensions::pro_key_available( 'delay_js' ) && ! empty( $settings['delay_js'] ) ),
			'js_safe_mode'       => ! empty( $settings['js_safe_mode'] ),
			'remove_unused_css'  => ( \QWSpeedCache\Free\Extensions::pro_key_available( 'remove_unused_css' ) && ! empty( $settings['remove_unused_css'] ) ),
			'object_cache'       => class_exists( '\QWSpeedCache\ObjectCache\Dropin' ) ? \QWSpeedCache\ObjectCache\Dropin::status() : array(),
			'preload_progress'  => class_exists( '\QWSpeedCache\Preload\Manager' ) ? \QWSpeedCache\Preload\Manager::progress() : array(),
			'last_events'        => array_slice( array_reverse( $log ), 0, 10 ),
		);
	}

	/**
	 * Lightweight health checks for REST/CLI.
	 *
	 * @return array{ok:bool,checks:array<int,array{id:string,ok:bool,message:string}>}
	 */
	public static function health() {
		$checks = array();
		$s      = \QWSpeedCache\Plugin::instance()->get_all_settings();

		$dir = defined( 'QWSC_CACHE_DIR' ) ? QWSC_CACHE_DIR : '';
		$writable = $dir && ( is_dir( $dir ) ? wp_is_writable( $dir ) : wp_is_writable( dirname( $dir ) ) );
		$checks[] = array(
			'id'      => 'cache_dir',
			'ok'      => (bool) $writable,
			'message' => $writable ? 'Cache directory writable' : 'Cache directory not writable',
		);

		$wp_cache = defined( 'WP_CACHE' ) && WP_CACHE;
		$adv_on   = ! empty( $s['advanced_cache_enabled'] );
		$adv_status = class_exists( '\\QWSpeedCache\\Cache\\AdvancedCache' )
			? \QWSpeedCache\Cache\AdvancedCache::status()
			: array( 'ours' => false, 'installed' => false, 'config_found' => false, 'config_writable' => false );
		$checks[] = array(
			'id'      => 'wp_cache',
			'ok'      => ! $adv_on || $wp_cache,
			'message' => $adv_on
				? ( $wp_cache ? 'WP_CACHE enabled for advanced-cache' : 'advanced-cache enabled but WP_CACHE is false' )
				: 'advanced-cache not required',
		);
		$checks[] = array(
			'id'      => 'advanced_cache_dropin',
			'ok'      => ! $adv_on || ! empty( $adv_status['ours'] ),
			'message' => ! $adv_on
				? 'advanced-cache not required'
				: ( ! empty( $adv_status['ours'] ) ? 'QW Optimize advanced-cache drop-in installed' : ( ! empty( $adv_status['installed'] ) ? 'Another plugin owns advanced-cache.php' : 'QW Optimize advanced-cache drop-in missing' ) ),
		);

		$conflicts = class_exists( '\\QWSpeedCache\\Safety\\ConflictDetector' )
			? \QWSpeedCache\Safety\ConflictDetector::active_conflicts()
			: array();
		$checks[] = array(
			'id'      => 'conflicts',
			'ok'      => empty( $conflicts ),
			'message' => empty( $conflicts ) ? 'No known conflicting plugins' : ( 'Conflicts: ' . implode( ', ', $conflicts ) ),
		);

		$delay_ok = ! \QWSpeedCache\Free\Extensions::pro_key_available( 'delay_js' ) || empty( $s['delay_js'] ) || ! empty( $s['js_safe_mode'] );
		$checks[] = array(
			'id'      => 'delay_js_safe',
			'ok'      => (bool) $delay_ok,
			'message' => $delay_ok ? 'Delay JS safe' : 'Delay JS on without safe mode',
		);

		$php_ok = version_compare( PHP_VERSION, '7.4', '>=' );
		$checks[] = array(
			'id'      => 'php_version',
			'ok'      => $php_ok,
			'message' => 'PHP ' . PHP_VERSION,
		);

		$ok = true;
		foreach ( $checks as $c ) {
			if ( empty( $c['ok'] ) ) {
				$ok = false;
				break;
			}
		}
		return array(
			'ok'      => $ok,
			'version' => defined( 'QWSC_VERSION' ) ? QWSC_VERSION : '',
			'checks'  => $checks,
		);
	}

	/**
	 * @param int $ts Unix time.
	 * @return string
	 */
	public static function human_ago( $ts ) {
		$ts = (int) $ts;
		if ( $ts <= 0 ) {
			return '';
		}
		$diff = max( 0, time() - $ts );
		if ( $diff < 60 ) {
			return $diff . 's ago';
		}
		if ( $diff < 3600 ) {
			return (int) floor( $diff / 60 ) . 'm ago';
		}
		if ( $diff < 86400 ) {
			return (int) floor( $diff / 3600 ) . 'h ago';
		}
		return (int) floor( $diff / 86400 ) . 'd ago';
	}
}