<?php
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}
// phpcs:disable WordPress.WP.AlternativeFunctions -- Reads /proc files and appends to tiny counter files inside wp-content/cache/velox; WP_Filesystem is unsuitable for per-request counters.

/**
 * Server and site statistics for the "Server" tab: load, memory, disk, PHP / OPcache, database,
 * cache and how many pages PHP had to build. Everything is read on demand in the admin; the only
 * front-end cost is appending one byte to a per-hour counter file when a page is built (a cache
 * miss). Cached pages are static files and are never counted, so the counter shows server work,
 * not visitors. An hourly snapshot keeps 7 days of history in one non-autoloaded option.
 */
class Velox_Server {

	const OPTION = 'velox_server_history';
	const KEEP   = 168; // 7 days of hourly points.

	private static function meta_dir() {
		return Velox_Cache::dir() . 'meta/';
	}

	/** Counts one page built by PHP (called on a cache miss). */
	public static function count_build() {
		$dir = self::meta_dir();
		if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) {
			return;
		}
		@file_put_contents( $dir . 'build-' . gmdate( 'YmdH' ) . '.cnt', '1', FILE_APPEND | LOCK_EX );
	}

	/** Pages built in a given UTC hour ('YmdH'). */
	private static function builds( $hour ) {
		$f = self::meta_dir() . 'build-' . $hour . '.cnt';
		return is_file( $f ) ? (int) filesize( $f ) : 0;
	}

	private static function cores() {
		$cores = get_transient( 'velox_cpu_cores' );
		if ( false !== $cores ) {
			return (int) $cores;
		}
		$cores = 0;
		if ( is_readable( '/proc/cpuinfo' ) ) {
			$cores = preg_match_all( '/^processor\s*:/m', (string) @file_get_contents( '/proc/cpuinfo' ) );
		}
		$cores = max( 1, (int) $cores );
		set_transient( 'velox_cpu_cores', $cores, DAY_IN_SECONDS );
		return $cores;
	}

	/** Processor model and operating system (read once a day). */
	private static function hardware() {
		$hw = get_transient( 'velox_hw_info' );
		if ( is_array( $hw ) ) {
			return $hw;
		}
		$cpu = '';
		if ( is_readable( '/proc/cpuinfo' ) && preg_match( '/^model name\s*:\s*(.+)$/m', (string) @file_get_contents( '/proc/cpuinfo' ), $m ) ) {
			$cpu = trim( preg_replace( '/\s+/', ' ', str_replace( array( '(R)', '(TM)', 'CPU ' ), '', $m[1] ) ) );
		}
		$os = '';
		if ( is_readable( '/etc/os-release' ) && preg_match( '/^PRETTY_NAME="?([^"\n]+)"?$/m', (string) @file_get_contents( '/etc/os-release' ), $m ) ) {
			$os = trim( $m[1] );
		}
		if ( '' === $os && function_exists( 'php_uname' ) ) {
			$os = php_uname( 's' ) . ' ' . php_uname( 'r' );
		}
		$hw = array(
			'cpu' => substr( sanitize_text_field( $cpu ), 0, 80 ),
			'os'  => substr( sanitize_text_field( $os ), 0, 80 ),
		);
		set_transient( 'velox_hw_info', $hw, DAY_IN_SECONDS );
		return $hw;
	}

	/**
	 * Best guess whether the site runs on shared hosting, where load and disk are the whole
	 * machine's: open_basedir set or a CloudLinux kernel. Only changes the wording of the Server tab;
	 * hosts can override the guess with the velox_shared_hosting filter.
	 */
	public static function shared_hosting() {
		$shared = '' !== (string) ini_get( 'open_basedir' )
			|| ( function_exists( 'php_uname' ) && false !== stripos( php_uname( 'r' ), 'lve' ) );
		return (bool) apply_filters( 'velox_shared_hosting', $shared );
	}

	private static function memory() {
		if ( ! is_readable( '/proc/meminfo' ) ) {
			return null;
		}
		$info = (string) @file_get_contents( '/proc/meminfo' );
		if ( ! preg_match( '/^MemTotal:\s+(\d+)/m', $info, $t ) ) {
			return null;
		}
		$total = (int) $t[1] * 1024;
		$avail = preg_match( '/^MemAvailable:\s+(\d+)/m', $info, $a ) ? (int) $a[1] * 1024 : 0;
		return array(
			'total' => $total,
			'used'  => max( 0, $total - $avail ),
			'pct'   => $total > 0 ? round( 100 * ( $total - $avail ) / $total ) : 0,
		);
	}

	private static function disk() {
		$total = @disk_total_space( VELOX_DIR );
		$free  = @disk_free_space( VELOX_DIR );
		if ( ! $total || false === $free ) {
			return null;
		}
		return array(
			'total' => (float) $total,
			'used'  => (float) $total - (float) $free,
			'pct'   => round( 100 * ( $total - $free ) / $total ),
		);
	}

	private static function opcache() {
		if ( ! function_exists( 'opcache_get_status' ) ) {
			return null;
		}
		$st = @opcache_get_status( false );
		if ( ! is_array( $st ) || empty( $st['opcache_enabled'] ) ) {
			return array( 'enabled' => false );
		}
		$mem = isset( $st['memory_usage'] ) ? $st['memory_usage'] : array();
		$all = ( isset( $mem['used_memory'] ) ? $mem['used_memory'] : 0 ) + ( isset( $mem['free_memory'] ) ? $mem['free_memory'] : 0 ) + ( isset( $mem['wasted_memory'] ) ? $mem['wasted_memory'] : 0 );
		return array(
			'enabled' => true,
			'hit'     => isset( $st['opcache_statistics']['opcache_hit_rate'] ) ? round( (float) $st['opcache_statistics']['opcache_hit_rate'], 1 ) : null,
			'mem_pct' => $all > 0 ? round( 100 * $mem['used_memory'] / $all ) : null,
		);
	}

	/** Database size and its largest tables (MySQL / MariaDB; cached for an hour). */
	private static function database() {
		$cached = get_transient( 'velox_db_size' );
		if ( is_array( $cached ) ) {
			return $cached;
		}
		global $wpdb;
		$wpdb->suppress_errors( true );
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching -- information_schema has no WP API; the result is cached in a transient for an hour.
		$rows = $wpdb->get_results( $wpdb->prepare( 'SELECT TABLE_NAME AS n, (DATA_LENGTH + INDEX_LENGTH) AS s FROM information_schema.TABLES WHERE TABLE_SCHEMA = %s ORDER BY s DESC', DB_NAME ), ARRAY_A );
		$wpdb->suppress_errors( false );
		if ( ! is_array( $rows ) || ! $rows ) {
			$out = array();
		} else {
			$total = 0;
			foreach ( $rows as $r ) {
				$total += (float) $r['s'];
			}
			$top = array();
			foreach ( $total > 0 ? array_slice( $rows, 0, 5 ) : array() as $r ) {
				$top[] = array(
					'name' => (string) $r['n'],
					'size' => (float) $r['s'],
				);
			}
			$out = $total <= 0 ? array() : array(
				'size'   => $total,
				'tables' => count( $rows ),
				'top'    => $top,
			);
		}
		set_transient( 'velox_db_size', $out, HOUR_IN_SECONDS );
		return $out;
	}

	/** Current values for the Server tab. */
	public static function now() {
		$cores = self::cores();
		$load  = function_exists( 'sys_getloadavg' ) ? @sys_getloadavg() : false;
		$cache = Velox_Cache::stats();
		$hour  = gmdate( 'YmdH' );
		return array(
			'cores'    => $cores,
			'load'     => is_array( $load ) ? array_map(
				function ( $v ) {
					return round( (float) $v, 2 );
				},
				$load
			) : null,
			'load_pct' => is_array( $load ) ? (int) min( 100, round( 100 * $load[0] / $cores ) ) : null,
			'memory'   => self::memory(),
			'disk'     => self::disk(),
			'opcache'  => self::opcache(),
			'hardware' => self::hardware(),
			'php'      => PHP_VERSION,
			'php_mem'  => (string) ini_get( 'memory_limit' ),
			'software' => isset( $_SERVER['SERVER_SOFTWARE'] ) ? sanitize_text_field( wp_unslash( $_SERVER['SERVER_SOFTWARE'] ) ) : '',
			'db'       => self::database(),
			'cache'    => $cache,
			'builds'   => self::builds( $hour ),
		);
	}

	/** Hourly snapshot (runs on the existing hourly AngelForce Cache event). */
	public static function snapshot() {
		$n       = self::now();
		$prev    = gmdate( 'YmdH', time() - HOUR_IN_SECONDS );
		$history = get_option( self::OPTION, array() );
		$history = is_array( $history ) ? $history : array();
		$point   = array(
			't'      => time(),
			'load'   => $n['load_pct'],
			'mem'    => $n['memory'] ? $n['memory']['pct'] : null,
			'disk'   => $n['disk'] ? $n['disk']['pct'] : null,
			'builds' => self::builds( $prev ),
			'pages'  => (int) $n['cache']['pages'],
		);
		$history[] = $point;
		$history   = array_slice( $history, -self::KEEP );
		update_option( self::OPTION, $history, false );
		// Counter files older than two hours are no longer needed.
		foreach ( glob( self::meta_dir() . 'build-*.cnt' ) ?: array() as $f ) {
			if ( preg_match( '/build-(\d{10})\.cnt$/', $f, $m ) && $m[1] < $prev ) {
				wp_delete_file( $f );
			}
		}
	}

	public static function history() {
		$h = get_option( self::OPTION, array() );
		return is_array( $h ) ? $h : array();
	}

	/**
	 * Line chart of one history series over 7 days (inline SVG, no library).
	 *
	 * @param string   $key   Series key in the history points.
	 * @param string   $label Accessible label.
	 * @param int|null $max   Fixed top of the scale (null = from the data).
	 * @param string   $unit  Unit shown in point titles.
	 */
	public static function chart_svg( $key, $label, $max = null, $unit = '' ) {
		$points = array_values(
			array_filter(
				self::history(),
				function ( $p ) use ( $key ) {
					return isset( $p[ $key ] ) && null !== $p[ $key ];
				}
			)
		);
		if ( count( $points ) < 2 ) {
			return '';
		}
		$w     = 600;
		$h     = 160;
		$pad   = 14;
		$t0    = time() - 7 * DAY_IN_SECONDS;
		$span  = 7 * DAY_IN_SECONDS;
		$vmax  = null !== $max ? (float) $max : max( 1, max( wp_list_pluck( $points, $key ) ) * 1.15 );
		$x     = function ( $t ) use ( $w, $pad, $t0, $span ) {
			return round( $pad + max( 0, $t - $t0 ) * ( $w - 2 * $pad ) / $span, 1 );
		};
		$y     = function ( $v ) use ( $h, $pad, $vmax ) {
			return round( $h - $pad - min( 1, $v / $vmax ) * ( $h - 2 * $pad ), 1 );
		};
		$line  = '';
		$area  = '';
		$first = null;
		$last  = null;
		foreach ( $points as $p ) {
			$px    = $x( $p['t'] );
			$py    = $y( (float) $p[ $key ] );
			$line .= ( '' === $line ? 'M' : 'L' ) . $px . ' ' . $py . ' ';
			$first = null === $first ? $px : $first;
			$last  = $px;
		}
		$area = $line . 'L' . $last . ' ' . ( $h - $pad ) . ' L' . $first . ' ' . ( $h - $pad ) . ' Z';
		$svg  = '<svg viewBox="0 0 ' . $w . ' ' . $h . '" class="vx-chart" role="img" aria-label="' . esc_attr( $label ) . '">';
		foreach ( array( 0.25, 0.5, 0.75 ) as $g ) {
			$gy   = $y( $vmax * $g );
			$svg .= '<line x1="0" x2="' . $w . '" y1="' . $gy . '" y2="' . $gy . '" stroke="currentColor" opacity=".08"/>';
		}
		$svg .= '<path d="' . esc_attr( $area ) . '" fill="#6366f1" opacity=".12"/>';
		$svg .= '<path d="' . esc_attr( $line ) . '" fill="none" stroke="#6366f1" stroke-width="2" stroke-linejoin="round"/>';
		$tail = end( $points );
		$svg .= '<circle cx="' . $x( $tail['t'] ) . '" cy="' . $y( (float) $tail[ $key ] ) . '" r="3.5" fill="#4f46e5"><title>' . esc_html( wp_date( 'j M H:i', $tail['t'] ) . ': ' . $tail[ $key ] . $unit ) . '</title></circle>';
		$svg .= '<text x="' . ( $w - $pad ) . '" y="14" text-anchor="end" font-size="11" fill="currentColor" opacity=".55">' . esc_html( round( $vmax ) . $unit ) . '</text>';
		// Day labels along the bottom (site time zone).
		for ( $d = 6; $d >= 0; $d-- ) {
			$dt   = strtotime( 'today', time() - $d * DAY_IN_SECONDS );
			$svg .= '<text x="' . $x( $dt + 12 * HOUR_IN_SECONDS ) . '" y="' . ( $h - 1 ) . '" text-anchor="middle" font-size="10" fill="currentColor" opacity=".45">' . esc_html( wp_date( 'D', $dt ) ) . '</text>';
		}
		$svg .= '</svg>';
		return $svg;
	}

	public static function ajax_now() {
		check_ajax_referer( 'velox_nonce', 'nonce' );
		if ( ! current_user_can( 'manage_options' ) ) {
			wp_send_json_error( array( 'message' => 'forbidden' ), 403 );
		}
		wp_send_json_success( self::now() );
	}
}