<?php
/**
 * JSON-lines logs in the storage directory (never in the database, which restores replace).
 *
 * @package AccessNow\Replica
 */

namespace AccessNow\Replica;

defined( 'ABSPATH' ) || exit;

/**
 * Activity log, source audit log and per-job logs.
 */
final class Logger {

	const MAX_BYTES = 2097152;

	/**
	 * Appends to the activity log.
	 *
	 * @param string $type    Category: pull, restore, source, backup, error, settings.
	 * @param string $message Plain-text message.
	 * @param array  $context Extra data (never secrets).
	 */
	public static function activity( $type, $message, array $context = array() ) {
		self::append( self::site_dir() . 'activity.jsonl', $type, $message, $context );
	}

	/**
	 * Appends to the source audit log (who pulled what, failures).
	 *
	 * @param string $message Plain-text message.
	 * @param array  $context Extra data.
	 */
	public static function audit( $message, array $context = array() ) {
		self::append( self::site_dir() . 'source-audit.jsonl', 'audit', $message, $context );
	}

	/**
	 * Appends a line to a job's log.
	 *
	 * @param string $job_id  Job ID.
	 * @param string $message Message.
	 * @param string $level   info|warning|error.
	 */
	public static function job( $job_id, $message, $level = 'info' ) {
		$line = gmdate( 'Y-m-d H:i:s' ) . ' [' . $level . '] ' . $message . "\n";
		$path = Storage::path( 'jobs/' . $job_id . '/log.txt' );
		if ( is_dir( dirname( $path ) ) ) {
			file_put_contents( $path, $line, FILE_APPEND | LOCK_EX ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents
		}
	}

	/**
	 * Last lines of a job log.
	 *
	 * @param string $job_id Job ID.
	 * @param int    $lines  Number of lines.
	 * @return string[]
	 */
	public static function job_tail( $job_id, $lines = 20 ) {
		return self::tail_lines( Storage::path( 'jobs/' . $job_id . '/log.txt' ), $lines );
	}

	/**
	 * Newest entries from a JSON-lines log.
	 *
	 * @param string $file  Relative log path (logs/activity.jsonl).
	 * @param int    $limit Entries.
	 * @return array[]
	 */
	public static function entries( $file, $limit = 100 ) {
		if ( ! Storage::exists() ) {
			return array(); // Nothing logged yet, and reading must not create the folder.
		}
		$out = array();
		foreach ( array_reverse( self::tail_lines( Storage::path( $file ), $limit ) ) as $line ) {
			$row = json_decode( $line, true );
			if ( is_array( $row ) ) {
				$out[] = $row;
			}
		}
		return $out;
	}

	/**
	 * Per-site log folder (relative), so sites sharing a storage folder keep separate logs.
	 */
	public static function site_dir() {
		$home = untrailingslashit( home_url() );
		$host = (string) wp_parse_url( $home, PHP_URL_HOST ) . '-' . trim( (string) wp_parse_url( $home, PHP_URL_PATH ), '/' );
		return 'logs/' . trim( sanitize_title( $host ), '-' ) . '-' . substr( md5( $home ), 0, 6 ) . '/';
	}

	/**
	 * Appends one JSON entry, rotating at MAX_BYTES.
	 *
	 * @param string $file    Relative log path.
	 * @param string $type    Type.
	 * @param string $message Message.
	 * @param array  $context Context.
	 */
	private static function append( $file, $type, $message, array $context ) {
		try {
			$path = Storage::path( $file );
		} catch ( \RuntimeException $e ) {
			return;
		}
		if ( ! is_dir( dirname( $path ) ) ) {
			wp_mkdir_p( dirname( $path ) );
		}
		if ( is_file( $path ) && filesize( $path ) > self::MAX_BYTES ) {
			@rename( $path, $path . '.1' ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged, WordPress.WP.AlternativeFunctions.rename_rename
		}
		$entry = array(
			'time'    => time(),
			'type'    => $type,
			'message' => $message,
		);
		if ( $context ) {
			$entry['context'] = $context;
		}
		file_put_contents( $path, wp_json_encode( $entry, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE ) . "\n", FILE_APPEND | LOCK_EX ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents
	}

	/**
	 * Reads the last N lines of a file without loading all of it.
	 *
	 * @param string $path  Absolute path.
	 * @param int    $lines Lines.
	 * @return string[]
	 */
	private static function tail_lines( $path, $lines ) {
		if ( ! is_readable( $path ) ) {
			return array();
		}
		$size = filesize( $path );
		$read = min( $size, max( 8192, $lines * 400 ) );
		$fh   = fopen( $path, 'rb' ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fopen
		if ( ! $fh ) {
			return array();
		}
		fseek( $fh, $size - $read );
		$chunk = (string) fread( $fh, $read ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fread
		fclose( $fh ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fclose
		$all = preg_split( "/\r?\n/", trim( $chunk ) );
		if ( $read < $size ) {
			array_shift( $all ); // First line is probably partial.
		}
		return array_slice( array_filter( $all, 'strlen' ), -$lines );
	}
}