<?php
/**
 * Export pipeline: enumerate → database → archive → finalize.
 */

defined( 'ABSPATH' ) || exit;

// phpcs:disable WordPress.WP.AlternativeFunctions
// Reason: archives can be many gigabytes and are streamed in resumable chunks
// with byte offsets; WP_Filesystem only reads/writes whole files in memory.

final class Marchnote_Export {

	const OPTIONS = array(
		'no_media',
		'no_plugins',
		'no_themes',
		'no_inactive_plugins',
		'no_inactive_themes',
		'no_muplugins',
		'no_database',
		'no_spam',
		'no_revisions',
		'no_transients',
	);

	/** Folders under wp-content that are never worth exporting. */
	const ALWAYS_SKIP = array(
		'cache',
		'upgrade',
		'upgrade-temp-backup',
		'wflogs',
		'litespeed',
		'et-cache',
		'debug.log',
		'ai1wm-backups',
		'updraft',
		'backups-dup-lite',
		'backups-dup-pro',
		'wpvividbackups',
	);

	public static function start( array $input ) {
		if ( is_multisite() ) {
			throw new RuntimeException( 'Multisite networks are not supported.' );
		}
		$opts = array();
		foreach ( self::OPTIONS as $k ) {
			$opts[ $k ] = ! empty( $input[ $k ] );
		}
		$opts['exclude_paths'] = array();
		foreach ( preg_split( '/[\r\n]+/', (string) ( $input['exclude_paths'] ?? '' ) ) as $line ) {
			$line = trim( wp_normalize_path( trim( $line ) ), '/' );
			if ( '' !== $line && Marchnote_Storage::is_safe_rel( $line ) ) {
				$opts['exclude_paths'][] = $line;
			}
		}

		$host = preg_replace( '/[^a-z0-9.-]+/', '-', strtolower( (string) wp_parse_url( home_url(), PHP_URL_HOST ) ) );
		$name = trim( $host, '-.' ) . '-' . gmdate( 'Ymd-His' ) . '-' . strtolower( wp_generate_password( 6, false, false ) ) . '.' . Marchnote_Archive::EXT;

		return Marchnote_Job::create(
			'export',
			array(
				'stage'   => 'enumerate',
				'opts'    => $opts,
				'archive' => $name,
			)
		);
	}

	public static function step( Marchnote_Job $job, $deadline ) {
		$d = &$job->data;
		switch ( $d['stage'] ) {
			case 'enumerate':
				self::enumerate( $job );
				$d['stage'] = $d['opts']['no_database'] ? 'archive' : 'database';
				if ( 'database' === $d['stage'] ) {
					$d['db'] = Marchnote_Database::dump_init();
				}
				return self::progress( $job, 5, sprintf( 'Found %s files (%s).', number_format_i18n( $d['files'] ), size_format( $d['bytes'] ) ) );

			case 'database':
				$done = Marchnote_Database::dump_step( $d['db'], $job->path( 'database.sql' ), $d['opts'], $deadline );
				$n    = count( $d['db']['tables'] );
				$pct  = 5 + (int) ( 25 * ( $n ? $d['db']['ti'] / $n : 1 ) );
				if ( $done ) {
					$d['stage'] = 'archive';
				}
				return self::progress( $job, $pct, sprintf( 'Exporting database: %d of %d tables, %s rows.', min( $d['db']['ti'] + 1, $n ), $n, number_format_i18n( $d['db']['rows'] ) ) );

			case 'archive':
				if ( empty( $d['arc'] ) ) {
					self::write_package( $job );
					$d['arc'] = array(
						'offset'   => 0,
						'specials' => array_values( array_filter( array( 'package.json', $d['opts']['no_database'] ? null : 'database.sql' ) ) ),
						'list_pos' => 0,
						'cur'      => null,
						'written'  => 0,
						'count'    => 0,
					);
				}
				$done = self::archive_step( $job, $deadline );
				$pct  = 30 + (int) ( 68 * ( $d['bytes'] ? min( 1, $d['arc']['written'] / max( 1, $d['bytes'] ) ) : 1 ) );
				if ( $done ) {
					$d['stage'] = 'finalize';
				}
				return self::progress( $job, $pct, sprintf( 'Archiving files: %s of %s.', number_format_i18n( $d['arc']['count'] ), number_format_i18n( $d['files'] ) ) );

			case 'finalize':
				$part  = Marchnote_Storage::backups_dir() . '/' . $d['archive'] . '.part';
				$final = Marchnote_Storage::backups_dir() . '/' . $d['archive'];
				if ( ! rename( $part, $final ) ) {
					throw new RuntimeException( 'Could not finalise the archive.' );
				}
				$size = filesize( $final );
				$job->destroy();
				return array(
					'status'   => 'done',
					'progress' => 100,
					'message'  => sprintf( 'Export complete: %s (%s).', $d['archive'], size_format( $size ) ),
					'data'     => array(
						'file'     => $d['archive'],
						'size'     => $size,
						'download' => Marchnote_Admin::download_url( $d['archive'] ),
					),
				);
		}
		throw new RuntimeException( 'Unknown export stage.' );
	}

	private static function progress( Marchnote_Job $job, $pct, $message ) {
		$job->save();
		return array(
			'status'   => 'continue',
			'progress' => $pct,
			'message'  => $message,
		);
	}

	/**
	 * Paths (relative to wp-content) left out of this export.
	 */
	public static function exclusions( array $opts ) {
		$ex   = self::ALWAYS_SKIP;
		$ex[] = Marchnote_Storage::rel_to_content( Marchnote_Storage::backups_dir() );
		$plug = Marchnote_Storage::rel_to_content( WP_PLUGIN_DIR );
		$them = Marchnote_Storage::rel_to_content( get_theme_root() );
		$up   = wp_upload_dir( null, false );
		$upl  = Marchnote_Storage::rel_to_content( $up['basedir'] );
		$mu   = Marchnote_Storage::rel_to_content( WPMU_PLUGIN_DIR );

		if ( null !== $plug ) {
			// The destination keeps its own copy of this plugin.
			$ex[] = $plug . '/' . dirname( MARCHNOTE_BASENAME );
			if ( $opts['no_plugins'] ) {
				$ex[] = $plug;
			} elseif ( $opts['no_inactive_plugins'] ) {
				if ( ! function_exists( 'get_plugins' ) ) {
					require_once ABSPATH . 'wp-admin/includes/plugin.php';
				}
				foreach ( array_keys( get_plugins() ) as $file ) {
					if ( ! is_plugin_active( $file ) ) {
						$ex[] = $plug . '/' . ( false === strpos( $file, '/' ) ? $file : dirname( $file ) );
					}
				}
			}
		}
		if ( null !== $them ) {
			if ( $opts['no_themes'] ) {
				$ex[] = $them;
			} elseif ( $opts['no_inactive_themes'] ) {
				foreach ( array_keys( wp_get_themes() ) as $slug ) {
					if ( get_template() !== $slug && get_stylesheet() !== $slug ) {
						$ex[] = $them . '/' . $slug;
					}
				}
			}
		}
		if ( null !== $upl && $opts['no_media'] ) {
			$ex[] = $upl;
		}
		if ( null !== $mu && $opts['no_muplugins'] ) {
			$ex[] = $mu;
		}
		return array_values( array_filter( array_unique( array_merge( $ex, $opts['exclude_paths'] ) ), 'strlen' ) );
	}

	private static function enumerate( Marchnote_Job $job ) {
		$root = Marchnote_Storage::content_dir();
		$ex   = self::exclusions( $job->data['opts'] );
		$list = fopen( $job->path( 'files.list' ), 'wb' );
		$n    = 0;
		$size = 0;

		$dir    = new RecursiveDirectoryIterator( $root, FilesystemIterator::SKIP_DOTS | FilesystemIterator::UNIX_PATHS );
		$filter = new RecursiveCallbackFilterIterator(
			$dir,
			function ( $f ) use ( $root, $ex ) {
				$rel = substr( wp_normalize_path( $f->getPathname() ), strlen( $root ) + 1 );
				return '.DS_Store' !== $f->getFilename() && ! Marchnote_Storage::matches( $rel, $ex );
			}
		);
		$it = new RecursiveIteratorIterator( $filter, RecursiveIteratorIterator::LEAVES_ONLY, RecursiveIteratorIterator::CATCH_GET_CHILD );

		foreach ( $it as $f ) {
			if ( ! $f->isFile() || ! $f->isReadable() ) {
				continue;
			}
			$rel = substr( wp_normalize_path( $f->getPathname() ), strlen( $root ) + 1 );
			if ( strlen( $rel ) > 4000 || preg_match( '/[\r\n]/', $rel ) ) {
				$job->log( "Skipped unusual filename: $rel" );
				continue;
			}
			fwrite( $list, $rel . "\n" );
			$n++;
			$size += $f->getSize();
		}
		fclose( $list );
		$job->data['files'] = $n;
		$job->data['bytes'] = $size;
	}

	private static function write_package( Marchnote_Job $job ) {
		global $wpdb;
		$up = wp_upload_dir( null, false );
		if ( ! function_exists( 'get_plugins' ) ) {
			require_once ABSPATH . 'wp-admin/includes/plugin.php';
		}
		$pkg = array(
			'format'         => 1,
			'plugin_version' => MARCHNOTE_VERSION,
			'created'        => time(),
			'siteurl'        => site_url(),
			'home'           => home_url(),
			'uploads_url'    => $up['baseurl'],
			'abspath'        => untrailingslashit( wp_normalize_path( ABSPATH ) ),
			'content_dir'    => Marchnote_Storage::content_dir(),
			'uploads_dir'    => untrailingslashit( wp_normalize_path( $up['basedir'] ) ),
			'prefix'         => $wpdb->prefix,
			'wp_version'     => get_bloginfo( 'version' ),
			'php_version'    => PHP_VERSION,
			'db_version'     => $wpdb->db_version(),
			'blogname'       => get_option( 'blogname' ),
			'template'       => get_template(),
			'stylesheet'     => get_stylesheet(),
			'active_plugins' => (array) get_option( 'active_plugins', array() ),
			'has_database'   => ! $job->data['opts']['no_database'],
			'files'          => $job->data['files'],
			'bytes'          => $job->data['bytes'],
			'options'        => $job->data['opts'],
		);
		file_put_contents( $job->path( 'package.json' ), wp_json_encode( $pkg, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES ) );
	}

	/**
	 * Append entries to the archive until done or out of time.
	 */
	private static function archive_step( Marchnote_Job $job, $deadline ) {
		$a    = &$job->data['arc'];
		$path = Marchnote_Storage::backups_dir() . '/' . $job->data['archive'] . '.part';
		$out  = fopen( $path, 'c+b' );
		if ( ! $out ) {
			throw new RuntimeException( 'Could not write the archive in ' . esc_html( Marchnote_Storage::backups_dir() ) );
		}
		// Drop anything a crashed request wrote after the last checkpoint.
		ftruncate( $out, $a['offset'] );
		fseek( $out, $a['offset'] );
		if ( 0 === $a['offset'] ) {
			fwrite( $out, Marchnote_Archive::MAGIC );
		}

		$list = fopen( $job->path( 'files.list' ), 'rb' );
		$root = Marchnote_Storage::content_dir();

		while ( microtime( true ) < $deadline ) {
			if ( ! $a['cur'] ) {
				if ( $a['specials'] ) {
					$special = array_shift( $a['specials'] );
					$src     = $job->path( $special );
					$name    = 'marchnote/' . $special;
				} else {
					fseek( $list, $a['list_pos'] );
					$line = fgets( $list );
					if ( false === $line ) {
						fwrite( $out, Marchnote_Archive::end_marker() );
						fclose( $list );
						fclose( $out );
						return true;
					}
					$a['list_pos'] = ftell( $list );
					$rel           = rtrim( $line, "\n" );
					$src           = $root . '/' . $rel;
					$name          = Marchnote_Archive::CONTENT . $rel;
					$a['count']++;
				}
				clearstatcache( true, $src );
				if ( ! is_file( $src ) || ! is_readable( $src ) ) {
					$job->log( "Skipped unreadable file: $src" );
					continue;
				}
				$size = filesize( $src );
				fwrite( $out, Marchnote_Archive::entry_header( $name, $size, (int) filemtime( $src ) ) );
				$a['cur'] = array(
					'src'  => $src,
					'size' => $size,
					'done' => 0,
					'file' => 0 === strpos( $name, Marchnote_Archive::CONTENT ),
				);
			}

			$cur = &$a['cur'];
			$eof = false;
			$in  = @fopen( $cur['src'], 'rb' );
			if ( $in ) {
				fseek( $in, $cur['done'] );
				while ( $cur['done'] < $cur['size'] && microtime( true ) < $deadline ) {
					$n = Marchnote_Archive::copy( $in, $out, min( 8 * Marchnote_Archive::CHUNK, $cur['size'] - $cur['done'] ) );
					if ( 0 === $n ) {
						$eof = true; // file shrank while we were reading it
						break;
					}
					$cur['done'] += $n;
					if ( $cur['file'] ) {
						$a['written'] += $n;
					}
				}
				fclose( $in );
			} else {
				$eof = true;
			}
			if ( $eof && $cur['done'] < $cur['size'] ) {
				// Keep the header's declared size honest if the source vanished or shrank.
				$job->log( 'File changed during export: ' . $cur['src'] );
				fwrite( $out, str_repeat( "\0", $cur['size'] - $cur['done'] ) );
				$cur['done'] = $cur['size'];
			}
			if ( $cur['done'] >= $cur['size'] ) {
				$a['cur'] = null;
			}
			unset( $cur );
			fflush( $out );
			$a['offset'] = ftell( $out );
		}
		fflush( $out );
		$a['offset'] = ftell( $out );
		fclose( $list );
		fclose( $out );
		return false;
	}
}