<?php
/**
 * Export-to-file endpoint: generates a .sql dump and serves a download URL.
 *
 * @package Shiftora\Api\Endpoints
 */

declare(strict_types=1);

namespace Shiftora\Api\Endpoints;

use Shiftora\Backup\SqlDumper;
use Shiftora\Support\DataDirectory;
use Shiftora\Support\PrivateFileName;
use WP_REST_Request;
use WP_REST_Response;
use WP_Error;

// Prevent direct file access.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * POST /shiftora/v1/export/file: dumps the requested tables and returns a
 * nonce-protected admin-post.php download URL.
 */
final class ExportFileEndpoint {

	public function register(): void {
		register_rest_route(
			'shiftora/v1',
			'/export/file',
			[
				'methods'             => 'POST',
				'callback'            => [ $this, 'handle' ],
				'permission_callback' => static function () {
					return current_user_can( 'manage_options' );
				},
			]
		);

		// The download itself is an admin-post handler, not REST.
		add_action( 'admin_post_shiftora_export_file', [ $this, 'serve_download' ] );
	}

	public function handle( WP_REST_Request $request ): WP_REST_Response|WP_Error {
		global $wpdb;

		$body   = $request->get_json_params();
		$tables = is_array( $body['tables'] ?? null ) ? $body['tables'] : [];

		if ( empty( $tables ) ) {
			return new WP_Error( 'shiftora_no_tables', __( 'No tables selected.', 'shiftora' ), [ 'status' => 400 ] );
		}

		// Views have no CREATE TABLE to dump and would fail the whole export.
		$all_tables = $wpdb->get_col( "SHOW FULL TABLES WHERE Table_type = 'BASE TABLE'" ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery -- SHOW FULL TABLES lists the live schema, which no WordPress API exposes.
		$safe_tables = array_values( array_filter( $tables, fn( $t ) => in_array( $t, $all_tables, true ) ) );

		if ( empty( $safe_tables ) ) {
			return new WP_Error( 'shiftora_invalid_tables', __( 'None of the given tables exist in this database.', 'shiftora' ), [ 'status' => 400 ] );
		}

		// Exports stay out of direct web reach.
		$tmp_dir = DataDirectory::ensure( DataDirectory::EXPORTS );
		if ( '' === $tmp_dir ) {
			return new WP_Error( 'shiftora_export_failed', __( 'The export folder under uploads could not be created.', 'shiftora' ), [ 'status' => 500 ] );
		}

		// An export nobody downloads would otherwise stay on disk for good.
		foreach ( glob( $tmp_dir . DIRECTORY_SEPARATOR . '*.sql' ) ?: [] as $stale ) {
			if ( filemtime( $stale ) < time() - HOUR_IN_SECONDS ) {
				wp_delete_file( $stale );
			}
		}

		$filename  = PrivateFileName::make( 'shiftora-export-' . gmdate( 'Ymd-His' ), '.sql' );
		$file_path = $tmp_dir . DIRECTORY_SEPARATOR . $filename;

		$dumper = new SqlDumper( $wpdb );
		try {
			$dumper->dump( array_values( $safe_tables ), $file_path );
		} catch ( \RuntimeException $e ) {
			return new WP_Error( 'shiftora_export_failed', $e->getMessage(), [ 'status' => 500 ] );
		}

		$token = bin2hex( random_bytes( 16 ) );
		set_transient( 'shiftora_export_' . $token, $file_path, 10 * MINUTE_IN_SECONDS );

		$download_url = add_query_arg(
			[
				'action'   => 'shiftora_export_file',
				'token'    => rawurlencode( $token ),
				'_wpnonce' => wp_create_nonce( 'shiftora_export_' . $token ),
			],
			admin_url( 'admin-post.php' )
		);

		return new WP_REST_Response( [ 'download_url' => $download_url ], 200 );
	}

	public function serve_download(): void {
		$token = isset( $_GET['token'] ) && is_string( $_GET['token'] ) ? sanitize_key( wp_unslash( $_GET['token'] ) ) : '';

		if ( ! current_user_can( 'manage_options' )
			|| empty( $token )
			|| ! isset( $_GET['_wpnonce'] )
			|| ! is_string( $_GET['_wpnonce'] )
			|| ! wp_verify_nonce( sanitize_text_field( wp_unslash( $_GET['_wpnonce'] ) ), 'shiftora_export_' . $token )
		) {
			wp_die( esc_html__( 'Permission denied or link expired.', 'shiftora' ), 403 );
		}

		$file_path = (string) get_transient( 'shiftora_export_' . $token );

		if ( empty( $file_path ) || ! is_file( $file_path ) ) {
			wp_die( esc_html__( 'Export file not found or has expired. Please generate a new export.', 'shiftora' ), 404 );
		}

		$real_path = realpath( $file_path );
		$base_dir  = realpath( DataDirectory::path( DataDirectory::EXPORTS ) );
		if ( false === $real_path || false === $base_dir || ! str_starts_with( $real_path, $base_dir . DIRECTORY_SEPARATOR ) ) {
			delete_transient( 'shiftora_export_' . $token );
			wp_die( esc_html__( 'Invalid export path.', 'shiftora' ), 403 );
		}

		// One-time link.
		delete_transient( 'shiftora_export_' . $token );

		$filename      = PrivateFileName::display( basename( $real_path ) );
		$safe_filename = sanitize_file_name( $filename );

		header( 'Content-Type: application/octet-stream' );
		header( "Content-Disposition: attachment; filename=\"{$safe_filename}\"; filename*=UTF-8''" . rawurlencode( $safe_filename ) );
		header( 'Content-Length: ' . (string) filesize( $real_path ) );
		// no-transform: a proxy that gzips or re-chunks a dump changes the bytes the importer receives.
		header( 'Cache-Control: no-cache, no-store, no-transform' );

		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_readfile -- readfile streams a verified file inside the plugin's own data folder to the browser
		readfile( $real_path );

		wp_delete_file( $real_path );

		exit;
	}
}