<?php
/**
 * Export and import all kgvvm plugin data as JSON.
 *
 * @package KGV\VereinManager
 */

namespace KGV\VereinManager;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

class DataTransfer {

	/** @var \wpdb */
	private $wpdb;

	/**
	 * Table keys in dependency order (parent before child).
	 *
	 * @var string[]
	 */
	private static $table_keys = array(
		'sections',
		'parcels',
		'tenants',
		'parcel_members',
		'parcel_tenants',
		'meters',
		'meter_readings',
		'chat_messages',
		'cost_years',
		'cost_rates',
		'cost_entries',
		'work_jobs',
		'work_year_config',
		'work_logs',
		'work_log_members',
	);

	public function __construct( \wpdb $wpdb ) {
		$this->wpdb = $wpdb;
	}

	// -------------------------------------------------------------------------
	// Export
	// -------------------------------------------------------------------------

	/**
	 * Build the export payload as an associative array.
	 *
	 * @return array
	 */
	public function build_export() {
		$payload = array(
			'plugin'    => 'kgv-verein-manager',
			'version'   => KGVVM_VERSION,
			'exported'  => gmdate( 'Y-m-d\TH:i:s\Z' ),
			'tables'    => array(),
		);

		foreach ( self::$table_keys as $key ) {
			$table = Schema::table( $key );
			if ( '' === $table ) {
				continue;
			}
			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared,WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
			$rows = $this->wpdb->get_results( "SELECT * FROM {$table}", ARRAY_A );
			$payload['tables'][ $key ] = is_array( $rows ) ? $rows : array();
		}

		return $payload;
	}

	/**
	 * Send the export as a JSON file download and exit.
	 *
	 * @return void
	 */
	public function send_download() {
		$payload  = $this->build_export();
		$json     = wp_json_encode( $payload, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE );
		$filename = 'kgvvm-export-' . gmdate( 'Y-m-d' ) . '.json';

		nocache_headers();
		header( 'Content-Type: application/json; charset=utf-8' );
		header( 'Content-Disposition: attachment; filename="' . $filename . '"' );
		header( 'Content-Length: ' . strlen( $json ) );
		echo $json; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
		exit;
	}

	// -------------------------------------------------------------------------
	// Import
	// -------------------------------------------------------------------------

	/**
	 * Validate and import data from a decoded JSON array.
	 *
	 * Returns an array with keys 'imported' (int[]), 'skipped' (string[]), 'errors' (string[]).
	 *
	 * @param array $payload Decoded JSON payload.
	 * @return array
	 */
	public function import( array $payload ) {
		$result = array(
			'imported' => array(),
			'skipped'  => array(),
			'errors'   => array(),
		);

		if ( empty( $payload['plugin'] ) || 'kgv-verein-manager' !== $payload['plugin'] ) {
			$result['errors'][] = __( 'Die Datei stammt nicht vom KGV Verein Manager Plugin.', KGVVM_TEXT_DOMAIN );
			return $result;
		}

		if ( empty( $payload['tables'] ) || ! is_array( $payload['tables'] ) ) {
			$result['errors'][] = __( 'Die Exportdatei enthält keine Tabellendaten.', KGVVM_TEXT_DOMAIN );
			return $result;
		}

		// Wrap everything in a transaction so a partial failure can be rolled back.
		$this->wpdb->query( 'SET FOREIGN_KEY_CHECKS = 0' ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery
		$this->wpdb->query( 'START TRANSACTION' ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery

		// Truncate in reverse dependency order.
		foreach ( array_reverse( self::$table_keys ) as $key ) {
			if ( ! isset( $payload['tables'][ $key ] ) ) {
				continue;
			}
			$table = Schema::table( $key );
			if ( '' === $table ) {
				continue;
			}
			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared,WordPress.DB.DirectDatabaseQuery.DirectQuery
			$this->wpdb->query( "TRUNCATE TABLE {$table}" );
		}

		// Re-insert in dependency order.
		foreach ( self::$table_keys as $key ) {
			if ( ! isset( $payload['tables'][ $key ] ) ) {
				$result['skipped'][] = $key;
				continue;
			}

			$table = Schema::table( $key );
			if ( '' === $table ) {
				$result['skipped'][] = $key;
				continue;
			}

			$rows  = (array) $payload['tables'][ $key ];
			$count = 0;

			foreach ( $rows as $row ) {
				if ( ! is_array( $row ) || empty( $row ) ) {
					continue;
				}
				// Sanitize keys – only allow simple column names.
				$clean = array();
				foreach ( $row as $col => $val ) {
					$col_clean = preg_replace( '/[^a-zA-Z0-9_]/', '', (string) $col );
					if ( '' !== $col_clean ) {
						$clean[ $col_clean ] = $val;
					}
				}

				$inserted = $this->wpdb->insert( $table, $clean ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery
				if ( false !== $inserted ) {
					$count++;
				} else {
					$result['errors'][] = sprintf(
						/* translators: 1: table key 2: DB error */
						__( 'Fehler beim Einfügen in %1$s: %2$s', KGVVM_TEXT_DOMAIN ),
						$key,
						(string) $this->wpdb->last_error
					);
				}
			}

			$result['imported'][ $key ] = $count;
		}

		if ( empty( $result['errors'] ) ) {
			$this->wpdb->query( 'COMMIT' ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery
		} else {
			$this->wpdb->query( 'ROLLBACK' ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery
		}

		$this->wpdb->query( 'SET FOREIGN_KEY_CHECKS = 1' ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery

		return $result;
	}
}