<?php
/**
 * Imports a package into this site.
 *
 * @package Transtrix
 */

namespace Transtrix\Modules\Core;

use Transtrix\Contracts\Importer;
use Transtrix\Contracts\Module;
use Transtrix\Import\Conflict_Resolver;
use Transtrix\Import\Three_Pass_Importer;
use Transtrix\Package\Package_Reader;
use Transtrix\Result\Dry_Run_Result;
use Transtrix\Result\Report;
use Transtrix\Runner\Job;

defined( 'ABSPATH' ) || exit;

/**
 * A thin adapter over Three_Pass_Importer.
 *
 * Validation of the package happens here so that neither the CLI nor, later, a
 * REST controller has to remember to do it (invariant A10).
 */
class Core_Importer implements Importer {

	/**
	 * The module whose hints apply.
	 *
	 * @var Module
	 */
	private $module;

	/**
	 * Per-object write check handed to the engine, or null to allow all.
	 *
	 * @var callable|null
	 */
	private $can_write;

	/**
	 * Constructor.
	 *
	 * @param Module        $module    The module whose hints apply.
	 * @param callable|null $can_write (array $postarr, int $existing_id) => bool.
	 */
	public function __construct( Module $module, ?callable $can_write = null ) {
		$this->module    = $module;
		$this->can_write = $can_write;
	}

	/**
	 * Report what importing the package would do.
	 *
	 * @param Job    $job          The import job.
	 * @param string $path         Package path.
	 * @param string $strategy     Conflict strategy.
	 * @param bool   $skip_missing Leave out types this site does not register.
	 * @return Dry_Run_Result|\WP_Error
	 */
	public function dry_run( Job $job, string $path, string $strategy = Conflict_Resolver::SKIP, bool $skip_missing = false ) {
		$reader = new Package_Reader( $path );
		$valid  = $reader->validate();

		if ( is_wp_error( $valid ) ) {
			return $valid;
		}

		try {
			return $this->importer( $reader, $job, $strategy, $skip_missing )->dry_run();
		} finally {
			$reader->cleanup();
		}
	}

	/**
	 * Import the package.
	 *
	 * @param Job    $job          The import job.
	 * @param string $path         Package path.
	 * @param string $strategy     Conflict strategy.
	 * @param bool   $skip_missing Leave out types this site does not register.
	 * @return Report|\WP_Error
	 */
	public function import( Job $job, string $path, string $strategy = Conflict_Resolver::SKIP, bool $skip_missing = false ) {
		$reader = new Package_Reader( $path );
		$valid  = $reader->validate();

		if ( is_wp_error( $valid ) ) {
			return $valid;
		}

		$importer = $this->importer( $reader, $job, $strategy, $skip_missing );
		$blockers = $importer->blockers();

		if ( array() !== $blockers ) {
			$reader->cleanup();

			return new \WP_Error( 'transtrix_import_blocked', implode( ' ', $blockers ), array( 'blockers' => $blockers ) );
		}

		try {
			return $importer->run();
		} finally {
			$reader->cleanup();
		}
	}

	/**
	 * Build the engine for one package.
	 *
	 * @param Package_Reader $reader       A validated package.
	 * @param Job            $job          The import job.
	 * @param string         $strategy     Conflict strategy.
	 * @param bool           $skip_missing Leave out types this site does not register.
	 * @return Three_Pass_Importer
	 */
	private function importer( Package_Reader $reader, Job $job, string $strategy, bool $skip_missing ): Three_Pass_Importer {
		return new Three_Pass_Importer( $reader, $this->module, new Conflict_Resolver( $strategy ), $job, $this->can_write, $skip_missing );
	}
}