<?php
/**
 * A unit of work.
 *
 * @package Transtrix
 */

namespace Transtrix\Runner;

defined( 'ABSPATH' ) || exit;

/**
 * One export or import job.
 *
 * A plain value object for now. Persistence belongs with the resumable batch
 * work (invariant A8), which is Phase 2 — storing state before anything reads
 * it would be a guess at the schema.
 */
class Job {

	/**
	 * Unique job id.
	 *
	 * @var string
	 */
	private $id;

	/**
	 * Which module this job belongs to.
	 *
	 * @var string
	 */
	private $module_id;

	/**
	 * The object ids in scope.
	 *
	 * @var int[]
	 */
	private $object_ids;

	/**
	 * Free-form job state.
	 *
	 * @var array<string,mixed>
	 */
	private $state = array();

	/**
	 * Creation timestamp, GMT.
	 *
	 * @var string
	 */
	private $created_at;

	/**
	 * Constructor.
	 *
	 * @param string $module_id  Module id.
	 * @param int[]  $object_ids Object ids in scope.
	 */
	public function __construct( string $module_id, array $object_ids = array() ) {
		$this->id         = uniqid( 'transtrix_', true );
		$this->module_id  = $module_id;
		$this->object_ids = array_values( array_map( 'intval', $object_ids ) );
		$this->created_at = gmdate( 'c' );
	}

	/**
	 * Job id.
	 *
	 * @return string
	 */
	public function id(): string {
		return $this->id;
	}

	/**
	 * Module id.
	 *
	 * @return string
	 */
	public function module_id(): string {
		return $this->module_id;
	}

	/**
	 * Object ids in scope.
	 *
	 * @return int[]
	 */
	public function object_ids(): array {
		return $this->object_ids;
	}

	/**
	 * Replace the object ids, so before_export() can widen or narrow the job.
	 *
	 * @param int[] $object_ids Object ids.
	 * @return void
	 */
	public function set_object_ids( array $object_ids ): void {
		$this->object_ids = array_values( array_map( 'intval', $object_ids ) );
	}

	/**
	 * Read a state value.
	 *
	 * @param string $key     State key.
	 * @param mixed  $fallback Fallback when unset.
	 * @return mixed
	 */
	public function get_state( string $key, $fallback = null ) {
		return array_key_exists( $key, $this->state ) ? $this->state[ $key ] : $fallback;
	}

	/**
	 * Write a state value.
	 *
	 * @param string $key   State key.
	 * @param mixed  $value Value.
	 * @return void
	 */
	public function set_state( string $key, $value ): void {
		$this->state[ $key ] = $value;
	}

	/**
	 * Creation timestamp.
	 *
	 * @return string
	 */
	public function created_at(): string {
		return $this->created_at;
	}
}