<?php

namespace DbCopy\Transform;

class FieldMap extends Transform
{
	private $_fields;

	public function __construct(array $fields)
	{
		$this->_fields = $fields;
	}

	public static function create(array $fields): FieldMap
	{
		return new FieldMap($fields);
	}

	public function __invoke($record): ?array
	{
		$new_record = [];
		foreach ($this->_fields as $src=>$dst)
		{
			if (isset($record[$src]))
			{
				$new_record[$dst] = $record[$src];
			}
		}
		return $new_record;
	}
}