<?php

namespace Psr\Http\Message;

use InvalidArgumentException;

/**
 * Representation of an outgoing, server-side response.
 *
 * Per the HTTP specification, this interface includes properties for
 * each of the following:
 *
 * - Protocol version
 * - Status code and reason phrase
 * - Headers
 * - Message body
 *
 * Responses are considered immutable; all methods that might change state MUST
 * be implemented such that they retain the internal state of the current
 * message and return an instance that contains the changed state.
 */
interface ResponseInterface extends MessageInterface {
	/**
	 * Gets the response status code.
	 *
	 * The status code is a 3-digit integer result code of the server's attempt
	 * to understand and satisfy the request.
	 *
	 * @return int Status code.
	 */
	public function getStatusCode();

	/**
	 * Return an instance with the specified status code and, optionally, reason phrase.
	 *
	 * If no reason phrase is specified, implementations MAY choose to default
	 * to the RFC 7231 or IANA recommended reason phrase for the response's
	 * status code.
	 *
	 * This method MUST be implemented in such a way as to retain the
	 * immutability of the message, and MUST return an instance that has the
	 * updated status and reason phrase.
	 *
	 * @link http://tools.ietf.org/html/rfc7231#section-6
	 * @link http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
	 *
	 * @param int $code The 3-digit integer result code to set.
	 * @param string $reasonPhrase The reason phrase to use with the
	 *     provided status code; if none is provided, implementations MAY
	 *     use the defaults as suggested in the HTTP specification.
	 *
	 * @return static
	 * @throws InvalidArgumentException For invalid status code arguments.
	 */
	public function withStatus( $code, $reasonPhrase = '' );

	/**
	 * Gets the response reason phrase associated with the status code.
	 *
	 * Because a reason phrase is not a required element in a response
	 * status line, the reason phrase value MAY be null. Implementations MAY
	 * choose to return the default RFC 7231 recommended reason phrase (or those
	 * listed in the IANA HTTP Status Code Registry) for the response's
	 * status code.
	 *
	 * @link http://tools.ietf.org/html/rfc7231#section-6
	 * @link http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
	 * @return string Reason phrase; must return an empty string if none present.
	 */
	public function getReasonPhrase();
}
