<?php
/**
 * Zend Framework (http://framework.zend.com/)
 *
 * @see       http://github.com/zendframework/zend-diactoros for the canonical source repository
 * @copyright Copyright (c) 2015-2016 Zend Technologies USA Inc. (http://www.zend.com)
 * @license   https://github.com/zendframework/zend-diactoros/blob/master/LICENSE.md New BSD License
 */

namespace Zend\Diactoros;

use InvalidArgumentException;
use Psr\Http\Message\StreamInterface;
use Psr\Http\Message\UriInterface;

/**
 * Trait with common request behaviors.
 *
 * Server and client-side requests differ slightly in how the Host header is
 * handled; on client-side, it should be calculated on-the-fly from the
 * composed URI (if present), while on server-side, it will be calculated from
 * the environment. As such, this trait exists to provide the common code
 * between both client-side and server-side requests, and each can then
 * use the headers functionality required by their implementations.
 *
 * @property array $headers
 * @property array $headerNames
 * @property StreamInterface $stream
 * @method bool hasHeader(string $header)
 */
trait RequestTrait
{
    /**
     * @var string
     */
    private $method = '';

    /**
     * The request-target, if it has been provided or calculated.
     *
     * @var null|string
     */
    private $requestTarget;

    /**
     * @var UriInterface
     */
    private $uri;

    /**
     * Initialize request state.
     *
     * Used by constructors.
     *
     * @param null|string|UriInterface $uri URI for the request, if any.
     * @param null|string $method HTTP method for the request, if any.
     * @param string|resource|StreamInterface $body Message body, if any.
     * @param array $headers Headers for the message, if any.
     * @throws InvalidArgumentException for any invalid value.
     */
    private function initialize($uri = null, $method = null, $body = 'php://memory', array $headers = [])
    {
        $this->validateMethod($method);

        $this->method = $method ?: '';
        $this->uri    = $this->createUri($uri);
        $this->stream = $this->getStream($body, 'wb+');

        list($this->headerNames, $headers) = $this->filterHeaders($headers);
        $this->assertHeaders($headers);
        $this->headers = $headers;

        // per PSR-7: attempt to set the Host header from a provided URI if no
        // Host header is provided
        if (! $this->hasHeader('Host') && $this->uri->getHost()) {
            $this->headerNames['host'] = 'Host';
            $this->headers['Host'] = [$this->getHostFromUri()];
        }
    }

    /**
     * Create and return a URI instance.
     *
     * If `$uri` is a already a `UriInterface` instance, returns it.
     *
     * If `$uri` is a string, passes it to the `Uri` constructor to return an
     * instance.
     *
     * If `$uri is null, creates and returns an empty `Uri` instance.
     *
     * Otherwise, it raises an exception.
     *
     * @param null|string|UriInterface $uri
     * @return UriInterface
     * @throws InvalidArgumentException
     */
    private function createUri($uri)
    {
        if ($uri instanceof UriInterface) {
            return $uri;
        }
        if (is_string($uri)) {
            return new Uri($uri);
        }
        if ($uri === null) {
            return new Uri();
        }
        throw new InvalidArgumentException(
            'Invalid URI provided; must be null, a string, or a Psr\Http\Message\UriInterface instance'
        );
    }

    /**
     * Retrieves the message's request target.
     *
     * Retrieves the message's request-target either as it will appear (for
     * clients), as it appeared at request (for servers), or as it was
     * specified for the instance (see withRequestTarget()).
     *
     * In most cases, this will be the origin-form of the composed URI,
     * unless a value was provided to the concrete implementation (see
     * withRequestTarget() below).
     *
     * If no URI is available, and no request-target has been specifically
     * provided, this method MUST return the string "/".
     *
     * @return string
     */
    public function getRequestTarget()
    {
        if (null !== $this->requestTarget) {
            return $this->requestTarget;
        }

        $target = $this->uri->getPath();
        if ($this->uri->getQuery()) {
            $target .= '?' . $this->uri->getQuery();
        }

        if (empty($target)) {
            $target = '/';
        }

        return $target;
    }

    /**
     * Create a new instance with a specific request-target.
     *
     * If the request needs a non-origin-form request-target — e.g., for
     * specifying an absolute-form, authority-form, or asterisk-form —
     * this method may be used to create an instance with the specified
     * request-target, verbatim.
     *
     * This method MUST be implemented in such a way as to retain the
     * immutability of the message, and MUST return a new instance that has the
     * changed request target.
     *
     * @link http://tools.ietf.org/html/rfc7230#section-2.7 (for the various
     *     request-target forms allowed in request messages)
     * @param mixed $requestTarget
     * @return static
     * @throws InvalidArgumentException if the request target is invalid.
     */
    public function withRequestTarget($requestTarget)
    {
        if (preg_match('#\s#', $requestTarget)) {
            throw new InvalidArgumentException(
                'Invalid request target provided; cannot contain whitespace'
            );
        }

        $new = clone $this;
        $new->requestTarget = $requestTarget;
        return $new;
    }

    /**
     * Retrieves the HTTP method of the request.
     *
     * @return string Returns the request method.
     */
    public function getMethod()
    {
        return $this->method;
    }

    /**
     * Return an instance with the provided HTTP method.
     *
     * While HTTP method names are typically all uppercase characters, HTTP
     * method names are case-sensitive and thus implementations SHOULD NOT
     * modify the given string.
     *
     * 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
     * changed request method.
     *
     * @param string $method Case-insensitive method.
     * @return static
     * @throws InvalidArgumentException for invalid HTTP methods.
     */
    public function withMethod($method)
    {
        $this->validateMethod($method);
        $new = clone $this;
        $new->method = $method;
        return $new;
    }

    /**
     * Retrieves the URI instance.
     *
     * This method MUST return a UriInterface instance.
     *
     * @link http://tools.ietf.org/html/rfc3986#section-4.3
     * @return UriInterface Returns a UriInterface instance
     *     representing the URI of the request, if any.
     */
    public function getUri()
    {
        return $this->uri;
    }

    /**
     * Returns an instance with the provided URI.
     *
     * This method will update the Host header of the returned request by
     * default if the URI contains a host component. If the URI does not
     * contain a host component, any pre-existing Host header will be carried
     * over to the returned request.
     *
     * You can opt-in to preserving the original state of the Host header by
     * setting `$preserveHost` to `true`. When `$preserveHost` is set to
     * `true`, the returned request will not update the Host header of the
     * returned message -- even if the message contains no Host header. This
     * means that a call to `getHeader('Host')` on the original request MUST
     * equal the return value of a call to `getHeader('Host')` on the returned
     * request.
     *
     * 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
     * new UriInterface instance.
     *
     * @link http://tools.ietf.org/html/rfc3986#section-4.3
     * @param UriInterface $uri New request URI to use.
     * @param bool $preserveHost Preserve the original state of the Host header.
     * @return static
     */
    public function withUri(UriInterface $uri, $preserveHost = false)
    {
        $new = clone $this;
        $new->uri = $uri;

        if ($preserveHost && $this->hasHeader('Host')) {
            return $new;
        }

        if (! $uri->getHost()) {
            return $new;
        }

        $host = $uri->getHost();
        if ($uri->getPort()) {
            $host .= ':' . $uri->getPort();
        }

        $new->headerNames['host'] = 'Host';

        // Remove an existing host header if present, regardless of current
        // de-normalization of the header name.
        // @see https://github.com/zendframework/zend-diactoros/issues/91
        foreach (array_keys($new->headers) as $header) {
            if (strtolower($header) === 'host') {
                unset($new->headers[$header]);
            }
        }

        $new->headers['Host'] = [$host];

        return $new;
    }

    /**
     * Validate the HTTP method
     *
     * @param null|string $method
     * @throws InvalidArgumentException on invalid HTTP method.
     */
    private function validateMethod($method)
    {
        if (null === $method) {
            return;
        }

        if (! is_string($method)) {
            throw new InvalidArgumentException(sprintf(
                'Unsupported HTTP method; must be a string, received %s',
                (is_object($method) ? get_class($method) : gettype($method))
            ));
        }

        if (! preg_match('/^[!#$%&\'*+.^_`\|~0-9a-z-]+$/i', $method)) {
            throw new InvalidArgumentException(sprintf(
                'Unsupported HTTP method "%s" provided',
                $method
            ));
        }
    }

    /**
     * Retrieve the host from the URI instance
     *
     * @return string
     */
    private function getHostFromUri()
    {
        $host  = $this->uri->getHost();
        $host .= $this->uri->getPort() ? ':' . $this->uri->getPort() : '';
        return $host;
    }

    /**
     * Ensure header names and values are valid.
     *
     * @param array $headers
     * @throws InvalidArgumentException
     */
    private function assertHeaders(array $headers)
    {
        foreach ($headers as $name => $headerValues) {
            HeaderSecurity::assertValidName($name);
            array_walk($headerValues, __NAMESPACE__ . '\HeaderSecurity::assertValid');
        }
    }
}
