<?php
/**
 * @see       https://github.com/zendframework/zend-diactoros for the canonical source repository
 * @copyright Copyright (c) 2015-2018 Zend Technologies USA Inc. (http://www.zend.com)
 * @license   https://github.com/zendframework/zend-diactoros/blob/master/LICENSE.md New BSD License
 */

declare(strict_types=1);

namespace Zend\Diactoros;

use Psr\Http\Message\MessageInterface;
use Psr\Http\Message\StreamInterface;

use function array_map;
use function array_merge;
use function get_class;
use function gettype;
use function implode;
use function is_array;
use function is_object;
use function is_resource;
use function is_string;
use function preg_match;
use function sprintf;
use function strtolower;

/**
 * Trait implementing the various methods defined in MessageInterface.
 *
 * @see https://github.com/php-fig/http-message/tree/master/src/MessageInterface.php
 */
trait MessageTrait
{
    /**
     * List of all registered headers, as key => array of values.
     *
     * @var array
     */
    protected $headers = [];

    /**
     * Map of normalized header name to original name used to register header.
     *
     * @var array
     */
    protected $headerNames = [];

    /**
     * @var string
     */
    private $protocol = '1.1';

    /**
     * @var StreamInterface
     */
    private $stream;

    /**
     * Retrieves the HTTP protocol version as a string.
     *
     * The string MUST contain only the HTTP version number (e.g., "1.1", "1.0").
     *
     * @return string HTTP protocol version.
     */
    public function getProtocolVersion() : string
    {
        return $this->protocol;
    }

    /**
     * Return an instance with the specified HTTP protocol version.
     *
     * The version string MUST contain only the HTTP version number (e.g.,
     * "1.1", "1.0").
     *
     * 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 protocol version.
     *
     * @param string $version HTTP protocol version
     * @return static
     */
    public function withProtocolVersion($version) : MessageInterface
    {
        $this->validateProtocolVersion($version);
        $new = clone $this;
        $new->protocol = $version;
        return $new;
    }

    /**
     * Retrieves all message headers.
     *
     * The keys represent the header name as it will be sent over the wire, and
     * each value is an array of strings associated with the header.
     *
     *     // Represent the headers as a string
     *     foreach ($message->getHeaders() as $name => $values) {
     *         echo $name . ": " . implode(", ", $values);
     *     }
     *
     *     // Emit headers iteratively:
     *     foreach ($message->getHeaders() as $name => $values) {
     *         foreach ($values as $value) {
     *             header(sprintf('%s: %s', $name, $value), false);
     *         }
     *     }
     *
     * @return array Returns an associative array of the message's headers. Each
     *     key MUST be a header name, and each value MUST be an array of strings.
     */
    public function getHeaders() : array
    {
        return $this->headers;
    }

    /**
     * Checks if a header exists by the given case-insensitive name.
     *
     * @param string $header Case-insensitive header name.
     * @return bool Returns true if any header names match the given header
     *     name using a case-insensitive string comparison. Returns false if
     *     no matching header name is found in the message.
     */
    public function hasHeader($header) : bool
    {
        return isset($this->headerNames[strtolower($header)]);
    }

    /**
     * Retrieves a message header value by the given case-insensitive name.
     *
     * This method returns an array of all the header values of the given
     * case-insensitive header name.
     *
     * If the header does not appear in the message, this method MUST return an
     * empty array.
     *
     * @param string $header Case-insensitive header field name.
     * @return string[] An array of string values as provided for the given
     *    header. If the header does not appear in the message, this method MUST
     *    return an empty array.
     */
    public function getHeader($header) : array
    {
        if (! $this->hasHeader($header)) {
            return [];
        }

        $header = $this->headerNames[strtolower($header)];

        return $this->headers[$header];
    }

    /**
     * Retrieves a comma-separated string of the values for a single header.
     *
     * This method returns all of the header values of the given
     * case-insensitive header name as a string concatenated together using
     * a comma.
     *
     * NOTE: Not all header values may be appropriately represented using
     * comma concatenation. For such headers, use getHeader() instead
     * and supply your own delimiter when concatenating.
     *
     * If the header does not appear in the message, this method MUST return
     * an empty string.
     *
     * @param string $name Case-insensitive header field name.
     * @return string A string of values as provided for the given header
     *    concatenated together using a comma. If the header does not appear in
     *    the message, this method MUST return an empty string.
     */
    public function getHeaderLine($name) : string
    {
        $value = $this->getHeader($name);
        if (empty($value)) {
            return '';
        }

        return implode(',', $value);
    }

    /**
     * Return an instance with the provided header, replacing any existing
     * values of any headers with the same case-insensitive name.
     *
     * While header names are case-insensitive, the casing of the header will
     * be preserved by this function, and returned from getHeaders().
     *
     * 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 and/or updated header and value.
     *
     * @param string $header Case-insensitive header field name.
     * @param string|string[] $value Header value(s).
     * @return static
     * @throws Exception\InvalidArgumentException for invalid header names or values.
     */
    public function withHeader($header, $value) : MessageInterface
    {
        $this->assertHeader($header);

        $normalized = strtolower($header);

        $new = clone $this;
        if ($new->hasHeader($header)) {
            unset($new->headers[$new->headerNames[$normalized]]);
        }

        $value = $this->filterHeaderValue($value);

        $new->headerNames[$normalized] = $header;
        $new->headers[$header]         = $value;

        return $new;
    }

    /**
     * Return an instance with the specified header appended with the
     * given value.
     *
     * Existing values for the specified header will be maintained. The new
     * value(s) will be appended to the existing list. If the header did not
     * exist previously, it will be added.
     *
     * 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 header and/or value.
     *
     * @param string $header Case-insensitive header field name to add.
     * @param string|string[] $value Header value(s).
     * @return static
     * @throws Exception\InvalidArgumentException for invalid header names or values.
     */
    public function withAddedHeader($header, $value) : MessageInterface
    {
        $this->assertHeader($header);

        if (! $this->hasHeader($header)) {
            return $this->withHeader($header, $value);
        }

        $header = $this->headerNames[strtolower($header)];

        $new = clone $this;
        $value = $this->filterHeaderValue($value);
        $new->headers[$header] = array_merge($this->headers[$header], $value);
        return $new;
    }

    /**
     * Return an instance without the specified header.
     *
     * Header resolution MUST be done without case-sensitivity.
     *
     * This method MUST be implemented in such a way as to retain the
     * immutability of the message, and MUST return an instance that removes
     * the named header.
     *
     * @param string $header Case-insensitive header field name to remove.
     * @return static
     */
    public function withoutHeader($header) : MessageInterface
    {
        if (! $this->hasHeader($header)) {
            return clone $this;
        }

        $normalized = strtolower($header);
        $original   = $this->headerNames[$normalized];

        $new = clone $this;
        unset($new->headers[$original], $new->headerNames[$normalized]);
        return $new;
    }

    /**
     * Gets the body of the message.
     *
     * @return StreamInterface Returns the body as a stream.
     */
    public function getBody() : StreamInterface
    {
        return $this->stream;
    }

    /**
     * Return an instance with the specified message body.
     *
     * The body MUST be a StreamInterface object.
     *
     * 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
     * new body stream.
     *
     * @param StreamInterface $body Body.
     * @return static
     * @throws Exception\InvalidArgumentException When the body is not valid.
     */
    public function withBody(StreamInterface $body) : MessageInterface
    {
        $new = clone $this;
        $new->stream = $body;
        return $new;
    }

    private function getStream($stream, string $modeIfNotInstance) : StreamInterface
    {
        if ($stream instanceof StreamInterface) {
            return $stream;
        }

        if (! is_string($stream) && ! is_resource($stream)) {
            throw new Exception\InvalidArgumentException(
                'Stream must be a string stream resource identifier, '
                . 'an actual stream resource, '
                . 'or a Psr\Http\Message\StreamInterface implementation'
            );
        }

        return new Stream($stream, $modeIfNotInstance);
    }

    /**
     * Filter a set of headers to ensure they are in the correct internal format.
     *
     * Used by message constructors to allow setting all initial headers at once.
     *
     * @param array $originalHeaders Headers to filter.
     */
    private function setHeaders(array $originalHeaders) : void
    {
        $headerNames = $headers = [];

        foreach ($originalHeaders as $header => $value) {
            $value = $this->filterHeaderValue($value);

            $this->assertHeader($header);

            $headerNames[strtolower($header)] = $header;
            $headers[$header] = $value;
        }

        $this->headerNames = $headerNames;
        $this->headers = $headers;
    }

    /**
     * Validate the HTTP protocol version
     *
     * @param string $version
     * @throws Exception\InvalidArgumentException on invalid HTTP protocol version
     */
    private function validateProtocolVersion($version) : void
    {
        if (empty($version)) {
            throw new Exception\InvalidArgumentException(
                'HTTP protocol version can not be empty'
            );
        }
        if (! is_string($version)) {
            throw new Exception\InvalidArgumentException(sprintf(
                'Unsupported HTTP protocol version; must be a string, received %s',
                (is_object($version) ? get_class($version) : gettype($version))
            ));
        }

        // HTTP/1 uses a "<major>.<minor>" numbering scheme to indicate
        // versions of the protocol, while HTTP/2 does not.
        if (! preg_match('#^(1\.[01]|2)$#', $version)) {
            throw new Exception\InvalidArgumentException(sprintf(
                'Unsupported HTTP protocol version "%s" provided',
                $version
            ));
        }
    }

    /**
     * @param mixed $values
     * @return string[]
     */
    private function filterHeaderValue($values) : array
    {
        if (! is_array($values)) {
            $values = [$values];
        }

        if ([] === $values) {
            throw new Exception\InvalidArgumentException(
                'Invalid header value: must be a string or array of strings; '
                . 'cannot be an empty array'
            );
        }

        return array_map(function ($value) {
            HeaderSecurity::assertValid($value);

            return (string) $value;
        }, array_values($values));
    }

    /**
     * Ensure header name and values are valid.
     *
     * @param string $name
     *
     * @throws Exception\InvalidArgumentException
     */
    private function assertHeader($name) : void
    {
        HeaderSecurity::assertValidName($name);
    }
}
