<?php

namespace GuzzleHttp\Psr7;

use Psr\Http\Message\StreamInterface;

/**
* Stream that when read returns bytes for a streaming multipart or
* multipart/form-data stream.
*
* @final
*/
class MultipartStream implements StreamInterface
{
use StreamDecoratorTrait;

private $boundary;

/**
* @param array $elements Array of associative arrays, each containing a
* required "name" key mapping to the form field,
* name, a required "contents" key mapping to a
* StreamInterface/resource/string, an optional
* "headers" associative array of custom headers,
* and an optional "filename" key mapping to a
* string to send as the filename in the part.
* @param string $boundary You can optionally provide a specific boundary
*
* @throws \InvalidArgumentException
*/
public function __construct(array $elements = [], $boundary = null)
{
$this->boundary = $boundary ?: sha1(uniqid('', true));
$this->stream = $this->createStream($elements);
}

/**
* Get the boundary
*
* @return string
*/
public function getBoundary()
{
return $this->boundary;
}

public function isWritable()
{
return false;
}

/**
* Get the headers needed before transferring the content of a POST file
*/
private function getHeaders(array $headers)
{
$str = '';
foreach ($headers as $key => $value) {
$str .= "{$key}: {$value}\r\n";
}

return "--{$this->boundary}\r\n" . trim($str) . "\r\n\r\n";
}

/**
* Create the aggregate stream that will be used to upload the POST data
*/
protected function createStream(array $elements)
{
$stream = new AppendStream();

foreach ($elements as $element) {
$this->addElement($stream, $element);
}

// Add the trailing boundary with CRLF
$stream->addStream(Utils::streamFor("--{$this->boundary}--\r\n"));

return $stream;
}

private function addElement(AppendStream $stream, array $element)
{
foreach (['contents', 'name'] as $key) {
if (!array_key_exists($key, $element)) {
throw new \InvalidArgumentException("A '{$key}' key is required");
}
}

$element['contents'] = Utils::streamFor($element['contents']);

if (empty($element['filename'])) {
$uri = $element['contents']->getMetadata('uri');
if (substr($uri, 0, 6) !== 'php://') {
$element['filename'] = $uri;
}
}

list($body, $headers) = $this->createElement(
$element['name'],
$element['contents'],
isset($element['filename']) ? $element['filename'] : null,
isset($element['headers']) ? $element['headers'] : []
);

$stream->addStream(Utils::streamFor($this->getHeaders($headers)));
$stream->addStream($body);
$stream->addStream(Utils::streamFor("\r\n"));
}

/**
* @return array
*/
private function createElement($name, StreamInterface $stream, $filename, array $headers)
{
// Set a default content-disposition header if one was no provided
$disposition = $this->getHeader($headers, 'content-disposition');
if (!$disposition) {
$headers['Content-Disposition'] = ($filename === '0' || $filename)
? sprintf(
'form-data; name="%s"; filename="%s"',
$name,
basename($filename)
)
: "form-data; name=\"{$name}\"";
}

// Set a default content-length header if one was no provided
$length = $this->getHeader($headers, 'content-length');
if (!$length) {
if ($length = $stream->getSize()) {
$headers['Content-Length'] = (string) $length;
}
}

// Set a default Content-Type if one was not supplied
$type = $this->getHeader($headers, 'content-type');
if (!$type && ($filename === '0' || $filename)) {
if ($type = MimeType::fromFilename($filename)) {
$headers['Content-Type'] = $type;
}
}

return [$stream, $headers];
}

private function getHeader(array $headers, $key)
{
$lowercaseHeader = strtolower($key);
foreach ($headers as $k => $v) {
if (strtolower($k) === $lowercaseHeader) {
return $v;
}
}

return null;
}
}