Allow multi value headers

[hollodotme]

Expected Behavior

1. A call to Response#getHeaders() will return a two-dimensional array like this:

$expectedHeaders = [
    'Set-Cookie' => [
        'yummy_cookie=choco',
        'tasty_cookie=strawberry',
    ],
    'Status' => [
        'HTTP/2.0 200 OK'
    ],
    'Content-type' => [
        'text/html; charset=utf-8',
    ],
];

$this->assertSame($expectedHeaders, $response->getHeaders());

2. A call to Response#getHeader($headerKey) will return a flat array with all values for the given key.

$expectedHeaderValues = [
    'yummy_cookie=choco',
    'tasty_cookie=strawberry',
];

$this->assertSame($expectedHeaderValues, $response->getHeader('Set-Cookie'));

3. A call to a new method Response#getHeaderLine($headerKey) will return all values, separated by comma, for the given key.

4. The results of Response#getHeader($headerKey) and Response#getHeaderLine($headerKey) will be the same for given keys in different case. (case-insensitive keys are accepted)

Actual Behavior

1. Currently a call to Response#getHeaders() will return a flat key-value array and provide only the last value of a multi-value header.

[
    'Set-Cookie' => 'tasty_cookie=strawberry',
    'Status' => 'HTTP/2.0 200 OK',
    'Content-type' => 'text/html; charset=utf-8',
];

2. Currently a call to Response#getHeader($headerKey) will return a string containing the last value for the given key.

3. A method Response#getHeaderLine($headerKey) does not exist.

4. Header keys are currently case-sensitive in Response#getHeader($headerKey).

Steps to Reproduce the Problem

1. Create a worker script that sends the following headers:

   header('Status: HTTP/2.0 200 OK');
   header('Set-Cookie: yummy_cookie=choco');
   header('Set-Cookie: tasty_cookie=strawberry');
   header('Content-type: text/html; charset=utf-8');

2. Issue a GET request to the worker script via the FastCGI client.
3. Read the headers using Response#getHeaders() or Response#getHeader('Set-Cookie') respectively.

Specifications

• Package version: <=2.7.0
• PHP version: ALL
• Platform/OS: ALL

Further comments

Changing the return type of Response#getHeaders() and Response#getHeader($headerKey) to array is a BC break and requires a new major version.

Proposed version: 3.0.0

[mnapoli]

👍

Do you think it could make sense to add a new method like getMultiHeader($key) to keep BC? Maybe it's not as clean as you want it to be though, in any case both options are fine for Bref since it's still wip ^^

[hollodotme]

@mnapoli I think I'll go with the PSR standard and also implement Response#getHeaderLine($headerKey) that returns a string with all header values.

So in the end:

public function getHeaders() : array # two-dimensional as state above

public function getHeader(string $headerKey) : array # 1-dimensional containing all values of the header

public function getHeaderLine(string $headerKey) : string # all values separated with comma

[mnapoli]

👍 makes sense!