Different authorization header for each operation in a Guzzle client service description - guzzle

Question

The API I'm accessing requires a custom authorization header that is a combination of the publicKey that is passed in when the client is instantiated and the complete URI of the API endpoint. I want to pull the baseUrl and operation uri out of the service description and use them to create the authorization header, but I can't figure out how to do this when calling the instantiated client.
This is the service description:
{
"name": "FranchiseSystem",
"apiVersion": "1",
"baseUrl": "https://apidev.example.com",
"description": "REST API client",
"operations": {
"GetFranchiseList": {
"httpMethod": "GET",
"uri": "v1/franchise",
"summary": "Returns an array of franchises."
},
"GetReviews": {
"httpMethod": "GET",
"uri": "v1/review",
"summary": "Returns an array of reviews."
}
}
}
This is the client setup:
$testClient = new JunknetClient([
'publicKey' => '1234567890',
]);
This is the call to the instantiated client with the name of the operation:
$result = $testClient->GetFranchiseList();
or:
$result = $testClient->GetReviews();
When testClient->GetFranchiseList is called, I need to create the authorization header using the publicKey and the values of baseUrl and uri for GetFranchiseList.
When testClient->GetReviews is called, I need to create the authorization header using the publicKey and the values of baseUrl and uri for GetReviews.

Answer 1

You might want to have a look at the following links from the Guzzle docs.
Request Options - Headers
Authentication Parameters

Answer 2

I was able to solve my problem by using and event emitter and subscriber. It's a bit messy, but it get's the job done.
private function handleCredentialsOptions(Collection $config) {
//Build authorization header from $config values
$this->getHttpClient()->getEmitter()->on('before',
function (BeforeEvent $e) use(&$config) {
$this->getHttpClient()->setDefaultOption('headers', [
'Authentication' => '',
]);
$path = $e->getRequest()->getUrl();
$authValue = $config['publicKey'].';;';
$authValue .= time().';';
$authValue .= strtoupper(md5($config['privateKey'] . $path));
$this->getHttpClient()->setDefaultOption('headers', [
'Authentication' => $authValue,
]);
});
}