How to translate curl arguments to php-curl?

for example, what is the php-curl translation of:

curl -v https://api-m.sandbox.paypal.com/v1/oauth2/token \
  -H "Accept: application/json" \
  -H "Accept-Language: en_US" \
  -u "client_id:secret" \
  -d "grant_type=client_credentials"

-v translates to

curl_setopt($ch,CURLOPT_VERBOSE, 1);

PS! by default, curl sends this data to stderr, and stderr is usually visible when running curl from the terminal, but when running php-curl behind a webserver ala nginx/apache, it's not uncommon that stderr is linked to *the web-server's errorlog*, hence the VERBOSE log may arrive in the server error log, rather than the browser. a quickfix to this would be to set a custom CURLOPT_STDERR, ala:

$php_output_handle = fopen("php://output", "wb");
curl_setopt_array($ch, array(
    CURLOPT_VERBOSE => 1,
    CURLOPT_STDERR => $php_output_handle
));

but because of php garbage collection, when using this quickfix, keep in mind that it will break if php garabge collector closes $php_output_handle before the last curl_exec() call to the same handle.. it's usually not a problem, but it can happen.

.. moving on,

https://api-m.sandbox.paypal.com/v1/oauth2/token translates to:

curl_setopt($ch,CURLOPT_URL, 'https://api-m.sandbox.paypal.com/v1/oauth2/token');

and

-H "Accept: application/json" \
-H "Accept-Language: en_US" \

translates to

curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    "Accept: application/json",
    "Accept-Language: en_US"
));

and -u "client_id:secret" translates to:

curl_setopt($ch,CURLOPT_USERPWD, "client_id:secret");

and -d "grant_type=client_credentials" (aka --data) translates to:

curl_setopt_array($ch, array(
    CURLOPT_POST => 1,
    CURLOPT_POSTFIELDS => http_build_query(array(
        "grant_type" => "client_credentials"
    ))
));

hence the full translation is:

$ch = curl_init();
curl_setopt_array($ch, array(
    CURLOPT_VERBOSE => 1,
    CURLOPT_URL => 'https://api-m.sandbox.paypal.com/v1/oauth2/token',
    CURLOPT_HTTPHEADER => array(
        "Accept: application/json",
        "Accept-Language: en_US"
    ),
    CURLOPT_USERPWD => 'client_id:secret',
    CURLOPT_POST => 1,
    CURLOPT_POSTFIELDS => http_build_query(array(
        "grant_type" => "client_credentials"
    ))
));
curl_exec($ch);

what is the translation of curl -F grant_type=client_credentials ? it's:

curl_setopt_array($ch, array(
    CURLOPT_POST => 1,
    CURLOPT_POSTFIELDS => array(
        "grant_type" => "client_credentials"
    )
));

what about uploading files, what's the translation of curl -F file=@file/path/to/upload.ext ? it's:

curl_setopt_array($ch, array(
    CURLOPT_POST => 1,
    CURLOPT_POSTFIELDS => array(
        "file" => new CURLFile("filepath/to/upload.ext")
    )
));

what's the translation of --location ? it's

curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);

how to upload JSON? like this:

curl_setopt_array($ch, array(
    CURLOPT_HTTPHEADER => array(
        "Content-Type: application/json"
    ),
    CURLOPT_POST => 1,
    CURLOPT_POSTFIELDS => json_encode(array(
        "whatever_key" => "whatever_data"
    ))
));

-X PUT translates to

curl_setopt($ch,CURLOPT_PUT,1);

as for --upload-file , there are several ways to do it, if you're dealing with small files which easily fits in ram, the easiest way to do it would be:

curl_setopt_array($ch, array(
    CURLOPT_PUT => 1,
    CURLOPT_POSTFIELDS => file_get_contents($file)
));

but if you need to support big files which you don't want to put in RAM,

$file = "file.ext";
$file_handle = fopen($file,"rb");
$file_size = filesize($file);
curl_setopt_array($ch, array(
    CURLOPT_UPLOAD => 1,
    CURLOPT_INFILESIZE=>$file_size,
    CURLOPT_INFILE=>$file_handle
));