Google Calendar API with refresh token - php

Question

My question relates to my previous question where I thought I had solved the issue. I've been able to obtain a refresh_token using scripts I found - including the ones in my previous question.
However now armed with this refresh token I am now trying to do some simple things in the first instance list the events in my test calendar
My problem is that trying to list the events using this URL returns an error - trying to get property of non object. This relates to this line of code:
$cAccessToken = $oToken->access_token;
So I assume there's something wrong in getting the access token.
In the part of my script where I obtained the code I needed to add this code:
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
This produced the token- so I added this line to the code getting the access token again but it simply produced a blank page.
I must admit to be very confused with the google API. I tried using the google-client-api code but don't quite get this either - I keep running into brick walls.
Here's my code:
<?php
$cPublisherID = '';
$cScope = 'https://www.google.com/calendar/feeds/';
$cClientID = 'XXXXXX.apps.googleusercontent.com';
$cClientSecret = 'XXXXXX';
$cRedirectURI = 'XXXXXX';
$cAuthCode = 'XXXXXX';
$cRefreshToken = 'XXXXXX';
$bRefresh = true;
if (empty($cAuthCode)) {
$rsParams = array(
'response_type' => 'code',
'client_id' => $cClientID,
'redirect_uri' => $cRedirectURI,
'scope' => $cScope
);
$cOauthURL = 'https://accounts.google.com/o/oauth2/auth?' . http_build_query($rsParams);
echo("Go to\n$cOauthURL\nand enter the given value into \$cAuthCode\n");
exit();
} // ends if (empty($cAuthCode))
elseif (empty($cRefreshToken)) {
$cTokenURL = 'https://accounts.google.com/o/oauth2/token';
$rsPostData = array(
'code' => $cAuthCode,
'client_id' => $cClientID,
'client_secret' => $cClientSecret,
'redirect_uri' => $cRedirectURI,
'grant_type' => 'authorization_code',
);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $cTokenURL);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $rsPostData);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
$cTokenReturn = curl_exec($ch);
$oToken = json_decode($cTokenReturn);
echo("Enter the following values:\n\n");
echo("\$cRefreshToken = '" . $oToken->refresh_token . "';\n");
} // ends
else {
// Get a new Access Token
$cTokenURL = 'https://accounts.google.com/o/oauth2/token';
$rsPostData = array(
'client_secret' => $cClientSecret,
'grant_type' => 'refresh_token',
'refresh_token' => $cRefreshToken,
'client_id' => $cClientID
);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $cTokenURL);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $rsPostData);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
//curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
$cTokenReturn = curl_exec($ch);
$oToken = json_decode($cTokenReturn);
$cAccessToken = $oToken->access_token;
// Get the results
//$cGANURL = 'https://www.googleapis.com/gan/v1beta1/publishers/' . $cPublisherID . '/events';
$rest_url = 'https://www.googleapis.com/calendar/v3/calendars/primary/events';
$cAuthHeader = "Authorization: OAuth " . $cAccessToken;
$ch = curl_init();
curl_setopt($ch, CURLOPT_HTTPHEADER, array($cAuthHeader));
curl_setopt($ch, CURLOPT_URL, $rest_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$cJsonReturn = curl_exec($ch);
print_r(json_decode($cJsonReturn));
} // ends else from <all authenticated>
?>
I really don't know enough to resolve this - so basically I think I'm getting the tokens I need including the refresh token but not sure how to test and understand what's going on.
I've used the oauth playground and can get results there but not with my own code. I used different codes by the way as I assumed they should be different?