Unable to get the authorization code from the google

Hi All,,

I am trying to get the authorization token from the salesforce for the google drive access. But I am getting the bad response error(400 ) for the access. I am not able to decipher the reason in the code.

String messageBody='';
Initialize();
httpReq.setMethod('POST');
httpReq.setEndpoint('https://accounts.google.com/o/oauth2/token');
httpReq.setHeader('content-type',
   'application/x-www-form-urlencoded');

messageBody ='client_id='+'288961038342.apps.googleusercontent.com'+
'&client_secret='+'OHLLahnI9DKD1xR5gVnyGA36'+'&redirect_uri='+'https://login.salesforce.com/services/authcallback/00D90000000dAqaEAE/GoogleLogin'+
   '&grant_type='+'authorization_code';
   System.debug('messagebody'+messageBody );

/* if(tokenType=='ALL')
   messageBody = messageBody +
   '&code='+<Fetch Authorization Code from Key Safe>+
   '&redirect_uri='+<Fetch Redirect URI from EndPoint>+
   '&grant_type='+'authorization_code';

else if(tokenType=='ACCESS_TOKEN')
   messageBody = messageBody +
   '&refresh_token='+<Fetch Refresh Token from Key Safe>+
   '&grant_type='+'refresh_token';
*/
httpReq.setHeader('Content-length',
    String.valueOf(messageBody.length()));

Please somebody help in this regard