"""Python Client Library for Health Graph API (http://developer.runkeeper.com/healthgraph). 

The API is used for accessing RunKeeper (http://runkeeper.com) for retrieving, 
updating, deleting and uploading Fitness Activity and Health Measurements Information.

This module implements sessions for making REST requests to the Health Graph API.

"""

import requests
from . import exceptions
from . import settings


__author__ = "Ali Onur Uyar"
__copyright__ = "Copyright 2012, Ali Onur Uyar"
__credits__ = []
__license__ = "GPL"
__version__ = "0.3.0"
__email__ = "aouyar at gmail.com"
__status__ = "Development"
    
    
class Session(object):
    
    def __init__(self, access_token):
        self._access_token = access_token
        
    def request(self, request_type, resource, content_type=None, 
                params=None, data=None):
        headers = {'Authorization': "Bearer %s" % self._access_token,}
        content_header = None
        if content_type is not None:
            if request_type == 'GET':
                content_header = 'Accept'
            elif request_type in ('POST', 'PUT'):
                content_header = 'Content-Type'
            else:
                content_header = None
            if content_header is not None:
                headers[content_header] = ('application/vnd.com.runkeeper.%s+json'
                                           % content_type)
        url = settings.API_URL + resource
        req = requests.request(request_type, url, headers=headers, 
                               params=params, data=data)
        return req
    
    def get(self, resource, content_type=None, params=None):
        return self.request('GET', resource, content_type, params=params)
    
    def post(self, resource, content_type=None, data=None):
        return self.request('POST', resource, content_type, data=data)
        
    def put(self, resource, content_type=None, data=None):
        return self.request('PUT', resource, content_type, data=data)
    
    def delete(self, resource):
        return self.request('DELETE', resource)
        
    def head(self, resource, content_type=None, params=None):
        return self.request('HEAD', resource, content_type, params=params)


class NullSession(Session):

    def __init__(self):
        self._access_token = None
        
    def request(self, request_type, resource, content_type=None, 
            params=None, data=None):
        raise exceptions.NoSessionError()


_default_session = NullSession()

def init_session(access_token):
    global _default_session
    _default_session = Session(access_token)
    
def get_session():
    return _default_session