#!/usr/bin/python

# 5/19/2016 - update to allow for authentication based on api-key, rather than username/pw

# See https://documentation.uts.nlm.nih.gov/rest/authentication.html for full explanation

import requests

from pyquery import PyQuery as pq

uri = "https://utslogin.nlm.nih.gov"

auth_endpoint = "/cas/v1/api-key"

class Authentication:

    def __init__(self, apikey):

        # self.username=username

        # self.password=password

        self.apikey = apikey

        self.service = "http://umlsks.nlm.nih.gov"

    def gettgt(self):

        # params = {'username': self.username,'password': self.password}

        params = {'apikey': self.apikey}

        h = {"Content-type": "application/x-www-form-urlencoded", "Accept": "text/plain", "User-Agent": "python" }

        r = requests.post(uri+auth_endpoint, data=params, headers=h, timeout=120)

        d = pq(r.text)

        # extract the entire URL needed from the HTML form (action attribute) returned 

        # looks similar to https://utslogin.nlm.nih.gov/cas/v1/tickets/TGT-36471-aYqNLN2rFIJPXKzxwdTNC5ZT7z3B3cTAKfSc5ndHQcUxeaDOLN-cas

        # we make a POST call to this URL in the getst method

        tgt = d.find('form').attr('action')

        return tgt

    def getst(self, tgt):

        params = {'service': self.service}

        h = {"Content-type": "application/x-www-form-urlencoded", 

             "Accept": "text/plain", "User-Agent": "python"}

        r = requests.post(tgt, data=params, headers=h)

        st = r.text

        return st