import boto3
from base64 import b64decode
from urlparse import parse_qs
import logging
import json
import urllib2
from urllib2 import Request, urlopen, URLError, HTTPError, build_opener

ENCRYPTED_EXPECTED_TOKEN = "<ENCRYPTED_EXPECTED_TOKEN>" # Enter the base-64 encoded, encrypted Slack command token (CiphertextBlob)
GITHUB_TOKEN = "token <GITHUB_TOKEN>"
GITHUB_OWNER = "smyleeface"

kms = boto3.client('kms')
expected_token = kms.decrypt(CiphertextBlob = b64decode(ENCRYPTED_EXPECTED_TOKEN))['Plaintext']

logger = logging.getLogger()
logger.setLevel(logging.INFO)

def lambda_handler(event, context):

    #get the body content
    req_body = event['body']
    #split body content
    params = parse_qs(req_body)
    #validate the token request
    token = params['token'][0]
    if token != expected_token:
        logger.error("Request token (%s) does not match exptected", token)
        raise Exception("Invalid request token")

    #get the values from the slack payload
    user = params['user_name'][0]
    command = params['command'][0]
    channel = params['channel_name'][0]
    command_text = params['text'][0]

    #get the values from the command
    split_text = command_text.split()
    command = split_text[0]
    repo = split_text[1]
    pullnumber = split_text[2]

    #make the header info
    header = {
      "Authorization" : GITHUB_TOKEN,
      "Content-Type" : "application/json"
    }

    valid_command = False

    #make the variables for the merge command
    if (command == "merge"):

        github_api_url = "https://api.github.com/repos/%s/%s/pulls/%s/merge"%(GITHUB_OWNER,repo,pullnumber)
        data = {}
        req = urllib2.Request(github_api_url, json.dumps(data), header)
        req.get_method = lambda: 'PUT'
        valid_command = True

    #make the variables for the open or close command
    elif (command == "close" or command == "open"):

        github_api_url = "https://api.github.com/repos/%s/%s/pulls/%s"%(GITHUB_OWNER,repo,pullnumber)
        data = {
                "state" : command
            }

        req = urllib2.Request(github_api_url, json.dumps(data), header)
        req.get_method = lambda: 'PATCH'
        valid_command = True

    #run the url if it's a valid command
    if (valid_command):
        try:
            response = urlopen(req)
            return "%s invoked %s from slack channel %s with the following text: %s" % (user, command, channel, command_text)

        except HTTPError as e:
            print e
            return e
    else:
        return "%s is not a valid command"%(command)