#!/usr/bin/python

import argparse
import httplib2

from apiclient.discovery import build
from oauth2client.client import flow_from_clientsecrets
from oauth2client.file import Storage
from oauth2client.tools import run_flow, argparser

# Parse the command-line arguments (e.g. --noauth_local_webserver)
parser = argparse.ArgumentParser(parents=[argparser])
flags = parser.parse_args()

# Path to the client_secret.json file downloaded from the Developer Console
CLIENT_SECRET_FILE = 'secret.json'

# Check https://developers.google.com/gmail/api/auth/scopes
# for all available scopes
OAUTH_SCOPE = 'https://www.googleapis.com/auth/gmail.readonly'

# Location of the credentials storage file
STORAGE = Storage('gmail.storage')

# Start the OAuth flow to retrieve credentials
flow = flow_from_clientsecrets(CLIENT_SECRET_FILE, scope=OAUTH_SCOPE)
http = httplib2.Http()

# Try to retrieve credentials from storage or run the flow to generate them
credentials = STORAGE.get()
if credentials is None or credentials.invalid:
  credentials = run_flow(flow, STORAGE, flags, http=http)

# Authorize the httplib2.Http object with our credentials
http = credentials.authorize(http)

# Build the Gmail service from discovery
gmail_service = build('gmail', 'v1', http=http)

# Retrieve a page of threads
threads = gmail_service.users().threads().list(userId='me',fields='threads(id)').execute()

if threads['threads']:
  for thread in threads['threads']:
    print 'Thread ID: %s has messages from' % (thread['id'])
    # Fetch the thread, which contains messages
    t = gmail_service.users().threads().get(userId='me',id=thread['id'],fields='messages/payload/headers').execute()
    for msg in t['messages']:
      # Find the 'From' in headers
      # There should be only one, but sometimes it's missing
      for header_from in [v for v in msg['payload']['headers'] if v['name'] == 'From']:
        from_field_val = header_from['value']
        print from_field_val
        # TODO Extract the email address and increment count