import argparse
import base64
import email
import json
import logging
import oauth2client
import os
import sys

from apiclient.discovery import build
from apiclient import errors
from datetime import datetime
from httplib2 import Http
from oauth2client import client
from pathlib import Path
from pytz import timezone
from send_email import get_gmail_service
from email.message import EmailMessage
from email.utils import parsedate_to_datetime

def ListMessagesWithLabels(service, user_id, label_ids=[]):
    """List all Messages of the user's mailbox with label_ids applied.

    Args:
     service: Authorized Gmail API service instance.
     user_id: User's email address. The special value "me"
     can be used to indicate the authenticated user.
     label_ids: Only return Messages with these labelIds applied.

    Returns:
     List of Messages that have all required Labels applied. Note that the
     returned list contains Message IDs, you must use get with the
     appropriate id to get the details of a Message.
    """
    try:
        response = service.users().messages().list(userId=user_id,
                                                   labelIds=label_ids).execute()
        messages = []
        if 'messages' in response:
            messages.extend(response['messages'])
        while 'nextPageToken' in response:
            page_token = response['nextPageToken']
            response = service.users().messages().list(userId=user_id,
                                                       labelIds=label_ids,
                                                       pageToken=page_token).execute()
            messages.extend(response['messages'])

        return messages
    except errors.HttpError as error:
        print(json.loads(error.content.decode('utf-8'))['error']['message'])

def ListHistory(service, user_id, label_id=None, start_history_id=10000):
  """List History of all changes to the user's mailbox.

  Args:
    service: Authorized Gmail API service instance.
    user_id: User's email address. The special value "me"
    can be used to indicate the authenticated user.
    start_history_id: Only return Histories at or after start_history_id.

  Returns:
    A list of mailbox changes that occurred after the start_history_id.
  """
  try:
    history = (service.users().history().list(userId=user_id,
                                              startHistoryId=start_history_id,
                                              historyTypes="messageAdded",
                                              labelId=label_id)
               .execute())
    changes = history['history'] if 'history' in history else []
    for change in changes:
        if 'messagesAdded' in change:
            for c in change['messagesAdded']:
                yield c['message']

    while 'nextPageToken' in history:
        page_token = history['nextPageToken']
        history = (service.users().history().list(userId=user_id,
                                                  startHistoryId=start_history_id,
                                                  pageToken=page_token).execute())
        for change in history['history']:
            if 'messagesAdded' in change:
                for c in change['messagesAdded']:
                    yield c['message']

  except errors.HttpError as error:
      print('An error occurred:', error)

def labels_dict(service, user_id):
    """Returns a dictionary mapping labels to labelids.

    Args:
     service: Authorized Gmail API service instance.
     user_id: User's email address. The special value "me"

    Returns:
     dictionary mapping labels to labelids.
    """
    try:
        response = service.users().labels().list(userId=user_id).execute()
        labels = response['labels']
        return {label['name']: label['id'] for label in labels}
    except errors.HttpError as error:
        print(json.loads(error.content.decode('utf-8'))['error']['message'])

class GmailMessage(EmailMessage):
    _service = get_gmail_service()

    def msgdict(self):
        return {'raw': base64.urlsafe_b64encode(self.as_bytes()).decode()}

    def send(self):
        try:
            message = (self._service.users().messages().
                       send(userId='me',body=self.msgdict())
                       .execute())
            print('Message Id: %s' % message['id'])
        except errors.HttpError as error:
            print('An error occurred: %s' % error)

    @classmethod
    def from_id(cls, msg_id, user_id='me'):
        try:
            message = (cls._service.users().messages().
                       get(userId=user_id, id=msg_id, format='raw').execute())
            instance = email.message_from_bytes(
                base64.urlsafe_b64decode(message['raw']),
                policy=email.policy.EmailPolicy())
            instance.history_id = message['historyId']
            return instance
        except errors.HttpError as error:
            print(json.loads(error.content.decode('utf-8'))['error']['message'])


def save_emails(update=True):
    """Download new emails that were labeled swaptions."""

    labelsdict = labels_dict(GmailMessage._service, 'me')
    p = Path(os.getenv("DATA_DIR")) / Path('swaptions')
    try:
        with open(os.path.join(os.environ['DATA_DIR'], '.lastHistoryId')) as fh:
            last_history_id = int(fh.read())
    except FileNotFoundError:
        sys.exit()
    if update:
        email_list = ListHistory(GmailMessage._service,
                                 'me',
                                 label_id=labelsdict['swaptions'],
                                 start_history_id=last_history_id)
    else:
        email_list = ListMessagesWithLabels(GmailMessage._service, 'me', labelsdict['swaptions'])

    for msg in email_list:
        try:
            message = GmailMessage.from_id(msg['id'])
            print(message.history_id)
            subject = message['subject']
            date = parsedate_to_datetime(message['date'])
            if date.tzinfo is None:
                date = date.replace(tzinfo=timezone('utc'))
            date = date.astimezone(timezone('America/New_York'))
            body = message.get_body('plain')
            content = body.get_content()
        except (KeyError, UnicodeDecodeError) as e:
            logging.error("error decoding " + msg['id'])
            continue
        else:
            email = p / "{:%Y-%m-%d %H-%M-%S}_{}".format(date, msg['id'])
            with email.open("w") as fh:
                fh.write(subject + "\r\n")
                fh.write(content)
    try:
        new_history_id = message.history_id
        with open(os.path.join(os.environ['DATA_DIR'], '.lastHistoryId'), 'w') as fh:
            fh.write(new_history_id)
    except UnboundLocalError:
        pass

    # for msg in ListMessagesWithLabels(GmailMessage._service, 'me', labelsdict['swaptions']):
        # if msg['id'] not in current_msgs:
        #     try:


if __name__ == '__main__':
    save_emails()