import base64
import email
import json
import logging
import os
import sys

from apiclient import errors
from pathlib import Path
from pytz import timezone
from gmail_helpers import GmailMessage
from email.utils import parsedate_to_datetime

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

    if update:
        try:
            last_history_id = int((DATA_DIR / ".lastHistoryId").read_text())
        except FileNotFoundError:
            logging.error("can't find .lastHistoryId file")
            sys.exit()
        existing_msgs = []
    else:
        p = DATA_DIR / "swaptions"
        existing_msgs = set(str(x).split("_")[1] for x in p.iterdir() if x.is_file())
        last_history_id = None

    for msg in GmailMessage.list_msg_ids('swaptions', last_history_id):
        if msg['id'] in existing_msgs:
            continue
        try:
            message = GmailMessage.from_id(msg['id'])
            logging.info(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, AttributeError) as e:
            logging.error("error decoding " + msg['id'])
            continue
        else:
            email = (DATA_DIR / "swaptions" /
                     f"{date:%Y-%m-%d %H-%M-%S}_{msg['id']}")
            with email.open("w") as fh:
                fh.write(subject + "\r\n")
                fh.write(content)
    try:
        new_history_id = message.history_id
        (DATA_DIR / ".lastHistoryId").write_text(message.history_id)
    except UnboundLocalError:
        pass

if __name__ == '__main__':
    try:
        save_emails()
    except errors.HttpError as e:
        logging.error(e)
        save_emails(update=False)