mailchimp.py

# -*- coding: utf-8 -*-

#
# Copyright Adam Pritchard 2015
# MIT License : https://adampritchard.mit-license.org/
#

import base64
import requests
import logging
import json
import flask

import config


_TIMEOUT = 45
_RETRIES = 1  # disabling retries for now

_api_url_base = f'https://{config.MAILCHIMP_DATACENTER}.api.mailchimp.com/3.0/lists/{config.MAILCHIMP_MEMBERS_LIST_ID}/'

_headers = {
        'Authorization': 'Basic %s' % base64.b64encode(f'anystring:{config.MAILCHIMP_API_KEY}'.encode('ascii')).decode()
    }

_EMAIL_ADDRESS = 'email_address'
_MERGE_FIELDS = 'merge_fields'
_STATUS_FIELD = 'status'
_STATUS_VALUE = 'subscribed'


def upsert_member_info(member_dict):
    """Create or update the MailChimp record corresponding to the given Member.
    Will raise with `flask.abort` on error.
    """

    if config.DEMO:
        # Mailchimp (and all email) is disabled in demo mode
        return

    list_member = _find_list_member(member_dict.get(config.SHEETS.member.fields.email.name), config.SHEETS.member.fields)

    if list_member and \
       (config.MAILCHIMP_MEMBER_TYPE_MEMBER !=
        list_member.get(_MERGE_FIELDS, {}).get(config.MAILCHIMP_MEMBER_TYPE_MERGE_TAG)):
        # The matched list item is not a Member (vs. Volunteer)
        logging.info('upsert_member_info: member already in MailChimp as volunteer; replacing: %s', member_dict)
        # Member status takes precedence over Volunteer (because they paid),
        # so we'll replace the existing entry.

    _upsert_member_or_volunteer_info(list_member, member_dict, config.SHEETS.member.fields, config.MAILCHIMP_MEMBER_TYPE_MEMBER)


def upsert_volunteer_info(volunteer_dict):
    """Create or update the MailChimp record corresponding to the given Volunteer.
    Will raise with `flask.abort` on error.
    """

    if config.DEMO:
        # Mailchimp (and all email) is disabled in demo mode
        return

    list_member = _find_list_member(volunteer_dict.get(config.SHEETS.volunteer.fields.email.name), config.SHEETS.volunteer.fields)

    if list_member and \
       (config.MAILCHIMP_MEMBER_TYPE_VOLUNTEER !=
        list_member.get(_MERGE_FIELDS, {}).get(config.MAILCHIMP_MEMBER_TYPE_MERGE_TAG)):
        # The matched list item is not a Volunteer (vs. Member)
        logging.info('upsert_member_info: volunteer already in MailChimp as member; skipping: %s', volunteer_dict)
        # Member status takes precedence over Volunteer (because they paid),
        # so we'll won't replace the existing entry, and will proceed as if we
        # succeeded (so the sheet gets updated).
        return

    _upsert_member_or_volunteer_info(list_member, volunteer_dict, config.SHEETS.volunteer.fields, config.MAILCHIMP_MEMBER_TYPE_VOLUNTEER)


def _upsert_member_or_volunteer_info(list_member, sheet_dict, fields, typename):
    """Helper for `upsert_member_info()` and `upsert_volunteer_info()`.
    """
    if list_member:
        # Update existing
        _update_mailchimp_record_from_dict(list_member, sheet_dict, fields, typename)
        url = 'members/%s' % list_member['id']
        logging.info('MailChimp: updating %s from %s', list_member, sheet_dict)
        _make_request(url, 'PATCH', body=json.dumps(list_member))
    else:
        # Create new
        list_member = _create_mailchimp_record_from_dict(sheet_dict, fields, typename)
        url = 'members'
        logging.info('MailChimp: creating %s from %s', list_member, sheet_dict)
        _make_request(url, 'POST', body=json.dumps(list_member))


def _find_list_member(member_email, fields):
    """Returns the list member dict that matches the given email address.
    Returns None if not found.
    """
    # TODO: Some day MailChimp will add support for filtering, and this can be
    # made less brute-force.

    if not member_email:
        logging.error('mailchimp._find_list_member called with empty member_email')
        flask.abort(500, description='bad data in sheet')

    # We may need to page through results to find the member we want.
    offset = 0
    while True:
        url = 'members?count=100&offset=%d' % (offset,)
        res = _make_request(url, 'GET')

        for member in res['members']:
            if member[_EMAIL_ADDRESS] == member_email:
                return member

        offset += len(res['members'])
        total = res['total_items']

        if offset >= total or not res['members']:
            # We paged all the way through
            break

    return None


def _make_request(url, method, body=None):
    attempt = 0
    while attempt < _RETRIES:
        attempt += 1

        url = _api_url_base + url
        response = requests.request(method, url, headers=_headers, data=body, timeout=_TIMEOUT)

        # This is pretty dirty. But PUT entry-creation reqs give a status
        # of 201, and basically all 20x statuses are successes, so...
        if response.status_code < 200 or response.status_code > 299:
            # Fail. Retry.
            logging.debug('mailchimp._make_request: response=%s; content=%s', response, str(response.content))
            continue

        return json.loads(response.content)

    # If we got to here, then the request failed repeatedly.

    # Hack: For certain email addresses (such as those with "spam" in the name
    # part), MailChimp will return an error like:
    #    `"status":400, "detail":" is already a list member. Use PATCH to update existing members."`
    # That condition will be permanent and unrecoverable if we treat it as an
    # error (or if we try to PATCH). So we're going to take the dirty route
    # and just proceed as if the request succeeded. This will result in the
    # spreadsheet getting updated for this member, allowing us to skip it in
    # the future.

    error_info = json.loads(response.content)

    if error_info.get('status') == 400 and error_info.get('detail', '').find('is already a list member') > 0:
        logging.warning('_make_request: got 400 "is already a member" error: %s : %s : %s', method, url, body)
        # Pretend success
        return
    elif error_info.get('status') == 400 and error_info.get('detail', '').find('looks fake or invalid') > 0:
        # This isn't successful, but it'll never succeed. If a user wants to give a
        # fake email address, that's up to them. Log a warning and continue.
        logging.warning('_make_request: got 400 "email address looks fake or invalid" error: %s : %s : %s', method, url, body)
        return

    flask.abort(response.status_code, description=str(response.content))


def _update_mailchimp_record_from_dict(mailchimp_record, sheet_dict, fields, typename):
    """Update a MailChimp list record object from a Member or Volunteer dict.
    Modifies `mailchimp_record` directly. No return value.
    """
    for field in fields:
        if not field.mailchimp_merge_tag:
            # Not a field for us to update
            continue
        mailchimp_record[_MERGE_FIELDS][field.mailchimp_merge_tag] = sheet_dict.get(field.name) or ''
    mailchimp_record[_EMAIL_ADDRESS] = sheet_dict[fields.email.name]
    mailchimp_record[_MERGE_FIELDS][config.MAILCHIMP_MEMBER_TYPE_MERGE_TAG] = typename


def _create_mailchimp_record_from_dict(sheet_dict, fields, typename):
    """Create a MailChimp list record object from a Member or Volunteer dict.
    Returns the MailChimp object.
    """
    mailchimp_record = { _MERGE_FIELDS: {} }
    _update_mailchimp_record_from_dict(mailchimp_record, sheet_dict, fields, typename)
    mailchimp_record[_STATUS_FIELD] = _STATUS_VALUE
    return mailchimp_record