"""Email Generation Logic.

Handles email generation and delivery via Amazon's SES email service.
"""

import boto
from boto import exception
from flask import g

from auth import config
from auth import response
from auth.models.email import Email


MESSAGE_SES_AUTH_FAILED = 'SES Auth Failed: No Amazon Credentials Found'
MESSAGE_SES_DELIVERY_FAILED = 'Email Failed for %s: %s'
MESSAGE_SES_UNKNON_EXCEPTION = 'Unknown Email Exception %s for: %s'
EMAIL_TITLE_FORGOTTEN_PASSWORD = 'Forgotten password reset'


def deliver_email(email):
    """Deliver an email based on the email object provided.

    Args:
        email (Email): the email to send.

    Returns:
        response (tuple): message and status code
    """
    ses = boto.connect_ses()
    result = response.Response()

    try:
        ses.send_email(
            email.sender, email.subject, email.to, text_body=email.text_body,
            html_body=email.html_body)

    except exception.NoAuthHandlerFound:
        result = response.create_fatal_response(MESSAGE_SES_AUTH_FAILED)
        g.log.critical(MESSAGE_SES_AUTH_FAILED)

    except exception.BotoServerError as e:
        message = MESSAGE_SES_DELIVERY_FAILED % (email.to, e.error_message)
        result = response.create_fatal_response(message=message)
        g.log.error(message)

    except Exception as e:
        message = MESSAGE_SES_UNKNON_EXCEPTION % (email.to, e)
        result = response.create_fatal_response(message)
        g.log.error(message)

    return result


def forgot_password_notification(user, token):
    """Generate a forgot password email based on user and token provided.

    Args:
        user (User): User object to provide user's email address, name, etc.
        token (str): Token to be included in password reset URL.

    Returns:
        Email: Generated Email object.
    """
    reset_url = '%s/reset/%s' % (config.APP_URL, token)
    return Email(
        to=user.email, subject=EMAIL_TITLE_FORGOTTEN_PASSWORD,
        text_body=reset_url, html_body=reset_url)