from typing import Optional

from sqlalchemy.exc import IntegrityError

from app.email_utils import (
    get_email_domain_part,
    send_cannot_create_directory_alias,
    send_cannot_create_domain_alias,
    email_belongs_to_alias_domains,
)
from app.extensions import db
from app.log import LOG
from app.models import (
    Alias,
    CustomDomain,
    Directory,
    User,
    DeletedAlias,
)


def try_auto_create(address: str) -> Optional[Alias]:
    """Try to auto-create the alias using directory or catch-all domain
    """
    alias = try_auto_create_catch_all_domain(address)
    if not alias:
        alias = try_auto_create_directory(address)

    return alias


def try_auto_create_directory(address: str) -> Optional[Alias]:
    """
    Try to create an alias with directory
    """
    # check if alias belongs to a directory, ie having directory/anything@EMAIL_DOMAIN format
    if email_belongs_to_alias_domains(address):
        # if there's no directory separator in the alias, no way to auto-create it
        if "/" not in address and "+" not in address and "#" not in address:
            return None

        # alias contains one of the 3 special directory separator: "/", "+" or "#"
        if "/" in address:
            sep = "/"
        elif "+" in address:
            sep = "+"
        else:
            sep = "#"

        directory_name = address[: address.find(sep)]
        LOG.d("directory_name %s", directory_name)

        directory = Directory.get_by(name=directory_name)
        if not directory:
            return None

        dir_user: User = directory.user

        if not dir_user.can_create_new_alias():
            send_cannot_create_directory_alias(dir_user, address, directory_name)
            return None

        # if alias has been deleted before, do not auto-create it
        if DeletedAlias.get_by(email=address):
            LOG.warning(
                "Alias %s was deleted before, cannot auto-create using directory %s, user %s",
                address,
                directory_name,
                dir_user,
            )
            return None

        LOG.d("create alias %s for directory %s", address, directory)

        alias = Alias.create(
            email=address,
            user_id=directory.user_id,
            directory_id=directory.id,
            mailbox_id=dir_user.default_mailbox_id,
        )

        db.session.commit()
        return alias


def try_auto_create_catch_all_domain(address: str) -> Optional[Alias]:
    """Try to create an alias with catch-all domain"""

    # try to create alias on-the-fly with custom-domain catch-all feature
    # check if alias is custom-domain alias and if the custom-domain has catch-all enabled
    alias_domain = get_email_domain_part(address)
    custom_domain = CustomDomain.get_by(domain=alias_domain)

    if not custom_domain:
        return None

    # custom_domain exists
    if not custom_domain.catch_all:
        return None

    # custom_domain has catch-all enabled
    domain_user: User = custom_domain.user

    if not domain_user.can_create_new_alias():
        send_cannot_create_domain_alias(domain_user, address, alias_domain)
        return None

    # if alias has been deleted before, do not auto-create it
    if DeletedAlias.get_by(email=address):
        LOG.warning(
            "Alias %s was deleted before, cannot auto-create using domain catch-all %s, user %s",
            address,
            custom_domain,
            domain_user,
        )
        return None

    LOG.d("create alias %s for domain %s", address, custom_domain)

    alias = Alias.create(
        email=address,
        user_id=custom_domain.user_id,
        custom_domain_id=custom_domain.id,
        automatic_creation=True,
        mailbox_id=domain_user.default_mailbox_id,
    )

    db.session.commit()
    return alias


def delete_alias(alias: Alias, user: User):
    email = alias.email
    Alias.delete(alias.id)
    db.session.commit()

    # try to save deleted alias
    try:
        DeletedAlias.create(email=email)
        db.session.commit()
    # this can happen when a previously deleted alias is re-created via catch-all or directory feature
    except IntegrityError:
        LOG.error("alias %s has been added before to DeletedAlias", email)
        db.session.rollback()