"""SimpleDBBackend class with methods for supported APIs."""
import re
from collections import defaultdict
from moto.core import BaseBackend, BaseModel
from moto.core.utils import BackendDict
from threading import Lock

from .exceptions import InvalidDomainName, UnknownDomainName


class FakeItem(BaseModel):
    def __init__(self):
        self.attributes = []
        self.lock = Lock()

    def get_attributes(self, names):
        if not names:
            return self.attributes
        return [attr for attr in self.attributes if attr["name"] in names]

    def put_attributes(self, attributes):
        # Replacing attributes involves quite a few loops
        # Lock this, so we know noone else touches this list while we're operating on it
        with self.lock:
            for attr in attributes:
                if attr.get("replace", "false").lower() == "true":
                    self._remove_attributes(attr["name"])
                self.attributes.append(attr)

    def _remove_attributes(self, name):
        self.attributes = [attr for attr in self.attributes if attr["name"] != name]


class FakeDomain(BaseModel):
    def __init__(self, name):
        self.name = name
        self.items = defaultdict(FakeItem)

    def get(self, item_name, attribute_names):
        item = self.items[item_name]
        return item.get_attributes(attribute_names)

    def put(self, item_name, attributes):
        item = self.items[item_name]
        item.put_attributes(attributes)


class SimpleDBBackend(BaseBackend):
    def __init__(self, region_name, account_id):
        super().__init__(region_name, account_id)
        self.domains = dict()

    def create_domain(self, domain_name):
        self._validate_domain_name(domain_name)
        self.domains[domain_name] = FakeDomain(name=domain_name)

    def list_domains(self):
        """
        The `max_number_of_domains` and `next_token` parameter have not been implemented yet - we simply return all domains.
        """
        return self.domains.keys()

    def delete_domain(self, domain_name):
        self._validate_domain_name(domain_name)
        # Ignore unknown domains - AWS does the same
        self.domains.pop(domain_name, None)

    def _validate_domain_name(self, domain_name):
        # Domain Name needs to have at least 3 chars
        # Can only contain characters: a-z, A-Z, 0-9, '_', '-', and '.'
        if not re.match("^[a-zA-Z0-9-_.]{3,}$", domain_name):
            raise InvalidDomainName(domain_name)

    def _get_domain(self, domain_name):
        if domain_name not in self.domains:
            raise UnknownDomainName()
        return self.domains[domain_name]

    def get_attributes(self, domain_name, item_name, attribute_names):
        """
        Behaviour for the consistent_read-attribute is not yet implemented
        """
        self._validate_domain_name(domain_name)
        domain = self._get_domain(domain_name)
        return domain.get(item_name, attribute_names)

    def put_attributes(self, domain_name, item_name, attributes):
        """
        Behaviour for the expected-attribute is not yet implemented.
        """
        self._validate_domain_name(domain_name)
        domain = self._get_domain(domain_name)
        domain.put(item_name, attributes)


sdb_backends = BackendDict(SimpleDBBackend, "sdb")
