import re
import unicodedata
from collections import defaultdict
from typing import Any, Dict, List, Optional, Sequence, Tuple, Union

from django.conf import settings
from django.core.exceptions import ValidationError
from django.db.models.query import QuerySet
from django.forms.models import model_to_dict
from django.utils.translation import ugettext as _
from zulip_bots.custom_exceptions import ConfigValidationError

from zerver.lib.avatar import avatar_url, get_avatar_field
from zerver.lib.cache import (
    bulk_cached_fetch,
    realm_user_dict_fields,
    user_profile_by_id_cache_key,
    user_profile_cache_key_id,
)
from zerver.lib.exceptions import OrganizationAdministratorRequired
from zerver.lib.request import JsonableError
from zerver.models import (
    CustomProfileField,
    CustomProfileFieldValue,
    Realm,
    Service,
    UserProfile,
    get_realm_user_dicts,
    get_user_profile_by_id_in_realm,
)


def check_full_name(full_name_raw: str) -> str:
    full_name = full_name_raw.strip()
    if len(full_name) > UserProfile.MAX_NAME_LENGTH:
        raise JsonableError(_("Name too long!"))
    if len(full_name) < UserProfile.MIN_NAME_LENGTH:
        raise JsonableError(_("Name too short!"))
    for character in full_name:
        if (unicodedata.category(character)[0] == 'C' or
                character in UserProfile.NAME_INVALID_CHARS):
            raise JsonableError(_("Invalid characters in name!"))
    # Names ending with e.g. `|15` could be ambiguous for
    # sloppily-written parsers of our Markdown syntax for mentioning
    # users with ambiguous names, and likely have no real use, so we
    # ban them.
    if re.search(r"\|\d+$", full_name_raw):
        raise JsonableError(_("Invalid format!"))
    return full_name

# NOTE: We don't try to absolutely prevent 2 bots from having the same
# name (e.g. you can get there by reactivating a deactivated bot after
# making a new bot with the same name).  This is just a check designed
# to make it unlikely to happen by accident.
def check_bot_name_available(realm_id: int, full_name: str) -> None:
    dup_exists = UserProfile.objects.filter(
        realm_id=realm_id,
        full_name=full_name.strip(),
        is_active=True,
    ).exists()

    if dup_exists:
        raise JsonableError(_("Name is already in use!"))

def check_short_name(short_name_raw: str) -> str:
    short_name = short_name_raw.strip()
    if len(short_name) == 0:
        raise JsonableError(_("Bad name or username"))
    return short_name

def check_valid_bot_config(bot_type: int, service_name: str,
                           config_data: Dict[str, str]) -> None:
    if bot_type == UserProfile.INCOMING_WEBHOOK_BOT:
        from zerver.lib.integrations import WEBHOOK_INTEGRATIONS
        config_options = None
        for integration in WEBHOOK_INTEGRATIONS:
            if integration.name == service_name:
                # key: validator
                config_options = {c[1]: c[2] for c in integration.config_options}
                break
        if not config_options:
            raise JsonableError(_("Invalid integration '{}'.").format(service_name))

        missing_keys = set(config_options.keys()) - set(config_data.keys())
        if missing_keys:
            raise JsonableError(_("Missing configuration parameters: {}").format(
                missing_keys,
            ))

        for key, validator in config_options.items():
            value = config_data[key]
            error = validator(key, value)
            if error:
                raise JsonableError(_("Invalid {} value {} ({})").format(
                                    key, value, error))

    elif bot_type == UserProfile.EMBEDDED_BOT:
        try:
            from zerver.lib.bot_lib import get_bot_handler
            bot_handler = get_bot_handler(service_name)
            if hasattr(bot_handler, 'validate_config'):
                bot_handler.validate_config(config_data)
        except ConfigValidationError:
            # The exception provides a specific error message, but that
            # message is not tagged translatable, because it is
            # triggered in the external zulip_bots package.
            # TODO: Think of some clever way to provide a more specific
            # error message.
            raise JsonableError(_("Invalid configuration data!"))

# Adds an outgoing webhook or embedded bot service.
def add_service(name: str, user_profile: UserProfile, base_url: Optional[str]=None,
                interface: Optional[int]=None, token: Optional[str]=None) -> None:
    Service.objects.create(name=name,
                           user_profile=user_profile,
                           base_url=base_url,
                           interface=interface,
                           token=token)

def check_bot_creation_policy(user_profile: UserProfile, bot_type: int) -> None:
    # Realm administrators can always add bot
    if user_profile.is_realm_admin:
        return

    if user_profile.realm.bot_creation_policy == Realm.BOT_CREATION_EVERYONE:
        return
    if user_profile.realm.bot_creation_policy == Realm.BOT_CREATION_ADMINS_ONLY:
        raise OrganizationAdministratorRequired()
    if user_profile.realm.bot_creation_policy == Realm.BOT_CREATION_LIMIT_GENERIC_BOTS and \
            bot_type == UserProfile.DEFAULT_BOT:
        raise OrganizationAdministratorRequired()

def check_valid_bot_type(user_profile: UserProfile, bot_type: int) -> None:
    if bot_type not in user_profile.allowed_bot_types:
        raise JsonableError(_('Invalid bot type'))

def check_valid_interface_type(interface_type: Optional[int]) -> None:
    if interface_type not in Service.ALLOWED_INTERFACE_TYPES:
        raise JsonableError(_('Invalid interface type'))

def is_administrator_role(role: int) -> bool:
    return role in {UserProfile.ROLE_REALM_ADMINISTRATOR, UserProfile.ROLE_REALM_OWNER}

def bulk_get_users(emails: List[str], realm: Optional[Realm],
                   base_query: 'QuerySet[UserProfile]'=None) -> Dict[str, UserProfile]:
    if base_query is None:
        assert realm is not None
        query = UserProfile.objects.filter(realm=realm, is_active=True)
        realm_id = realm.id
    else:
        # WARNING: Currently, this code path only really supports one
        # version of `base_query` being used (because otherwise,
        # they'll share the cache, which can screw up the filtering).
        # If you're using this flow, you'll need to re-do any filters
        # in base_query in the code itself; base_query is just a perf
        # optimization.
        query = base_query
        realm_id = 0

    def fetch_users_by_email(emails: List[str]) -> List[UserProfile]:
        # This should be just
        #
        # UserProfile.objects.select_related("realm").filter(email__iexact__in=emails,
        #                                                    realm=realm)
        #
        # But chaining __in and __iexact doesn't work with Django's
        # ORM, so we have the following hack to construct the relevant where clause
        where_clause = "upper(zerver_userprofile.email::text) IN (SELECT upper(email) FROM unnest(%s) AS email)"
        return query.select_related("realm").extra(
            where=[where_clause],
            params=(emails,))

    def user_to_email(user_profile: UserProfile) -> str:
        return user_profile.email.lower()

    return bulk_cached_fetch(
        # Use a separate cache key to protect us from conflicts with
        # the get_user cache.
        lambda email: 'bulk_get_users:' + user_profile_cache_key_id(email, realm_id),
        fetch_users_by_email,
        [email.lower() for email in emails],
        id_fetcher=user_to_email,
    )

def get_user_id(user: UserProfile) -> int:
    return user.id

def user_ids_to_users(user_ids: Sequence[int], realm: Realm) -> List[UserProfile]:
    # TODO: Consider adding a flag to control whether deactivated
    # users should be included.

    def fetch_users_by_id(user_ids: List[int]) -> List[UserProfile]:
        return list(UserProfile.objects.filter(id__in=user_ids).select_related())

    user_profiles_by_id: Dict[int, UserProfile] = bulk_cached_fetch(
        cache_key_function=user_profile_by_id_cache_key,
        query_function=fetch_users_by_id,
        object_ids=user_ids,
        id_fetcher=get_user_id,
    )

    found_user_ids = user_profiles_by_id.keys()
    missed_user_ids = [user_id for user_id in user_ids if user_id not in found_user_ids]
    if missed_user_ids:
        raise JsonableError(_("Invalid user ID: {}").format(missed_user_ids[0]))

    user_profiles = list(user_profiles_by_id.values())
    for user_profile in user_profiles:
        if user_profile.realm != realm:
            raise JsonableError(_("Invalid user ID: {}").format(user_profile.id))
    return user_profiles

def access_bot_by_id(user_profile: UserProfile, user_id: int) -> UserProfile:
    try:
        target = get_user_profile_by_id_in_realm(user_id, user_profile.realm)
    except UserProfile.DoesNotExist:
        raise JsonableError(_("No such bot"))
    if not target.is_bot:
        raise JsonableError(_("No such bot"))
    if not user_profile.can_admin_user(target):
        raise JsonableError(_("Insufficient permission"))
    return target

def access_user_by_id(user_profile: UserProfile, user_id: int,
                      allow_deactivated: bool=False, allow_bots: bool=False,
                      read_only: bool=False) -> UserProfile:
    try:
        target = get_user_profile_by_id_in_realm(user_id, user_profile.realm)
    except UserProfile.DoesNotExist:
        raise JsonableError(_("No such user"))
    if target.is_bot and not allow_bots:
        raise JsonableError(_("No such user"))
    if not target.is_active and not allow_deactivated:
        raise JsonableError(_("User is deactivated"))
    if read_only:
        # Administrative access is not required just to read a user.
        return target
    if not user_profile.can_admin_user(target):
        raise JsonableError(_("Insufficient permission"))
    return target

def get_accounts_for_email(email: str) -> List[Dict[str, Optional[str]]]:
    profiles = UserProfile.objects.select_related('realm').filter(delivery_email__iexact=email.strip(),
                                                                  is_active=True,
                                                                  realm__deactivated=False,
                                                                  is_bot=False).order_by('date_joined')
    return [{"realm_name": profile.realm.name,
             "string_id": profile.realm.string_id,
             "full_name": profile.full_name,
             "avatar": avatar_url(profile)}
            for profile in profiles]

def get_api_key(user_profile: UserProfile) -> str:
    return user_profile.api_key

def get_all_api_keys(user_profile: UserProfile) -> List[str]:
    # Users can only have one API key for now
    return [user_profile.api_key]

def validate_user_custom_profile_field(realm_id: int, field: CustomProfileField,
                                       value: Union[int, str, List[int]]) -> Union[int, str, List[int]]:
    validators = CustomProfileField.FIELD_VALIDATORS
    field_type = field.field_type
    var_name = f'{field.name}'
    if field_type in validators:
        validator = validators[field_type]
        return validator(var_name, value)
    elif field_type == CustomProfileField.CHOICE:
        choice_field_validator = CustomProfileField.CHOICE_FIELD_VALIDATORS[field_type]
        field_data = field.field_data
        # Put an assertion so that mypy doesn't complain.
        assert field_data is not None
        return choice_field_validator(var_name, field_data, value)
    elif field_type == CustomProfileField.USER:
        user_field_validator = CustomProfileField.USER_FIELD_VALIDATORS[field_type]
        return user_field_validator(realm_id, value, False)
    else:
        raise AssertionError("Invalid field type")

def validate_user_custom_profile_data(realm_id: int,
                                      profile_data: List[Dict[str, Union[int, str, List[int]]]]) -> None:
    # This function validate all custom field values according to their field type.
    for item in profile_data:
        field_id = item['id']
        try:
            field = CustomProfileField.objects.get(id=field_id)
        except CustomProfileField.DoesNotExist:
            raise JsonableError(_('Field id {id} not found.').format(id=field_id))

        try:
            validate_user_custom_profile_field(realm_id, field, item['value'])
        except ValidationError as error:
            raise JsonableError(error.message)

def compute_show_invites_and_add_streams(user_profile: Optional[UserProfile]) -> Tuple[bool, bool]:
    if user_profile is None:
        return False, False

    if user_profile.is_guest:
        return False, False

    if user_profile.is_realm_admin:
        return True, True

    if user_profile.realm.invite_by_admins_only:
        return False, True

    return True, True

def format_user_row(realm: Realm, acting_user: Optional[UserProfile], row: Dict[str, Any],
                    client_gravatar: bool, user_avatar_url_field_optional: bool,
                    custom_profile_field_data: Optional[Dict[str, Any]] = None) -> Dict[str, Any]:
    """Formats a user row returned by a database fetch using
    .values(*realm_user_dict_fields) into a dictionary representation
    of that user for API delivery to clients.  The acting_user
    argument is used for permissions checks.
    """

    is_admin = is_administrator_role(row['role'])
    is_owner = row['role'] == UserProfile.ROLE_REALM_OWNER
    is_guest = row['role'] == UserProfile.ROLE_GUEST
    is_bot = row['is_bot']
    result = dict(
        email=row['email'],
        user_id=row['id'],
        avatar_version=row['avatar_version'],
        is_admin=is_admin,
        is_owner=is_owner,
        is_guest=is_guest,
        is_bot=is_bot,
        full_name=row['full_name'],
        timezone=row['timezone'],
        is_active = row['is_active'],
        date_joined = row['date_joined'].isoformat(),
    )

    # Zulip clients that support using `GET /avatar/{user_id}` as a
    # fallback if we didn't send an avatar URL in the user object pass
    # user_avatar_url_field_optional in client_capabilities.
    #
    # This is a major network performance optimization for
    # organizations with 10,000s of users where we would otherwise
    # send avatar URLs in the payload (either because most users have
    # uploaded avatars or because EMAIL_ADDRESS_VISIBILITY_ADMINS
    # prevents the older client_gravatar optimization from helping).
    # The performance impact is large largely because the hashes in
    # avatar URLs structurally cannot compress well.
    #
    # The user_avatar_url_field_optional gives the server sole
    # discretion in deciding for which users we want to send the
    # avatar URL (Which saves clients an RTT at the cost of some
    # bandwidth).  At present, the server looks at `long_term_idle` to
    # decide which users to include avatars for, piggy-backing on a
    # different optimization for organizations with 10,000s of users.
    include_avatar_url = not user_avatar_url_field_optional or not row['long_term_idle']
    if include_avatar_url:
        result['avatar_url'] = get_avatar_field(user_id=row['id'],
                                                realm_id=realm.id,
                                                email=row['delivery_email'],
                                                avatar_source=row['avatar_source'],
                                                avatar_version=row['avatar_version'],
                                                medium=False,
                                                client_gravatar=client_gravatar)

    if acting_user is not None and (realm.email_address_visibility == Realm.EMAIL_ADDRESS_VISIBILITY_ADMINS and
                                    acting_user.is_realm_admin):
        result['delivery_email'] = row['delivery_email']

    if is_bot:
        result["bot_type"] = row["bot_type"]
        if row['email'] in settings.CROSS_REALM_BOT_EMAILS:
            result['is_cross_realm_bot'] = True

        # Note that bot_owner_id can be None with legacy data.
        result['bot_owner_id'] = row['bot_owner_id']
    elif custom_profile_field_data is not None:
        result['profile_data'] = custom_profile_field_data
    return result

def user_profile_to_user_row(user_profile: UserProfile) -> Dict[str, Any]:
    # What we're trying to do is simulate the user_profile having been
    # fetched from a QuerySet using `.values(*realm_user_dict_fields)`
    # even though we fetched UserProfile objects.  This is messier
    # than it seems.
    #
    # What we'd like to do is just call model_to_dict(user,
    # fields=realm_user_dict_fields).  The problem with this is
    # that model_to_dict has a different convention than
    # `.values()` in its handling of foreign keys, naming them as
    # e.g. `bot_owner`, not `bot_owner_id`; we work around that
    # here.
    #
    # This could be potentially simplified in the future by
    # changing realm_user_dict_fields to name the bot owner with
    # the less readable `bot_owner` (instead of `bot_owner_id`).
    user_row = model_to_dict(user_profile,
                             fields=[*realm_user_dict_fields, 'bot_owner'])
    user_row['bot_owner_id'] = user_row['bot_owner']
    del user_row['bot_owner']
    return user_row

def get_cross_realm_dicts() -> List[Dict[str, Any]]:
    users = bulk_get_users(list(settings.CROSS_REALM_BOT_EMAILS), None,
                           base_query=UserProfile.objects.filter(
                           realm__string_id=settings.SYSTEM_BOT_REALM)).values()
    result = []
    for user in users:
        # Important: We filter here, is addition to in
        # `base_query`, because of how bulk_get_users shares its
        # cache with other UserProfile caches.
        if user.realm.string_id != settings.SYSTEM_BOT_REALM:  # nocoverage
            continue
        user_row = user_profile_to_user_row(user)
        # Because we want to avoid clients becing exposed to the
        # implementation detail that these bots are self-owned, we
        # just set bot_owner_id=None.
        user_row['bot_owner_id'] = None

        result.append(format_user_row(user.realm,
                                      acting_user=user,
                                      row=user_row,
                                      client_gravatar=False,
                                      user_avatar_url_field_optional=False,
                                      custom_profile_field_data=None))

    return result

def get_custom_profile_field_values(custom_profile_field_values:
                                    List[CustomProfileFieldValue]) -> Dict[int, Dict[str, Any]]:
    profiles_by_user_id: Dict[int, Dict[str, Any]] = defaultdict(dict)
    for profile_field in custom_profile_field_values:
        user_id = profile_field.user_profile_id
        if profile_field.field.is_renderable():
            profiles_by_user_id[user_id][str(profile_field.field_id)] = {
                "value": profile_field.value,
                "rendered_value": profile_field.rendered_value,
            }
        else:
            profiles_by_user_id[user_id][str(profile_field.field_id)] = {
                "value": profile_field.value,
            }
    return profiles_by_user_id

def get_raw_user_data(realm: Realm, acting_user: Optional[UserProfile], *, target_user: Optional[UserProfile]=None,
                      client_gravatar: bool, user_avatar_url_field_optional: bool,
                      include_custom_profile_fields: bool=True) -> Dict[int, Dict[str, str]]:
    """Fetches data about the target user(s) appropriate for sending to
    acting_user via the standard format for the Zulip API.  If
    target_user is None, we fetch all users in the realm.
    """
    profiles_by_user_id = None
    custom_profile_field_data = None
    # target_user is an optional parameter which is passed when user data of a specific user
    # is required. It is 'None' otherwise.
    if target_user is not None:
        user_dicts = [user_profile_to_user_row(target_user)]
    else:
        user_dicts = get_realm_user_dicts(realm.id)

    if include_custom_profile_fields:
        base_query = CustomProfileFieldValue.objects.select_related("field")
        # TODO: Consider optimizing this query away with caching.
        if target_user is not None:
            custom_profile_field_values = base_query.filter(user_profile=target_user)
        else:
            custom_profile_field_values = base_query.filter(field__realm_id=realm.id)
        profiles_by_user_id = get_custom_profile_field_values(custom_profile_field_values)

    result = {}
    for row in user_dicts:
        if profiles_by_user_id is not None:
            custom_profile_field_data = profiles_by_user_id.get(row['id'], {})

        result[row['id']] = format_user_row(realm,
                                            acting_user=acting_user,
                                            row=row,
                                            client_gravatar=client_gravatar,
                                            user_avatar_url_field_optional=user_avatar_url_field_optional,
                                            custom_profile_field_data=custom_profile_field_data,
                                            )
    return result