import logging
import os
import random
import shutil
from collections import defaultdict
from concurrent.futures import ProcessPoolExecutor, as_completed
from functools import partial
from typing import (
    AbstractSet,
    Any,
    Callable,
    Dict,
    Iterable,
    Iterator,
    List,
    Mapping,
    Optional,
    Protocol,
    Set,
    Tuple,
    TypeVar,
)

import orjson
import requests
from django.forms.models import model_to_dict
from django.utils.timezone import now as timezone_now
from typing_extensions import TypeAlias

from zerver.data_import.sequencer import NEXT_ID
from zerver.lib.avatar_hash import user_avatar_path_from_ids
from zerver.lib.stream_color import STREAM_ASSIGNMENT_COLORS as STREAM_COLORS
from zerver.models import (
    Attachment,
    Huddle,
    Message,
    Realm,
    RealmEmoji,
    Recipient,
    Stream,
    Subscription,
    UserProfile,
)
from zproject.backends import all_implemented_backend_names

# stubs
ZerverFieldsT: TypeAlias = Dict[str, Any]


class SubscriberHandler:
    def __init__(self) -> None:
        self.stream_info: Dict[int, Set[int]] = {}
        self.huddle_info: Dict[int, Set[int]] = {}

    def set_info(
        self,
        users: Set[int],
        stream_id: Optional[int] = None,
        huddle_id: Optional[int] = None,
    ) -> None:
        if stream_id is not None:
            self.stream_info[stream_id] = users
        elif huddle_id is not None:
            self.huddle_info[huddle_id] = users
        else:
            raise AssertionError("stream_id or huddle_id is required")

    def get_users(
        self, stream_id: Optional[int] = None, huddle_id: Optional[int] = None
    ) -> Set[int]:
        if stream_id is not None:
            return self.stream_info[stream_id]
        elif huddle_id is not None:
            return self.huddle_info[huddle_id]
        else:
            raise AssertionError("stream_id or huddle_id is required")


def build_zerver_realm(
    realm_id: int, realm_subdomain: str, time: float, other_product: str
) -> List[ZerverFieldsT]:
    realm = Realm(
        id=realm_id,
        name=realm_subdomain,
        string_id=realm_subdomain,
        description=f"Organization imported from {other_product}!",
    )
    realm_dict = model_to_dict(realm)
    realm_dict["date_created"] = time
    return [realm_dict]


def build_user_profile(
    avatar_source: str,
    date_joined: Any,
    delivery_email: str,
    email: str,
    full_name: str,
    id: int,
    is_active: bool,
    role: int,
    is_mirror_dummy: bool,
    realm_id: int,
    short_name: str,
    timezone: str,
    is_bot: bool = False,
    bot_type: Optional[int] = None,
) -> ZerverFieldsT:
    obj = UserProfile(
        avatar_source=avatar_source,
        date_joined=date_joined,
        delivery_email=delivery_email,
        email=email,
        full_name=full_name,
        id=id,
        is_mirror_dummy=is_mirror_dummy,
        is_active=is_active,
        role=role,
        realm_id=realm_id,
        timezone=timezone,
        is_bot=is_bot,
        bot_type=bot_type,
    )
    dct = model_to_dict(obj)

    """
    Even though short_name is no longer in the Zulip
    UserProfile, it's helpful to have it in our import
    dictionaries for legacy reasons.
    """
    dct["short_name"] = short_name
    return dct


def build_avatar(
    zulip_user_id: int,
    realm_id: int,
    email: str,
    avatar_url: str,
    timestamp: Any,
    avatar_list: List[ZerverFieldsT],
) -> None:
    avatar = dict(
        path=avatar_url,  # Save original avatar URL here, which is downloaded later
        realm_id=realm_id,
        content_type=None,
        user_profile_id=zulip_user_id,
        last_modified=timestamp,
        user_profile_email=email,
        s3_path="",
        size="",
    )
    avatar_list.append(avatar)


def make_subscriber_map(zerver_subscription: List[ZerverFieldsT]) -> Dict[int, Set[int]]:
    """
    This can be convenient for building up UserMessage
    rows.
    """
    subscriber_map: Dict[int, Set[int]] = {}
    for sub in zerver_subscription:
        user_id = sub["user_profile"]
        recipient_id = sub["recipient"]
        if recipient_id not in subscriber_map:
            subscriber_map[recipient_id] = set()
        subscriber_map[recipient_id].add(user_id)

    return subscriber_map


def make_user_messages(
    zerver_message: List[ZerverFieldsT],
    subscriber_map: Dict[int, Set[int]],
    is_pm_data: bool,
    mention_map: Dict[int, Set[int]],
    wildcard_mention_map: Mapping[int, bool] = {},
) -> List[ZerverFieldsT]:
    zerver_usermessage = []

    for message in zerver_message:
        message_id = message["id"]
        recipient_id = message["recipient"]
        sender_id = message["sender"]
        mention_user_ids = mention_map[message_id]
        wildcard_mention = wildcard_mention_map.get(message_id, False)
        subscriber_ids = subscriber_map.get(recipient_id, set())
        user_ids = subscriber_ids | {sender_id}

        for user_id in user_ids:
            is_mentioned = user_id in mention_user_ids
            user_message = build_user_message(
                user_id=user_id,
                message_id=message_id,
                is_private=is_pm_data,
                is_mentioned=is_mentioned,
                wildcard_mention=wildcard_mention,
            )
            zerver_usermessage.append(user_message)

    return zerver_usermessage


def build_subscription(recipient_id: int, user_id: int, subscription_id: int) -> ZerverFieldsT:
    subscription = Subscription(color=random.choice(STREAM_COLORS), id=subscription_id)
    subscription_dict = model_to_dict(subscription, exclude=["user_profile", "recipient_id"])
    subscription_dict["user_profile"] = user_id
    subscription_dict["recipient"] = recipient_id
    return subscription_dict


class GetUsers(Protocol):
    def __call__(self, stream_id: int = ..., huddle_id: int = ...) -> Set[int]:
        ...


def build_stream_subscriptions(
    get_users: GetUsers,
    zerver_recipient: List[ZerverFieldsT],
    zerver_stream: List[ZerverFieldsT],
) -> List[ZerverFieldsT]:
    subscriptions: List[ZerverFieldsT] = []

    stream_ids = {stream["id"] for stream in zerver_stream}

    recipient_map = {
        recipient["id"]: recipient["type_id"]  # recipient_id -> stream_id
        for recipient in zerver_recipient
        if recipient["type"] == Recipient.STREAM and recipient["type_id"] in stream_ids
    }

    for recipient_id, stream_id in recipient_map.items():
        user_ids = get_users(stream_id=stream_id)
        for user_id in user_ids:
            subscription = build_subscription(
                recipient_id=recipient_id,
                user_id=user_id,
                subscription_id=NEXT_ID("subscription"),
            )
            subscriptions.append(subscription)

    return subscriptions


def build_huddle_subscriptions(
    get_users: GetUsers,
    zerver_recipient: List[ZerverFieldsT],
    zerver_huddle: List[ZerverFieldsT],
) -> List[ZerverFieldsT]:
    subscriptions: List[ZerverFieldsT] = []

    huddle_ids = {huddle["id"] for huddle in zerver_huddle}

    recipient_map = {
        recipient["id"]: recipient["type_id"]  # recipient_id -> stream_id
        for recipient in zerver_recipient
        if recipient["type"] == Recipient.HUDDLE and recipient["type_id"] in huddle_ids
    }

    for recipient_id, huddle_id in recipient_map.items():
        user_ids = get_users(huddle_id=huddle_id)
        for user_id in user_ids:
            subscription = build_subscription(
                recipient_id=recipient_id,
                user_id=user_id,
                subscription_id=NEXT_ID("subscription"),
            )
            subscriptions.append(subscription)

    return subscriptions


def build_personal_subscriptions(zerver_recipient: List[ZerverFieldsT]) -> List[ZerverFieldsT]:
    subscriptions: List[ZerverFieldsT] = []

    personal_recipients = [
        recipient for recipient in zerver_recipient if recipient["type"] == Recipient.PERSONAL
    ]

    for recipient in personal_recipients:
        recipient_id = recipient["id"]
        user_id = recipient["type_id"]
        subscription = build_subscription(
            recipient_id=recipient_id,
            user_id=user_id,
            subscription_id=NEXT_ID("subscription"),
        )
        subscriptions.append(subscription)

    return subscriptions


def build_recipient(type_id: int, recipient_id: int, type: int) -> ZerverFieldsT:
    recipient = Recipient(
        type_id=type_id,  # stream id
        id=recipient_id,
        type=type,
    )
    recipient_dict = model_to_dict(recipient)
    return recipient_dict


def build_recipients(
    zerver_userprofile: Iterable[ZerverFieldsT],
    zerver_stream: Iterable[ZerverFieldsT],
    zerver_huddle: Iterable[ZerverFieldsT] = [],
) -> List[ZerverFieldsT]:
    """
    This function was only used HipChat import, this function may be
    required for future conversions. The Slack and Gitter conversions do it more
    tightly integrated with creating other objects.
    """

    recipients = []

    for user in zerver_userprofile:
        type_id = user["id"]
        type = Recipient.PERSONAL
        recipient = Recipient(
            type_id=type_id,
            id=NEXT_ID("recipient"),
            type=type,
        )
        recipient_dict = model_to_dict(recipient)
        recipients.append(recipient_dict)

    for stream in zerver_stream:
        type_id = stream["id"]
        type = Recipient.STREAM
        recipient = Recipient(
            type_id=type_id,
            id=NEXT_ID("recipient"),
            type=type,
        )
        recipient_dict = model_to_dict(recipient)
        recipients.append(recipient_dict)

    for huddle in zerver_huddle:
        type_id = huddle["id"]
        type = Recipient.HUDDLE
        recipient = Recipient(
            type_id=type_id,
            id=NEXT_ID("recipient"),
            type=type,
        )
        recipient_dict = model_to_dict(recipient)
        recipients.append(recipient_dict)
    return recipients


def build_realm(
    zerver_realm: List[ZerverFieldsT], realm_id: int, domain_name: str
) -> ZerverFieldsT:
    realm = dict(
        zerver_client=[
            {"name": "populate_db", "id": 1},
            {"name": "website", "id": 2},
            {"name": "API", "id": 3},
        ],
        zerver_customprofilefield=[],
        zerver_customprofilefieldvalue=[],
        zerver_userpresence=[],  # shows last logged in data, which is not available
        zerver_userprofile_mirrordummy=[],
        zerver_realmdomain=[
            {"realm": realm_id, "allow_subdomains": False, "domain": domain_name, "id": realm_id}
        ],
        zerver_useractivity=[],
        zerver_realm=zerver_realm,
        zerver_huddle=[],
        zerver_userprofile_crossrealm=[],
        zerver_useractivityinterval=[],
        zerver_reaction=[],
        zerver_realmemoji=[],
        zerver_realmfilter=[],
        zerver_realmplayground=[],
        zerver_realmauthenticationmethod=[
            {"realm": realm_id, "name": name, "id": i}
            for i, name in enumerate(all_implemented_backend_names(), start=1)
        ],
    )
    return realm


def build_usermessages(
    zerver_usermessage: List[ZerverFieldsT],
    subscriber_map: Dict[int, Set[int]],
    recipient_id: int,
    mentioned_user_ids: List[int],
    message_id: int,
    is_private: bool,
    long_term_idle: AbstractSet[int] = set(),
) -> Tuple[int, int]:
    user_ids = subscriber_map.get(recipient_id, set())

    user_messages_created = 0
    user_messages_skipped = 0
    if user_ids:
        for user_id in sorted(user_ids):
            is_mentioned = user_id in mentioned_user_ids

            if not is_mentioned and not is_private and user_id in long_term_idle:
                # these users are long-term idle
                user_messages_skipped += 1
                continue
            user_messages_created += 1

            usermessage = build_user_message(
                user_id=user_id,
                message_id=message_id,
                is_private=is_private,
                is_mentioned=is_mentioned,
            )

            zerver_usermessage.append(usermessage)
    return (user_messages_created, user_messages_skipped)


def build_user_message(
    user_id: int,
    message_id: int,
    is_private: bool,
    is_mentioned: bool,
    wildcard_mention: bool = False,
) -> ZerverFieldsT:
    flags_mask = 1  # For read
    if is_mentioned:
        flags_mask += 8  # For mentioned
    if wildcard_mention:
        flags_mask += 16
    if is_private:
        flags_mask += 2048  # For is_private

    id = NEXT_ID("user_message")

    usermessage = dict(
        id=id,
        user_profile=user_id,
        message=message_id,
        flags_mask=flags_mask,
    )
    return usermessage


def build_defaultstream(realm_id: int, stream_id: int, defaultstream_id: int) -> ZerverFieldsT:
    defaultstream = dict(stream=stream_id, realm=realm_id, id=defaultstream_id)
    return defaultstream


def build_stream(
    date_created: Any,
    realm_id: int,
    name: str,
    description: str,
    stream_id: int,
    deactivated: bool = False,
    invite_only: bool = False,
    stream_post_policy: int = 1,
) -> ZerverFieldsT:
    # Other applications don't have the distinction of "private stream with public history"
    # vs "private stream with hidden history" - and we've traditionally imported private "streams"
    # of other products as private streams with hidden history.
    # So we can set the history_public_to_subscribers value based on the invite_only flag.
    history_public_to_subscribers = not invite_only

    stream = Stream(
        name=name,
        deactivated=deactivated,
        description=description.replace("\n", " "),
        # We don't set rendered_description here; it'll be added on import
        date_created=date_created,
        invite_only=invite_only,
        id=stream_id,
        stream_post_policy=stream_post_policy,
        history_public_to_subscribers=history_public_to_subscribers,
    )
    stream_dict = model_to_dict(stream, exclude=["realm"])
    stream_dict["realm"] = realm_id
    return stream_dict


def build_huddle(huddle_id: int) -> ZerverFieldsT:
    huddle = Huddle(
        id=huddle_id,
    )
    return model_to_dict(huddle)


def build_message(
    *,
    topic_name: str,
    date_sent: float,
    message_id: int,
    content: str,
    rendered_content: Optional[str],
    user_id: int,
    recipient_id: int,
    realm_id: int,
    has_image: bool = False,
    has_link: bool = False,
    has_attachment: bool = True,
) -> ZerverFieldsT:
    zulip_message = Message(
        rendered_content_version=1,  # this is Zulip specific
        id=message_id,
        content=content,
        rendered_content=rendered_content,
        has_image=has_image,
        has_attachment=has_attachment,
        has_link=has_link,
    )
    zulip_message.set_topic_name(topic_name)
    zulip_message_dict = model_to_dict(
        zulip_message, exclude=["recipient", "sender", "sending_client"]
    )
    zulip_message_dict["sender"] = user_id
    zulip_message_dict["sending_client"] = 1
    zulip_message_dict["recipient"] = recipient_id
    zulip_message_dict["date_sent"] = date_sent

    return zulip_message_dict


def build_attachment(
    realm_id: int,
    message_ids: Set[int],
    user_id: int,
    fileinfo: ZerverFieldsT,
    s3_path: str,
    zerver_attachment: List[ZerverFieldsT],
) -> None:
    """
    This function should be passed a 'fileinfo' dictionary, which contains
    information about 'size', 'created' (created time) and ['name'] (filename).
    """
    attachment_id = NEXT_ID("attachment")

    attachment = Attachment(
        id=attachment_id,
        size=fileinfo["size"],
        create_time=fileinfo["created"],
        is_realm_public=True,
        path_id=s3_path,
        file_name=fileinfo["name"],
    )

    attachment_dict = model_to_dict(attachment, exclude=["owner", "messages", "realm"])
    attachment_dict["owner"] = user_id
    attachment_dict["messages"] = list(message_ids)
    attachment_dict["realm"] = realm_id

    zerver_attachment.append(attachment_dict)


def get_avatar(avatar_dir: str, size_url_suffix: str, avatar_upload_item: List[str]) -> None:
    avatar_url = avatar_upload_item[0]

    image_path = os.path.join(avatar_dir, avatar_upload_item[1])
    original_image_path = os.path.join(avatar_dir, avatar_upload_item[2])

    response = requests.get(avatar_url + size_url_suffix, stream=True)
    with open(image_path, "wb") as image_file:
        shutil.copyfileobj(response.raw, image_file)
    shutil.copy(image_path, original_image_path)


def process_avatars(
    avatar_list: List[ZerverFieldsT],
    avatar_dir: str,
    realm_id: int,
    threads: int,
    size_url_suffix: str = "",
) -> List[ZerverFieldsT]:
    """
    This function gets the avatar of the user and saves it in the
    user's avatar directory with both the extensions '.png' and '.original'
    Required parameters:

    1. avatar_list: List of avatars to be mapped in avatars records.json file
    2. avatar_dir: Folder where the downloaded avatars are saved
    3. realm_id: Realm ID.

    We use this for Slack and Gitter conversions, where avatars need to be
    downloaded.  For simpler conversions see write_avatar_png.
    """

    logging.info("######### GETTING AVATARS #########\n")
    logging.info("DOWNLOADING AVATARS .......\n")
    avatar_original_list = []
    avatar_upload_list = []
    for avatar in avatar_list:
        avatar_hash = user_avatar_path_from_ids(avatar["user_profile_id"], realm_id)
        avatar_url = avatar["path"]
        avatar_original = dict(avatar)

        image_path = f"{avatar_hash}.png"
        original_image_path = f"{avatar_hash}.original"

        avatar_upload_list.append([avatar_url, image_path, original_image_path])
        # We don't add the size field here in avatar's records.json,
        # since the metadata is not needed on the import end, and we
        # don't have it until we've downloaded the files anyway.
        avatar["path"] = image_path
        avatar["s3_path"] = image_path

        avatar_original["path"] = original_image_path
        avatar_original["s3_path"] = original_image_path
        avatar_original_list.append(avatar_original)

    # Run downloads in parallel
    run_parallel_wrapper(
        partial(get_avatar, avatar_dir, size_url_suffix), avatar_upload_list, threads=threads
    )

    logging.info("######### GETTING AVATARS FINISHED #########\n")
    return avatar_list + avatar_original_list


ListJobData = TypeVar("ListJobData")


def wrapping_function(f: Callable[[ListJobData], None], item: ListJobData) -> None:
    try:
        f(item)
    except Exception:
        logging.exception("Error processing item: %s", item, stack_info=True)


def run_parallel_wrapper(
    f: Callable[[ListJobData], None], full_items: List[ListJobData], threads: int = 6
) -> None:
    logging.info("Distributing %s items across %s threads", len(full_items), threads)

    with ProcessPoolExecutor(max_workers=threads) as executor:
        count = 0
        for future in as_completed(
            executor.submit(wrapping_function, f, item) for item in full_items
        ):
            future.result()
            count += 1
            if count % 1000 == 0:
                logging.info("Finished %s items", count)


def get_uploads(upload_dir: str, upload: List[str]) -> None:
    upload_url = upload[0]
    upload_path = upload[1]
    upload_path = os.path.join(upload_dir, upload_path)

    response = requests.get(upload_url, stream=True)
    os.makedirs(os.path.dirname(upload_path), exist_ok=True)
    with open(upload_path, "wb") as upload_file:
        shutil.copyfileobj(response.raw, upload_file)


def process_uploads(
    upload_list: List[ZerverFieldsT], upload_dir: str, threads: int
) -> List[ZerverFieldsT]:
    """
    This function downloads the uploads and saves it in the realm's upload directory.
    Required parameters:

    1. upload_list: List of uploads to be mapped in uploads records.json file
    2. upload_dir: Folder where the downloaded uploads are saved
    """
    logging.info("######### GETTING ATTACHMENTS #########\n")
    logging.info("DOWNLOADING ATTACHMENTS .......\n")
    upload_url_list = []
    for upload in upload_list:
        upload_url = upload["path"]
        upload_s3_path = upload["s3_path"]
        upload_url_list.append([upload_url, upload_s3_path])
        upload["path"] = upload_s3_path

    # Run downloads in parallel
    run_parallel_wrapper(partial(get_uploads, upload_dir), upload_url_list, threads=threads)

    logging.info("######### GETTING ATTACHMENTS FINISHED #########\n")
    return upload_list


def build_realm_emoji(realm_id: int, name: str, id: int, file_name: str) -> ZerverFieldsT:
    return model_to_dict(
        RealmEmoji(
            realm_id=realm_id,
            name=name,
            id=id,
            file_name=file_name,
        ),
    )


def get_emojis(emoji_dir: str, upload: List[str]) -> None:
    emoji_url = upload[0]
    emoji_path = upload[1]
    upload_emoji_path = os.path.join(emoji_dir, emoji_path)

    response = requests.get(emoji_url, stream=True)
    os.makedirs(os.path.dirname(upload_emoji_path), exist_ok=True)
    with open(upload_emoji_path, "wb") as emoji_file:
        shutil.copyfileobj(response.raw, emoji_file)


def process_emojis(
    zerver_realmemoji: List[ZerverFieldsT],
    emoji_dir: str,
    emoji_url_map: ZerverFieldsT,
    threads: int,
) -> List[ZerverFieldsT]:
    """
    This function downloads the custom emojis and saves in the output emoji folder.
    Required parameters:

    1. zerver_realmemoji: List of all RealmEmoji objects to be imported
    2. emoji_dir: Folder where the downloaded emojis are saved
    3. emoji_url_map: Maps emoji name to its url
    """
    emoji_records = []
    upload_emoji_list = []
    logging.info("######### GETTING EMOJIS #########\n")
    logging.info("DOWNLOADING EMOJIS .......\n")
    for emoji in zerver_realmemoji:
        emoji_url = emoji_url_map[emoji["name"]]
        emoji_path = RealmEmoji.PATH_ID_TEMPLATE.format(
            realm_id=emoji["realm"], emoji_file_name=emoji["name"]
        )

        upload_emoji_list.append([emoji_url, emoji_path])

        emoji_record = dict(emoji)
        emoji_record["path"] = emoji_path
        emoji_record["s3_path"] = emoji_path
        emoji_record["realm_id"] = emoji_record["realm"]
        emoji_record.pop("realm")

        emoji_records.append(emoji_record)

    # Run downloads in parallel
    run_parallel_wrapper(partial(get_emojis, emoji_dir), upload_emoji_list, threads=threads)

    logging.info("######### GETTING EMOJIS FINISHED #########\n")
    return emoji_records


def create_converted_data_files(data: Any, output_dir: str, file_path: str) -> None:
    output_file = output_dir + file_path
    os.makedirs(os.path.dirname(output_file), exist_ok=True)
    with open(output_file, "wb") as fp:
        fp.write(orjson.dumps(data, option=orjson.OPT_INDENT_2))


# External user-id
ExternalId = TypeVar("ExternalId")


def long_term_idle_helper(
    message_iterator: Iterator[ZerverFieldsT],
    user_from_message: Callable[[ZerverFieldsT], Optional[ExternalId]],
    timestamp_from_message: Callable[[ZerverFieldsT], float],
    zulip_user_id_from_user: Callable[[ExternalId], int],
    all_user_ids_iterator: Iterator[ExternalId],
    zerver_userprofile: List[ZerverFieldsT],
) -> Set[int]:
    """Algorithmically, we treat users who have sent at least 10 messages
    or have sent a message within the last 60 days as active.
    Everyone else is treated as long-term idle, which means they will
    have a slightly slower first page load when coming back to
    Zulip.
    """
    sender_counts: Dict[ExternalId, int] = defaultdict(int)
    recent_senders: Set[ExternalId] = set()
    NOW = float(timezone_now().timestamp())
    for message in message_iterator:
        timestamp = timestamp_from_message(message)
        user = user_from_message(message)
        if user is None:
            continue

        if user in recent_senders:
            continue

        if NOW - timestamp < 60 * 24 * 60 * 60:
            recent_senders.add(user)

        sender_counts[user] += 1
    for user, count in sender_counts.items():
        if count > 10:
            recent_senders.add(user)

    long_term_idle = set()

    for user_id in all_user_ids_iterator:
        if user_id in recent_senders:
            continue
        zulip_user_id = zulip_user_id_from_user(user_id)
        long_term_idle.add(zulip_user_id)

    for user_profile_row in zerver_userprofile:
        if user_profile_row["id"] in long_term_idle:
            user_profile_row["long_term_idle"] = True
            # Setting last_active_message_id to 1 means the user, if
            # imported, will get the full message history for the
            # streams they were on.
            user_profile_row["last_active_message_id"] = 1

    return long_term_idle
