import re
from typing import Any, TypeAlias

from django.http import HttpRequest
from django.http.response import HttpResponse
from django.utils.translation import gettext as _

from zerver.data_import.slack import check_token_access, get_slack_api_data
from zerver.data_import.slack_message_conversion import (
    SLACK_BOLD_REGEX,
    SLACK_ITALIC_REGEX,
    SLACK_STRIKETHROUGH_REGEX,
    SLACK_USERMENTION_REGEX,
    convert_link_format,
    convert_mailto_format,
    convert_markdown_syntax,
)
from zerver.decorator import webhook_view
from zerver.lib.exceptions import JsonableError, UnsupportedWebhookEventTypeError
from zerver.lib.request import RequestVariableMissingError
from zerver.lib.response import json_success
from zerver.lib.typed_endpoint import typed_endpoint
from zerver.lib.validator import WildValue, check_none_or, check_string, to_wild_value
from zerver.lib.webhooks.common import check_send_webhook_message
from zerver.models import UserProfile

FILE_LINK_TEMPLATE = "\n*[{file_name}]({file_link})*"
ZULIP_MESSAGE_TEMPLATE = "**{sender}**: {text}"
VALID_OPTIONS = {"SHOULD_NOT_BE_MAPPED": "0", "SHOULD_BE_MAPPED": "1"}

SlackFileListT: TypeAlias = list[dict[str, str]]
SlackAPIResponseT: TypeAlias = dict[str, Any]

SLACK_CHANNELMENTION_REGEX = r"(?<=<#)(.*)(?=>)"


def is_zulip_slack_bridge_bot_message(payload: WildValue) -> bool:
    app_api_id = payload.get("api_app_id").tame(check_none_or(check_string))
    bot_app_id = (
        payload.get("event", {})
        .get("bot_profile", {})
        .get("app_id")
        .tame(check_none_or(check_string))
    )
    return bot_app_id is not None and app_api_id == bot_app_id


def get_slack_channel_name(channel_id: str, token: str) -> str:
    slack_channel_data = get_slack_api_data(
        "https://slack.com/api/conversations.info",
        get_param="channel",
        token=token,
        channel=channel_id,
    )
    return slack_channel_data["name"]


def get_slack_sender_name(user_id: str, token: str) -> str:
    slack_user_data = get_slack_api_data(
        "https://slack.com/api/users.info", get_param="user", token=token, user=user_id
    )
    return slack_user_data["name"]


def convert_slack_user_and_channel_mentions(text: str, app_token: str) -> str:
    tokens = text.split(" ")
    for iterator in range(len(tokens)):
        slack_usermention_match = re.search(SLACK_USERMENTION_REGEX, tokens[iterator], re.VERBOSE)
        slack_channelmention_match = re.search(
            SLACK_CHANNELMENTION_REGEX, tokens[iterator], re.MULTILINE
        )
        if slack_usermention_match:
            # Convert Slack user mentions to a mention-like syntax since there
            # is no way to map Slack and Zulip users.
            slack_id = slack_usermention_match.group(2)
            user_name = get_slack_sender_name(user_id=slack_id, token=app_token)
            tokens[iterator] = "@**" + user_name + "**"
        elif slack_channelmention_match:
            # Convert Slack channel mentions to a mention-like syntax so that
            # a mention isn't triggered for a Zulip channel with the same name.
            channel_info: list[str] = slack_channelmention_match.group(0).split("|")
            channel_name = channel_info[1]
            tokens[iterator] = f"**#{channel_name}**" if channel_name else "**#[private channel]**"
    text = " ".join(tokens)
    return text


# This is a modified version of `convert_to_zulip_markdown` in
# `slack_message_conversion.py`, which cannot be used directly
# due to differences in the Slack import data and Slack webhook
# payloads.
def convert_to_zulip_markdown(text: str, slack_app_token: str) -> str:
    text = convert_slack_formatting(text)
    text = convert_slack_workspace_mentions(text)
    text = convert_slack_user_and_channel_mentions(text, slack_app_token)
    return text


def convert_slack_formatting(text: str) -> str:
    text = convert_markdown_syntax(text, SLACK_BOLD_REGEX, "**")
    text = convert_markdown_syntax(text, SLACK_STRIKETHROUGH_REGEX, "~~")
    text = convert_markdown_syntax(text, SLACK_ITALIC_REGEX, "*")
    return text


def convert_slack_workspace_mentions(text: str) -> str:
    # Map Slack's <!everyone>, <!channel> and <!here> mentions to @**all**.
    # No regex for this as it can be present anywhere in the sentence.
    text = text.replace("<!everyone>", "@**all**")
    text = text.replace("<!channel>", "@**all**")
    text = text.replace("<!here>", "@**all**")
    return text


def replace_links(text: str) -> str:
    text, _ = convert_link_format(text)
    text, _ = convert_mailto_format(text)
    return text


def convert_raw_file_data(file_dict: WildValue) -> SlackFileListT:
    files = [
        {
            "file_link": file.get("permalink").tame(check_string),
            "file_name": file.get("title").tame(check_string),
        }
        for file in file_dict
    ]
    return files


def get_message_body(text: str, sender: str, files: SlackFileListT) -> str:
    body = ZULIP_MESSAGE_TEMPLATE.format(sender=sender, text=text)
    for file in files:
        body += FILE_LINK_TEMPLATE.format(**file)
    return body


def is_challenge_handshake(payload: WildValue) -> bool:
    return payload.get("type").tame(check_string) == "url_verification"


def handle_slack_webhook_message(
    request: HttpRequest,
    user_profile: UserProfile,
    content: str,
    channel: str | None,
    channels_map_to_topics: str | None,
) -> None:
    topic_name = "Message from Slack"
    if channels_map_to_topics is None:
        check_send_webhook_message(request, user_profile, topic_name, content)
    elif channels_map_to_topics == VALID_OPTIONS["SHOULD_BE_MAPPED"]:
        topic_name = f"channel: {channel}"
        check_send_webhook_message(request, user_profile, topic_name, content)
    elif channels_map_to_topics == VALID_OPTIONS["SHOULD_NOT_BE_MAPPED"]:
        check_send_webhook_message(
            request,
            user_profile,
            topic_name,
            content,
            stream=channel,
        )
    else:
        raise JsonableError(_("Error: channels_map_to_topics parameter other than 0 or 1"))


def is_retry_call_from_slack(request: HttpRequest) -> bool:
    return "X-Slack-Retry-Num" in request.headers


@webhook_view("Slack", notify_bot_owner_on_invalid_json=False)
@typed_endpoint
def api_slack_webhook(
    request: HttpRequest,
    user_profile: UserProfile,
    *,
    slack_app_token: str = "",
    channels_map_to_topics: str | None = None,
) -> HttpResponse:
    if request.content_type != "application/json":
        # Handle Slack's legacy Outgoing Webhook Service payload.
        expected_legacy_variable = ["user_name", "text", "channel_name"]
        legacy_payload = {}
        for variable in expected_legacy_variable:
            if variable in request.POST:
                legacy_payload[variable] = request.POST[variable]
            elif variable in request.GET:  # nocoverage
                legacy_payload[variable] = request.GET[variable]
            else:
                raise RequestVariableMissingError(variable)

        text = convert_slack_formatting(legacy_payload["text"])
        text = replace_links(text)
        text = get_message_body(text, legacy_payload["user_name"], [])
        handle_slack_webhook_message(
            request,
            user_profile,
            text,
            legacy_payload["channel_name"],
            channels_map_to_topics,
        )
        return json_success(request)

    try:
        val = request.body.decode(request.encoding or "utf-8")
    except UnicodeDecodeError:  # nocoverage
        raise JsonableError(_("Malformed payload"))
    payload = to_wild_value("payload", val)

    # Handle initial URL verification handshake for Slack Events API.
    if is_challenge_handshake(payload):
        challenge = payload.get("challenge").tame(check_string)
        check_token_access(slack_app_token)
        check_send_webhook_message(
            request,
            user_profile,
            "Integration events",
            "Successfully verified webhook URL with Slack!",
        )
        return json_success(request=request, data={"challenge": challenge})

    # A Slack fail condition occurs when we don't respond with HTTP 200
    # within 3 seconds after Slack calls our endpoint. If this happens,
    # Slack will retry sending the same payload. This is often triggered
    # because of we have to do two callbacks for each call. To avoid
    # sending the same message multiple times, we block subsequent retry
    # calls from Slack.
    if is_retry_call_from_slack(request):
        return json_success(request)

    # Prevent any Zulip messages sent through the Slack Bridge from looping
    # back here.
    if is_zulip_slack_bridge_bot_message(payload):
        return json_success(request)

    event_dict = payload.get("event", {})
    event_type = event_dict.get("type").tame(check_string)

    if event_type != "message":
        raise UnsupportedWebhookEventTypeError(event_type)

    raw_files = event_dict.get("files")
    files = convert_raw_file_data(raw_files) if raw_files else []
    raw_text = event_dict.get("text", "").tame(check_string)
    text = convert_to_zulip_markdown(raw_text, slack_app_token)
    user_id = event_dict.get("user").tame(check_none_or(check_string))
    if user_id is None:
        # This is likely a Slack integration bot message. The sender of these
        # messages doesn't have a user profile and would require additional
        # formatting to handle. Refer to the Slack Incoming Webhook integration
        # for how to add support for this type of payload.
        raise UnsupportedWebhookEventTypeError(
            "integration bot message"
            if event_dict["subtype"] == "bot_message"
            else "unknown Slack event"
        )
    sender = get_slack_sender_name(user_id, slack_app_token)
    content = get_message_body(text, sender, files)
    channel_id = event_dict.get("channel").tame(check_string)
    channel = (
        get_slack_channel_name(channel_id, slack_app_token) if channels_map_to_topics else None
    )

    handle_slack_webhook_message(request, user_profile, content, channel, channels_map_to_topics)
    return json_success(request)