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import json
import re
from typing import Any, Dict, Optional

from airflow.exceptions import AirflowException
from airflow.providers.http.hooks.http import HttpHook


class DiscordWebhookHook(HttpHook):
    """
    This hook allows you to post messages to Discord using incoming webhooks.
    Takes a Discord connection ID with a default relative webhook endpoint. The
    default endpoint can be overridden using the webhook_endpoint parameter
    (https://discordapp.com/developers/docs/resources/webhook).
    Each Discord webhook can be pre-configured to use a specific username and
    avatar_url. You can override these defaults in this hook.
    :param http_conn_id: Http connection ID with host as "https://discord.com/api/" and
                         default webhook endpoint in the extra field in the form of
                         {"webhook_endpoint": "webhooks/{webhook.id}/{webhook.token}"}
    :type http_conn_id: str
    :param webhook_endpoint: Discord webhook endpoint in the form of
                             "webhooks/{webhook.id}/{webhook.token}"
    :type webhook_endpoint: str
    :param message: The message you want to send to your Discord channel
                    (max 2000 characters)
    :type message: str
    :param username: Override the default username of the webhook
    :type username: str
    :param avatar_url: Override the default avatar of the webhook
    :type avatar_url: str
    :param tts: Is a text-to-speech message
    :type tts: bool
    :param proxy: Proxy to use to make the Discord webhook call
    :type proxy: str
    """

    def __init__(
        self,
        http_conn_id: Optional[str] = None,
        webhook_endpoint: Optional[str] = None,
        message: str = "",
        username: Optional[str] = None,
        avatar_url: Optional[str] = None,
        tts: bool = False,
        proxy: Optional[str] = None,
        *args: Any,
        **kwargs: Any,
    ) -> None:
        super().__init__(*args, **kwargs)
        self.http_conn_id: Any = http_conn_id
        self.webhook_endpoint = self._get_webhook_endpoint(
            http_conn_id, webhook_endpoint
        )
        self.message = message
        self.username = username
        self.avatar_url = avatar_url
        self.tts = tts
        self.proxy = proxy

    def _get_webhook_endpoint(
        self, http_conn_id: Optional[str], webhook_endpoint: Optional[str]
    ) -> str:
        """
        Given a Discord http_conn_id, return the default webhook endpoint or override if a
        webhook_endpoint is manually supplied.
        :param http_conn_id: The provided connection ID
        :param webhook_endpoint: The manually provided webhook endpoint
        :return: Webhook endpoint (str) to use
        """
        if webhook_endpoint:
            endpoint = webhook_endpoint
        elif http_conn_id:
            conn = self.get_connection(http_conn_id)
            extra = conn.extra_dejson
            endpoint = extra.get("webhook_endpoint", "")
        else:
            raise AirflowException(
                "Cannot get webhook endpoint: No valid Discord webhook endpoint or http_conn_id supplied."
            )

        # make sure endpoint matches the expected Discord webhook format
        if not re.match("^webhooks/[0-9]+/[a-zA-Z0-9_-]+$", endpoint):
            raise AirflowException(
                'Expected Discord webhook endpoint in the form of "webhooks/{webhook.id}/{webhook.token}".'
            )

        return endpoint

    def _build_discord_payload(self) -> str:
        """
        Construct the Discord JSON payload. All relevant parameters are combined here
        to a valid Discord JSON payload.
        :return: Discord payload (str) to send
        """
        payload: Dict[str, Any] = {}

        if self.username:
            payload["username"] = self.username
        if self.avatar_url:
            payload["avatar_url"] = self.avatar_url

        payload["tts"] = self.tts

        if len(self.message) <= 2000:
            payload["content"] = self.message
        else:
            raise AirflowException(
                "Discord message length must be 2000 or fewer characters."
            )

        return json.dumps(payload)

    def execute(self) -> None:
        """Execute the Discord webhook call"""
        proxies = {}
        if self.proxy:
            # we only need https proxy for Discord
            proxies = {"https": self.proxy}

        discord_payload = self._build_discord_payload()

        self.run(
            endpoint=self.webhook_endpoint,
            data=discord_payload,
            headers={"Content-type": "application/json"},
            extra_options={"proxies": proxies},
        )