import hashlib
import hmac
import json
import os
from ipaddress import ip_address, ip_network

import requests
from dotenv import load_dotenv
from flask import Flask, abort, request


def create_app():
    app = Flask(__name__)
    load_dotenv()
    app.config["GITHUB_SECRET"] = os.getenv("GITHUB_SECRET")
    app.config["DISCORD_WEBHOOK"] = os.getenv("DISCORD_WEBHOOK")

    return app


app = create_app()


def verify_src_ip(src_ip):
    allowed_ips = requests.get("https://api.github.com/meta").json()["hooks"]
    return any(src_ip in ip_network(valid_ip) for valid_ip in allowed_ips)


def verify_hmac_hash(data, signature):
    github_secret = bytes(app.config["GITHUB_SECRET"], "ascii")
    mac = hmac.new(github_secret, msg=data, digestmod=hashlib.sha1)
    return hmac.compare_digest("sha1=" + mac.hexdigest(), signature)


@app.route("/github-payload", methods=["POST"])
def github_payload():
    src_ip = ip_address(request.headers.get("X-Real-IP", request.access_route[0]))
    if not verify_src_ip(src_ip):
        app.logger.debug(f"invalid source ip: {src_ip}... aborting request")
        abort(403)

    signature = request.headers.get("X-Hub-Signature")
    data = request.data
    if not verify_hmac_hash(data, signature):
        app.logger.debug("failed to verify signature... aborting request")
        abort(403)

    payload = request.get_json()
    match event_type := request.headers.get("X-GitHub-Event"):
        case "ping":
            return json.dumps({"msg": "pong"})
        case "issues":
            issues_handler(payload)
        case _:
            app.logger.debug(f"no handler defined for event {event_type}... continuing")
    return ("", 200, None)


def issues_handler(payload):
    embed = {
        "author": {
            "name": payload["sender"]["login"],
            "icon_url": payload["sender"]["avatar_url"],
        },
        "title": f"[{payload['repository']['full_name']}] Issue {payload['action'].capitalize()}: #{payload['issue']['number']} {payload['issue']['title']}",
        "url": payload["issue"]["html_url"],
        "description": payload["issue"].get("body"),
    }
    data = {
        "username": "Github-OpenGist",
        "embeds": [embed],
    }
    send_discord_webhook(app.config["DISCORD_WEBHOOK"], data)


def send_discord_webhook(webhook_url, data):
    requests.post(webhook_url, json=data)


if __name__ == "__main__":
    app.run(debug=True, port=5000)