import asyncio
import hashlib
import hmac
import json
import time
from collections import defaultdict, deque
from http.server import HTTPServer, BaseHTTPRequestHandler
from urllib.parse import urlparse
import threading

# Configuration
SHARED_SECRET = b"my_secret_key"
DISCORD_WEBHOOK_URL = "https://discord.com/api/webhooks/1234567890/test"
MAX_DISCORD_RATE = 5  # events per second
RATE_LIMIT_WINDOW = 1.0  # seconds

# In-memory stores
idempotency_store = {}  # event_id -> timestamp
discord_forward_count = 0
discord_forward_times = deque(maxlen=MAX_DISCORD_RATE)  # timestamps of forwards

# Token bucket for rate limiting
bucket_tokens = MAX_DISCORD_RATE
last_refill = time.time()
bucket_lock = threading.Lock()

def verify_signature(body, signature):
    """Verify HMAC signature of the request body."""
    expected = hmac.new(SHARED_SECRET, body, hashlib.sha256).hexdigest()
    return hmac.compare_digest(signature, expected)

def is_idempotent(event_id):
    """Check if event has been seen recently."""
    now = time.time()
    if event_id in idempotency_store:
        if now - idempotency_store[event_id] < 300:  # 5 minutes
            return True
    idempotency_store[event_id] = now
    return False

def rate_limit():
    """Check if we can make a Discord forward."""
    global bucket_tokens, last_refill
    with bucket_lock:
        now = time.time()
        # Refill tokens based on time passed
        elapsed = now - last_refill
        if elapsed > RATE_LIMIT_WINDOW:
            bucket_tokens = min(MAX_DISCORD_RATE, bucket_tokens + elapsed / RATE_LIMIT_WINDOW * MAX_DISCORD_RATE)
            last_refill = now
        if bucket_tokens >= 1:
            bucket_tokens -= 1
            return True
        return False

async def discord_send(payload):
    """Simulate sending to Discord webhook."""
    # Simulate occasional 429
    import random
    if random.random() < 0.05:  # 5% chance of 429
        retry_after = random.randint(1, 3)
        raise Exception(f"HTTP 429: Retry-After {retry_after}")
    # Simulate success
    return True

class WebhookHandler(BaseHTTPRequestHandler):
    def do_POST(self):
        if self.path != "/webhook":
            self.send_response(404)
            self.end_headers()
            return

        # Read body
        content_length = int(self.headers.get('Content-Length', 0))
        if not content_length:
            self.send_response(400)
            self.end_headers()
            return

        body = self.rfile.read(content_length)
        signature = self.headers.get('X-Signature')
        if not signature:
            self.send_response(401)
            self.end_headers()
            return

        # Verify signature
        if not verify_signature(body, signature):
            self.send_response(401)
            self.end_headers()
            return

        try:
            data = json.loads(body)
        except json.JSONDecodeError:
            self.send_response(400)
            self.end_headers()
            return

        event_id = data.get("event_id")
        if not event_id:
            self.send_response(400)
            self.end_headers()
            return

        # Check idempotency
        if is_idempotent(event_id):
            self.send_response(200)
            self.end_headers()
            return

        # Forward to Discord
        asyncio.run(self.forward_to_discord(data))
        self.send_response(200)
        self.end_headers()

    async def forward_to_discord(self, data):
        """Forward event to Discord with rate limiting and retries."""
        # Rate limit check
        while not rate_limit():
            await asyncio.sleep(0.1)

        # Prepare payload for Discord
        summary = {
            "content": f"Event {data['type']}: {data.get('data', {}).get('message', 'No message')}"
        }

        retry_after = 0
        while True:
            try:
                await discord_send(summary)
                break
            except Exception as e:
                if "HTTP 429" in str(e):
                    # Extract retry-after
                    import re
                    match = re.search(r"Retry-After (\d+)", str(e))
                    if match:
                        retry_after = int(match.group(1))
                    else:
                        retry_after = 1
                    await asyncio.sleep(retry_after)
                else:
                    # Log error but don't fail silently
                    print(f"Discord send failed: {e}")
                    break

if __name__ == "__main__":
    # Run tests
    import unittest
    import threading
    import time

    class TestWebhookBridge(unittest.TestCase):
        def setUp(self):
            self.handler = WebhookHandler.__new__(WebhookHandler)
            self.handler.path = "/webhook"
            self.handler.headers = {}
            self.handler.rfile = None
            self.handler.wfile = None

        def test_signature_verification(self):
            body = b'{"event_id": "123", "type": "chat", "data": {}}'
            signature = hmac.new(SHARED_SECRET, body, hashlib.sha256).hexdigest()
            self.assertTrue(verify_signature(body, signature))
            # Tampered signature
            self.assertFalse(verify_signature(body, "wrong_signature"))

        def test_idempotency(self):
            event_id = "test_event"
            # First time - should not be idempotent
            self.assertFalse(is_idempotent(event_id))
            # Second time - should be idempotent
            self.assertTrue(is_idempotent(event_id))

        def test_rate_limiting(self):
            # Fill bucket
            for _ in range(MAX_DISCORD_RATE):
                self.assertTrue(rate_limit())
            # Next should fail
            self.assertFalse(rate_limit())

    # Run tests
    unittest.main(argv=[''], exit=False, verbosity=2)

    # Start HTTP server
    server = HTTPServer(('localhost', 8080), WebhookHandler)
    print("Starting server on http://localhost:8080")
    try:
        server.serve_forever()
    except KeyboardInterrupt:
        print("\nShutting down...")