#!/usr/bin/env python3
"""Tiny token endpoint for the voice UI.

Serves POST /token -> { "token": "<signed JWT>" }
Signs a LiveKit access token with HS256 using the API key/secret from env.

The token carries a roomConfig claim requesting the voice-assistant agent, so
LiveKit dispatches the agent when the participant joins. Without this, the
auto-created room would get no agent at all.

Runs as a separate supervisord process; nginx proxies /token to it.
"""
import base64
import hashlib
import hmac
import json
import os
import time
import uuid

from http.server import BaseHTTPRequestHandler, HTTPServer

API_KEY = os.environ.get("LIVEKIT_API_KEY", "devkey")
API_SECRET = os.environ.get("LIVEKIT_API_SECRET", "devsecret")
AGENT_NAME = os.environ.get("VOICE_AGENT_NAME", "voice-assistant")


def b64url(data: bytes) -> str:
    return base64.urlsafe_b64encode(data).rstrip(b"=").decode()


def make_token(room_name: str, identity: str) -> str:
    now = int(time.time())
    header = {"alg": "HS256", "typ": "JWT"}
    payload = {
        "iss": API_KEY,
        "sub": identity,
        "nbf": now - 5,
        "exp": now + 3600,
        "jti": str(uuid.uuid4()),
        "identity": identity,
        "video": {
            "roomJoin": True,
            "room": room_name,
            "canPublish": True,
            "canSubscribe": True,
            "canPublishData": True,
        },
        "roomConfig": {
            "agents": [{"agentName": AGENT_NAME, "jobType": "JT_ROOM"}],
        },
    }
    h = b64url(json.dumps(header).encode())
    p = b64url(json.dumps(payload).encode())
    signing_input = f"{h}.{p}".encode()
    sig = hmac.new(API_SECRET.encode(), signing_input, hashlib.sha256).digest()
    return f"{h}.{p}.{b64url(sig)}"


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

        length = int(self.headers.get("Content-Length", 0))
        body = json.loads(self.rfile.read(length) or b"{}")
        # Unique room per session so LiveKit dispatches the agent at creation.
        room_name = f"voice-{uuid.uuid4().hex[:8]}"
        identity = body.get("identity") or f"user-{uuid.uuid4().hex[:8]}"

        token = make_token(room_name, identity)
        resp = json.dumps({"token": token}).encode()
        self.send_response(200)
        self.send_header("Content-Type", "application/json")
        self.send_header("Content-Length", str(len(resp)))
        self.end_headers()
        self.wfile.write(resp)

    def log_message(self, format, *args):
        pass  # silence request logging


if __name__ == "__main__":
    server = HTTPServer(("127.0.0.1", 8091), Handler)
    print("token endpoint listening on 127.0.0.1:8091")
    server.serve_forever()