"""hello-world: an OpenAI-compatible chat server that greets you back (stdlib only).

m64 does the rest: it serves AGENT.md at /agent, human/ at /human/, and its own
/status, and lets only the chat routes through to this server.
"""

import json
import os
import time
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer

PORT = int(os.environ["M64_PORT"])
MODEL = "hello-world"


def reply_to(messages):
    """The whole "model": greet, and repeat the last user message."""
    last = next((m.get("content") for m in reversed(messages) if m.get("role") == "user"), "")
    if isinstance(last, list):  # content parts: keep the text ones
        last = " ".join(p.get("text", "") for p in last if isinstance(p, dict))
    return f"Hello, world! You said: {last}" if last else "Hello, world!"


class Handler(BaseHTTPRequestHandler):
    protocol_version = "HTTP/1.1"

    def log_message(self, fmt, *args):
        if self.path != "/health":  # health is polled often; keep the log readable
            super().log_message(fmt, *args)

    def _json(self, status, obj):
        data = json.dumps(obj).encode()
        self.send_response(status)
        self.send_header("Content-Type", "application/json")
        self.send_header("Content-Length", str(len(data)))
        self.end_headers()
        self.wfile.write(data)

    def do_GET(self):
        if self.path == "/health":
            return self._json(200, {"status": "ok"})
        if self.path == "/v1/models":
            return self._json(200, {"object": "list", "data": [{"id": MODEL, "object": "model", "owned_by": "hello-world"}]})
        return self._json(404, {"error": "not found"})

    def do_POST(self):
        if self.path != "/v1/chat/completions":
            return self._json(404, {"error": "not found"})
        try:
            body = json.loads(self.rfile.read(int(self.headers.get("Content-Length") or 0)) or b"{}")
            messages = body["messages"]
            assert isinstance(messages, list)
        except (ValueError, KeyError, AssertionError):
            return self._json(400, {"error": "send a JSON body with a messages list"})
        text = reply_to(messages)
        now = int(time.time())
        if body.get("stream") is True:
            return self._stream(text, now)
        return self._json(200, {
            "id": f"hello-{now}", "object": "chat.completion", "created": now, "model": MODEL,
            "choices": [{"index": 0, "message": {"role": "assistant", "content": text}, "finish_reason": "stop"}],
            "usage": {"prompt_tokens": 0, "completion_tokens": len(text.split()), "total_tokens": len(text.split())},
        })

    def _stream(self, text, now):
        """Server-sent events, one word per chunk, the way OpenAI-compatible clients expect."""
        self.send_response(200)
        self.send_header("Content-Type", "text/event-stream")
        self.send_header("Cache-Control", "no-cache")
        self.send_header("Connection", "close")
        self.end_headers()
        self.close_connection = True
        words = text.split(" ")
        for i, word in enumerate(words):
            delta = {"content": word + (" " if i < len(words) - 1 else "")}
            chunk = {"id": f"hello-{now}", "object": "chat.completion.chunk", "created": now, "model": MODEL,
                     "choices": [{"index": 0, "delta": delta, "finish_reason": None}]}
            self.wfile.write(f"data: {json.dumps(chunk)}\n\n".encode())
        done = {"id": f"hello-{now}", "object": "chat.completion.chunk", "created": now, "model": MODEL,
                "choices": [{"index": 0, "delta": {}, "finish_reason": "stop"}]}
        self.wfile.write(f"data: {json.dumps(done)}\n\ndata: [DONE]\n\n".encode())


def main():
    server = ThreadingHTTPServer(("0.0.0.0", PORT), Handler)
    server.daemon_threads = True
    # Tell m64 we are ready; it still waits for /health to answer 200.
    with open(os.environ["M64_STATUS"], "a") as f:
        f.write(json.dumps({"phase": "ready", "detail": "saying hello"}) + "\n")
    server.serve_forever()


if __name__ == "__main__":
    main()