#!/usr/bin/env python3
"""A fake OpenAI-compatible model for tests/pi-live.sh: streams a short reply
to /v1/chat/completions, after a delay taken from the last user message
("slow 3" waits 3 seconds), or fails as a provider does ("fail 401": an
authentication error). Asked to name a session, it answers "About <the
latest user message>". Prints its port, then serves until killed."""
import json
import re
import sys
import time
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer


def last_user_text(body):
    for message in reversed(body.get("messages", [])):
        if message.get("role") == "user":
            content = message.get("content")
            if isinstance(content, list):
                return " ".join(part.get("text", "") for part in content if isinstance(part, dict))
            return content or ""
    return ""


class Handler(BaseHTTPRequestHandler):
    def log_message(self, *args):
        pass

    def do_GET(self):
        self.send_response(200)
        self.send_header("Content-Type", "application/json")
        self.end_headers()
        self.wfile.write(json.dumps({"object": "list", "data": [{"id": "fake-model", "object": "model"}]}).encode())

    def do_POST(self):
        body = json.loads(self.rfile.read(int(self.headers.get("Content-Length", 0))) or b"{}")
        text = last_user_text(body)
        if "Name this coding-agent session" in text:
            said = re.findall(r"^User: (.*)$", text, re.M)
            self.reply("About " + (said[-1][:40] if said else "nothing"))
            return
        match = re.search(r"slow (\d+(?:\.\d+)?)", text)
        time.sleep(float(match.group(1)) if match else 0.2)
        failure = re.search(r"fail (\d{3})", text)
        if failure:
            error = json.dumps({"type": "error", "error": {"type": "authentication_error", "message": "invalid x-api-key"}})
            self.send_response(int(failure.group(1)))
            self.send_header("Content-Type", "application/json")
            self.end_headers()
            self.wfile.write(error.encode())
            return
        self.reply("Done: fake reply.")

    def reply(self, text):
        self.send_response(200)
        self.send_header("Content-Type", "text/event-stream")
        self.send_header("Cache-Control", "no-cache")
        self.end_headers()

        def chunk(delta, finish=None, usage=None):
            data = {"id": "fake", "object": "chat.completion.chunk", "created": int(time.time()), "model": "fake-model",
                    "choices": [{"index": 0, "delta": delta, "finish_reason": finish}]}
            if usage:
                data["usage"] = usage
            self.wfile.write(f"data: {json.dumps(data)}\n\n".encode())
            self.wfile.flush()

        chunk({"role": "assistant", "content": text})
        chunk({}, "stop", {"prompt_tokens": 10, "completion_tokens": 3, "total_tokens": 13})
        self.wfile.write(b"data: [DONE]\n\n")
        self.wfile.flush()


server = ThreadingHTTPServer(("127.0.0.1", 0), Handler)
print(server.server_address[1], flush=True)
server.serve_forever()