#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""OpenAI 兼容的 mock 模型服务 —— 只为验证 LlmService 的「真实 HTTP 流式」链路。

为什么需要它
------------
本机常常没有可用的大模型端点（Ollama 没启动、外网被 http_proxy 拦掉），
但 LlmService 的核心风险恰恰在 HTTP 这一段（SSE 分片解析、usage 提取、
错误码映射），全 mock 的单测覆盖不到。这个 mock 端点让 LlmService 真实走一遍：

    DB 模型配置 -> AgentModelFactory -> HTTP SSE -> 分片拼接 -> LlmResult

用法
----
    # 终端 1
    python mock-openai-server.py 18999

    # 终端 2
    mvn -pl ai-server test -Dtest=LlmServiceHttpTest -Dmock.llm.port=18999

模型名约定（测试用来触发特定分支）
----------------------------------
* 普通模型名          -> SSE 逐片吐 CHUNKS，末帧带 usage
* mock-unauthorized   -> 返回 401，验证「模型报错不能被误报成超时」
* mock-slow           -> 先睡 30s，验证超时分支（504）
"""

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

# 分片拼接后应为：DuckDB 是一个嵌入式的 OLAP 数据库。
CHUNKS = ["DuckDB", " 是", "一个", "嵌入式", "的 OLAP", " 数据库", "。"]
PROMPT_TOKENS = 11


class Handler(BaseHTTPRequestHandler):

    protocol_version = "HTTP/1.1"

    def log_message(self, fmt, *args):
        sys.stderr.write("[mock-openai] " + (fmt % args) + "\n")
        sys.stderr.flush()

    # ---------- 工具 ----------

    def _read_json(self):
        length = int(self.headers.get("Content-Length") or 0)
        raw = self.rfile.read(length) if length > 0 else b"{}"
        try:
            return json.loads(raw.decode("utf-8") or "{}")
        except Exception:
            return {}

    def _write_json(self, status, payload):
        body = json.dumps(payload, ensure_ascii=False).encode("utf-8")
        self.send_response(status)
        self.send_header("Content-Type", "application/json; charset=utf-8")
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        self.wfile.write(body)

    def _chunk(self, data: bytes):
        """写一个 HTTP/1.1 chunked 分片"""
        self.wfile.write(("%X\r\n" % len(data)).encode("ascii"))
        self.wfile.write(data)
        self.wfile.write(b"\r\n")

    # ---------- 路由 ----------

    def do_GET(self):
        """健康检查：Java 测试用它确认端口已就绪"""
        self._write_json(200, {"status": "ok", "chunks": len(CHUNKS)})

    def do_POST(self):
        req = self._read_json()
        model = req.get("model") or "mock-model"

        if model == "mock-unauthorized":
            self._write_json(401, {"error": {
                "message": "Incorrect API key provided",
                "type": "invalid_request_error",
                "code": "invalid_api_key",
            }})
            return

        self.send_response(200)
        self.send_header("Content-Type", "text/event-stream; charset=utf-8")
        self.send_header("Cache-Control", "no-cache")
        self.send_header("Transfer-Encoding", "chunked")
        self.end_headers()

        if model == "mock-slow":
            time.sleep(30)

        base = {
            "id": "chatcmpl-mock",
            "object": "chat.completion.chunk",
            "created": int(time.time()),
            "model": model,
        }
        for piece in CHUNKS:
            event = dict(base, choices=[{
                "index": 0,
                "delta": {"content": piece},
                "finish_reason": None,
            }])
            self._chunk(("data: " + json.dumps(event, ensure_ascii=False) + "\n\n").encode("utf-8"))

        final = dict(
            base,
            choices=[{"index": 0, "delta": {}, "finish_reason": "stop"}],
            usage={
                "prompt_tokens": PROMPT_TOKENS,
                "completion_tokens": len(CHUNKS),
                "total_tokens": PROMPT_TOKENS + len(CHUNKS),
            },
        )
        self._chunk(("data: " + json.dumps(final, ensure_ascii=False) + "\n\n").encode("utf-8"))
        self._chunk(b"data: [DONE]\n\n")
        self.wfile.write(b"0\r\n\r\n")
        self.wfile.flush()


def main():
    port = int(sys.argv[1]) if len(sys.argv) > 1 else 18999
    server = ThreadingHTTPServer(("127.0.0.1", port), Handler)
    sys.stderr.write("[mock-openai] listening on http://127.0.0.1:%d\n" % port)
    sys.stderr.flush()
    server.serve_forever()


if __name__ == "__main__":
    main()