const port = process.env.PORT;
const token = process.env.OPENCLAW_GATEWAY_TOKEN;
const backendModel = process.env.MODEL_REF || "openai/gpt-5.4-mini";
const timeoutSeconds = Number.parseInt(
  process.env.OPENCLAW_OPENAI_CHAT_TOOLS_TIMEOUT_SECONDS ?? "180",
  10,
);
const maxBodyBytes = Number.parseInt(
  process.env.OPENCLAW_OPENAI_CHAT_TOOLS_MAX_BODY_BYTES ?? "1048576",
  10,
);

if (!port || !token) {
  throw new Error("missing PORT/OPENCLAW_GATEWAY_TOKEN");
}
if (!Number.isFinite(timeoutSeconds) || timeoutSeconds <= 0) {
  throw new Error(`invalid OPENCLAW_OPENAI_CHAT_TOOLS_TIMEOUT_SECONDS: ${timeoutSeconds}`);
}
if (!Number.isFinite(maxBodyBytes) || maxBodyBytes <= 0) {
  throw new Error(`invalid OPENCLAW_OPENAI_CHAT_TOOLS_MAX_BODY_BYTES: ${maxBodyBytes}`);
}

async function readBoundedResponseText(response, byteLimit) {
  const reader = response.body?.getReader();
  if (!reader) {
    return "";
  }
  const chunks = [];
  let totalBytes = 0;
  for (;;) {
    const { done, value } = await reader.read();
    if (done) {
      break;
    }
    totalBytes += value.byteLength;
    if (totalBytes > byteLimit) {
      await reader.cancel();
      throw new Error(`chat completions response body exceeded ${byteLimit} bytes`);
    }
    chunks.push(Buffer.from(value));
  }
  return Buffer.concat(chunks, totalBytes).toString("utf8");
}

const controller = new AbortController();
const timeout = setTimeout(() => controller.abort(), timeoutSeconds * 1000);
const started = Date.now();
let response;
let text;
try {
  response = await fetch(`http://127.0.0.1:${port}/v1/chat/completions`, {
    method: "POST",
    headers: {
      authorization: `Bearer ${token}`,
      "content-type": "application/json",
      "x-openclaw-model": backendModel,
    },
    body: JSON.stringify({
      model: "openclaw",
      stream: false,
      messages: [
        {
          role: "user",
          content:
            "Use the get_weather tool exactly once for Paris, France. Return the tool call only.",
        },
      ],
      tool_choice: "auto",
      tools: [
        {
          type: "function",
          function: {
            name: "get_weather",
            description: "Return weather for a city.",
            strict: true,
            parameters: {
              type: "object",
              additionalProperties: false,
              properties: {
                city: { type: "string", description: "City and country." },
              },
              required: ["city"],
            },
          },
        },
      ],
    }),
    signal: controller.signal,
  });
  text = await readBoundedResponseText(response, maxBodyBytes);
} finally {
  clearTimeout(timeout);
}

let body;
try {
  body = text ? JSON.parse(text) : {};
} catch {
  throw new Error(`non-JSON response ${response.status}: ${text}`);
}

if (!response.ok) {
  throw new Error(`chat completions request failed ${response.status}: ${JSON.stringify(body)}`);
}

const choice = body.choices?.[0];
const toolCalls = choice?.message?.tool_calls;
if (choice?.finish_reason !== "tool_calls") {
  throw new Error(`expected finish_reason tool_calls: ${JSON.stringify(body)}`);
}
if (!Array.isArray(toolCalls) || toolCalls.length !== 1) {
  throw new Error(`expected exactly one tool call: ${JSON.stringify(body)}`);
}
const [toolCall] = toolCalls;
if (toolCall?.type !== "function" || toolCall?.function?.name !== "get_weather") {
  throw new Error(`unexpected tool call: ${JSON.stringify(toolCall)}`);
}

let args = {};
try {
  args = JSON.parse(toolCall.function.arguments || "{}");
} catch {
  throw new Error(`tool arguments were not valid JSON: ${toolCall.function.arguments}`);
}
if (typeof args.city !== "string" || !/paris/i.test(args.city)) {
  throw new Error(`expected Paris city argument: ${JSON.stringify(args)}`);
}

console.log(
  JSON.stringify({
    ok: true,
    elapsedMs: Date.now() - started,
    finishReason: choice.finish_reason,
    toolName: toolCall.function.name,
    args,
  }),
);