import { fetchAuthenticated } from "../../../auth/api-client";
import type {
  AssistantEvent,
  AssistantRequest,
} from "../../../shared/assets/assistant";

export class AssistantRequestError extends Error {
  constructor(
    message: string,
    public status: number,
  ) {
    super(message);
    this.name = "AssistantRequestError";
  }
}

export async function askAssetAssistant(
  input: AssistantRequest,
  signal: AbortSignal,
  onEvent: (event: AssistantEvent) => void,
) {
  const response = await fetchAuthenticated("/api/asset-assistant/ask", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify(input),
    signal,
  });
  if (!response.ok) {
    const body = await response.json().catch(() => null);
    throw new AssistantRequestError(
      body?.error || "查询服务暂时不可用。",
      response.status,
    );
  }
  if (!response.body) throw new Error("当前浏览器无法读取查询进度。");
  const reader = response.body.getReader();
  const decoder = new TextDecoder();
  let buffer = "",
    completed = false;
  try {
    while (true) {
      const { value, done } = await reader.read();
      buffer += decoder.decode(value, { stream: !done });
      const frames = buffer.split(/\r?\n\r?\n/);
      buffer = frames.pop() || "";
      for (const frame of frames) {
        const data = frame
          .split(/\r?\n/)
          .filter((line) => line.startsWith("data:"))
          .map((line) => line.slice(5).trim())
          .join("\n");
        if (!data) continue;
        const event = JSON.parse(data) as AssistantEvent;
        if (event.type === "result" || event.type === "error") completed = true;
        onEvent(event);
      }
      if (done) break;
    }
    if (!completed && !signal.aborted)
      throw new Error("连接中断，请重新提问。");
  } finally {
    reader.releaseLock();
  }
}