"use client";

import { useParams, usePathname, useSearchParams } from "next/navigation";
import { useEffect, useState } from "react";


export function useThreadChat() {
  const pathname = usePathname();
  const params = useParams<{ thread_id: string }>();
  const searchParams = useSearchParams();
  const threadIdFromSearchParams = searchParams.get("thread_id")?.trim();
  // showWelcomeStyle的子判断
  const isChattingFromQuery = (() => {
    const isChatting = searchParams.get("is_chatting");
    return isChatting === "true";
  })();
  // 兜底：当 params 还未就绪时，从 pathname 解析 thread_id。
  const threadIdFromPathname = (() => {
    const parts = pathname.split("?")[0]?.split("/") ?? [];
    const idx = parts.lastIndexOf("chats");
    if (idx >= 0 && parts.length > idx + 1) {
      return parts[idx + 1];
    }
    return undefined;
  })();
  const rawPathThreadId = params?.thread_id ?? threadIdFromPathname;

  const isNewRoute = rawPathThreadId === "new";
  const threadIdFromPathOrParams = isNewRoute
    ? normalizeThreadId(threadIdFromSearchParams)
    : normalizeThreadId(rawPathThreadId);
  // console.log("[useThreadChat] pathname", pathname);
  // console.log("[useThreadChat] params.thread_id", params?.thread_id);
  // console.log("[useThreadChat] threadIdFromPathname", threadIdFromPathname);
  // console.log("[useThreadChat] threadIdFromPath", threadIdFromPath);
  // New session is only controlled by `/workspace/chats/new`.
  const [isNewThread, setIsNewThread] = useState(() => isNewRoute);

  const [showWelcomeStyle, setShowWelcomeStyle] = useState(() => {
    return isNewRoute || !isChattingFromQuery;
  });
  // console.log("[useThreadChat] effectiveThreadIdFromPath", effectiveThreadIdFromPath);

  const [threadId, setThreadId] = useState<string>(() => {
    return threadIdFromPathOrParams ?? "";
  });


  useEffect(() => {
    // 记住最近一次有效的 thread_id，供下次加载兜底使用。
    if (threadId && threadId !== "new" && typeof window !== "undefined") {
      window.sessionStorage.setItem("workspace.thread_id", threadId);
    }
    setIsNewThread(isNewRoute);
    // Prefer path thread id, fall back to query thread_id when path is /new.
    setThreadId(threadIdFromPathOrParams ?? "");
    setShowWelcomeStyle(isNewRoute || !isChattingFromQuery);
  }, [
    isNewRoute,
    pathname,
    searchParams,
    isChattingFromQuery,
    threadId,
    threadIdFromPathOrParams,
  ]);
  const isMock = searchParams.get("mock") === "true";
  return {
    threadId,
    isNewThread,
    setIsNewThread,
    isMock,
    showWelcomeStyle,
  };
}

function normalizeThreadId(value?: string | null): string | undefined {
  if (!value) return undefined;
  return isValidThreadId(value) ? value.trim() : undefined;
}

function isValidThreadId(value?: string | null): value is string {
  if (!value) return false;
  const normalized = value.trim().toLowerCase();
  return (
    normalized.length > 0 &&
    normalized !== "new" &&
    normalized !== "undefined" &&
    normalized !== "null"
  );
}