"use client";

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

import { resolveThreadQueryIntent } from "@/core/threads/utils";

export function useThreadChat() {
  const pathname = usePathname();
  const params = useParams<{ thread_id?: string }>();
  // 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 threadIdFromPath = isNewRoute ? undefined : 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);
  // 持久化兜底：用于处理首屏水合或 params 时序问题。
  const readStoredThreadId = () => {
    if (typeof window === "undefined") {
      return undefined;
    }
    const stored = window.sessionStorage.getItem("workspace.thread_id");
    return isValidThreadId(stored) ? stored : undefined;
  };

  const searchParams = useSearchParams();
  // 读取 query 的 thread_id（先用 hook，必要时用 window 兜底）。
  const readQueryThreadId = () => {
    const fromHook = searchParams.get("thread_id")?.trim();
    if (isValidThreadId(fromHook)) {
      return fromHook;
    }
    if (typeof window === "undefined") {
      return undefined;
    }
    const fromLocation = new URLSearchParams(window.location.search).get(
      "thread_id",
    );
    if (isValidThreadId(fromLocation)) {
      return fromLocation.trim();
    }
    return undefined;
  };
  
  const queryThreadIdFromParams = readQueryThreadId();
  // console.log("[useThreadChat] query.thread_id", queryThreadIdFromParams);
  // 归一化：当值为 "new" 时，替换为 query 中的 thread_id（如果存在）。
  const normalizeThreadId = useCallback(
    (value?: string | null) => {
      if (!value) {
        return undefined;
      }
      return value === "new" ? queryThreadIdFromParams : value;
    },
    [queryThreadIdFromParams],
  );
  const intent = resolveThreadQueryIntent({
    pathThreadId: threadIdFromPath,
    queryThreadId: queryThreadIdFromParams,
    isNewRoute,
  });
  const { isNewThread: isNewRequested, showWelcomeStyle, invalidNewRoute } = intent;
  const effectiveThreadIdFromPath =
    invalidNewRoute
      ? undefined
      : normalizeThreadId(threadIdFromPath) ??
        (isNewRoute ? undefined : readStoredThreadId());
  // console.log("[useThreadChat] effectiveThreadIdFromPath", effectiveThreadIdFromPath);
  
  const [threadId, setThreadId] = useState(() => {
    return effectiveThreadIdFromPath ?? undefined;
  });

  // New session is only controlled by `/workspace/chats/new`.
  const [isNewThread, setIsNewThread] = useState(() => isNewRequested);

  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(
      invalidNewRoute ? undefined : normalizeThreadId(threadIdFromPath),
    );
  }, [
    invalidNewRoute,
    isNewRoute,
    normalizeThreadId,
    pathname,
    searchParams,
    threadId,
    threadIdFromPath,
  ]);
  const isMock = searchParams.get("mock") === "true";
  return {
    threadId,
    isNewThread,
    setIsNewThread,
    isMock,
    showWelcomeStyle,
    invalidNewRoute,
  };
}

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"
  );
}