"use client";

import { useParams, usePathname, useRouter } from "next/navigation";
import {
  createContext,
  useCallback,
  useContext,
  useEffect,
  useRef,
  useState,
  type ReactNode,
} from "react";
import { toast } from "sonner";

import { Button } from "@/components/ui/button";
import {
  Dialog,
  DialogContent,
  DialogDescription,
  DialogFooter,
  DialogHeader,
  DialogTitle,
} from "@/components/ui/dialog";
import { resetThreadChatAfterDelete } from "@/components/workspace/chats/use-thread-chat";
import { useI18n } from "@/core/i18n/hooks";
import { useDeleteThread } from "@/core/threads/hooks";
import type { AgentThread } from "@/core/threads/types";
import { pathOfThread, titleOfThread } from "@/core/threads/utils";

type DeleteTarget = {
  thread: AgentThread;
  recentThreadId?: string | undefined;
};
const ThreadDeleteContext = createContext<
  ((target: DeleteTarget) => void) | null
>(null);

export function useThreadDeleteDialog() {
  const requestDelete = useContext(ThreadDeleteContext);
  if (!requestDelete) throw new Error("ThreadDeleteDialogProvider is required");
  return requestDelete;
}

export function ThreadDeleteDialogProvider({
  children,
}: {
  children: ReactNode;
}) {
  const { t } = useI18n();
  const router = useRouter();
  const pathname = usePathname();
  const { thread_id: threadIdFromPath, agent_name: agentNameFromPath } =
    useParams<{ thread_id: string; agent_name?: string }>();
  const {
    mutateAsync: deleteThread,
    isPending: isDeleting,
    isError: deleteFailed,
  } = useDeleteThread();
  // A partial deletion can remove the row on a list refresh. Keep its snapshot
  // and the retry dialog in this stable host, outside the virtualized lists.
  const [target, setTarget] = useState<DeleteTarget | null>(null);
  const deleteInFlight = useRef(false);
  const deleteCancelRef = useRef<HTMLButtonElement>(null);

  useEffect(() => {
    // Wait for React to re-enable the button before restoring focus.
    if (target && deleteFailed && !isDeleting) deleteCancelRef.current?.focus();
  }, [target, deleteFailed, isDeleting]);

  const handleDelete = useCallback(async () => {
    if (!target || deleteInFlight.current) return;
    const { thread, recentThreadId } = target;
    deleteInFlight.current = true;
    const currentPathname =
      typeof window === "undefined" ? pathname : window.location.pathname;
    const threadPath = pathOfThread(thread);
    const nextThreadPath = pathOfThread("new", {
      agent_name: agentNameFromPath,
    });
    const isNewThreadPath = currentPathname === nextThreadPath;
    const isCurrentThread =
      thread.thread_id === threadIdFromPath ||
      threadPath === currentPathname ||
      (isNewThreadPath && recentThreadId === thread.thread_id);

    try {
      await deleteThread({
        threadId: thread.thread_id,
        onDeleted: isCurrentThread
          ? () => {
              resetThreadChatAfterDelete({
                deletedThreadId: thread.thread_id,
                nextPath: nextThreadPath,
                force: true,
              });
              void router.replace(nextThreadPath);
            }
          : undefined,
      });
      setTarget(null);
    } catch (error) {
      console.error("Failed to delete chat:", error);
      toast.error(
        error instanceof Error && error.message
          ? error.message
          : t.chats.deleteFailed,
      );
    } finally {
      deleteInFlight.current = false;
    }
  }, [
    agentNameFromPath,
    deleteThread,
    pathname,
    router,
    target,
    threadIdFromPath,
    t.chats.deleteFailed,
  ]);

  const requestDelete = useCallback((next: DeleteTarget) => {
    if (!deleteInFlight.current) setTarget(next);
  }, []);
  return (
    <ThreadDeleteContext.Provider value={requestDelete}>
      {children}
      <Dialog
        open={target !== null}
        onOpenChange={(open) => {
          if (!open && !deleteInFlight.current) setTarget(null);
        }}
      >
        <DialogContent
          showCloseButton={!isDeleting}
          onOpenAutoFocus={(event) => {
            event.preventDefault();
            deleteCancelRef.current?.focus();
          }}
          onEscapeKeyDown={(event) => {
            if (deleteInFlight.current) event.preventDefault();
          }}
          onInteractOutside={(event) => {
            if (deleteInFlight.current) event.preventDefault();
          }}
        >
          <DialogHeader>
            <DialogTitle>{t.chats.deleteChat}</DialogTitle>
            <DialogDescription className="break-words">
              {target && t.chats.deleteConfirm(titleOfThread(target.thread))}
            </DialogDescription>
          </DialogHeader>
          <DialogFooter>
            <Button
              ref={deleteCancelRef}
              variant="outline"
              onClick={() => setTarget(null)}
              disabled={isDeleting}
            >
              {t.common.cancel}
            </Button>
            <Button
              variant="destructive"
              onClick={() => void handleDelete()}
              disabled={isDeleting}
            >
              {isDeleting ? t.common.loading : t.common.delete}
            </Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </ThreadDeleteContext.Provider>
  );
}