import type { UIMessage } from "ai";

import { act, renderHook } from "@testing-library/react";
import { describe, expect, mock, test } from "bun:test";

import { useChatScroll } from "../../../src/web/consoles/workbench/components/chat/use-chat-scroll";

interface MockedElement {
  addEventListener: ReturnType<typeof mock>;
  clientHeight: number;
  removeEventListener: ReturnType<typeof mock>;
  scrollHeight: number;
  scrollTo: ReturnType<typeof mock>;
  scrollTop: number;
}

function asHTMLElement(el: MockedElement): HTMLElement {
  return el as unknown as HTMLElement;
}

function asRef(el: MockedElement): React.RefObject<HTMLElement | null> {
  return { current: asHTMLElement(el) };
}

function createScrollElement(overrides: Partial<MockedElement> = {}): MockedElement {
  return {
    addEventListener: mock(() => {}),
    clientHeight: 400,
    removeEventListener: mock(() => {}),
    scrollHeight: 1000,
    scrollTo: mock(() => {}),
    scrollTop: 600,
    ...overrides,
  };
}

describe("useChatScroll", () => {
  test("在底部附近时自动滚动", () => {
    const el = createScrollElement({ scrollHeight: 1000, scrollTop: 920 });
    const scrollRef = asRef(el);
    const messages: UIMessage[] = [{ id: "1", parts: [], role: "user" }] as UIMessage[];

    const { rerender } = renderHook(
      ({
        messages,
        scrollRef,
        status,
      }: {
        messages: UIMessage[];
        scrollRef: React.RefObject<HTMLElement | null>;
        status: string;
      }) => useChatScroll({ messages, scrollRef, status }),
      {
        initialProps: { messages, scrollRef, status: "streaming" },
      },
    );

    const newMessages: UIMessage[] = [
      { id: "1", parts: [], role: "user" },
      { id: "2", parts: [], role: "assistant" },
    ] as UIMessage[];

    rerender({ messages: newMessages, scrollRef, status: "streaming" });

    expect(el.scrollTo).toHaveBeenCalled();
  });

  test("不在底部时不自动滚动", () => {
    const el = createScrollElement({ scrollHeight: 1000, scrollTop: 200 });
    const scrollRef = asRef(el);
    const messages: UIMessage[] = [{ id: "1", parts: [], role: "user" }] as UIMessage[];

    const { rerender } = renderHook(
      ({
        messages,
        scrollRef,
        status,
      }: {
        messages: UIMessage[];
        scrollRef: React.RefObject<HTMLElement | null>;
        status: string;
      }) => useChatScroll({ messages, scrollRef, status }),
      {
        initialProps: { messages, scrollRef, status: "streaming" },
      },
    );

    const handlerCalls = el.addEventListener.mock.calls as unknown[][];
    const scrollHandler = handlerCalls.find((c) => c[0] === "scroll")?.[1];

    if (scrollHandler) {
      el.scrollTop = 200;
      (scrollHandler as () => void)();
    }

    el.scrollTo.mockClear();

    const newMessages: UIMessage[] = [
      { id: "1", parts: [], role: "user" },
      { id: "2", parts: [], role: "assistant" },
    ] as UIMessage[];

    rerender({ messages: newMessages, scrollRef, status: "streaming" });

    const scrollToCalls = el.scrollTo.mock.calls as unknown[][];
    expect(scrollToCalls.length).toBe(0);
  });

  test("scrollToBottom 使用 smooth 滚动", () => {
    const el = createScrollElement({ scrollHeight: 1000, scrollTop: 200 });
    const scrollRef = asRef(el);
    const messages: UIMessage[] = [];

    const { result } = renderHook(() => useChatScroll({ messages, scrollRef, status: "ready" }));

    act(() => {
      result.current.scrollToBottom();
    });

    expect(el.scrollTo).toHaveBeenCalledWith({ behavior: "smooth", top: 1000 });
  });

  test("流式时使用 instant 滚动", () => {
    const el = createScrollElement({ scrollHeight: 1000, scrollTop: 920 });
    const scrollRef = asRef(el);
    const messages: UIMessage[] = [{ id: "1", parts: [], role: "user" }] as UIMessage[];

    renderHook(() => useChatScroll({ messages, scrollRef, status: "streaming" }));

    const calls = el.scrollTo.mock.calls as unknown[][];
    const instantCall = calls.find((call) => {
      const opts = call[0] as Record<string, unknown> | undefined;
      return opts?.["behavior"] === "instant";
    });
    expect(instantCall).toBeTruthy();
  });
});