import React, { useState } from "react";
import { describe, it, expect, vi, beforeEach } from "vitest";
import { render, screen, fireEvent } from "@testing-library/react";
import { Board } from "../Board";
import { ListView } from "../ListView";
import "../../styles.css";

vi.mock("../../api", () => ({
  fetchWorkflowSteps: vi.fn().mockResolvedValue([]),
  fetchModels: vi.fn().mockResolvedValue({ models: [], favoriteProviders: [], favoriteModels: [] }),
  fetchSettings: vi.fn().mockResolvedValue({
    modelPresets: [],
    autoSelectModelPreset: false,
    defaultPresetBySize: {},
    maxConcurrent: 2,
    maxWorktrees: 4,
    pollIntervalMs: 30000,
    groupOverlappingFiles: true,
    autoMerge: true,
  }),
  fetchTaskDetail: vi.fn(),
  batchUpdateTaskModels: vi.fn(),
  fetchNodes: vi.fn().mockResolvedValue([]),
}));

vi.mock("../../hooks/useConfirm", () => ({
  useConfirm: () => ({ confirm: vi.fn() }),
}));

vi.mock("../../hooks/useBadgeWebSocket", () => ({
  useBadgeWebSocket: () => ({
    badgeUpdates: new Map(),
    isConnected: false,
    subscribeToBadge: vi.fn(),
    unsubscribeFromBadge: vi.fn(),
  }),
}));

vi.mock("../../hooks/useSessionFiles", () => ({
  useSessionFiles: () => ({ files: [], loading: false }),
}));

vi.mock("../../hooks/useTaskDiffStats", () => ({
  useTaskDiffStats: () => ({ stats: null, loading: false }),
}));

vi.mock("../Column", () => ({
  Column: React.memo(({ column }: { column: string }) => (
    <div data-testid={`column-${column}`} />
  )),
}));

function ensureMatchMedia() {
  if (!window.matchMedia) {
    Object.defineProperty(window, "matchMedia", {
      writable: true,
      value: vi.fn(),
    });
  }
}

function mockMobileViewport() {
  ensureMatchMedia();
  Object.defineProperty(window, "innerWidth", { value: 375, configurable: true });
  return vi.spyOn(window, "matchMedia").mockImplementation((query: string) => ({
    matches: query === "(max-width: 768px)",
    media: query,
    onchange: null,
    addListener: vi.fn(),
    removeListener: vi.fn(),
    addEventListener: vi.fn(),
    removeEventListener: vi.fn(),
    dispatchEvent: vi.fn(),
  }));
}

function ViewSwitchHarness() {
  const [view, setView] = useState<"list" | "board">("list");

  const boardProps = {
    tasks: [],
    maxConcurrent: 2,
    onMoveTask: vi.fn(async () => ({}) as any),
    onOpenDetail: vi.fn(),
    addToast: vi.fn(),
    onQuickCreate: vi.fn(async () => ({}) as any),
    onNewTask: vi.fn(),
    autoMerge: true,
    onToggleAutoMerge: vi.fn(),
    globalPaused: false,
  };

  const listProps = {
    tasks: [],
    onMoveTask: vi.fn(async () => ({}) as any),
    onRetryTask: vi.fn(async () => ({}) as any),
    onDeleteTask: vi.fn(async () => ({}) as any),
    onMergeTask: vi.fn(async () => ({ merged: false })),
    onOpenDetail: vi.fn(),
    addToast: vi.fn(),
    onNewTask: vi.fn(),
    projectId: "proj-123",
  };

  return (
    <div>
      <button data-testid="switch-to-list" onClick={() => setView("list")}>
        List
      </button>
      <button data-testid="switch-to-board" onClick={() => setView("board")}>
        Board
      </button>
      <div className="project-content">
        {view === "board" ? <Board {...boardProps} /> : <ListView {...listProps} />}
      </div>
    </div>
  );
}

describe("Board mobile view switch (FN-001)", () => {
  beforeEach(() => {
    vi.clearAllMocks();
    localStorage.clear();
  });

  it("renders .board as <main> with the board class after switching from list view on mobile", () => {
    const viewportSpy = mockMobileViewport();

    render(<ViewSwitchHarness />);

    // Start in list view
    expect(document.querySelector(".list-view")).not.toBeNull();
    expect(document.querySelector(".board")).toBeNull();

    // Switch to board view
    fireEvent.click(screen.getByTestId("switch-to-board"));

    const board = document.querySelector(".board");
    expect(board).not.toBeNull();
    expect(board!.tagName).toBe("MAIN");
    expect(board!.id).toBe("board");

    viewportSpy.mockRestore();
  });

  it("preserves board structure through list -> board -> list -> board cycle on mobile", () => {
    const viewportSpy = mockMobileViewport();

    render(<ViewSwitchHarness />);

    fireEvent.click(screen.getByTestId("switch-to-board"));
    expect(document.querySelector(".board")).not.toBeNull();
    expect(document.querySelector(".list-view")).toBeNull();

    fireEvent.click(screen.getByTestId("switch-to-list"));
    expect(document.querySelector(".list-view")).not.toBeNull();
    expect(document.querySelector(".board")).toBeNull();

    fireEvent.click(screen.getByTestId("switch-to-board"));
    const board = document.querySelector(".board");
    expect(board).not.toBeNull();
    expect(board!.tagName).toBe("MAIN");

    viewportSpy.mockRestore();
  });

  it("does not reintroduce scroll-snap-type: x mandatory after switching on mobile", () => {
    const viewportSpy = mockMobileViewport();

    render(<ViewSwitchHarness />);
    fireEvent.click(screen.getByTestId("switch-to-board"));

    const board = document.querySelector(".board") as HTMLElement;
    expect(board).not.toBeNull();
    expect(board.className).toContain("board");

    viewportSpy.mockRestore();
  });
});