import { describe, it, expect, vi, beforeEach } from "vitest";
import { render, screen, fireEvent, waitFor } from "@testing-library/react";
import { UnsavedChangesDialog } from "@/components/po/unsaved-changes-dialog";
import { useUnsavedChanges } from "@/components/po/use-unsaved-changes";

const push = vi.fn();
vi.mock("next/navigation", () => ({
  useRouter: () => ({ push, back: vi.fn() }),
}));

beforeEach(() => {
  push.mockReset();
});

// ── Dialog ────────────────────────────────────────────────────────────────────

describe("UnsavedChangesDialog", () => {
  const noop = async () => ({ ok: true });

  it("renders the three choices when open", () => {
    render(
      <UnsavedChangesDialog open onSaveDraft={noop} onDiscard={vi.fn()} onStay={vi.fn()} />
    );
    expect(screen.getByRole("button", { name: /save as draft/i })).toBeInTheDocument();
    expect(screen.getByRole("button", { name: /discard changes/i })).toBeInTheDocument();
    expect(screen.getByRole("button", { name: /stay on page/i })).toBeInTheDocument();
  });

  it("renders nothing when closed", () => {
    const { container } = render(
      <UnsavedChangesDialog open={false} onSaveDraft={noop} onDiscard={vi.fn()} onStay={vi.fn()} />
    );
    expect(container).toBeEmptyDOMElement();
  });

  it("invokes onDiscard / onStay when those buttons are clicked", () => {
    const onDiscard = vi.fn();
    const onStay = vi.fn();
    render(
      <UnsavedChangesDialog open onSaveDraft={noop} onDiscard={onDiscard} onStay={onStay} />
    );
    fireEvent.click(screen.getByRole("button", { name: /discard changes/i }));
    expect(onDiscard).toHaveBeenCalledOnce();
    fireEvent.click(screen.getByRole("button", { name: /stay on page/i }));
    expect(onStay).toHaveBeenCalledOnce();
  });

  it("shows an error and keeps the prompt open when saving the draft fails", async () => {
    const onSaveDraft = vi.fn(async () => ({ ok: false, error: "Title is required" }));
    const onStay = vi.fn();
    render(
      <UnsavedChangesDialog open onSaveDraft={onSaveDraft} onDiscard={vi.fn()} onStay={onStay} />
    );
    fireEvent.click(screen.getByRole("button", { name: /save as draft/i }));
    expect(onSaveDraft).toHaveBeenCalledOnce();
    await waitFor(() => expect(screen.getByText("Title is required")).toBeInTheDocument());
    // still open — user can recover
    expect(onStay).not.toHaveBeenCalled();
    expect(screen.getByRole("button", { name: /stay on page/i })).toBeInTheDocument();
  });

  it("uses a custom save label when provided", () => {
    render(
      <UnsavedChangesDialog open onSaveDraft={noop} onDiscard={vi.fn()} onStay={vi.fn()} saveLabel="Save Draft" />
    );
    expect(screen.getByRole("button", { name: "Save Draft" })).toBeInTheDocument();
  });
});

// ── Hook ────────────────────────────────────────────────────────────────────

function Harness({ dirty }: { dirty: boolean }) {
  const { promptOpen, guard, leave, stay } = useUnsavedChanges(dirty);
  return (
    <div>
      <span data-testid="open">{String(promptOpen)}</span>
      <a href="/dashboard">internal link</a>
      <a href="/po/new#section">same page anchor</a>
      <a href="https://example.com/x">external link</a>
      <button onClick={() => guard(() => push("/programmatic"))}>cancel</button>
      <button onClick={leave}>leave</button>
      <button onClick={stay}>stay</button>
    </div>
  );
}

describe("useUnsavedChanges", () => {
  it("intercepts internal link clicks while dirty", () => {
    render(<Harness dirty />);
    expect(screen.getByTestId("open")).toHaveTextContent("false");
    fireEvent.click(screen.getByText("internal link"));
    expect(screen.getByTestId("open")).toHaveTextContent("true");
    expect(push).not.toHaveBeenCalled();
  });

  it("does not intercept link clicks when clean", () => {
    render(<Harness dirty={false} />);
    fireEvent.click(screen.getByText("internal link"));
    expect(screen.getByTestId("open")).toHaveTextContent("false");
  });

  it("ignores external links", () => {
    render(<Harness dirty />);
    fireEvent.click(screen.getByText("external link"));
    expect(screen.getByTestId("open")).toHaveTextContent("false");
  });

  it("intercepts guarded programmatic navigation while dirty, then proceeds on leave", () => {
    render(<Harness dirty />);
    fireEvent.click(screen.getByText("cancel"));
    expect(screen.getByTestId("open")).toHaveTextContent("true");
    expect(push).not.toHaveBeenCalled();
    fireEvent.click(screen.getByText("leave"));
    expect(push).toHaveBeenCalledWith("/programmatic");
    expect(screen.getByTestId("open")).toHaveTextContent("false");
  });

  it("runs programmatic navigation immediately when clean", () => {
    render(<Harness dirty={false} />);
    fireEvent.click(screen.getByText("cancel"));
    expect(push).toHaveBeenCalledWith("/programmatic");
    expect(screen.getByTestId("open")).toHaveTextContent("false");
  });

  it("closes the prompt without navigating on stay", () => {
    render(<Harness dirty />);
    fireEvent.click(screen.getByText("cancel"));
    expect(screen.getByTestId("open")).toHaveTextContent("true");
    fireEvent.click(screen.getByText("stay"));
    expect(screen.getByTestId("open")).toHaveTextContent("false");
    expect(push).not.toHaveBeenCalled();
  });

  it("warns via beforeunload while dirty", () => {
    render(<Harness dirty />);
    const evt = new Event("beforeunload", { cancelable: true });
    window.dispatchEvent(evt);
    expect(evt.defaultPrevented).toBe(true);
  });

  it("does not warn via beforeunload when clean", () => {
    render(<Harness dirty={false} />);
    const evt = new Event("beforeunload", { cancelable: true });
    window.dispatchEvent(evt);
    expect(evt.defaultPrevented).toBe(false);
  });
});