import React from 'react';
import { render, screen, fireEvent } from '@testing-library/react';
import dayjs from 'dayjs';

import { DateRangeFields } from '@/components/ds/DateRangeFields';

/**
 * The two ranges that can only ever return nothing.
 *
 * Both were accepted silently by the report pages before this component
 * existed: an inverted range (from 30 Sep, to 1 Sep) and a future one. Neither
 * input reported invalid, no message appeared, and the table showed zero rows —
 * which an operator reads as "no orders in this period" rather than "this
 * filter is impossible". An empty result presented as a finding is the same
 * class of defect as a silently truncated count.
 *
 * `min`/`max` cover the picker, which is how it is actually used. The clamp in
 * onChange covers typing and pasting, which ignore those attributes — so both
 * are asserted here.
 */

const today = dayjs().format('YYYY-MM-DD');
const yesterday = dayjs().subtract(1, 'day').format('YYYY-MM-DD');
const lastWeek = dayjs().subtract(7, 'day').format('YYYY-MM-DD');
const nextYear = dayjs().add(1, 'year').format('YYYY-MM-DD');

const setup = (value) => {
  const onChange = jest.fn();
  render(<DateRangeFields value={value} onChange={onChange} />);
  return {
    onChange,
    from: screen.getByLabelText('From date'),
    to: screen.getByLabelText('To date')
  };
};

describe('bounds the picker itself', () => {
  it('neither field offers a day after today', () => {
    const { from, to } = setup({ from: lastWeek, to: yesterday });
    expect(to).toHaveAttribute('max', today);
    // from is capped by the to-date, which is tighter than today here
    expect(from).toHaveAttribute('max', yesterday);
  });

  it('the to-field cannot go earlier than the from-field', () => {
    const { to } = setup({ from: lastWeek, to: today });
    expect(to).toHaveAttribute('min', lastWeek);
  });

  it('with no to-date yet, from is capped at today', () => {
    const { from } = setup({ from: '', to: '' });
    expect(from).toHaveAttribute('max', today);
  });
});

describe('clamps what the picker cannot — typing and pasting', () => {
  it('a future from-date is pulled back to today', () => {
    const { from, onChange } = setup({ from: today, to: today });
    fireEvent.change(from, { target: { value: nextYear } });
    expect(onChange).toHaveBeenCalledWith({ from: today, to: today });
  });

  it('a future to-date is pulled back to today', () => {
    const { to, onChange } = setup({ from: lastWeek, to: today });
    fireEvent.change(to, { target: { value: nextYear } });
    expect(onChange).toHaveBeenCalledWith({ from: lastWeek, to: today });
  });

  it('moving from PAST to drags to along, rather than inverting', () => {
    // The edit is honoured — you have moved to a later period — and the other
    // end follows. Rejecting the keystroke with no explanation is worse.
    const { from, onChange } = setup({ from: lastWeek, to: yesterday });
    fireEvent.change(from, { target: { value: today } });
    expect(onChange).toHaveBeenCalledWith({ from: today, to: today });
  });

  it('moving to BEFORE from drags from back, rather than inverting', () => {
    const { to, onChange } = setup({ from: yesterday, to: today });
    fireEvent.change(to, { target: { value: lastWeek } });
    expect(onChange).toHaveBeenCalledWith({ from: lastWeek, to: lastWeek });
  });

  it('never emits a range where from is after to', () => {
    // The property, stated once. Every emission from any edit must hold it.
    const cases = [
      [{ from: lastWeek, to: yesterday }, 'From date', today],
      [{ from: yesterday, to: today }, 'To date', lastWeek],
      [{ from: today, to: today }, 'From date', nextYear],
      [{ from: lastWeek, to: today }, 'To date', nextYear]
    ];
    cases.forEach(([value, label, typed]) => {
      const onChange = jest.fn();
      const { unmount } = render(<DateRangeFields value={value} onChange={onChange} />);
      fireEvent.change(screen.getByLabelText(label), { target: { value: typed } });
      const next = onChange.mock.calls[0][0];
      expect(next.from <= next.to).toBe(true);
      expect(next.to <= today).toBe(true);
      unmount();
    });
  });
});

describe('a cleared field is not an invalid one', () => {
  it('passes an empty value through untouched', () => {
    const { to, onChange } = setup({ from: lastWeek, to: today });
    fireEvent.change(to, { target: { value: '' } });
    expect(onChange).toHaveBeenCalledWith({ from: lastWeek, to: '' });
  });
});

describe('the ceiling is overridable', () => {
  it('max={null} allows a future date, for a picker that should look ahead', () => {
    const onChange = jest.fn();
    render(<DateRangeFields value={{ from: today, to: today }} onChange={onChange} max={null} />);
    const from = screen.getByLabelText('From date');
    fireEvent.change(from, { target: { value: nextYear } });
    expect(onChange).toHaveBeenCalledWith({ from: nextYear, to: nextYear });
  });
});