import type { Page } from '@playwright/test'
import { expect } from '@playwright/test'

// Swedish labels from src/i18n/sv/calendar.ts — the suite pins
// `locale: 'sv-SE'` in playwright.config.ts so these are stable.
const MONTH_SELECT_LABEL = 'Välj månad'
const YEAR_SELECT_LABEL = 'Välj år'

/** Navigate the Calendar page to the month containing `date` (UTC). */
export async function goToCalendarMonth(page: Page, date: Date): Promise<void> {
  await page.goto('/calendar')
  await expect(page.getByTestId('calendar')).toBeVisible()

  await page.getByLabel(YEAR_SELECT_LABEL).selectOption(String(date.getUTCFullYear()))
  await page.getByLabel(MONTH_SELECT_LABEL).selectOption(String(date.getUTCMonth()))
}

/** The exact `data-testid="calendar-day"` cell for an ISO date, wherever it
 * falls in the currently-displayed grid (including a leading/trailing day
 * from an adjacent month). */
export function calendarDayCell(page: Page, isoDate: string) {
  return page.locator(`[data-testid="calendar-day"][aria-label^="${isoDate}"]`)
}

/**
 * Drives a real drag-select across the given ISO dates (in order), the way
 * `Calendar.tsx` expects it: `CalendarDay` wires plain `onPointerDown`/
 * `onPointerEnter` handlers (see `CalendarWeek.tsx`), and the page only
 * treats the gesture as a multi-day drag if `pointerenter` actually fired
 * for every intermediate cell before `pointerup` — see the `dates.length
 * === 1` branch in `Calendar.tsx`'s `pointerup` handler, which opens the
 * single-day modal instead of creating a period.
 *
 * A single fast `mouse.move` (or Playwright's default `hover()`/`dragTo()`)
 * can collapse into one native pointer event and skip the intermediate
 * cells entirely, which reads as a click on the anchor date. Moving in
 * several steps per cell, with a short pause between cells, is what
 * reliably fires a `pointerenter` on each one.
 */
export async function dragSelectDates(page: Page, isoDates: string[]): Promise<void> {
  if (isoDates.length < 2) {
    throw new Error('dragSelectDates needs at least two dates to actually drag across')
  }

  const centerOf = async (isoDate: string): Promise<{ x: number; y: number }> => {
    const box = await calendarDayCell(page, isoDate).boundingBox()
    if (!box) throw new Error(`calendar day cell not visible for ${isoDate} — is it in the current month view?`)
    return { x: box.x + box.width / 2, y: box.y + box.height / 2 }
  }

  const [firstDate, ...restDates] = isoDates
  if (!firstDate) throw new Error('dragSelectDates needs at least two dates to actually drag across')
  const start = await centerOf(firstDate)
  await page.mouse.move(start.x, start.y)
  await page.mouse.down()

  for (const isoDate of restDates) {
    const point = await centerOf(isoDate)
    await page.mouse.move(point.x, point.y, { steps: 10 })
    await page.waitForTimeout(50)
  }

  await page.mouse.up()
}