import { useState } from 'react'

interface EventScheduleConstraintInput {
  now: Date
  startDate?: string
  startTime?: number
  endDate?: string
}

export interface EventScheduleConstraints {
  todayIso: string
  startMinimumTime: number
  endMinimumTime: number
}

function isSameLocalDate(first: string | undefined, second: string): boolean {
  if (!first) return false

  const firstDate = new Date(first)
  const secondDate = new Date(second)

  return (
    Number.isFinite(firstDate.getTime()) &&
    Number.isFinite(secondDate.getTime()) &&
    firstDate.getFullYear() === secondDate.getFullYear() &&
    firstDate.getMonth() === secondDate.getMonth() &&
    firstDate.getDate() === secondDate.getDate()
  )
}

export function getEventScheduleConstraints({
  now,
  startDate,
  startTime,
  endDate,
}: EventScheduleConstraintInput): EventScheduleConstraints {
  const today = new Date(now)

  today.setHours(0, 0, 0, 0)
  const todayIso = today.toISOString()
  const nextMinute = Math.min(1440, now.getHours() * 60 + now.getMinutes() + 1)
  const startMinimumTime = isSameLocalDate(startDate, todayIso) ? nextMinute : 0
  const endMinimumTime = isSameLocalDate(endDate, startDate || todayIso)
    ? Math.max(0, (startTime ?? 0) + 1)
    : isSameLocalDate(endDate, todayIso)
      ? nextMinute
      : 0

  return { todayIso, startMinimumTime, endMinimumTime }
}

export function useEventScheduleConstraints(
  startDate: string | undefined,
  startTime: number | undefined,
  endDate: string | undefined
): EventScheduleConstraints {
  const [constraintNow] = useState(() => new Date())

  return getEventScheduleConstraints({
    now: constraintNow,
    startDate,
    startTime,
    endDate,
  })
}