export default async (req, res) => {
  const calendarId =
    'c_e7c63a427761b0f300ede97f432ba4af24033daad26be86da0551b40b7968f00@group.calendar.google.com'
  const apiKey = 'AIzaSyD_8dEnTDle3WmaoOTvEW6L1GW540FU_wg' // Replace with your API Key

  let allBusyDays = new Set()

  try {
    const currentDateTime = new Date()
    const adjustedDateTime = new Date(
      currentDateTime.getTime() +
        (currentDateTime.getTimezoneOffset() + 240) * 60 * 1000
    ) // Adjust to GMT-04
    const startTime = adjustedDateTime.toISOString()
    const endTime = new Date(
      adjustedDateTime.getTime() + 30 * 24 * 60 * 60 * 1000
    ).toISOString()

    const response = await fetch(
      `https://www.googleapis.com/calendar/v3/freeBusy?key=${apiKey}`,
      {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json'
        },
        body: JSON.stringify({
          timeMin: startTime,
          timeMax: endTime,
          items: [{ id: calendarId }]
        })
      }
    )

    const data = await response.json()

    if (data.error) {
      return res.status(400).json({ error: data.error.message })
    }

    // Assuming there are time ranges where the calendar is busy:
    const busyTimes = data.calendars[calendarId].busy

    // For each busy time range, extract all days that are busy:
    for (let busy of busyTimes) {
      let startDate = new Date(busy.start)
      let endDate = new Date(busy.end)

      // Adjust dates to GMT-04
      startDate = new Date(
        startDate.getTime() + (startDate.getTimezoneOffset() + 240) * 60 * 1000
      )
      endDate = new Date(
        endDate.getTime() + (endDate.getTimezoneOffset() + 240) * 60 * 1000
      )

      while (startDate < endDate) {
        allBusyDays.add(startDate.toISOString().split('T')[0])
        startDate = new Date(startDate.getTime() + 24 * 60 * 60 * 1000) // Adding 24 hours for the next date
      }
    }

    return res.status(200).json([...allBusyDays])
  } catch (error) {
    return res.status(500).json({ error: 'Failed to fetch busy times.' })
  }
}