Sessions.scala

import java.text.SimpleDateFormat
import java.util.{Calendar, Date}

object Sessions extends App {

  def survey(logs: List[String]): Boolean = {

    val formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")
    val dates: List[Date] = logs.map(formatter.parse).sortBy(_.getTime)

    def getCalendar(d: Date): Calendar = {
      val c = Calendar.getInstance()
      c.setTime(d)
      c
    }

    def sameDay(d1: Date, d2: Date): Boolean = {
      val c1 = getCalendar(d1)
      val c2 = getCalendar(d2)
      c1.get(Calendar.YEAR) == c2.get(Calendar.YEAR) &&
        c1.get(Calendar.DAY_OF_YEAR) == c2.get(Calendar.DAY_OF_YEAR)
    }

    def nextDay(d1: Date, d2: Date): Boolean = {
      val c1 = getCalendar(d1)
      val c2 = getCalendar(d2)
      c1.add(Calendar.DATE, 1)
      c1.get(Calendar.YEAR) == c2.get(Calendar.YEAR) &&
        c1.get(Calendar.DAY_OF_YEAR) == c2.get(Calendar.DAY_OF_YEAR)
    }

    def threeDays(dates: List[Date]): Boolean = {
      var consecutive = 1
      for(i <- 0 until dates.length - 1) {
        val current = dates(i)
        val next = dates(i + 1)
        if (nextDay(current, next)) consecutive += 1
        else if (!sameDay(current, next)) consecutive = 1
        if(consecutive >= 3) return true
      }
      false
    }

    def sixSessions(dates: List[Date]): Boolean = {
      var sessions = 1
      for(i <- 0 until dates.length - 1) {
        val c = getCalendar(dates(i))
        c.add(Calendar.MINUTE, 10)
        if(dates(i + 1).after(c.getTime)) sessions += 1
        if (sessions >= 6) return true
      }
      false
    }

    threeDays(dates) && sixSessions(dates)
  }

}