from tudelft.utilities.immutablelist.AbstractImmutableList import AbstractImmutableList
from typing import TypeVar
from tudelft.utilities.immutablelist.ImmutableList import ImmutableList

E = TypeVar('E')
class Repeat (AbstractImmutableList[E]):
	'''
	Creates repeated list.
	
	@param <E> type of the elements
	'''

	def __init__(self,lst: ImmutableList[E] , n:int, isHeadToTail:bool): 
		'''
		A n-time repeat of another list.
		
		@param list         the list to be repeated
		@param n            the number of repeats of the list
		@param isHeadToTail suppose list=[1,2,3] and n=2. if true, the lists are
		                    repeated head to tail, eg [1,2,3,1,2,3]. if false,
		                    the lists are repeated per-element, eg [1,1,2,2,3,3].
		'''
		if lst == None or n == None:
			raise ValueError("list and n must be not null")
		self.__lst:ImmutableList[E] = lst
		self.__n:int = n
		self.__isHeadToTail:bool = isHeadToTail
		self.__listsize:int = lst.size()
		self.__fullsize:int = self.__listsize * n

	#Override
	def get(self, index:int) ->E:
		if index >= self.__fullsize:
			raise IndexError("Requested index " + str(index) + " > list size")
		if self.__isHeadToTail:
			return self.__lst.get(index % self.__listsize)
		else:
			# divide returns floor(a/b)
			return self.__lst.get(index // self.__n)

	#Override
	def  size(self) ->int:
		return self.__fullsize