# Fred Baptiste Python Deep Dive (Part 2 - Iterators and Generators)

from functools import lru_cache

class Fib:
    def __init__(self, n):
        self._n = n
        
    def __len__(self):
        return self._n
        
    def __getitem__(self, s):
        if isinstance(s, int):
            if s < 0:
                s = self._n + s
            if 0 < s > self._n - 1:
                raise IndexError
            return self._fib(s)
        else:
            # s = 'python'
            # s = slice(0, 6, 2)
            # print(f'[{s.start}:{s.stop}:{s.step}]')
            # print(s.indices(6))
            idx = s.indices(self._n)
            return [self._fib(n) for n in range(idx[0], idx[1], idx[2])]
            
    # https://stackabuse.com/pythons-classmethod-and-staticmethod-explained/
    @staticmethod
    @lru_cache(2**10)
    def _fib(n):
        if n < 2:
            return 1
        else:
            return Fib._fib(n-1) + Fib._fib(n-2)

f = Fib(10)
print(f[0:5])
print(f[5::-1])
print(f[5])
print(list(f))
print(f[0:10])
print(f[::-1])
print(len(f))