Pointers malfunctioning in the implementation of double ended queues

I learnt the below implemented logic from a book but it seems as though my front pointer isn't where it should be once I start to add elements from rear and front. The order of elements does not become as expected.

Suggestions on how I might fix my logic in the add_first and add_last method?

class Deque():
    DEFAULT_CAPACITY = 10

def __init__(self):
    self._data = [None]*Deque.DEFAULT_CAPACITY
    self._size = 0
    self._front = 0
    
def __len__(self):
    return self._size

def is_empty(self):
    return self._size == 0

def first(self):
    if self.is_empty():
        raise Exception('Queue is empty')
    return self._data[self._front]

def last(self):
    if self.is_empty():
        raise Exception('Queue is empty')
    back = (self._front + self._size - 1) % len(self._data)
    return self._data[back]

def delete_first(self):
    if self.is_empty():
        raise Exception('Queue is empty')
    answer = self._data[self._front]
    self._data[self._front] = None
    self._front = (self._front + 1) % len(self._data)
    self._size -= 1
    return answer

def delete_last(self):
    if self.is_empty():
        raise Exception('Queue is empty')
    back = (self._front + self._size - 1) % len(self._data)
    answer = self._data[back]
    self._data[back] = None
    self._size -= 1
    return answer
    
def add_first(self, e):
    if self._size == len(self._data):
        self._resize(2*len(self.data))
    self._front = (self._front - 1) % len(self._data)
    self._data[self._front] = e
    self._size += 1
    
def add_last(self, e):
    if self._size == len(self._data):
        self._resize(2*len(self.data))
    avail = (self._front + self._size) % len(self._data)
    self._data[avail] = e
    self._size += 1
    
def _resize(self, cap):
    old = self._data
    self._data = [None]*cap
    walk = self._front
    for k in range(self._size):
        self._data[k] = old[walk]
        walk = (1 + walk) % len(old)
    self._front = 0

The problem with your class method add_first is that if front pointer points 0 it changes to the last element. I changed as minimum as I could and added comments hope it helps.

 def add_first(self, e):
        if self._size == len(self._data) or self._front==0: #if front is atfirst element we need resize
            self._resize(2 * len(self._data))
        self._front = (self._front - 1) % len(self._data)
        self._data[self._front] = e
        self._size += 1



    def add_last(self, e):
        if self._front+self._size == len(self._data):#As there might be Nones at the beginning
            self._resize(2 * len(self._data))
        avail = (self._front + self._size) % len(self._data)
        self._data[avail] = e
        self._size += 1


    def _resize(self, cap):
        ##adding cap//4 Nones at the beginning and cap//4 Nones at the end. This shifts front by cap//4
        self._front = cap//4+self._front
        old = self._data
        self._data = [None] * (cap//4)+old+[None] * (cap//4)