# NodeModule.py
#!/usr/bin/python
""" A model containing Node class """

__author__ = "Lin Chen"
__version__ = "0.1"

class Node:
    """Single node in a data structure"""

    def __init__(self, data):
        """Initialize a Node
        
        Args:
            data : data saved in the node
        """
        self._data = data
        self._next = None

    @property
    def data(self):
        return self._data

    @data.setter
    def data(self, d):
        self._data = d

    @data.deleter
    def data(self):
        del self._data

    @property
    def next(self):
        return self._next

    @next.setter
    def next(self, n):
        self._next = n

    @next.deleter
    def next(self):
        del self._next

    def __str__(self):
        return str(self._data)
			

# ListModule.py
#!/usr/bin/python
""" A modeule containing List class"""
 
from NodeModule import Node
 
class List:
    """Linked List class with a pre-defined Node class"""
 
    def __init__(self):
        """Initialize a List
        """
        self._head = None
        self._count = 0
 
    def __iter__(self):
        return self
 
    def __next__(self):
        if self._head is not None:
            temp = self._head
            self._head = self._head.next
            return temp
        else:
            raise StopIteration('End of iteration List ...')
 
    def isEmpty(self):
        """Check if the list is empty
 
        Args:
            None
 
        Returns:
            boolean : True, if list is empty; False, otherwise
        """
        return self._count == 0
 
    def getSize(self):
        """Return the size of the list
        
        Returns:
            int : size of the list
        """
        return self._count
 
    def contains(self, v):
        """Check if a specific value is included in the list
 
        Args:
            v : a data which can be saved in a node
 
        Returns:
            boolean: True, if the value is contained in a node of the list; False, otherwise
        """
        current = self._head
 
        while current is not None:
            if current.data == v:
                return True
            else:
                current = current.next
 
        return False
 
    def insert(self, index, v):
        """Insert a valude to a specific location in the list
 
        Args:
            index (int): location of insertion, 0 is the location before the first element, 1 is the location after the first element
            v : data which can be saved in a node
 
        Returns:
            boolean: True, if the value is inserted succefully; False, otherwise
        """
        if index < 0 or index > self._count:
            return False
 
        n = Node(v) # create a node
 
        if index == 0:
            n.next = self._head
            self._head = n
            self._count += 1
            return True
 
        current = self._head
        for i in range(index-1):
            current = current.next
        n.next = current.next
        current.next = n
        self._count += 1
        return True
 
    def delete(self, index):
        """Delete a valude located at a specific location in the list
 
        Args:
            index (int): location of deletion, 0 is the location before the first element, 1 is the location after the first element
 
        Returns:
            boolean: True, if the value is deleted succefully; False, otherwise
        """
        if index < 0 or index > self._count-1:
            return False
 
        if index == 0:
            self._head = self._head.next
            self._count -= 1
            return True
 
        current = self._head
        for i in range(index-1):
            current = current.next
 
        current.next  = current.next.next
        self._count -= 1
        return True
 
    def __str__(self):
        """Convert the list to a string
 
        Returns:
            string : a string represents the list
        """
        if self.isEmpty():
            return "Empty"
 
        current = self._head
        output = []
 
        while current is not None:
            output.append(str(current))
            current = current.next
 
        return " -> ".join(output)
			

#!/usr/bin/python
 
from ListModule import List
 
def main():
    l = List()
 
    l.insert(0, 10)
    l.insert(0, 20)
    l.insert(0, 30)
    print(l) # 30 -> 20 -> 10
 
    l.insert(1, 40)
    print(l) # 30 -> 40 -> 20 -> 10
 
    l.insert(4, 50)
    print(l) # 30 -> 40 -> 20 -> 10 -> 50
 
    l.delete(0)
    print(l) # 40 -> 20 -> 10 -> 50
 
    l.delete(2)
    print(l) # 40 -> 20 -> 50
 
    if l.contains(20):
        print("Contains 20 ...")
    else:
        print("Not contains 20 ...")
 
    # convert List to iteration
    l = iter(l)
 
    while True:
        try:
            print(next(l))
        except StopIteration as err:
            print(err)
            break
 
if __name__ == '__main__':
    main()