"""
A module with a simple Point class.

This module has a simpler version of the Point class than what we saw in previous labs.  
It shows off the minimum that we need to get started with a class.

Author: Walker M. White (wmw2)
Date:   October 1, 2017 (Python 3 Version)
"""
import math


class Point(object):
    """
    A class to represent a point in 3D space
    
    INSTANCE ATTRIBUTES:
        x: x-coordinate [float]
        y: y-coordinate [float]
        z: z-coordinate [float]
    """

    def __init__(self,x=0.0,y=0.0,z=0.0): 
        """
        Initializer:  makes a new Point
        
        Precondition: x, y, and z are floats
        """
        self.x = x # x is parameter, self.x is attribute  
        self.y = y # y is parameter, self.y is attribute  
        self.z = z # z is parameter, self.z is attribute  
    
    def __str__(self):
        """
        Returns: this Point as a string '(x, y, z)'
        """
        return '('+str(self.x)+', '+str(self.y)+', '+str(self.z)+')'
    
    def __repr__(self):
        """
        Returns: unambiguous representation of Point
        """
        return str(self.__class__)+str(self)
    
    def __eq__(self,other):
        """
        Returns: True if other is a point equal to this one.
        
        Parameter other: The point to compare
        Precondition: other is a Point
        """
        assert type(other) == Point, repr(other)+' is not a Point'
        return self.x == other.x and self.y == other.y and self.z == other.z
    
    def __add__(self,other):
        """
        Returns: A new point that is the pointwise sum of self and other
        
        Parameter other: The point to add
        Precondition: other is a Point
        """
        assert type(other) == Point, repr(other)+' is not a Point'
        return Point(self.x + other.x, self.y + other.y, self.z + other.z)
    
    def distance(self,other):
        """
        Returns: Distance from self to other
        
        Parameter other: The point to compare
        Precondition: other is a Point
        """
        assert type(other) == Point, repr(other)+' is not a Point'
        dx = (self.x-other.x)*(self.x-other.x)
        dy = (self.y-other.y)*(self.y-other.y)
        dz = (self.z-other.z)*(self.z-other.z)
        return math.sqrt(dx+dy+dz)