#!/usr/bin/python3
# -*- coding: utf-8 -*-
"""
Loops - The first major way to repeat sequences of statements
Recursion is the other.

General form:

for element in iterable:
    statements, potentially using element
"""
from typing import List


# Indentation matters here too
for letter in "primes":
    print(letter)

# Preview: this is a List (more next time)
primes: List[int] = [2, 3, 5, 7]
# It is "iterable" thus and can be looped over
for prime in primes:
    print(prime)

"""
For loops iterate over lists
prints:
    dog is a mammal
    cat is a mammal
    mouse is a mammal
"""
for animal in ["dog", "cat", "mouse"]:
    # You can use format() to interpolate formatted strings
    print("{} is a mammal".format(animal))

"""
"range(number)" returns an iterable of numbers
from zero to the given number
prints:
    0
    1
    2
    3
"""
for i in range(4):
    print(i)

"""
"range(lower, upper)" returns an iterable of numbers
from the lower number to the upper number
prints:
    4
    5
    6
    7
"""
for i in range(4, 8):
    print(i)

"""
"range(lower, upper, step)" returns an iterable of numbers
from the lower number to the upper number, while incrementing
by step. If step is not indicated, the default value is 1.
prints:
    4
    6
"""
for i in range(4, 8, 2):
    print(i)

"""
To loop over a list,
and retrieve both the index and the value of each item in the list
prints:
    0 dog
    1 cat
    2 mouse
"""
animals = ["dog", "cat", "mouse"]
for i, value in enumerate(animals):
    print(i, value)

"""
While loops go until a condition is no longer met.
prints:
    0
    1
    2
    3
"""
x: int = 0
while x < 4:
    y = 45
    print(x)
    x += 1  # Shorthand for x = x + 1

for x in range(5):
    print(x)

# A common pattern, accumulating values onto the end of an array or string:
myaccumarray: List[int] = []
for x in range(3, 6):
    myaccumarray.append(x)
    print(x)
print(myaccumarray)

for x in range(3, 8, 2):
    print(x)

for letter in "Python":  # traversal of a string sequence
    print("Current Letter :", letter)

fruits: List[str] = ["banana", "apple", "mango"]
for fruit in fruits:  # traversal of List sequence
    print("Current fruit :", fruit)

fruits = ["banana", "apple", "mango"]
for index in range(len(fruits)):
    print("Current fruit :", fruits[index])

count: int = 0
while count < 9:
    print("The count is:", count)
    count = count + 1
print("Good bye!")

count = 0
while count < 5:
    print(count)
    count += 1  # This is the same as count = count + 1

# while true loop (aka while 1:)
# NOTE: this is a common strategy, pay attention here!
count = 0
while True:
    print(count)
    count += 1
    if count >= 5:
        break

for letter in "Python":  # First Example
    if letter == "h":
        break
    print("Current Letter :", letter)

var: int = 10  # Second Example
while var > 0:
    print("Current variable value :", var)
    var = var - 1
    if var == 5:
        break

# Prints the odd numbers:
for x in range(10):
    if x % 2 == 0:
        continue
    print(x)

for letter in "Python":  # First Example
    if letter == "h":
        continue
    print("Current Letter :", letter)

var = 10  # Second Example
while var > 0:
    var = var - 1
    if var == 5:
        continue
    print("Current variable value :", var)

# While has an else
count = 0
while count < 5:
    print(count)
    count += 1
else:
    print("count value reached %d" % (count))

# for also has an else
for i in range(1, 10):
    if i % 5 == 0:
        break
    print(i)
else:
    print("this is not printed, because break terminates for loop")

# Why use that else?
condition: bool = True

flag: bool = False
thing: int = 5
while thing < 10:
    if condition:
        flag = True
        break
    thing += 1
if not flag:
    print("not break")

# Becomes
thing = 5
while thing < 10:
    if condition:
        break
    thing += 1
else:
    print("not break")

# nested loops.
for i in range(1, 11):
    for j in range(1, 11):
        k = i * j
        print(k, end="")
    print()

# can make something like a do while loop:
i = 1
while i < 2:  # Loop expression
    print("these are a bit wierd")
    i += 1
    # Loop body: Sub-statements to execute if
    # the expression evaluated to True
else:
    print("but they exist")
    # Else body: Sub-statements to execute once
    # if the expression evaluated to False
print("Statements to execute after the loop")


for char in "iterable":
    print(char)
    # Loop body: Sub-statements to execute
    # for each item in iterable
else:
    print("nothing here this time")
    # Else body: Sub-statements to execute
    # once when loop completes
print("Statements to execute after the loop")


# to get item number in loop, you might try this:
words = ["cool", "powerful", "readable"]
for i in range(0, len(words)):
    print((i, words[i]))

# but this is easier
for index, item in enumerate(words):
    print((index, item))

# recall:
num1, num2 = [350, 400]
# or
num1, num2 = (350, 400)

# enumerate is similar:
origins: List[int] = [4, 8, 10]
for (myindex, myvalue) in enumerate(origins):
    print("Element %d: %s" % (myindex, myvalue))

# don't need the () tuple syntax
origins = [4, 8, 10]
for myindex, myvalue in enumerate(origins):
    print(myindex, myvalue)