# lecture 6, repetition statements / loops
print("Welcome!")

# NEW FILE

# a simple for-loop: 10 cycles
# basically: we ask Python to run this
# line of code 10 in a row
# first cycle: x is 0
# last cycle: x is 9
for x in range(10):
    print(f"Cycle: {x}")

# NEW FILE

# save these to variable for
# easier modification later
start = 2018
end = 2024

# you can also define the start and end of the range
# for example: a year range
for year in range(start, end):
    print(year)

# NEW FILE, version 2

# save these to variable for
# easier modification later
start = 2018
end = 2024

# you can also define the start and end of the range
# for example: a year range
# you can also use the third parameter
# if you wish to skip numbers in the for-loop
# in this case: only print every other number
for year in range(start, end, 2):
    print(year)

# NEW FILE
print("Start!")

# try this code in Python Tutor
# in order to see the execution of the for -loop!
for cycle in range(10):
    number = cycle * 2
    print(f"Number: {number}")

print("End!")

# NEW FILE

# try this also in Python Tutor
# initialize an empty string variable
text = ""

# the idea is to build the text-variable
# from pieces in a loop
for year in range(2018, 2025):
    text = text + str(year) + "-"

# we can use a substring to remove the final dash from the end
text = text[:-1]

# print the text-variable AFTER
# the loop has added all the years into it
print(text)

# NEW FILE

print("Start!")

# for loop for 10 cycles
for x in range(10):
    if x % 2 == 0:
        print(f"Cycle: {x} (even)")
    else:
        print("SKIP! (odd number)")

print("End!")

# NEW FILE

print("APPLICATION STARTED!")

counter = 1

# while-loop, in other words:
# run this code AS LONG AS the counter variable
# is less or equal to 10
while counter <= 10:
    print(f"Cycle: {counter}")

    # you have to increase the counter yourself
    # or otherwise you might get an infinite loop
    counter = counter + 1

# loop done, inform user
print("THANK YOU FOR USING THE APPLICATION!")

# NEW FILE

# variable that controls
# if the app should be running still
running = True

# in this situation we can't know the exact number
# of cycles, so this is why while-loop is more natural
# (when compared to for-loop)
while running:
    print("Run application! Ask stuff from user, calculate something etc...")
    print()

    # here comes all the code that should be run
    # on each cycle (ask user inputs, make calculations etc.)
    number = input("Give a number:\n")
    number = int(number)

    # double the number and print it out
    total = number * 2
    print(f"Number doubled: {total}")
    print()

    # FINAL PHASE: ask user whether they wish to continue
    answer = input("Would you like to continue? (y/n)\n")

    # if user wants to quit, they write "n"
    if answer.lower() == "n":
        running = False

# thank the user and end application
print("\nThank you for using the application! (end program)")

# NEW FILE
print("Start!\n")

# MAIN LOOP -> Run this 3 times only
for x in range(3):
    print(f"MAIN LOOP: x = {x}")

    for y in range(5):
        print(f"\t\tnested loop: y = {y}")


print("\nEND APPLICATION!")

# NEW FILE

# A MORE PRACTICAL VERSION OF NESTED LOOPS
print("Today's sales report:\n")

# our logic is this =>
# we have orders, each order has certain amount of products

# so, orders => products
# we could have more complex stuff as well,
# e.g. department => order => product
# first, let's loop the orders (main loop)
for order in range(3):
    print(f"Start processing order no.: {order + 1}")

    # process each product in this order
    # here we assume each order has exactly 5 products
    for product in range(5):
        print(f"\t\tProcessing order no: {order + 1}, product: {product + 1}")

print("\nEnd of today's report (all orders processed).")

# NEW FILE

# use loops to do automated parts of code
total = 0

# use loops to automate
# repeating structures in code
for x in range(10):
    number = int(input("Give number:\n"))
    total = total + number

print("Total sum of the numbers:")
print(total)

# NEW FILE

# let's allow the user to choose the amount
# of cycles in the for loop later
cycles = input("How many numbers would you like to give?\n")
cycles = int(cycles)

# use loops to do automated parts of code
total = 0

# use loops to automate
# repeating structures in code
# using cycles from user to determine the
# amount of cycles
for x in range(cycles):
    number = int(input("Give number:\n"))
    total = total + number

print("Total sum of the numbers:")
print(total)

# NEW FILE

# interest calculator, loop version

# compound interest with loops instead of mathematics
# yearly interest is 7%
# add 2000 €in the beginning of each year
start_money = 15000
yearly_money = 2000

# interest in modifier format 1 + 0.07
interest = 1.07

# our money in the start
total = start_money

# the goal is to find new money after 10 years

# use Python to calculate the interest for our money
# for 10 years in a row
for year in range(10):
    total = total + yearly_money
    total = total * interest


# finalize the calculations
total = round(total, 2)

# remove the inital investment plus the yearly investments
new_money = total - start_money - 10 * yearly_money
print(f"Total money after 10 years: {total} €")
print(f"New money accumulated: {new_money} €")

# NEW FILE

# VERSION 2: Interest calculator / compound interest
# how many years does it take for us to reach a certain profit

start_money = 15000
yearly_money = 2000

# what is our target savings
target_profit = 150000

# 7% interest per each year
interest = 1.07

# helper variables for the loop to keep track of current situation
total = start_money
current_profit = 0

# for-loop for years 1-30
for year in range(1, 31):
    # add the yearly money
    total = total + yearly_money

    # add interest
    total = total * interest

    # update how much profit we have earned so far
    current_profit = total - start_money - (year * yearly_money)

    # check if we have met our goal yet
    if current_profit >= target_profit:
        print(f"We met our goal in the year: {year}")
        # since we already know the year, no point continuing
        # the loop => break
        break

# if we didn't get to the target profit
# print an informing message for the user
if current_profit < target_profit:
    print("This goal cannot be met within this time limit and starting investment.")

# NEW FILE

# ANOTHER EXAMPLE, CLASSIC: FIBONACCI

# Fibonacci sequence: every number is the sum of two previous numbers
# first 9 numbers are: 0, 1, 1, 2, 3, 5, 8, 13, 21

# OUR GOAL: ask user a number: which Fibonacci number do they
# want to see, and count the value with a for-loop

# examples:
# if user inputs 5 = 1 + 2 = 3
# if user inputs 6 = 2 + 3 = 5
# if user inputs 7 = 3 + 5 = 8
# if user inputs 8 = 5 + 8 = 13
# x. number is old number + new number = fibonacci number

# helper variables to keep track of old and new number
old_number = 0
new_number = 1

# initialize fibonacci number to be 1 in the beginning
fibonacci = 1


choice = input("Which Fibonacci number would you like to see?\n")
choice = int(choice) - 2
print()

# for-loop that counts the Fibonacci number
# until the choice-variable dictates

for number in range(choice):
    print("New cycle!")
    # calculate the current value
    fibonacci = old_number + new_number

    print(f"Fibonacci is now: {old_number} + {new_number} = {fibonacci}")

    # update the old number
    old_number = new_number

    # update the new number to be whatever fibonacci is now
    new_number = fibonacci

    print(f"After this cycle: old_number = {old_number}, new number = {new_number}")
    print()

print()
print(f"Fibonacci number = {fibonacci}")