# coding workshop 23.9.2021

from datetime import date
import math

start_money = 35000

# typical yearly interest in math problems = 4-7%
interest = 7

# datetime module to calculate amount of days and years between two dates
save_date = date(2021, 9, 23)
withdrawal_date = date(2025, 12, 31)

delta = withdrawal_date - save_date
days = delta.days
years = days // 365
leftover_days = days % 365

# compound interest formula:
# A = P*(1+interest)^years
# A = P* (1+r/n)^nt
total_money = start_money * math.pow((1 + (interest/100)), years)
total_money = round(total_money, 2)
print(total_money)

# how much we earned?
new_money = total_money - start_money
print(f"We earned {new_money} € during {years} time!")

# the missing days are not taken into account as partial interest
# you can do that if you wish to calculate this a bit better

# NEW FILE

import math
from datetime import datetime

coffee_break = datetime(2021, 9, 23, 11, 0, 0)
evening = datetime(2021, 9, 23, 20, 0, 0)

duration = evening - coffee_break
seconds = duration.total_seconds()

minutes = seconds / 60

# hours between the two timestamps
hours = minutes // 60
hours = int(hours)

# let's use half life of 4 hours for coffee
half_life = 8

# our coffee cup is 300 ml!
cup = 300

# half-life calculation
# y(9) = 1 e(ln(0.5)/6)×9 = 0.35
logarithm = math.log(0.5) / half_life
coffee_in_body = cup * math.exp(logarithm * hours)
coffee_in_body = int(coffee_in_body)

coffee_mg = 0.4

print(f"It has been {hours} hours since the coffee cup ({cup} ml)")
print(f"Half-life was set to {half_life} hours.")
print(f"Based on the calculation, we still have {coffee_in_body} ml left in our body!")

# 40mg per 100ml
coffee_mg_left = coffee_in_body * coffee_mg
coffee_mg_left = round(coffee_mg_left)
print(f"This means, we still have about {coffee_mg_left} mg worth of caffeine still in the body.")