import json
from decimal import *
from datetime import *

##############################################################################
#
# This is the BQL query to put into Fava to generate the CSV that can be used
# to create the JSON file for this.  Might consider reading in the CSV directly
# and prompting for the other information?
#
# select date, number where year=2022 And account~".*:CreditLine"
#
##############################################################################
#
# Consider altering this program to generate the text to go into the beancount
# files directly so that it can just be a cut and paste job.
#
##############################################################################


def main():
    filename = '2023.gtploc.json'
    account = loadAccountInformation(getFullPathofFile(filename))

    starting_balance = Decimal(account['starting_balance'])
    apr = Decimal(account['interest_rate']) / 100
    daily_interest_rate = apr / 360

    fiscal_year = account['fiscal_year']
    first_day = datetime(fiscal_year, 1, 1)
    last_day = datetime(fiscal_year, 12, 31)
    days_in_year = (last_day - first_day).days + 2
    print("Line of Credit Report")
    print("Fiscal Year: {1} Input File Name: {0}".format(filename, fiscal_year))
    print("Starting Balance: {0} Interest Rate: {1}".format(starting_balance, account['interest_rate']))
    print("Report Run Date: {0}".format(datetime.now()))
    print("\n=========================================================================================\n")

    day_nets = {}
    transactions = account['transactions']
    print("Summarizing {0} transactions:".format(len(transactions)))
    for entry in transactions:
        entry_date = entry[0]
        entry_amount = Decimal(entry[1])

        if entry_date not in day_nets:
            day_nets[entry_date] = entry_amount
        else:
            day_nets[entry_date] = day_nets[entry_date] + entry_amount

    for key in day_nets.keys():
        print("Date: {0} Net Change: {1}".format(key, day_nets[key]))

    print("Summary complete.")

    current_balance = starting_balance
    accummulated_interest = Decimal('0.00')
    daily_interest = calculateDailyInterest(current_balance, daily_interest_rate)

    print("\n=========================================================================================\n")
    print("Calculating interest charges...")
#    print("Beginning Balance: {1} Daily Interest: {2}".format(first_day,starting_balance, daily_interest))
    for i in range(1, days_in_year):
        current_date = (first_day + timedelta(days=i-1)).date()

        if current_date.day == 1:
            print("BEGIN MONTH: {0} Starting Balance: {1} Starting Daily Interest: {2}".format(current_date,
                                                                                               current_balance,
                                                                                               daily_interest))

        if current_date.__str__() in day_nets:
            current_balance = current_balance + day_nets[current_date.__str__()]
            daily_interest = calculateDailyInterest(current_balance, daily_interest_rate)
            print("Balance Change: Date: {0} Net: {1} New Balance: {2}".format(
                current_date, day_nets[current_date.__str__()], current_balance))

        accummulated_interest = accummulated_interest + daily_interest

        if is_last_day_of_month(current_date):
            current_balance = current_balance + accummulated_interest
            daily_interest = calculateDailyInterest(current_balance, daily_interest_rate)
            print("END MONTH: Date: {0} Post Accumulated Interest: {1} New Balance: {2} New Daily Interest: {3}".format(
                current_date, accummulated_interest, current_balance, daily_interest))
            accummulated_interest = 0


def is_last_day_of_month(some_date):
    if some_date.day < 28:
        return False

    next_day = some_date + timedelta(days=1)
    if next_day.month == some_date.month:
        return False
    return True


def calculateDailyInterest(principal, rate):
    return (principal*rate).quantize(Decimal('.001'))


def loadAccountInformation(filename):
    return getDatastore(filename)


def getDatastore(filename=None):
    try:
        if filename:
            with open(filename, 'r') as f:
                datastore = json.load(f)

    except Exception as e:
        print("An error occurred opening your file '%s'. " % filename)
        print("The Exception:")
        print(e.__repr__())
        quit()

    return datastore


def getFullPathofFile(filename):
    return '/Users/john/PycharmProjects/LoCInterestCalculator/' + filename


if __name__ == '__main__':
    main()