/// <summary>
/// Calculates from the last six months' average expense, that how can the user save enough money to afford a future
/// transaction. It lists how much money the user needs to save from each expense category to achieve the goal amount.
/// </summary>
public void Calculate()
{
decimal cumulativeAmount = 0;
List <UserCategory> allCategories;
List <Transactions> transactionsLastSixMonths;
DateTime startDayOfCalculation;
DateTime lastDayOfLastMonth;
CalculationResult.Clear();
HasCalculation = false;
// do all the actions that needs database
using (var db = new DataModel())
{
CurrentBalance = (int)db.AccountBalance
.First(ab => ab.AccountID == MainViewModel.CurrentAccount.AccountID)
.Balance
.GetValueOrDefault();
// if balance included, then set the start amount of calculation to the balance of the current account
if (CalculationFilter.BalanceIncluded)
{
cumulativeAmount = (decimal)CurrentBalance;
}
// set the initial dates
DateTime lastMonth = DateTime.Today.AddMonths(-1);
startDayOfCalculation = new DateTime(lastMonth.Year, lastMonth.Month, 1).AddMonths(-5);
lastDayOfLastMonth = DateTime.Today.AddDays(-(DateTime.Today.Day));
Console.WriteLine("Before calc: {0} - {1}", startDayOfCalculation, lastDayOfLastMonth);
// get the transactions for the last six months
transactionsLastSixMonths = db.Transactions
.Include(t => t.Categories.CategoryDirections)
.Where(t => t.TransactionDate >= startDayOfCalculation &&
t.TransactionDate <= lastDayOfLastMonth &&
t.AccountID == MainViewModel.CurrentAccount.AccountID)
.ToList <Transactions>();
// get all the categories which are not excluded from calculation
allCategories = db.UserCategory
.Include(uc => uc.Category.CategoryDirections)
.Where(uc => uc.UserID == MainViewModel.CurrentUser.UserID)
.ToList <UserCategory>();
}
//if there is no previous transaction then we can't calculate
if (transactionsLastSixMonths.Count == 0)
{
windowService.UserMessage("Nincs korábbi tranzakció, ami alapján kalkulálni lehetne!");
return;
}
// get the create date of the first transaction
DateTime firstTransactionDate = transactionsLastSixMonths.Select(t => t.TransactionDate).Min();
// if the first transactions date is a later date then startDayOfCalculation
// then set the first day to the transaction date
if (firstTransactionDate > startDayOfCalculation)
{
startDayOfCalculation = new DateTime(firstTransactionDate.Year, firstTransactionDate.Month, 1);
}
Console.WriteLine("Start: {0}\nEnd: {1}", startDayOfCalculation, lastDayOfLastMonth);
// get the months between the starting date and the last month
int monthDifference = CommonFunctionService.MonthDifference(lastDayOfLastMonth, startDayOfCalculation) + 1;
Console.WriteLine("Month difference: {0}", monthDifference);
// get the average amount spent by each category
var averageAmountByCategories = transactionsLastSixMonths
.GroupBy(t => t.Categories.CategoryName)
.Select(t => new
{
Category = t.Key,
CategoryDirection = t.First().Categories.CategoryDirections.DirectionName,
Amount = t.Sum(s => s.Amount) / monthDifference
})
.ToList();
CalculationFilter.CalculationData.Clear();
// create calculation data for each category, and initialize the limit with the average amount
foreach (var category in allCategories)
{
var currentCategory = averageAmountByCategories
.FirstOrDefault(c => c.Category == category.Category.CategoryName);
decimal average = 0;
if (currentCategory != null)
{
average = currentCategory.Amount;
}
var newCalcData = new CalculationData
{
CategoryID = category.CategoryID,
Average = average,
Limit = average
};
CalculationFilter.CalculationData.Add(newCalcData);
}
// average income in a month
decimal incomes = averageAmountByCategories
.Where(c => c.CategoryDirection == "Bevétel")
.Sum(c => c.Amount);
// average expense in a month
decimal expenses = averageAmountByCategories
.Where(c => c.CategoryDirection == "Kiadás")
.Sum(c => c.Amount);
// average balance in a month
decimal averageBalance = incomes - expenses;
// get the difference in months between today and the due date
int monthToGoal = CommonFunctionService.MonthDifference(CalculationFilter.DueDate, DateTime.Today) - 1;
Console.WriteLine("{0}*{1}+{2}={3}", monthToGoal, averageBalance, cumulativeAmount,
monthToGoal * averageBalance + cumulativeAmount);
Console.WriteLine("{0}", CalculationFilter.Amount);
cumulativeAmount += monthToGoal * averageBalance;
// if the average savings plus the start balance is reaching the goal amount, then no
// calculation is needed
if (cumulativeAmount >= CalculationFilter.Amount)
{
windowService.UserMessage("A jelenlegi bevétel-kiadás arány mellett nem szükséges további spórolás a kitűzött cél megvalósításához");
return;
}
// get the priority levels that are not excluded from calculation
var categoryPriority = allCategories
.Where(uc => uc.Category.CategoryDirections.DirectionName == "Kiadás" &&
uc.ExcludeFromCalculation == false)
.Select(uc => new
{
Priority = uc.Priority,
CategoryID = uc.CategoryID,
CategoryName = uc.Category.CategoryName,
Percentage = uc.Limit
})
.OrderBy(t => t.Priority)
.ThenByDescending(t => t.Percentage)
.ToList();
var priorityLevels = categoryPriority
.Select(t => t.Priority)
.Distinct()
.ToList <int>();
bool goalReached = false;
// go through each priority level
foreach (var priority in priorityLevels)
{
var currentPriority = categoryPriority
.Where(uc => uc.Priority == priority)
.ToList();
int cycleCounter = 1;
double maxPercentage = currentPriority.Max(t => t.Percentage);
bool exit = false;
Console.WriteLine("Priority {0}:", priority);
while (!exit)
{
Console.WriteLine("{0}. round:", cycleCounter);
foreach (var category in currentPriority)
{
// calculate only if we didn't reach the limit
if (category.Percentage >= cycleCounter * 0.01)
{
var currentCalcData = CalculationFilter
.CalculationData
.First(cd => cd.CategoryID == category.CategoryID);
currentCalcData.Limit -= currentCalcData.Average * 0.01M;
// increase the saved amount by the amount we subtracted from limit for each month
cumulativeAmount += currentCalcData.Average * 0.01M * monthToGoal;
Console.WriteLine("{0}: {1}->{2}", category.CategoryName, currentCalcData.Average, currentCalcData.Limit);
// if the saved amount equals or greater than the planned amount, then we are done
if (cumulativeAmount >= CalculationFilter.Amount)
{
exit = true;
goalReached = true;
break;
}
}
}
Console.WriteLine("Amount after {0}. round: {1}", cycleCounter, cumulativeAmount);
// if we reached the category with the highest percentage then go to next level
if (maxPercentage <= cycleCounter * 0.01)
{
exit = true;
}
cycleCounter++;
}
// after each level we need to check, if we reached the goal already
if (goalReached)
{
break;
}
}
if (goalReached)
{
// create a collection for display
foreach (var category in allCategories)
{
// if category is not type of expense then skip
if (category.Category.CategoryDirections.DirectionName != "Kiadás")
{
continue;
}
var calcData = CalculationFilter.CalculationData.First(cd => cd.CategoryID == category.CategoryID);
var displayCalculationData = new CalcDataDisplay
{
CategoryName = category.Category.CategoryName,
Average = calcData.Average,
Limit = calcData.Limit,
Saved = calcData.Average - calcData.Limit
};
CalculationResult.Add(displayCalculationData);
}
CreateCalculationReport(incomes, expenses);
}
else
{
windowService.UserMessage("Nem sikerült eleget spórolni a cél eléréséhez!");
}
HasCalculation = CalculationResult.Count > 0;
}