import moment from 'moment';

// Function to simulate monthly financial projection
// src/utils/FinancialProjectionService.js

export function simulateFinancialProjection(userProfile) {
    const {
        currentSalary,
        monthlyExpenses,
        monthlyDebtPayments,
        studentLoanAmount,
        interestRate,            // ✅ Corrected
        loanTerm,                // ✅ Corrected
        extraPayment,
        expectedSalary,
        emergencySavings,
        retirementSavings,
        monthlyRetirementContribution,
        monthlyEmergencyContribution,
        gradDate,
        fullTimeCollegeStudent: inCollege,
        partTimeIncome,
        startDate,
        programType,
        isFullyOnline,
        creditHoursPerYear,
        calculatedTuition,
        hoursCompleted,
        loanDeferralUntilGraduation,
        programLength
    } = userProfile;

    const monthlyLoanPayment = calculateLoanPayment(studentLoanAmount, interestRate, loanTerm);

    let totalEmergencySavings = emergencySavings;
    let totalRetirementSavings = retirementSavings;
    let loanBalance = studentLoanAmount;
    let projectionData = [];

    const graduationDate = gradDate ? new Date(gradDate) : null;
    let milestoneIndex = 0;
    let loanPaidOffMonth = null;

    // Dynamic credit hours based on the program type
    let requiredCreditHours;
    switch (programType) {
        case "Associate Degree":
            requiredCreditHours = 60;
            break;
        case "Bachelor's Degree":
            requiredCreditHours = 120;
            break;
        case "Master's Degree":
            requiredCreditHours = 30;
            break;
        case "Doctoral Degree":
            requiredCreditHours = 60;
            break;
        default:
            requiredCreditHours = 120;
    }

    const remainingCreditHours = requiredCreditHours - hoursCompleted;
    const programDuration = Math.ceil(remainingCreditHours / creditHoursPerYear);
    const tuitionCost = calculatedTuition;
    const totalTuitionCost = tuitionCost * programDuration;

    const date = new Date(startDate);
    for (let month = 0; month < 240; month++) {
        date.setMonth(date.getMonth() + 1);

        if (loanBalance <= 0 && !loanPaidOffMonth) {
            loanPaidOffMonth = `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, '0')}`;
        }

        let tuitionCostThisMonth = 0;
        if (inCollege && !loanDeferralUntilGraduation) {
            tuitionCostThisMonth = totalTuitionCost / programDuration / 12;
        }

        let thisMonthLoanPayment = 0;

        if (loanDeferralUntilGraduation && graduationDate && date < graduationDate) {
            const interestForMonth = loanBalance * (interestRate / 100 / 12);  // ✅ Corrected here
            loanBalance += interestForMonth;
        } else if (loanBalance > 0) {
            const interestForMonth = loanBalance * (interestRate / 100 / 12);  // ✅ Corrected here
            const principalForMonth = Math.min(loanBalance, monthlyLoanPayment + extraPayment - interestForMonth);
            loanBalance -= principalForMonth;
            loanBalance = Math.max(loanBalance, 0);
            thisMonthLoanPayment = monthlyLoanPayment + extraPayment;
        }

        const salaryNow = graduationDate && date >= graduationDate ? expectedSalary : currentSalary;

        const totalMonthlyExpenses = monthlyExpenses 
        + tuitionCostThisMonth 
        + monthlyDebtPayments 
        + thisMonthLoanPayment;

        const monthlyIncome = salaryNow / 12;

        let extraCash = monthlyIncome - totalMonthlyExpenses - monthlyRetirementContribution - monthlyEmergencyContribution;
        extraCash = Math.max(extraCash, 0);

        // update savings explicitly with contributions first
        totalEmergencySavings += monthlyEmergencyContribution + (extraCash * 0.3);
        totalRetirementSavings += monthlyRetirementContribution + (extraCash * 0.7);
        totalRetirementSavings *= (1 + 0.07 / 12);

        // netSavings calculation fixed
        projectionData.push({
            month: `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, '0')}`,
            salary: salaryNow,
            monthlyIncome: monthlyIncome,
            expenses: totalMonthlyExpenses,
            loanPayment: thisMonthLoanPayment,
            retirementContribution: monthlyRetirementContribution,
            emergencyContribution: monthlyEmergencyContribution,
            netSavings: monthlyIncome - totalMonthlyExpenses,  // Exclude contributions here explicitly!
            totalEmergencySavings,
            totalRetirementSavings,
            loanBalance
        });

            }
            
              
            return { projectionData, loanPaidOffMonth, emergencySavings };
        }

function calculateLoanPayment(principal, annualRate, years) {
    const monthlyRate = annualRate / 100 / 12;
    const numPayments = years * 12;
    return (principal * monthlyRate) / (1 - Math.pow(1 + monthlyRate, -numPayments));
}