budgetManager.cpp

/**
 * @file budgetManager.cpp
 * @brief Implementation of the BudgetManager widget.
 *
 * Provides UI and logic to set monthly budgets, allocate funds per category,
 * and visualize budget usage and progress. Integrates with the database layer
 * to persist and retrieve budget data.
 *
 * @author Armaan Sharma
 */

#include "budgetManager.h"
#include "database.h"
#include <QSqlQuery>
#include <QMessageBox>
#include <QDate>
#include <QHeaderView>
#include <QScrollArea>


/**
 * @brief Constructor for BudgetManager.
 * 
 * Sets up UI layout, initializes widgets, connects signals to slots,
 * and populates data from the database.
 * 
 */

 BudgetManager::BudgetManager(QWidget *parent) : QWidget(parent)
 {
     mainLayout = new QVBoxLayout(); ///< Main vertical layout.
 
     // Title label setup
     QLabel *title = new QLabel("Budget Manager", this);
     title->setStyleSheet("font-size: 24px; font-weight: bold;");
     mainLayout->addWidget(title);
 
     // Top form layout: month dropdown + total budget input + save button
     QHBoxLayout *topFormLayout = new QHBoxLayout();
 
     // Month selection dropdown
     monthDropdown = new QComboBox();
     int currentYear = QDate::currentDate().year();
     QStringList monthNames = {
         "January", "February", "March", "April", "May", "June",
         "July", "August", "September", "October", "November", "December"
     };
 
     // Populate dropdown with months and corresponding values
     for (int m = 1; m <= 12; ++m) {
         QString internalValue = QString("%1-%2").arg(currentYear).arg(m, 2, 10, QLatin1Char('0'));
         QString displayText = QString("%1 %2").arg(monthNames[m - 1]).arg(currentYear);
         monthDropdown->addItem(displayText, internalValue);
     }
 
     // Connect month change to UI refresh
     connect(monthDropdown, &QComboBox::currentTextChanged, this, &BudgetManager::refreshUI);
     monthDropdown->setStyleSheet("padding: 8px;");
 
     // Monthly total budget input field
     totalBudgetInput = new QLineEdit();
     totalBudgetInput->setPlaceholderText("Monthly Budget ($)");
     totalBudgetInput->setStyleSheet("padding: 8px; border-radius: 5px; border: 1px solid #ccc;");
 
     // Save button to store monthly budget
     saveMonthlyButton = new QPushButton("Save Monthly Budget");
     saveMonthlyButton->setStyleSheet("background-color: #3498db; color: white; padding: 10px; border-radius: 5px;");
     connect(saveMonthlyButton, &QPushButton::clicked, this, &BudgetManager::saveMonthlyBudget);
 
     // Add form elements to layout
     topFormLayout->addWidget(monthDropdown);
     topFormLayout->addWidget(totalBudgetInput);
     topFormLayout->addWidget(saveMonthlyButton);
     mainLayout->addLayout(topFormLayout);
 
     // Section header for allocations
     QLabel *allocationHeader = new QLabel("Category Allocations", this);
     allocationHeader->setStyleSheet("font-size: 18px; font-weight: bold; margin-top: 15px;");
     mainLayout->addWidget(allocationHeader);
 
     // Layout for category input form
     QHBoxLayout *categoryFormLayout = new QHBoxLayout();
 
     // Category selection dropdown
     categoryDropdown = new QComboBox();
     categoryDropdown->addItems({"Food", "Shopping", "Bills", "Entertainment", "Other"});
     categoryDropdown->setStyleSheet("padding: 8px;");
 
     // Input field for allocation amount
     categoryAmountInput = new QLineEdit();
     categoryAmountInput->setPlaceholderText("Amount ($)");
     categoryAmountInput->setStyleSheet("padding: 8px; border-radius: 5px; border: 1px solid #ccc;");
 
     // Button to add category budget
     addCategoryButton = new QPushButton("Add Category Budget");
     addCategoryButton->setStyleSheet("background-color: #2ecc71; color: white; padding: 10px; border-radius: 5px;");
     connect(addCategoryButton, &QPushButton::clicked, this, &BudgetManager::addCategoryBudget);
 
     // Assemble category form
     categoryFormLayout->addWidget(categoryDropdown);
     categoryFormLayout->addWidget(categoryAmountInput);
     categoryFormLayout->addWidget(addCategoryButton);
     mainLayout->addLayout(categoryFormLayout);
 
     // Label showing total allocated
     totalAllocatedLabel = new QLabel(this);
     totalAllocatedLabel->setStyleSheet("font-weight: bold; padding: 6px;");
     totalAllocatedLabel->setAlignment(Qt::AlignCenter);
     mainLayout->addWidget(totalAllocatedLabel);
 
     // Label for budget over-allocation alerts
     mainBudgetAlertLabel = new QLabel(this);
     mainBudgetAlertLabel->setStyleSheet("color: red; font-weight: bold;");
     mainBudgetAlertLabel->hide();
     mainLayout->addWidget(mainBudgetAlertLabel);
 
     // Main progress bar showing overall spending
     monthlyProgressBar = new QProgressBar(this);
     monthlyProgressBar->setTextVisible(true);
     monthlyProgressBar->setMinimumHeight(25);
     mainLayout->addWidget(monthlyProgressBar);
 
     // Table displaying per-category budget details
     categoryTable = new QTableWidget(this);
     categoryTable->setColumnCount(6);
     categoryTable->setHorizontalHeaderLabels({"Category", "Allocated", "Spent", "Progress", "Alert", "Delete"});
     categoryTable->horizontalHeader()->setStretchLastSection(true);
     categoryTable->horizontalHeader()->setSectionResizeMode(QHeaderView::Stretch);
     categoryTable->setMinimumHeight(300);
     mainLayout->addWidget(categoryTable);
 
     // Final alert label at the bottom
     alertLabel = new QLabel(this);
     alertLabel->setStyleSheet("color: red; font-weight: bold;");
     mainLayout->addWidget(alertLabel);
 
     // Wrap everything inside a scroll area for responsiveness
     QScrollArea *scrollArea = new QScrollArea(this);
     scrollArea->setWidgetResizable(true);
     QWidget *container = new QWidget;
     container->setLayout(mainLayout);
     scrollArea->setWidget(container);
 
     QVBoxLayout *outerLayout = new QVBoxLayout(this);
     outerLayout->addWidget(scrollArea);
     setLayout(outerLayout);
 
     refreshUI(); ///< Populate UI on load.
 }


/**
 * @brief Saves the selected monthly budget to the database.
 */
void BudgetManager::saveMonthlyBudget()
{
    QString month = monthDropdown->currentData().toString();
    double total = totalBudgetInput->text().toDouble();
    if (total <= 0) return;

    QSqlQuery q(DatabaseManager::getDatabase());
    q.prepare("REPLACE INTO monthly_budgets (user_id, month, total_amount) VALUES (:uid, :month, :amount)");
    q.bindValue(":uid", DatabaseManager::currentUserId);
    q.bindValue(":month", month);
    q.bindValue(":amount", total);
    q.exec();

    refreshUI();
}

/**
 * @brief Calculates the sum of all allocated category budgets for the selected month.
 * 
 * @return double Total allocated amount.
 */
double BudgetManager::calculateTotalAllocated()
{
    QString month = monthDropdown->currentData().toString();
    double total = 0.0;

    QSqlQuery query(DatabaseManager::getDatabase());
    query.prepare("SELECT SUM(amount) FROM category_budgets WHERE user_id = :uid AND month = :month");
    query.bindValue(":uid", DatabaseManager::currentUserId);
    query.bindValue(":month", month);

    if (query.exec() && query.next()) {
        total = query.value(0).toDouble();
    }

    return total;
}

/**
 * @brief Adds a category budget allocation for the selected month.
 * 
 * Validates against the total budget and updates the database.
 */
void BudgetManager::addCategoryBudget()
{
    QString month = monthDropdown->currentData().toString();
    QString cat = categoryDropdown->currentText();
    double amt = categoryAmountInput->text().toDouble();
    if (amt <= 0) return;

    double totalAllocatedLabel = calculateTotalAllocated();
    if (totalAllocatedLabel + amt > currentMonthlyBudget) {
        QMessageBox::warning(this, "Allocation Error", "Exceeds total monthly budget.");
        return;
    }

    QSqlQuery q(DatabaseManager::getDatabase());
    q.prepare("REPLACE INTO category_budgets (user_id, month, category, amount) VALUES (:uid, :month, :cat, :amt)");
    q.bindValue(":uid", DatabaseManager::currentUserId);
    q.bindValue(":month", month);
    q.bindValue(":cat", cat);
    q.bindValue(":amt", amt);
    q.exec();

    categoryAmountInput->clear();
    refreshUI();
}

/**
 *
 * Pulls data from the database to update UI components including:
 * - Monthly total budget
 * - Per-category allocations
 * - Expenses
 * - Progress bars and warnings
 */
void BudgetManager::refreshUI()
{
    QString month = monthDropdown->currentData().toString();
    categoryTable->setRowCount(0);
    alertLabel->clear();
    currentMonthlyBudget = 0.0;

    // Step 1: Get Monthly Budget Total
    QSqlQuery monthlyQuery(DatabaseManager::getDatabase());
    monthlyQuery.prepare("SELECT total_amount FROM monthly_budgets WHERE user_id = :uid AND month = :month");
    monthlyQuery.bindValue(":uid", DatabaseManager::currentUserId);
    monthlyQuery.bindValue(":month", month);

    if (monthlyQuery.exec() && monthlyQuery.next()) {
        currentMonthlyBudget = monthlyQuery.value(0).toDouble();
        totalBudgetInput->setText(QString::number(currentMonthlyBudget, 'f', 2));
        mainBudgetAlertLabel->hide();
        monthlyProgressBar->show();
    } else {
        totalBudgetInput->clear();
        mainBudgetAlertLabel->setText(" No monthly budget set for this month.");
        mainBudgetAlertLabel->show();
        monthlyProgressBar->hide();
        return;
    }

    // Step 2: Get Category Budgets for this month
    QSqlQuery categoryQuery(DatabaseManager::getDatabase());
    categoryQuery.prepare("SELECT category, amount FROM category_budgets WHERE user_id = :uid AND month = :month");
    categoryQuery.bindValue(":uid", DatabaseManager::currentUserId);
    categoryQuery.bindValue(":month", month);

    double totalAllocated = 0.0;
    if (!categoryQuery.exec()) return;

    while (categoryQuery.next()) {
        QString category = categoryQuery.value(0).toString();
        double allocated = categoryQuery.value(1).toDouble();
        totalAllocated += allocated;

        // Step 3: Get total spent in this category this month
        QSqlQuery spentQuery(DatabaseManager::getDatabase());
        QString queryStr;
        if (category == "Other") {
            // Any category not in main predefined list = "Other"
            queryStr =
                "SELECT SUM(amount) FROM expenses "
                "WHERE user_id = :uid AND strftime('%Y-%m', date) = :month "
                "AND (category NOT IN ('Food', 'Shopping', 'Bills', 'Entertainment'))";
        } else {
            queryStr =
                "SELECT SUM(amount) FROM expenses "
                "WHERE user_id = :uid AND category = :cat AND strftime('%Y-%m', date) = :month";
        }

        spentQuery.prepare(queryStr);
        spentQuery.bindValue(":uid", DatabaseManager::currentUserId);
        spentQuery.bindValue(":month", month);
        if (category != "Other") {
            spentQuery.bindValue(":cat", category);
        }
        spentQuery.bindValue(":month", month);

        double spent = 0.0;
        if (spentQuery.exec() && spentQuery.next())
            spent = spentQuery.value(0).toDouble();

        int row = categoryTable->rowCount();
        categoryTable->insertRow(row);
        categoryTable->setItem(row, 0, new QTableWidgetItem(category));
        categoryTable->setItem(row, 1, new QTableWidgetItem("$" + QString::number(allocated, 'f', 2)));
        categoryTable->setItem(row, 2, new QTableWidgetItem("$" + QString::number(spent, 'f', 2)));

        // Step 4: Progress Bar
        QString alertText;
        QProgressBar *bar = new QProgressBar();


        // Set value and max such that overspending doesn't break the bar
        int barValue = static_cast<int>(spent);
        int barMax = static_cast<int>(qMax(spent, allocated));
        bar->setRange(0, barMax);
        bar->setValue(barValue);
        bar->setTextVisible(true);  // Optional: turn off if you want a clean look

        // Set color based on condition
        if (spent >= allocated) {
            bar->setStyleSheet(
                "QProgressBar {"
                "  border: none;"
                "  background-color: transparent;"
                "  text-align: center;"
                "}"
                "QProgressBar::chunk {"
                "  background-color: red;"
                "  border-radius: 5px;"
                "}"
                );
            alertText = "❗ Overspent by $" + QString::number(spent - allocated, 'f', 2);
        }
        else if ((allocated - spent) <= 50.0) {
            bar->setStyleSheet(
                "QProgressBar {"
                "  border: none;"
                "  background-color: transparent;"
                "  text-align: center;"
                "}"
                "QProgressBar::chunk {"
                "  background-color: orange;"
                "  border-radius: 5px;"
                "}"
                );
            alertText = "⚠ Close to limit";
        }
        else {
            bar->setStyleSheet(
                "QProgressBar {"
                "  border: none;"
                "  background-color: transparent;"
                "  text-align: center;"
                "}"
                "QProgressBar::chunk {"
                "  background-color: #3498db;"
                "  border-radius: 5px;"
                "}"
                );
        }


        categoryTable->setCellWidget(row, 3, bar);
        categoryTable->setItem(row, 4, new QTableWidgetItem(alertText));

        QPushButton *deleteBtn = new QPushButton("✖");
        deleteBtn->setStyleSheet(
            "QPushButton {"
            "  background-color: #e74c3c;"
            "  color: white;"
            "  font-weight: bold;"
            "  border: none;"
            "  padding: 4px 8px;"
            "  border-radius: 4px;"
            "}"
            "QPushButton:hover {"
            "  background-color: #c0392b;"
            "}"
            );
        deleteBtn->setToolTip("Delete this category");
        categoryTable->setCellWidget(row, 5, deleteBtn);

        // Connect the delete button with category + month context
        connect(deleteBtn, &QPushButton::clicked, this, [=]() {
            auto confirm = QMessageBox::question(this, "Delete Category",
                                                 "Are you sure you want to delete the budget for \"" + category + "\"?");
            if (confirm == QMessageBox::Yes) {
                QSqlQuery del(DatabaseManager::getDatabase());
                del.prepare("DELETE FROM category_budgets WHERE user_id = :uid AND month = :month AND category = :cat");
                del.bindValue(":uid", DatabaseManager::currentUserId);
                del.bindValue(":month", month);
                del.bindValue(":cat", category);
                del.exec();
                refreshUI();
            }
        });

    }



    // Step 5: Update allocation summary
    totalAllocatedLabel->setText("💰 <b>Allocated:</b> <span style='color:#2c3e50;'>$" +
                                 QString::number(totalAllocated, 'f', 2) + "</span>");

    if (totalAllocated > currentMonthlyBudget) {
        alertLabel->setText("⚠ Total category allocations exceed monthly budget!");
    }

    // Step 6: Total Monthly Spending
    QSqlQuery spentQuery(DatabaseManager::getDatabase());
    spentQuery.prepare("SELECT SUM(amount) FROM expenses "
                       "WHERE user_id = :uid AND strftime('%Y-%m', date) = :month");
    spentQuery.bindValue(":uid", DatabaseManager::currentUserId);
    spentQuery.bindValue(":month", month);

    double totalSpent = 0.0;
    if (spentQuery.exec() && spentQuery.next())
        totalSpent = spentQuery.value(0).toDouble();

    // Step 7: Update Master Progress Bar
    int overallPercent = (currentMonthlyBudget > 0) ? static_cast<int>((totalSpent / currentMonthlyBudget) * 100.0) : 0;
    monthlyProgressBar->setValue(overallPercent);
    monthlyProgressBar->setFormat(QString("$%1 / $%2")
                                      .arg(QString::number(totalSpent, 'f', 2))
                                      .arg(QString::number(currentMonthlyBudget, 'f', 2)));
    QFont boldFont;
    boldFont.setBold(true);
    boldFont.setPointSize(11); // ⬅️ Increase this value as needed
    monthlyProgressBar->setFont(boldFont);


    // Ensure bar doesn't cap at 100%
    int masterValue = static_cast<int>(totalSpent);
    int masterMax = static_cast<int>(qMax(totalSpent, currentMonthlyBudget));
    monthlyProgressBar->setRange(0, masterMax);
    monthlyProgressBar->setValue(masterValue);

    // Style based on distance to limit
    if (totalSpent >= currentMonthlyBudget) {
        monthlyProgressBar->setStyleSheet(
            "QProgressBar {"
            "  border: none;"
            "  background-color: transparent;"
            "  text-align: center;"
            "}"
            "QProgressBar::chunk {"
            "  background-color: red;"
            "  border-radius: 5px;"
            "}"
            );

        // Optional: show alert label
        mainBudgetAlertLabel->setText("❗ You have reached your budget!");
        mainBudgetAlertLabel->setStyleSheet("color: red; font-size: 16px; font-weight: bold;");
        mainBudgetAlertLabel->show();
    }
    else if (totalSpent >= currentMonthlyBudget - 100.0) {
        monthlyProgressBar->setStyleSheet(
            "QProgressBar {"
            "  border: none;"
            "  background-color: transparent;"
            "  text-align: center;"
            "}"
            "QProgressBar::chunk {"
            "  background-color: orange;"
            "  border-radius: 5px;"
            "}"
            );
        mainBudgetAlertLabel->hide();
    }
    else {
        monthlyProgressBar->setStyleSheet(
            "QProgressBar {"
            "  border: none;"
            "  background-color: transparent;"
            "  text-align: center;"
            "}"
            "QProgressBar::chunk {"
            "  background-color: #3498db;"
            "  border-radius: 5px;"
            "}"
            );
        mainBudgetAlertLabel->hide();
    }

    mainBudgetAlertLabel->hide(); // reset first

}