<?php
require_once 'auth.php';
$auth->requireLogin();

$page_title = 'Sales Management';
$success_message = '';
$error_message = '';

// Handle form submissions
if ($_SERVER['REQUEST_METHOD'] == 'POST' && isset($_POST['action'])) {
    
    if ($_POST['action'] == 'record_sale') {
        $sale_date = $_POST['sale_date'] ?? '';
        $customer_name = trim($_POST['customer_name'] ?? '');
        $customer_phone = trim($_POST['customer_phone'] ?? '');
        $payment_status = $_POST['payment_status'] ?? 'paid';
        $payment_method = $_POST['payment_method'] ?? 'cash';
        $notes = trim($_POST['notes'] ?? '');
        
        // Get line items from individual form fields
        $products = $_POST['product_id'] ?? [];
        $quantities = $_POST['quantity'] ?? [];
        $unit_prices = $_POST['unit_price'] ?? [];
        $line_totals = $_POST['line_total'] ?? [];
        
        // Validation
        if (empty($sale_date)) {
            $error_message = 'Sale date is required.';
        } elseif (empty($products) || !is_array($products)) {
            $error_message = 'At least one product/service must be added.';
        } else {
            // Build line items array
            $line_items = [];
            $total_amount = 0;
            
            for ($i = 0; $i < count($products); $i++) {
                if (!empty($products[$i]) && !empty($quantities[$i]) && isset($unit_prices[$i]) && isset($line_totals[$i])) {
                    $product_id = intval($products[$i]);
                    $quantity = floatval($quantities[$i]);
                    $unit_price = floatval($unit_prices[$i]);
                    $line_total = floatval($line_totals[$i]);
                    
                    if ($product_id > 0 && $quantity > 0 && $unit_price >= 0 && $line_total >= 0) {
                        $line_items[] = [
                            'product_id' => $product_id,
                            'quantity' => $quantity,
                            'unit_price' => $unit_price,
                            'line_total' => $line_total
                        ];
                        $total_amount += $line_total;
                    }
                }
            }
            
            if (empty($line_items)) {
                $error_message = 'At least one valid product/service must be added.';
            } elseif ($total_amount <= 0) {
                $error_message = 'Total amount must be greater than zero.';
            } else {
                try {
                    // Generate bill number
                    $bill_number = 'BILL' . date('YmdHis') . rand(100, 999);
                    
                    // Start transaction
                    $pdo->beginTransaction();
                    
                    // Insert sale
                    $stmt = $pdo->prepare("
                        INSERT INTO sales (bill_number, sale_date, customer_name, customer_phone, 
                                         total_amount, payment_status, payment_method, notes, created_by) 
                        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
                    ");
                    
                    $stmt->execute([
                        $bill_number, $sale_date, $customer_name, $customer_phone, 
                        $total_amount, $payment_status, $payment_method, $notes, $_SESSION['user_id']
                    ]);
                    
                    $sale_id = $pdo->lastInsertId();
                    
                    // Insert line items
                    $stmt = $pdo->prepare("
                        INSERT INTO sales_items (sale_id, product_service_id, quantity, unit_price, line_total) 
                        VALUES (?, ?, ?, ?, ?)
                    ");
                    
                    foreach ($line_items as $item) {
                        $stmt->execute([
                            $sale_id, $item['product_id'], $item['quantity'], 
                            $item['unit_price'], $item['line_total']
                        ]);
                    }
                    
                    $pdo->commit();
                    $_SESSION['success_message'] = 'Sale recorded successfully! Bill: ' . $bill_number;
                    
                    // Redirect to prevent form resubmission
                    header("Location: sales.php");
                    exit();
                    
                } catch (Exception $e) {
                    $pdo->rollBack();
                    $error_message = 'Error recording sale: ' . $e->getMessage();
                }
            }
        }
    }
    
    elseif ($_POST['action'] == 'delete_sale') {
        $sale_id = intval($_POST['sale_id'] ?? 0);
        
        if ($sale_id > 0) {
            try {
                $pdo->beginTransaction();
                
                // Delete sales items first
                $stmt = $pdo->prepare("DELETE FROM sales_items WHERE sale_id = ?");
                $stmt->execute([$sale_id]);
                
                // Delete sale
                $stmt = $pdo->prepare("DELETE FROM sales WHERE id = ?");
                $result = $stmt->execute([$sale_id]);
                
                if ($result) {
                    $pdo->commit();
                    $_SESSION['success_message'] = 'Sale deleted successfully.';
                } else {
                    $pdo->rollBack();
                    $_SESSION['error_message'] = 'Failed to delete sale.';
                }
                
            } catch (Exception $e) {
                $pdo->rollBack();
                $_SESSION['error_message'] = 'Error deleting sale: ' . $e->getMessage();
            }
        }
        
        header("Location: sales.php");
        exit();
    }
}

// Fetch products/services
try {
    $stmt = $pdo->prepare("
        SELECT ps.*, u.unit_name, u.unit_symbol 
        FROM products_services ps 
        JOIN units u ON ps.unit_id = u.id 
        WHERE ps.status = 'active' 
        ORDER BY ps.name
    ");
    $stmt->execute();
    $products_services = $stmt->fetchAll(PDO::FETCH_ASSOC);
} catch (PDOException $e) {
    $products_services = [];
}

// Fetch sales with filters
$filter_date_from = $_GET['filter_date_from'] ?? '';
$filter_date_to = $_GET['filter_date_to'] ?? '';

$where_clause = "1=1";
$params = [];

if (!empty($filter_date_from)) {
    $where_clause .= " AND s.sale_date >= ?";
    $params[] = $filter_date_from;
}

if (!empty($filter_date_to)) {
    $where_clause .= " AND s.sale_date <= ?";
    $params[] = $filter_date_to;
}

try {
    // Get sales stats
    $stmt = $pdo->prepare("
        SELECT 
            COUNT(*) as total_sales,
            COALESCE(SUM(total_amount), 0) as total_revenue,
            COALESCE(SUM(CASE WHEN payment_status = 'paid' THEN total_amount ELSE 0 END), 0) as paid_amount
        FROM sales s WHERE $where_clause
    ");
    $stmt->execute($params);
    $stats = $stmt->fetch(PDO::FETCH_ASSOC);
    
    // Get sales records
    $stmt = $pdo->prepare("
        SELECT s.*, u.full_name as created_by_name
        FROM sales s
        JOIN users u ON s.created_by = u.id
        WHERE $where_clause
        ORDER BY s.created_at DESC
        LIMIT 50
    ");
    $stmt->execute($params);
    $sales = $stmt->fetchAll(PDO::FETCH_ASSOC);
    
    // Get line items for each sale
    foreach ($sales as &$sale) {
        $stmt = $pdo->prepare("
            SELECT si.*, ps.name as product_name, u.unit_symbol
            FROM sales_items si
            JOIN products_services ps ON si.product_service_id = ps.id
            JOIN units u ON ps.unit_id = u.id
            WHERE si.sale_id = ?
        ");
        $stmt->execute([$sale['id']]);
        $sale['items'] = $stmt->fetchAll(PDO::FETCH_ASSOC);
    }
    
} catch (PDOException $e) {
    $stats = ['total_sales' => 0, 'total_revenue' => 0, 'paid_amount' => 0];
    $sales = [];
    $error_message = 'Error fetching sales data.';
}

include 'includes/header.php';
?>

<div class="page-header">
    <h1 class="page-title">Sales Management</h1>
    <p class="page-subtitle">Record and track your fish sales</p>
</div>

<?php if ($error_message): ?>
    <div class="alert alert-error"><?php echo htmlspecialchars($error_message); ?></div>
<?php endif; ?>

<!-- Stats -->
<div class="dashboard-grid mb-3">
    <div class="stat-card">
        <div class="stat-number"><?php echo $stats['total_sales']; ?></div>
        <div class="stat-label">Total Sales</div>
    </div>
    <div class="stat-card">
        <div class="stat-number">₹<?php echo number_format($stats['total_revenue'], 2); ?></div>
        <div class="stat-label">Total Revenue</div>
    </div>
    <div class="stat-card" style="background: linear-gradient(135deg, #4caf50 0%, #66bb6a 100%);">
        <div class="stat-number">₹<?php echo number_format($stats['paid_amount'], 2); ?></div>
        <div class="stat-label">Paid Amount</div>
    </div>
</div>

<!-- Record Sale -->
<div class="card">
    <div class="card-header">
        <h2 class="card-title">Record New Sale</h2>
    </div>
    
    <?php if (empty($products_services)): ?>
        <div class="alert alert-warning">
            Please <a href="settings.php#products-section">create products or services</a> first.
        </div>
    <?php else: ?>
        <form method="POST" id="saleForm" onsubmit="return validateForm();">
            <input type="hidden" name="action" value="record_sale">
            
            <!-- Sale Info -->
            <div style="display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 1rem; margin-bottom: 2rem;">
                <div class="form-group">
                    <label class="form-label">Sale Date</label>
                    <input type="date" name="sale_date" class="form-input" value="<?php echo date('Y-m-d'); ?>" required>
                </div>
                <div class="form-group">
                    <label class="form-label">Customer Name</label>
                    <input type="text" name="customer_name" class="form-input" placeholder="Optional">
                </div>
                <div class="form-group">
                    <label class="form-label">Customer Phone</label>
                    <input type="text" name="customer_phone" class="form-input" placeholder="Optional">
                </div>
            </div>
            
            <!-- Line Items -->
            <div class="card-header">
                <h3 class="card-title">Products/Services</h3>
            </div>
            
            <div id="lineItems">
                <!-- First line item -->
                <div class="line-item" style="display: grid; grid-template-columns: 2fr 1fr 1fr 1fr auto; gap: 1rem; align-items: end; margin-bottom: 1rem; padding: 1rem; background: #f9f9f9; border-radius: 8px;">
                    <div class="form-group">
                        <label class="form-label">Product/Service</label>
                        <select name="product_id[]" class="form-select product-select" onchange="updatePrice(this)" required>
                            <option value="">Select Product/Service</option>
                            <?php foreach ($products_services as $ps): ?>
                                <option value="<?php echo $ps['id']; ?>" 
                                        data-rate="<?php echo $ps['unit_rate']; ?>"
                                        data-symbol="<?php echo $ps['unit_symbol']; ?>">
                                    <?php echo htmlspecialchars($ps['name']); ?> - ₹<?php echo number_format($ps['unit_rate'], 2); ?>/<?php echo $ps['unit_symbol']; ?>
                                </option>
                            <?php endforeach; ?>
                        </select>
                    </div>
                    <div class="form-group">
                        <label class="form-label">Quantity</label>
                        <input type="number" name="quantity[]" class="form-input quantity-input" step="0.001" min="0.001" onchange="calculateTotal(this)" required>
                    </div>
                    <div class="form-group">
                        <label class="form-label">Unit Price (₹)</label>
                        <input type="number" name="unit_price[]" class="form-input price-input" step="0.01" min="0" onchange="calculateTotal(this)" required>
                    </div>
                    <div class="form-group">
                        <label class="form-label">Line Total (₹)</label>
                        <input type="number" name="line_total[]" class="form-input total-input" step="0.01" min="0" onchange="updateGrandTotal()" required>
                    </div>
                    <button type="button" class="btn btn-danger" onclick="removeLineItem(this)" style="margin-top: 1.5rem;">Remove</button>
                </div>
            </div>
            
            <button type="button" class="btn btn-secondary" onclick="addLineItem()" style="margin-bottom: 2rem;">Add Another Item</button>
            
            <!-- Grand Total -->
            <div style="text-align: right; margin-bottom: 2rem;">
                <h3>Grand Total: ₹<span id="grandTotal">0.00</span></h3>
            </div>
            
            <!-- Payment Info -->
            <div style="display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 1rem; margin-bottom: 2rem;">
                <div class="form-group">
                    <label class="form-label">Payment Status</label>
                    <select name="payment_status" class="form-select">
                        <option value="paid">Paid</option>
                        <option value="pending">Pending</option>
                        <option value="partial">Partial</option>
                    </select>
                </div>
                <div class="form-group">
                    <label class="form-label">Payment Method</label>
                    <select name="payment_method" class="form-select">
                        <option value="cash">Cash</option>
                        <option value="upi">UPI</option>
                    </select>
                </div>
            </div>
            
            <div class="form-group">
                <label class="form-label">Notes</label>
                <textarea name="notes" class="form-textarea" rows="3" placeholder="Optional notes..."></textarea>
            </div>
            
            <button type="submit" class="btn btn-primary btn-full" id="submitBtn">Record Sale</button>
        </form>
    <?php endif; ?>
</div>

<!-- Filters -->
<div class="card">
    <div class="card-header">
        <h2 class="card-title">Filter Sales</h2>
    </div>
    
    <form method="GET">
        <div style="display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 1rem; align-items: end;">
            <div class="form-group">
                <label class="form-label">From Date</label>
                <input type="date" name="filter_date_from" class="form-input" value="<?php echo htmlspecialchars($filter_date_from); ?>">
            </div>
            <div class="form-group">
                <label class="form-label">To Date</label>
                <input type="date" name="filter_date_to" class="form-input" value="<?php echo htmlspecialchars($filter_date_to); ?>">
            </div>
            <button type="submit" class="btn btn-primary">Apply Filter</button>
            <a href="sales.php" class="btn btn-secondary">Clear</a>
        </div>
    </form>
</div>

<!-- Sales List -->
<div class="card">
    <div class="card-header">
        <h2 class="card-title">Sales Records</h2>
    </div>
    
    <?php if (empty($sales)): ?>
        <div class="empty-state">
            <h3>No Sales Found</h3>
            <p>Record your first sale using the form above.</p>
        </div>
    <?php else: ?>
        <div class="table-container">
            <table class="table">
                <thead>
                    <tr>
                        <th>Bill#</th>
                        <th>Date</th>
                        <th>Items</th>
                        <th>Total</th>
                        <th>Customer</th>
                        <th>Payment</th>
                        <th>Action</th>
                    </tr>
                </thead>
                <tbody>
                    <?php foreach ($sales as $sale): ?>
                        <tr>
                            <td><strong><?php echo htmlspecialchars($sale['bill_number']); ?></strong></td>
                            <td><?php echo date('M j, Y', strtotime($sale['sale_date'])); ?></td>
                            <td>
                                <?php foreach ($sale['items'] as $item): ?>
                                    <div style="margin-bottom: 4px; font-size: 0.9rem;">
                                        <?php echo htmlspecialchars($item['product_name']); ?>: 
                                        <?php echo number_format($item['quantity'], 3); ?> <?php echo $item['unit_symbol']; ?> 
                                        @ ₹<?php echo number_format($item['unit_price'], 2); ?> = 
                                        <strong>₹<?php echo number_format($item['line_total'], 2); ?></strong>
                                    </div>
                                <?php endforeach; ?>
                            </td>
                            <td><strong>₹<?php echo number_format($sale['total_amount'], 2); ?></strong></td>
                            <td>
                                <?php if ($sale['customer_name']): ?>
                                    <?php echo htmlspecialchars($sale['customer_name']); ?>
                                    <?php if ($sale['customer_phone']): ?>
                                        <br><small><?php echo htmlspecialchars($sale['customer_phone']); ?></small>
                                    <?php endif; ?>
                                <?php else: ?>
                                    -
                                <?php endif; ?>
                            </td>
                            <td>
                                <span style="color: <?php echo $sale['payment_status'] == 'paid' ? '#4caf50' : '#ff9800'; ?>">
                                    <?php echo ucfirst($sale['payment_status']); ?>
                                </span>
                                <br><small><?php echo $sale['payment_method'] == 'upi' ? 'UPI' : 'Cash'; ?></small>
                            </td>
                            <td>
                                <form method="POST" style="display: inline;" onsubmit="return confirm('Delete this sale?');">
                                    <input type="hidden" name="action" value="delete_sale">
                                    <input type="hidden" name="sale_id" value="<?php echo $sale['id']; ?>">
                                    <button type="submit" class="btn btn-danger" style="padding: 0.4rem 0.8rem; font-size: 0.8rem;">Delete</button>
                                </form>
                            </td>
                        </tr>
                        <?php if ($sale['notes']): ?>
                            <tr>
                                <td colspan="7" style="background: #f9f9f9; padding: 0.5rem 1rem; font-style: italic;">
                                    <strong>Notes:</strong> <?php echo htmlspecialchars($sale['notes']); ?>
                                </td>
                            </tr>
                        <?php endif; ?>
                    <?php endforeach; ?>
                </tbody>
            </table>
        </div>
    <?php endif; ?>
</div>

<script>
let isSubmitting = false;

function updatePrice(selectElement) {
    const row = selectElement.closest('.line-item');
    const priceInput = row.querySelector('.price-input');
    const selected = selectElement.options[selectElement.selectedIndex];
    
    if (selected.value) {
        priceInput.value = selected.dataset.rate || '';
        calculateTotal(priceInput);
    } else {
        priceInput.value = '';
    }
}

function calculateTotal(input) {
    const row = input.closest('.line-item');
    const quantity = parseFloat(row.querySelector('.quantity-input').value) || 0;
    const price = parseFloat(row.querySelector('.price-input').value) || 0;
    const totalInput = row.querySelector('.total-input');
    
    totalInput.value = (quantity * price).toFixed(2);
    updateGrandTotal();
}

function updateGrandTotal() {
    const totalInputs = document.querySelectorAll('.total-input');
    let grandTotal = 0;
    
    totalInputs.forEach(input => {
        grandTotal += parseFloat(input.value) || 0;
    });
    
    document.getElementById('grandTotal').textContent = grandTotal.toFixed(2);
}

function addLineItem() {
    const container = document.getElementById('lineItems');
    const firstItem = container.querySelector('.line-item');
    const newItem = firstItem.cloneNode(true);
    
    // Reset values
    newItem.querySelectorAll('select, input').forEach(el => {
        el.value = '';
        if (el.type !== 'hidden') el.removeAttribute('required');
    });
    
    // Make first select required
    newItem.querySelector('.product-select').required = true;
    
    container.appendChild(newItem);
    updateGrandTotal();
}

function removeLineItem(button) {
    const container = document.getElementById('lineItems');
    if (container.children.length > 1) {
        button.closest('.line-item').remove();
        updateGrandTotal();
    } else {
        alert('At least one item is required.');
    }
}

function validateForm() {
    if (isSubmitting) {
        return false;
    }
    
    const grandTotal = parseFloat(document.getElementById('grandTotal').textContent);
    if (grandTotal <= 0) {
        alert('Please add at least one valid item.');
        return false;
    }
    
    isSubmitting = true;
    const submitBtn = document.getElementById('submitBtn');
    submitBtn.disabled = true;
    submitBtn.textContent = 'Recording...';
    
    return true;
}

// Initialize
document.addEventListener('DOMContentLoaded', function() {
    updateGrandTotal();
});
</script>

<?php include 'includes/footer.php'; ?>