<?php
require_once 'db/config.php';
$pageTitle = 'Import Expenses';

$message = '';
$error = '';
$results = [];

// Helper to get maps for lookups
function getLookupMaps() {
    $db = db();
    $maps = [
        'projects' => [],
        'suppliers' => [],
        'types' => []
    ];
    
    $s = $db->query("SELECT id, project_code FROM projects");
    while($r = $s->fetch(PDO::FETCH_ASSOC)) $maps['projects'][strtolower($r['project_code'])] = $r['id'];
    
    $s = $db->query("SELECT id, name FROM suppliers");
    while($r = $s->fetch(PDO::FETCH_ASSOC)) $maps['suppliers'][strtolower($r['name'])] = $r['id'];
    
    $s = $db->query("SELECT id, name FROM expense_types");
    while($r = $s->fetch(PDO::FETCH_ASSOC)) $maps['types'][strtolower($r['name'])] = $r['id'];
    
    return $maps;
}

if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_FILES['csv_file'])) {
    $file = $_FILES['csv_file'];
    
    if ($file['error'] !== UPLOAD_ERR_OK) {
        $error = 'File upload failed.';
    } else {
        $handle = fopen($file['tmp_name'], 'r');
        $header = fgetcsv($handle);
        
        $expected = ['project_code', 'supplier_name', 'expense_type', 'amount', 'date', 'notes'];
        
        if (!$header || count(array_intersect($expected, $header)) < 3) {
            $error = 'Invalid CSV format. Please ensure project_code, supplier_name, and expense_type are present.';
        } else {
            $columnMap = array_flip($header);
            $maps = getLookupMaps();
            $rowCount = 0;
            $importCount = 0;
            $skippedCount = 0;
            
            db()->beginTransaction();
            try {
                $stmt = db()->prepare("INSERT INTO expenses (tenant_id, project_id, supplier_id, expense_type_id, amount, allocation_percent, entry_date, notes) VALUES (?, ?, ?, ?, ?, ?, ?, ?)");
                
                while (($row = fgetcsv($handle)) !== false) {
                    $rowCount++;
                    $data = [];
                    foreach ($expected as $col) {
                        $data[$col] = isset($columnMap[$col]) && isset($row[$columnMap[$col]]) ? trim($row[$columnMap[$col]]) : '';
                    }
                    
                    $projId = $maps['projects'][strtolower($data['project_code'])] ?? null;
                    $suppId = $maps['suppliers'][strtolower($data['supplier_name'])] ?? null;
                    $typeId = $maps['types'][strtolower($data['expense_type'])] ?? null;
                    
                    if (!$projId) {
                        $results[] = "Row $rowCount: Skipped (Unknown Project Code: " . htmlspecialchars($data['project_code']) . ")";
                        $skippedCount++;
                        continue;
                    }
                    if (!$suppId) {
                        $results[] = "Row $rowCount: Skipped (Unknown Supplier: " . htmlspecialchars($data['supplier_name']) . ")";
                        $skippedCount++;
                        continue;
                    }
                    if (!$typeId) {
                        $results[] = "Row $rowCount: Skipped (Unknown Expense Type: " . htmlspecialchars($data['expense_type']) . ")";
                        $skippedCount++;
                        continue;
                    }
                    
                    $amount = floatval($data['amount']);
                    $date = empty($data['date']) ? date('Y-m-d') : $data['date'];
                    
                    $stmt->execute([
                        1, // tenant_id
                        $projId,
                        $suppId,
                        $typeId,
                        $amount,
                        100.00, // Default allocation_percent
                        $date,
                        $data['notes']
                    ]);
                    $importCount++;
                }
                db()->commit();
                $message = "Import completed. $importCount expenses imported, $skippedCount skipped.";
            } catch (Exception $e) {
                db()->rollBack();
                $error = 'Database error: ' . $e->getMessage();
            }
        }
        fclose($handle);
    }
}

include 'includes/header.php';
?>

<div class="container mt-4">
    <div class="d-flex justify-content-between align-items-center mb-4">
        <h2><i class="bi bi-receipt me-2"></i>Import Expenses</h2>
        <a href="samples/expenses_template.csv" class="btn btn-outline-primary btn-sm">
            <i class="bi bi-download me-1"></i>Download Template
        </a>
    </div>

    <?php if ($message): ?>
        <div class="alert alert-success alert-dismissible fade show" role="alert">
            <?= $message ?>
            <button type="button" class="btn-close" data-bs-dismiss="alert"></button>
        </div>
    <?php endif; ?>

    <?php if ($error): ?>
        <div class="alert alert-danger alert-dismissible fade show" role="alert">
            <?= $error ?>
            <button type="button" class="btn-close" data-bs-dismiss="alert"></button>
        </div>
    <?php endif; ?>

    <div class="row">
        <div class="col-md-6">
            <div class="card shadow-sm border-0">
                <div class="card-body p-4">
                    <form action="import_expenses.php" method="POST" enctype="multipart/form-data">
                        <div class="mb-4">
                            <label for="csv_file" class="form-label fw-bold">Select CSV File</label>
                            <input type="file" class="form-control" id="csv_file" name="csv_file" accept=".csv" required>
                            <div class="form-text mt-2">
                                Max file size: 2MB. Only .csv files are allowed.
                            </div>
                        </div>
                        <button type="submit" class="btn btn-primary w-100 py-2">
                            <i class="bi bi-upload me-2"></i>Upload and Import
                        </button>
                    </form>
                </div>
            </div>
        </div>
        <div class="col-md-6">
            <div class="card shadow-sm border-0 h-100">
                <div class="card-header bg-white py-3">
                    <h5 class="mb-0">Import Instructions</h5>
                </div>
                <div class="card-body">
                    <ol class="small text-muted">
                        <li>Download the CSV template.</li>
                        <li>Ensure <strong>project_code</strong>, <strong>supplier_name</strong>, and <strong>expense_type</strong> match existing records in the system.</li>
                        <li><strong>amount</strong> should be a numeric value.</li>
                        <li><strong>date</strong> should be in YYYY-MM-DD format (defaults to today if empty).</li>
                    </ol>
                    <div class="alert alert-warning py-2 small mb-0">
                        <i class="bi bi-exclamation-triangle me-1"></i> Rows with unknown projects, suppliers, or types will be skipped.
                    </div>
                </div>
            </div>
        </div>
    </div>

    <?php if (!empty($results)): ?>
        <div class="card shadow-sm border-0 mt-4">
            <div class="card-header bg-white py-3">
                <h5 class="mb-0">Import Logs</h5>
            </div>
            <div class="card-body">
                <div class="list-group list-group-flush small">
                    <?php foreach ($results as $res): ?>
                        <div class="list-group-item px-0 border-0 py-1">
                            <i class="bi bi-dot me-1"></i><?= $res ?>
                        </div>
                    <?php endforeach; ?>
                </div>
            </div>
        </div>
    <?php endif; ?>
</div>

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