<?php
/**
 * Common Functions for Kayal Aqua Application
 * Reusable PHP functions for the fish business management system
 */

/**
 * Generate secure random password
 */
function generateSecurePassword($length = 12) {
    $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()';
    return substr(str_shuffle($chars), 0, $length);
}

/**
 * Hash password using PHP's password_hash
 */
function hashPassword($password) {
    return password_hash($password, PASSWORD_DEFAULT);
}

/**
 * Verify password using PHP's password_verify
 */
function verifyPassword($password, $hash) {
    return password_verify($password, $hash);
}

/**
 * Send JSON response
 */
function sendJsonResponse($data, $statusCode = 200) {
    http_response_code($statusCode);
    header('Content-Type: application/json');
    echo json_encode($data);
    exit;
}

/**
 * Validate email format
 */
function isValidEmail($email) {
    return filter_var($email, FILTER_VALIDATE_EMAIL) !== false;
}

/**
 * Validate phone number (Indian format)
 */
function isValidPhone($phone) {
    $phone = preg_replace('/[^0-9+]/', '', $phone);
    return preg_match('/^(\+91)?[6-9]\d{9}$/', $phone);
}

/**
 * Generate unique filename for uploads
 */
function generateUniqueFilename($originalName) {
    $extension = pathinfo($originalName, PATHINFO_EXTENSION);
    $filename = pathinfo($originalName, PATHINFO_FILENAME);
    $filename = preg_replace('/[^a-zA-Z0-9_-]/', '', $filename);
    return $filename . '_' . uniqid() . '.' . $extension;
}

/**
 * Handle file upload with validation
 */
function handleFileUpload($fileInput, $uploadDir = 'uploads/', $allowedTypes = ['jpg', 'jpeg', 'png', 'pdf']) {
    if (!isset($_FILES[$fileInput]) || $_FILES[$fileInput]['error'] !== UPLOAD_ERR_OK) {
        throw new Exception('File upload failed');
    }

    $file = $_FILES[$fileInput];
    $extension = strtolower(pathinfo($file['name'], PATHINFO_EXTENSION));

    // Validate file type
    if (!in_array($extension, $allowedTypes)) {
        throw new Exception('Invalid file type. Allowed types: ' . implode(', ', $allowedTypes));
    }

    // Validate file size (5MB max)
    if ($file['size'] > MAX_FILE_SIZE) {
        throw new Exception('File too large. Maximum size: ' . (MAX_FILE_SIZE / 1024 / 1024) . 'MB');
    }

    // Create upload directory if it doesn't exist
    if (!is_dir($uploadDir)) {
        mkdir($uploadDir, 0755, true);
    }

    // Generate unique filename
    $filename = generateUniqueFilename($file['name']);
    $filepath = $uploadDir . $filename;

    // Move uploaded file
    if (!move_uploaded_file($file['tmp_name'], $filepath)) {
        throw new Exception('Failed to save uploaded file');
    }

    return $filepath;
}

/**
 * Get dashboard statistics
 */
function getDashboardStats($userId = null) {
    // Total Revenue
    $revenueQuery = "SELECT COALESCE(SUM(amount), 0) as total_revenue FROM sales WHERE 1=1";
    $params = [];
    
    if ($userId) {
        $revenueQuery .= " AND created_by = ?";
        $params[] = $userId;
    }
    
    $totalRevenue = fetchRow($revenueQuery, $params)['total_revenue'];

    // Total Expenses
    $expenseQuery = "SELECT COALESCE(SUM(amount), 0) as total_expenses FROM expenses WHERE 1=1";
    $expenseParams = [];
    
    if ($userId) {
        $expenseQuery .= " AND created_by = ?";
        $expenseParams[] = $userId;
    }
    
    $totalExpenses = fetchRow($expenseQuery, $expenseParams)['total_expenses'];

    // Monthly Revenue (current month)
    $monthlyRevenueQuery = "SELECT COALESCE(SUM(amount), 0) as monthly_revenue 
                           FROM sales 
                           WHERE MONTH(sale_date) = MONTH(CURRENT_DATE()) 
                           AND YEAR(sale_date) = YEAR(CURRENT_DATE())";
    $monthlyParams = [];
    
    if ($userId) {
        $monthlyRevenueQuery .= " AND created_by = ?";
        $monthlyParams[] = $userId;
    }
    
    $monthlyRevenue = fetchRow($monthlyRevenueQuery, $monthlyParams)['monthly_revenue'];

    // Active Investments/Loans
    $investmentQuery = "SELECT COALESCE(SUM(amount), 0) as total_investments 
                       FROM investments 
                       WHERE status = 'active'";
    
    $totalInvestments = fetchRow($investmentQuery)['total_investments'];

    // Profit Calculation
    $profit = $totalRevenue - $totalExpenses;
    $profitMargin = $totalRevenue > 0 ? ($profit / $totalRevenue) * 100 : 0;

    return [
        'total_revenue' => $totalRevenue,
        'total_expenses' => $totalExpenses,
        'monthly_revenue' => $monthlyRevenue,
        'total_investments' => $totalInvestments,
        'profit' => $profit,
        'profit_margin' => $profitMargin
    ];
}

/**
 * Get recent transactions for dashboard
 */
function getRecentTransactions($limit = 10, $userId = null) {
    $query = "
        (SELECT 'sale' as type, id, title, amount, sale_date as transaction_date, 
                customer_name as party_name, created_at 
         FROM sales WHERE 1=1" . ($userId ? " AND created_by = ?" : "") . ")
        UNION ALL
        (SELECT 'expense' as type, id, title, amount, expense_date as transaction_date, 
                '' as party_name, created_at 
         FROM expenses WHERE 1=1" . ($userId ? " AND created_by = ?" : "") . ")
        ORDER BY transaction_date DESC, created_at DESC
        LIMIT ?";
    
    $params = [];
    if ($userId) {
        $params[] = $userId;
        $params[] = $userId;
    }
    $params[] = $limit;
    
    return fetchAll($query, $params);
}

/**
 * Get business segment performance
 */
function getSegmentPerformance() {
    $query = "SELECT 
                bs.name as segment_name,
                COALESCE(SUM(s.amount), 0) as revenue,
                COALESCE(SUM(e.amount), 0) as expenses,
                (COALESCE(SUM(s.amount), 0) - COALESCE(SUM(e.amount), 0)) as profit
              FROM business_segments bs
              LEFT JOIN sales s ON bs.id = s.segment_id
              LEFT JOIN expenses e ON bs.id = e.segment_id
              WHERE bs.status = 'active'
              GROUP BY bs.id, bs.name
              ORDER BY revenue DESC";
    
    return fetchAll($query);
}

/**
 * Get monthly trends data for charts
 */
function getMonthlyTrends($year = null) {
    if (!$year) {
        $year = date('Y');
    }
    
    $query = "SELECT 
                MONTH(t.transaction_date) as month,
                MONTHNAME(t.transaction_date) as month_name,
                SUM(CASE WHEN t.type = 'sale' THEN t.amount ELSE 0 END) as revenue,
                SUM(CASE WHEN t.type = 'expense' THEN t.amount ELSE 0 END) as expenses
              FROM (
                SELECT 'sale' as type, amount, sale_date as transaction_date FROM sales
                UNION ALL
                SELECT 'expense' as type, amount, expense_date as transaction_date FROM expenses
              ) t
              WHERE YEAR(t.transaction_date) = ?
              GROUP BY MONTH(t.transaction_date), MONTHNAME(t.transaction_date)
              ORDER BY MONTH(t.transaction_date)";
    
    return fetchAll($query, [$year]);
}

/**
 * Search function for sales, expenses, etc.
 */
function performSearch($query, $table, $searchFields, $userId = null, $limit = 50) {
    $searchConditions = [];
    $params = [];
    
    // Build search conditions
    foreach ($searchFields as $field) {
        $searchConditions[] = "$field LIKE ?";
        $params[] = "%$query%";
    }
    
    $sql = "SELECT * FROM $table WHERE (" . implode(' OR ', $searchConditions) . ")";
    
    // Add user filter if provided
    if ($userId) {
        $sql .= " AND created_by = ?";
        $params[] = $userId;
    }
    
    $sql .= " ORDER BY created_at DESC LIMIT ?";
    $params[] = $limit;
    
    return fetchAll($sql, $params);
}

/**
 * Generate report data
 */
function generateReport($type, $startDate, $endDate, $segmentId = null) {
    $params = [$startDate, $endDate];
    
    switch ($type) {
        case 'sales':
            $query = "SELECT s.*, bs.name as segment_name, c.name as category_name
                     FROM sales s
                     LEFT JOIN business_segments bs ON s.segment_id = bs.id
                     LEFT JOIN categories c ON s.category_id = c.id
                     WHERE s.sale_date BETWEEN ? AND ?";
            break;
            
        case 'expenses':
            $query = "SELECT e.*, bs.name as segment_name, c.name as category_name
                     FROM expenses e
                     LEFT JOIN business_segments bs ON e.segment_id = bs.id
                     LEFT JOIN categories c ON e.category_id = c.id
                     WHERE e.expense_date BETWEEN ? AND ?";
            break;
            
        case 'profit_loss':
            $query = "SELECT 
                        'Revenue' as type, 
                        SUM(amount) as total_amount,
                        COUNT(*) as transaction_count
                      FROM sales 
                      WHERE sale_date BETWEEN ? AND ?
                      UNION ALL
                      SELECT 
                        'Expenses' as type, 
                        SUM(amount) as total_amount,
                        COUNT(*) as transaction_count
                      FROM expenses 
                      WHERE expense_date BETWEEN ? AND ?";
            $params = [$startDate, $endDate, $startDate, $endDate];
            break;
            
        default:
            throw new Exception('Invalid report type');
    }
    
    // Add segment filter if provided
    if ($segmentId && in_array($type, ['sales', 'expenses'])) {
        $query .= " AND segment_id = ?";
        $params[] = $segmentId;
    }
    
    if ($type !== 'profit_loss') {
        $query .= " ORDER BY " . ($type === 'sales' ? 'sale_date' : 'expense_date') . " DESC";
    }
    
    return fetchAll($query, $params);
}

/**
 * Export data to CSV
 */
function exportToCSV($data, $filename, $headers = null) {
    header('Content-Type: text/csv');
    header('Content-Disposition: attachment; filename="' . $filename . '"');
    header('Cache-Control: no-cache, must-revalidate');
    header('Pragma: no-cache');
    
    $output = fopen('php://output', 'w');
    
    // Add headers if provided or use array keys from first row
    if ($headers) {
        fputcsv($output, $headers);
    } elseif (!empty($data)) {
        fputcsv($output, array_keys($data[0]));
    }
    
    // Add data rows
    foreach ($data as $row) {
        fputcsv($output, $row);
    }
    
    fclose($output);
    exit;
}

/**
 * Calculate loan EMI
 */
function calculateEMI($principal, $rate, $tenure) {
    $monthlyRate = $rate / (12 * 100);
    $emi = ($principal * $monthlyRate * pow(1 + $monthlyRate, $tenure)) / (pow(1 + $monthlyRate, $tenure) - 1);
    return round($emi, 2);
}

/**
 * Send email notification (basic implementation)
 */
function sendEmail($to, $subject, $message, $isHTML = true) {
    $headers = [
        'From: ' . APP_NAME . ' <noreply@' . parse_url(APP_URL, PHP_URL_HOST) . '>',
        'Reply-To: noreply@' . parse_url(APP_URL, PHP_URL_HOST),
        'X-Mailer: PHP/' . phpversion()
    ];
    
    if ($isHTML) {
        $headers[] = 'Content-Type: text/html; charset=UTF-8';
        $headers[] = 'MIME-Version: 1.0';
    }
    
    return mail($to, $subject, $message, implode("\r\n", $headers));
}

/**
 * Log system activity
 */
function logSystemActivity($activity, $details = '', $userId = null) {
    if (!$userId && isLoggedIn()) {
        $userId = $_SESSION['user_id'];
    }
    
    $data = [
        'user_id' => $userId,
        'activity' => $activity,
        'details' => $details,
        'ip_address' => $_SERVER['REMOTE_ADDR'] ?? '',
        'user_agent' => $_SERVER['HTTP_USER_AGENT'] ?? '',
        'created_at' => date('Y-m-d H:i:s')
    ];
    
    try {
        insertData('activity_logs', $data);
    } catch (Exception $e) {
        error_log("Failed to log activity: " . $e->getMessage());
    }
}

/**
 * Get application settings
 */
function getAppSettings() {
    static $settings = null;
    
    if ($settings === null) {
        $settingsData = fetchAll("SELECT setting_key, setting_value FROM settings");
        $settings = [];
        foreach ($settingsData as $setting) {
            $settings[$setting['setting_key']] = $setting['setting_value'];
        }
    }
    
    return $settings;
}

/**
 * Update application setting
 */
function updateAppSetting($key, $value) {
    $existing = fetchRow("SELECT id FROM settings WHERE setting_key = ?", [$key]);
    
    if ($existing) {
        updateData('settings', ['setting_value' => $value], 'setting_key = ?', [$key]);
    } else {
        insertData('settings', [
            'setting_key' => $key,
            'setting_value' => $value,
            'description' => ''
        ]);
    }
    
    // Clear cached settings
    getAppSettings.clear();
}

/**
 * Format number for Indian currency
 */
function formatIndianCurrency($number) {
    return '₹' . number_format($number, 2);
}

/**
 * Convert number to words (for invoices, etc.)
 */
function numberToWords($number) {
    $words = [
        0 => 'Zero',
        1 => 'One',
        2 => 'Two',
        3 => 'Three',
        4 => 'Four',
        5 => 'Five',
        6 => 'Six',
        7 => 'Seven',
        8 => 'Eight',
        9 => 'Nine',
        10 => 'Ten',
        11 => 'Eleven',
        12 => 'Twelve',
        13 => 'Thirteen',
        14 => 'Fourteen',
        15 => 'Fifteen',
        16 => 'Sixteen',
        17 => 'Seventeen',
        18 => 'Eighteen',
        19 => 'Nineteen',
        20 => 'Twenty',
        30 => 'Thirty',
        40 => 'Forty',
        50 => 'Fifty',
        60 => 'Sixty',
        70 => 'Seventy',
        80 => 'Eighty',
        90 => 'Ninety'
    ];
    
    if ($number < 21) {
        return $words[$number];
    } elseif ($number < 100) {
        return $words[10 * floor($number / 10)] . ($number % 10 ? ' ' . $words[$number % 10] : '');
    } elseif ($number < 1000) {
        return $words[floor($number / 100)] . ' Hundred' . ($number % 100 ? ' ' . numberToWords($number % 100) : '');
    } elseif ($number < 100000) {
        return numberToWords(floor($number / 1000)) . ' Thousand' . ($number % 1000 ? ' ' . numberToWords($number % 1000) : '');
    } elseif ($number < 10000000) {
        return numberToWords(floor($number / 100000)) . ' Lakh' . ($number % 100000 ? ' ' . numberToWords($number % 100000) : '');
    } else {
        return numberToWords(floor($number / 10000000)) . ' Crore' . ($number % 10000000 ? ' ' . numberToWords($number % 10000000) : '');
    }
}

/**
 * Generate invoice number
 */
function generateInvoiceNumber($prefix = 'KA') {
    $year = date('Y');
    $month = date('m');
    
    // Get last invoice number for this month
    $lastInvoice = fetchRow(
        "SELECT invoice_number FROM sales 
         WHERE invoice_number LIKE ? 
         ORDER BY invoice_number DESC LIMIT 1",
        [$prefix . $year . $month . '%']
    );
    
    $sequence = 1;
    if ($lastInvoice) {
        $lastSequence = (int) substr($lastInvoice['invoice_number'], -4);
        $sequence = $lastSequence + 1;
    }
    
    return $prefix . $year . $month . str_pad($sequence, 4, '0', STR_PAD_LEFT);
}

/**
 * Check if user has permission
 */
function hasPermission($permission, $userId = null) {
    if (!$userId && isLoggedIn()) {
        $userId = $_SESSION['user_id'];
    }
    
    if (!$userId) {
        return false;
    }
    
    $user = fetchRow("SELECT role FROM users WHERE id = ?", [$userId]);
    
    if (!$user) {
        return false;
    }
    
    // Define role permissions
    $permissions = [
        'admin' => ['*'], // Admin has all permissions
        'manager' => ['view_dashboard', 'manage_sales', 'manage_expenses', 'view_reports', 'manage_categories'],
        'staff' => ['view_dashboard', 'add_sales', 'add_expenses', 'view_own_data']
    ];
    
    $userPermissions = $permissions[$user['role']] ?? [];
    
    return in_array('*', $userPermissions) || in_array($permission, $userPermissions);
}

/**
 * Backup database
 */
function backupDatabase($filename = null) {
    if (!$filename) {
        $filename = 'backup_' . date('Y-m-d_H-i-s') . '.sql';
    }
    
    $backupDir = __DIR__ . '/../backups/';
    if (!is_dir($backupDir)) {
        mkdir($backupDir, 0755, true);
    }
    
    $backupFile = $backupDir . $filename;
    
    $command = sprintf(
        'mysqldump --user=%s --password=%s --host=%s %s > %s',
        DB_USER,
        DB_PASS,
        DB_HOST,
        DB_NAME,
        escapeshellarg($backupFile)
    );
    
    exec($command, $output, $return);
    
    return $return === 0 ? $backupFile : false;
}

/**
 * Get file size in human readable format
 */
function humanFileSize($size, $precision = 2) {
    for ($i = 0; ($size / 1024) > 0.9; $i++, $size /= 1024) {}
    return round($size, $precision) . ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'][$i];
}

/**
 * Clean old log files
 */
function cleanOldLogs($days = 30) {
    $cutoffDate = date('Y-m-d H:i:s', strtotime("-$days days"));
    
    try {
        executeQuery("DELETE FROM activity_logs WHERE created_at < ?", [$cutoffDate]);
        return true;
    } catch (Exception $e) {
        error_log("Failed to clean old logs: " . $e->getMessage());
        return false;
    }
}
?>