<?php
// Set up error reporting for debugging
error_reporting(E_ALL);
ini_set('display_errors', 1);

// Manual database connection
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "popularcomputer";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("<h1>Connection failed: " . $conn->connect_error . "</h1>");
}

echo "<h1>Updating Enrollment Numbers</h1>";

// Get count of records with null enrollment_number
$count_query = $conn->query("SELECT COUNT(*) as count FROM enrollments WHERE enrollment_number IS NULL");
$row = $count_query->fetch_assoc();
$null_count = $row['count'];

echo "<p>Found " . $null_count . " enrollments without enrollment numbers.</p>";

if ($null_count > 0) {
    // Update existing enrollments with generated enrollment numbers
    $update_query = $conn->query("SELECT e.id, e.user_id, e.course_id, c.course_code 
                                FROM enrollments e 
                                LEFT JOIN courses c ON e.course_id = c.id
                                WHERE e.enrollment_number IS NULL");

    if ($update_query && $update_query->num_rows > 0) {
        $updated_count = 0;
        while ($enrollment = $update_query->fetch_assoc()) {
            $enrollment_id = $enrollment['id'];
            $user_id = $enrollment['user_id'];
            $course_id = $enrollment['course_id'];
            $course_code = $enrollment['course_code'] ?: 'C' . sprintf('%03d', $course_id);
            
            // Generate enrollment number: COURSE_CODE-STUDENT_ID-YEAR-RANDOM
            $year = date('Y');
            $random = strtoupper(substr(md5(uniqid()), 0, 4));
            $enrollment_number = $course_code . '-' . $user_id . '-' . $year . '-' . $random;
            
            // Update the enrollment with the generated number
            if ($conn->query("UPDATE enrollments SET enrollment_number = '$enrollment_number' WHERE id = $enrollment_id")) {
                $updated_count++;
                echo "<p>Updated enrollment ID $enrollment_id with number: $enrollment_number</p>";
            } else {
                echo "<p>Error updating enrollment ID $enrollment_id: " . $conn->error . "</p>";
            }
        }
        
        if ($updated_count > 0) {
            echo "<h2>Successfully updated $updated_count enrollment records.</h2>";
        }
    } else {
        echo "<p>Error retrieving enrollments or no records found: " . ($conn->error ?: "No records found") . "</p>";
    }
} else {
    echo "<p>All enrollment records already have enrollment numbers.</p>";
    
    // Show some sample enrollment numbers
    $sample_query = $conn->query("SELECT id, enrollment_number FROM enrollments WHERE enrollment_number IS NOT NULL LIMIT 5");
    if ($sample_query && $sample_query->num_rows > 0) {
        echo "<h3>Sample enrollment numbers:</h3>";
        echo "<ul>";
        while ($row = $sample_query->fetch_assoc()) {
            echo "<li>ID " . $row['id'] . ": " . $row['enrollment_number'] . "</li>";
        }
        echo "</ul>";
    }
}

echo "<p>Process completed. <a href='enroll/payment.php'>Return to payment page</a></p>";

// Close the connection
$conn->close();
?>