<?php
// Start session
session_start();

// Check if user has admin privileges
if (!isset($_SESSION['role']) || ($_SESSION['role'] !== 'admin' && $_SESSION['role'] !== 'director')) {
    echo json_encode(['success' => false, 'message' => 'Unauthorized access']);
    exit;
}

// Include database configuration
require_once '../../admin/database/db_config.php';

// Check if data is submitted via POST
if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    echo json_encode(['success' => false, 'message' => 'Invalid request method']);
    exit;
}

// Check if enrollment ID is provided
if (!isset($_POST['enrollment_id']) || empty($_POST['enrollment_id'])) {
    echo json_encode(['success' => false, 'message' => 'Invalid enrollment ID']);
    exit;
}

$enrollment_id = intval($_POST['enrollment_id']);
$admin_notes = trim($_POST['admin_notes'] ?? '');

// Begin transaction
$conn->begin_transaction();

try {
    // Get enrollment details
    $query = "SELECT user_id, course_id FROM enrollments WHERE id = ?";
    $stmt = $conn->prepare($query);
    $stmt->bind_param("i", $enrollment_id);
    $stmt->execute();
    $result = $stmt->get_result();
    
    if ($result->num_rows === 0) {
        throw new Exception('Enrollment not found');
    }
    
    $enrollment = $result->fetch_assoc();
    
    // Check if there's an application record
    $app_query = "SELECT id FROM enrollment_applications 
                 WHERE user_id = ? AND course_id = ? AND status = 'completed' 
                 ORDER BY updated_at DESC LIMIT 1";
    $stmt = $conn->prepare($app_query);
    $stmt->bind_param("ii", $enrollment['user_id'], $enrollment['course_id']);
    $stmt->execute();
    $app_result = $stmt->get_result();
    
    if ($app_result->num_rows > 0) {
        // Update application notes
        $app_id = $app_result->fetch_assoc()['id'];
        $update_app_query = "UPDATE enrollment_applications SET admin_notes = ? WHERE id = ?";
        $stmt = $conn->prepare($update_app_query);
        $stmt->bind_param("si", $admin_notes, $app_id);
        
        if (!$stmt->execute()) {
            throw new Exception('Failed to update application notes: ' . $conn->error);
        }
    }
    
    // Update enrollment notes table (create if it doesn't exist)
    $create_notes_table = "CREATE TABLE IF NOT EXISTS enrollment_notes (
        id INT(11) NOT NULL AUTO_INCREMENT,
        enrollment_id INT(11) NOT NULL,
        admin_notes TEXT DEFAULT NULL,
        admin_id INT(11) NOT NULL,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        PRIMARY KEY (id),
        KEY enrollment_id (enrollment_id)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;";
    
    if (!$conn->query($create_notes_table)) {
        throw new Exception('Failed to create notes table: ' . $conn->error);
    }
    
    // Check if entry exists
    $check_query = "SELECT id FROM enrollment_notes WHERE enrollment_id = ?";
    $stmt = $conn->prepare($check_query);
    $stmt->bind_param("i", $enrollment_id);
    $stmt->execute();
    $check_result = $stmt->get_result();
    
    if ($check_result->num_rows > 0) {
        // Update existing notes
        $notes_id = $check_result->fetch_assoc()['id'];
        $update_query = "UPDATE enrollment_notes SET admin_notes = ?, admin_id = ?, created_at = NOW() WHERE id = ?";
        $stmt = $conn->prepare($update_query);
        $stmt->bind_param("sii", $admin_notes, $_SESSION['user_id'], $notes_id);
    } else {
        // Insert new notes
        $insert_query = "INSERT INTO enrollment_notes (enrollment_id, admin_notes, admin_id) VALUES (?, ?, ?)";
        $stmt = $conn->prepare($insert_query);
        $stmt->bind_param("isi", $enrollment_id, $admin_notes, $_SESSION['user_id']);
    }
    
    if (!$stmt->execute()) {
        throw new Exception('Failed to update enrollment notes: ' . $conn->error);
    }
    
    // Log activity
    try {
        $log_query = "INSERT INTO activities (user_id, user_type, activity_type, activity_description, created_at) 
                      VALUES (?, 'admin', 'enrollment_note', ?, NOW())";
        $stmt = $conn->prepare($log_query);
        $activity_description = "Updated notes for enrollment #" . $enrollment_id;
        $stmt->bind_param("is", $_SESSION['user_id'], $activity_description);
        $stmt->execute();
    } catch (Exception $e) {
        // Just log error but don't fail the transaction
        error_log('Failed to log activity: ' . $e->getMessage());
    }
    
    // Commit transaction
    $conn->commit();
    
    echo json_encode(['success' => true, 'message' => 'Notes updated successfully']);
    
} catch (Exception $e) {
    // Rollback transaction
    $conn->rollback();
    echo json_encode(['success' => false, 'message' => $e->getMessage()]);
}
?>