<?php

// Disable error display in the output
ini_set('display_errors', 0);
error_reporting(E_ALL);

// Apply rate limiting
require_once dirname(__DIR__) . '/middleware/RateLimitMiddleware.php';
RateLimitMiddleware::apply('api');

// Start output buffering to capture any errors
ob_start();

try {
    // Include required files with proper error handling
    $configPath = dirname(__DIR__) . '/config/config.php';
    $commentModelPath = dirname(__DIR__) . '/models/CommentModel.php';
    $auditLogModelPath = dirname(__DIR__) . '/models/AuditLogModel.php';

    if (!file_exists($configPath)) {
        throw new Exception("Config file not found: $configPath");
    }

    if (!file_exists($commentModelPath)) {
        throw new Exception("CommentModel file not found: $commentModelPath");
    }

    require_once $configPath;
    require_once $commentModelPath;
    require_once $auditLogModelPath;
    require_once dirname(__DIR__) . '/helpers/Database.php';
    require_once dirname(__DIR__) . '/models/TicketModel.php';
    require_once dirname(__DIR__) . '/helpers/NotificationHelper.php';
    require_once dirname(__DIR__) . '/helpers/SynapseHelper.php';

    // Check authentication via session
    if (session_status() === PHP_SESSION_NONE) {
        session_start();
    }
    if (!isset($_SESSION['user']) || !isset($_SESSION['user']['user_id'])) {
        ob_end_clean();
        http_response_code(401);
        header('Content-Type: application/json');
        echo json_encode(['success' => false, 'error' => 'Authentication required']);
        exit;
    }

    // CSRF Protection for all state-changing methods (any non-GET/HEAD request)
    require_once dirname(__DIR__) . '/middleware/CsrfMiddleware.php';
    if (!in_array($_SERVER['REQUEST_METHOD'], ['GET', 'HEAD'], true)) {
        $csrfToken = $_SERVER['HTTP_X_CSRF_TOKEN'] ?? '';
        if (!CsrfMiddleware::validateToken($csrfToken)) {
            http_response_code(403);
            header('Content-Type: application/json');
            echo json_encode([
                'success' => false,
                'error' => 'Invalid CSRF token',
                'csrf_token' => CsrfMiddleware::getToken()
            ]);
            exit;
        }
        // Rotate token after successful validation
        $newCsrfToken = CsrfMiddleware::rotateToken();
    }

    $currentUser = $_SESSION['user'];
    $userId = $currentUser['user_id'];

    // Use centralized database connection
    $conn = Database::getConnection();

    // Get POST data
    $data = json_decode(file_get_contents('php://input'), true);

    if (!$data) {
        http_response_code(400);
        ob_end_clean();
        header('Content-Type: application/json');
        echo json_encode(['success' => false, 'error' => 'Invalid JSON data received']);
        exit;
    }

    $ticketId = isset($data['ticket_id']) ? trim((string)$data['ticket_id']) : '';
    if (!ctype_digit($ticketId) || (int)$ticketId <= 0) {
        http_response_code(400);
        ob_end_clean();
        header('Content-Type: application/json');
        echo json_encode(['success' => false, 'error' => 'Invalid ticket ID']);
        exit;
    }

    // Reject empty/whitespace-only comments
    $commentTextRaw = isset($data['comment_text']) ? trim((string)$data['comment_text']) : '';
    if ($commentTextRaw === '') {
        http_response_code(400);
        ob_end_clean();
        header('Content-Type: application/json');
        echo json_encode(['success' => false, 'error' => 'Comment text cannot be empty']);
        exit;
    }

    // Never trust a client-supplied display name — always attribute the comment to
    // the authenticated session user.
    $data['user_name'] = $currentUser['display_name'] ?? $currentUser['username'] ?? 'User';

    // Verify user can access the ticket before allowing a comment
    $ticketModel = new TicketModel($conn);
    $ticket = $ticketModel->getTicketById($ticketId);
    if (!$ticket) {
        http_response_code(404);
        ob_end_clean();
        header('Content-Type: application/json');
        echo json_encode(['success' => false, 'error' => 'Ticket not found']);
        exit;
    }
    if (!$ticketModel->canUserAccessTicket($ticket, $currentUser)) {
        http_response_code(403);
        ob_end_clean();
        header('Content-Type: application/json');
        echo json_encode(['success' => false, 'error' => 'Access denied']);
        exit;
    }

    // Initialize models
    $commentModel = new CommentModel($conn);
    $auditLog = new AuditLogModel($conn);

    // If replying, the parent comment must belong to this same (accessible) ticket.
    if (isset($data['parent_comment_id']) && $data['parent_comment_id'] !== null && $data['parent_comment_id'] !== '') {
        $parentComment = $commentModel->getCommentById((int)$data['parent_comment_id']);
        if (!$parentComment || (string)$parentComment['ticket_id'] !== (string)$ticketId) {
            http_response_code(400);
            ob_end_clean();
            header('Content-Type: application/json');
            echo json_encode(['success' => false, 'error' => 'Invalid parent comment']);
            exit;
        }
    }

    // Extract @mentions from comment text
    $mentions = $commentModel->extractMentions($data['comment_text'] ?? '');
    $mentionedUsers = [];
    if (!empty($mentions)) {
        $mentionedUsers = $commentModel->getMentionedUsers($mentions);
    }

    // Add comment with user tracking
    $result = $commentModel->addComment($ticketId, $data, $userId);

    // Log comment creation to audit log
    if ($result['success'] && isset($result['comment_id'])) {
        $auditLog->logCommentCreate($userId, $result['comment_id'], $ticketId);

        // Log mentions to audit log
        foreach ($mentionedUsers as $mentionedUser) {
            $auditLog->log(
                $userId,
                'mention',
                'user',
                (string)$mentionedUser['user_id'],
                [
                    'ticket_id' => $ticketId,
                    'comment_id' => $result['comment_id'],
                    'mentioned_username' => $mentionedUser['username']
                ]
            );
        }

        // Matrix notifications
        $authorDisplay = $currentUser['display_name'] ?? $currentUser['username'] ?? null;
        $commentText   = $data['comment_text'] ?? '';
        $ticketTitle   = $ticket['title'] ?? "Ticket #{$ticketId}";
        $ticketVisibility = $ticket['visibility'] ?? 'public';

        // @mention notifications — resolve usernames → Matrix IDs via Synapse Admin API
        if (!empty($mentionedUsers)) {
            $mentionedUsernames = array_column($mentionedUsers, 'username');
            $mentionedMatrixIds = SynapseHelper::resolveUsernames($mentionedUsernames);
            if (!empty($mentionedMatrixIds)) {
                NotificationHelper::sendMentionNotification($ticketId, $ticketTitle, $commentText, $authorDisplay, $mentionedMatrixIds);
            }
        }

        // General comment notification (opt-in via MATRIX_NOTIFY_COMMENTS)
        if (!empty($GLOBALS['config']['MATRIX_NOTIFY_COMMENTS'])) {
            NotificationHelper::sendCommentNotification(
                $ticketId,
                $ticketTitle,
                $commentText,
                $authorDisplay,
                $ticketVisibility !== 'public',
                $ticketVisibility
            );
        }

        // Notify watchers of the new comment
        NotificationHelper::notifyWatchers(
            $conn,
            $ticketId,
            $ticketTitle,
            'comment_added',
            ['author' => $authorDisplay, 'preview' => mb_strimwidth($commentText, 0, 200, '…')],
            (int)$userId,
            $ticketVisibility
        );

        // Add mentioned users to result for frontend
        $result['mentions'] = array_map(function ($u) {
            return $u['username'];
        }, $mentionedUsers);
    }

    // Add user info to result for frontend avatar rendering
    if ($result['success']) {
        $result['user_name'] = $currentUser['display_name'] ?? $currentUser['username'];
        $result['user_id']   = $userId;
        if (isset($newCsrfToken)) {
            $result['csrf_token'] = $newCsrfToken;
        }
    }

    // Discard any unexpected output
    ob_end_clean();

    // Return JSON response
    if ($result['success']) {
        http_response_code(201);
    }
    header('Content-Type: application/json');
    echo json_encode($result);
} catch (Exception $e) {
    // Discard any unexpected output
    ob_end_clean();

    // Log error details but don't expose to client
    error_log("Add comment API error: " . $e->getMessage());

    // Return error response
    http_response_code(500);
    header('Content-Type: application/json');
    echo json_encode([
        'success' => false,
        'error' => 'An internal error occurred'
    ]);
}