<?php
/**
 * Export Tickets API
 *
 * Exports tickets to CSV format with optional filtering
 * Respects ticket visibility settings
 */

// 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');

try {
    // Include required files
    require_once dirname(__DIR__) . '/config/config.php';
    require_once dirname(__DIR__) . '/helpers/Database.php';
    require_once dirname(__DIR__) . '/models/TicketModel.php';
    require_once dirname(__DIR__) . '/models/CommentModel.php';
    require_once dirname(__DIR__) . '/models/AuditLogModel.php';

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

    $currentUser = $_SESSION['user'];

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

    // Get filter parameters
    $status = isset($_GET['status']) ? $_GET['status'] : null;
    $category = isset($_GET['category']) ? $_GET['category'] : null;
    $type = isset($_GET['type']) ? $_GET['type'] : null;
    $search = isset($_GET['search']) ? trim($_GET['search']) : null;
    $format   = isset($_GET['format'])    ? $_GET['format']    : 'csv';
    $ticketIds = isset($_GET['ticket_ids']) ? $_GET['ticket_ids'] : null;
    $singleIdRaw = isset($_GET['ticket_id']) ? trim($_GET['ticket_id']) : null;
    $singleId    = ($singleIdRaw !== null && ctype_digit($singleIdRaw) && (int)$singleIdRaw > 0) ? $singleIdRaw : null;

    // Initialize model
    $ticketModel = new TicketModel($conn);

    // Check if specific ticket IDs are provided
    if ($ticketIds) {
        // Parse and validate ticket IDs
        $ticketIdArray = array_filter(array_map('trim', explode(',', $ticketIds)));
        if (empty($ticketIdArray)) {
            header('Content-Type: application/json');
            http_response_code(400);
            echo json_encode(['success' => false, 'error' => 'No valid ticket IDs provided']);
            exit;
        }

        // Get specific tickets by IDs
        $allTickets = $ticketModel->getTicketsByIds($ticketIdArray);

        // Filter tickets based on visibility - only export tickets the user can access
        $tickets = [];
        foreach ($allTickets as $ticket) {
            if ($ticketModel->canUserAccessTicket($ticket, $currentUser)) {
                $tickets[] = $ticket;
            }
        }
    } else {
        // Get all tickets with filters (no pagination for export)
        // Pass $currentUser so visibility filtering is applied correctly
        $result = $ticketModel->getAllTickets(1, 10000, $status, 'created_at', 'desc', $category, $type, $search, [], $currentUser);
        $tickets = $result['tickets'];
    }

    if ($format === 'csv') {
        // CSV Export
        header('Content-Type: text/csv; charset=utf-8');
        header('Content-Disposition: attachment; filename="tickets_export_' . date('Y-m-d_His') . '.csv"');
        header('Cache-Control: no-cache, must-revalidate');
        header('Pragma: no-cache');

        // Create output stream
        $output = fopen('php://output', 'w');

        // Add BOM for Excel UTF-8 compatibility
        fprintf($output, chr(0xEF) . chr(0xBB) . chr(0xBF));

        // CSV Headers
        $headers = [
            'Ticket ID',
            'Title',
            'Status',
            'Priority',
            'Category',
            'Type',
            'Created By',
            'Assigned To',
            'Created At',
            'Updated At',
            'Description'
        ];
        fputcsv($output, $headers);

        // CSV Data
        foreach ($tickets as $ticket) {
            $row = [
                $ticket['ticket_id'],
                $ticket['title'],
                $ticket['status'],
                'P' . $ticket['priority'],
                $ticket['category'],
                $ticket['type'],
                $ticket['creator_display_name'] ?? $ticket['creator_username'] ?? 'System',
                $ticket['assigned_display_name'] ?? $ticket['assigned_username'] ?? 'Unassigned',
                $ticket['created_at'],
                $ticket['updated_at'],
                $ticket['description']
            ];
            fputcsv($output, $row);
        }

        fclose($output);
        exit;

    } elseif ($format === 'json') {
        // JSON Export
        header('Content-Type: application/json');
        header('Content-Disposition: attachment; filename="tickets_export_' . date('Y-m-d_His') . '.json"');

        echo json_encode([
            'exported_at' => date('c'),
            'total_tickets' => count($tickets),
            'tickets' => array_map(function($t) {
                return [
                    'ticket_id' => $t['ticket_id'],
                    'title' => $t['title'],
                    'status' => $t['status'],
                    'priority' => $t['priority'],
                    'category' => $t['category'],
                    'type' => $t['type'],
                    'description' => $t['description'],
                    'created_by' => $t['creator_display_name'] ?? $t['creator_username'],
                    'assigned_to' => $t['assigned_display_name'] ?? $t['assigned_username'],
                    'created_at' => $t['created_at'],
                    'updated_at' => $t['updated_at']
                ];
            }, $tickets)
        ], JSON_PRETTY_PRINT);
        exit;

    } elseif ($format === 'full') {
        // Full single-ticket export: ticket + all comments + audit timeline
        if (!$singleId) {
            header('Content-Type: application/json');
            http_response_code(400);
            echo json_encode(['success' => false, 'error' => 'format=full requires a ticket_id parameter']);
            exit;
        }

        $ticket = $ticketModel->getTicketById($singleId);
        if (!$ticket || !$ticketModel->canUserAccessTicket($ticket, $currentUser)) {
            header('Content-Type: application/json');
            http_response_code(404);
            echo json_encode(['success' => false, 'error' => 'Ticket not found']);
            exit;
        }

        $commentModel   = new CommentModel($conn);
        $auditLogModel  = new AuditLogModel($conn);

        // Load flat comment list (no threading nesting in export)
        $rawComments = $commentModel->getCommentsByTicketId($ticket['ticket_id'], false);
        $timeline    = $auditLogModel->getTicketTimeline((string)$ticket['ticket_id']);

        $comments = array_map(function($c) {
            return [
                'comment_id'        => $c['comment_id'],
                'author'            => $c['display_name'] ?? $c['username'] ?? 'Unknown',
                'created_at'        => $c['created_at'],
                'updated_at'        => $c['updated_at'] ?? null,
                'comment_text'      => $c['comment_text'],
                'parent_comment_id' => $c['parent_comment_id'] ?? null,
            ];
        }, $rawComments);

        $timelineOut = array_map(function($row) {
            $details = $row['details'];
            if (is_string($details)) {
                $details = json_decode($details, true) ?? $details;
            }
            return [
                'action'     => $row['action_type'],
                'entity'     => $row['entity_type'],
                'actor'      => $row['display_name'] ?? $row['username'] ?? 'System',
                'details'    => $details,
                'created_at' => $row['created_at'],
            ];
        }, $timeline);

        header('Content-Type: application/json');
        header('Content-Disposition: attachment; filename="ticket_' . $ticket['ticket_id'] . '_full_' . date('Y-m-d_His') . '.json"');
        header('Cache-Control: no-cache, must-revalidate');

        echo json_encode([
            'exported_at'    => date('c'),
            'ticket' => [
                'ticket_id'   => $ticket['ticket_id'],
                'title'       => $ticket['title'],
                'status'      => $ticket['status'],
                'priority'    => 'P' . $ticket['priority'],
                'category'    => $ticket['category'],
                'type'        => $ticket['type'],
                'visibility'  => $ticket['visibility'] ?? 'public',
                'description' => $ticket['description'],
                'created_by'  => $ticket['creator_display_name'] ?? $ticket['creator_username'] ?? 'System',
                'assigned_to' => $ticket['assigned_display_name'] ?? $ticket['assigned_username'] ?? 'Unassigned',
                'created_at'  => $ticket['created_at'],
                'updated_at'  => $ticket['updated_at'],
                'closed_at'   => $ticket['closed_at'] ?? null,
            ],
            'comments'       => $comments,
            'comment_count'  => count($comments),
            'timeline'       => $timelineOut,
        ], JSON_PRETTY_PRINT);
        exit;

    } else {
        header('Content-Type: application/json');
        http_response_code(400);
        echo json_encode(['success' => false, 'error' => 'Invalid format. Use csv, json, or full.']);
        exit;
    }

} catch (Exception $e) {
    error_log("Export tickets API error: " . $e->getMessage());
    header('Content-Type: application/json');
    http_response_code(500);
    echo json_encode([
        'success' => false,
        'error' => 'An internal error occurred'
    ]);
}