<?php
require_once 'includes/config.php';
require_once 'includes/functions.php';
require_once 'includes/auth.php';
require_once 'includes/db.php';

try {
    $auth = new Auth();
    if (!$auth->isLoggedIn()) {
        throw new Exception('Unauthorized');
    }

    $surveyId = isset($_POST['survey_id']) ? (int)$_POST['survey_id'] : null;
    $projectId = isset($_POST['project_id']) ? (int)$_POST['project_id'] : null;
    $redirect = isset($_POST['redirect']) ? $_POST['redirect'] : null;
    
    if (!$surveyId || !$projectId) {
        throw new Exception('Survey ID and Project ID are required');
    }

    $db = Database::getInstance();
    
    // Check if the project exists and user has access
    $stmt = $db->prepare("SELECT id FROM projects WHERE id = ? AND created_by = ?");
    $stmt->bind_param('ii', $projectId, $_SESSION['user_id']);
    $stmt->execute();
    if ($stmt->get_result()->num_rows == 0) {
        throw new Exception('Project not found or access denied');
    }
    
    // Check if the survey exists and user has access
    $stmt = $db->prepare("SELECT id FROM surveys WHERE id = ? AND created_by = ?");
    $stmt->bind_param('ii', $surveyId, $_SESSION['user_id']);
    $stmt->execute();
    if ($stmt->get_result()->num_rows == 0) {
        throw new Exception('Survey not found or access denied');
    }
    
    // Check if already connected
    $stmt = $db->prepare("SELECT id FROM project_surveys WHERE project_id = ? AND survey_id = ?");
    $stmt->bind_param('ii', $projectId, $surveyId);
    $stmt->execute();
    if ($stmt->get_result()->num_rows > 0) {
        throw new Exception('Survey is already connected to this project');
    }
    
    // Remove any existing connections for this project first (since only one survey can be connected)
    $stmt = $db->prepare("DELETE FROM project_surveys WHERE project_id = ?");
    $stmt->bind_param('i', $projectId);
    $stmt->execute();
    
    // Connect survey to project
    $stmt = $db->prepare("INSERT INTO project_surveys (project_id, survey_id, created_by) VALUES (?, ?, ?)");
    $stmt->bind_param('iii', $projectId, $surveyId, $_SESSION['user_id']);
    if (!$stmt->execute()) {
        throw new Exception('Failed to connect survey to project');
    }
    
    // Handle redirect or JSON response
    if ($redirect) {
        // Set a success message in session
        $_SESSION['success_message'] = 'Survey connected successfully';
        redirectTo($redirect);
        exit;
    } else {
        // Return JSON response
        header('Content-Type: application/json');
        echo json_encode([
            'success' => true,
            'message' => 'Survey connected successfully'
        ]);
    }
    
} catch (Exception $e) {
    if (isset($_POST['redirect'])) {
        // Set error message in session
        $_SESSION['error_message'] = $e->getMessage();
        redirectTo($_POST['redirect']);
        exit;
    } else {
        // Return JSON error
        header('Content-Type: application/json');
        echo json_encode([
            'success' => false,
            'message' => $e->getMessage()
        ]);
    }
}
?>