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

header('Content-Type: application/json');

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

    // Get input data
    $input = json_decode(file_get_contents('php://input'), true);
    if (!isset($input['question_id'])) {
        throw new Exception('Question ID is required');
    }
    
    $questionId = (int)$input['question_id'];
    
    $db = Database::getInstance();
    
    // Get survey ID for this question
    $stmt = $db->prepare("SELECT survey_id FROM survey_questions WHERE id = ?");
    $stmt->bind_param('i', $questionId);
    $stmt->execute();
    $result = $stmt->get_result();
    
    if ($result->num_rows === 0) {
        throw new Exception('Question not found');
    }
    
    $surveyId = $result->fetch_assoc()['survey_id'];
    
    // Verify user has access to this survey
    $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('Access denied');
    }
    
    // Delete the question
    $stmt = $db->prepare("DELETE FROM survey_questions WHERE id = ?");
    $stmt->bind_param('i', $questionId);
    
    if (!$stmt->execute()) {
        throw new Exception('Failed to delete question');
    }
    
    // Reorder remaining questions
    $stmt = $db->prepare("
        SET @rank = 0;
        UPDATE survey_questions 
        SET question_order = @rank := @rank + 1 
        WHERE survey_id = ? 
        ORDER BY question_order
    ");
    $stmt->bind_param('i', $surveyId);
    $stmt->execute();
    
    echo json_encode([
        'success' => true,
        'message' => 'Question deleted successfully'
    ]);

} catch (Exception $e) {
    echo json_encode([
        'success' => false,
        'error' => $e->getMessage()
    ]);
}
?>