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

// Basic input validation and sanitization
if (!isset($_POST['qid']) || empty($_POST['qid'])) {
    echo json_encode(['error' => 'Missing QID parameter']);
    exit;
}

$qid = $_POST['qid'];

// Database connection (adjust credentials accordingly)
//
$config = require 'config.php';
$host = $config['db_host'];
$db   = $config['db_name'];
$user = $config['db_user'];
$pass = $config['db_pass'];
$charset = 'utf8mb4';

$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
$options = [
    PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
];

try {
    $pdo = new PDO($dsn, $user, $pass, $options);

    $sql = "
        SELECT value, COUNT(*) AS count
        FROM Answers
        WHERE QID = :qid
          AND value BETWEEN -3 AND 3
        GROUP BY value
        ORDER BY value
    ";

    $stmt = $pdo->prepare($sql);
    $stmt->execute(['qid' => $qid]);
    $results = $stmt->fetchAll();

    // Initialize array with all possible values from -3 to 3 with zero counts
    $counts = [];
    for ($i = -3; $i <= 3; $i++) {
        $counts[$i] = 0;
    }

    // Fill in counts from query results
    foreach ($results as $row) {
        $counts[(int)$row['value']] = (int)$row['count'];
    }

    // Return as JSON array of objects [{value: -3, count: 5}, ...]
    $response = [];
    foreach ($counts as $value => $count) {
        $response[] = ['value' => $value, 'count' => $count];
    }

    echo json_encode($response);

} catch (PDOException $e) {
    echo json_encode(['error' => 'Database error: ' . $e->getMessage()]);
    exit;
}