<?php
include 'db_connection.php';

// Fetch restaurants and their median scores
$stmt = $db->prepare("
    SELECT
        r.id,
        r.name,
        ROUND(MEDIAN(b.bewertung)) AS median_score
    FROM Restaurant r
    LEFT JOIN Bewertung b ON r.id = b.fk_restaurant_id
    GROUP BY r.id, r.name
    ORDER BY median_score DESC NULLS LAST
");
$stmt->execute();
$restaurants = $stmt->fetchAll(PDO::FETCH_ASSOC);

$tiers = [];
foreach ($restaurants as $restaurant) {
    $score = $restaurant['median_score'];
    if ($score >= 9) {
        $tiers['S'][] = $restaurant;
    } elseif ($score >= 7) {
        $tiers['A'][] = $restaurant;
    } elseif ($score >= 5) {
        $tiers['B'][] = $restaurant;
    } elseif ($score >= 3) {
        $tiers['C'][] = $restaurant;
    } elseif ($score >= 1) {
        $tiers['D'][] = $restaurant;
    } else {
        $tiers['Unrated'][] = $restaurant; // For restaurants with no reviews
    }
}

echo json_encode($tiers);
?>