<?php
declare(strict_types=1);

/** JSON response helpers. Every API answer goes through here. */
final class Response
{
    public static function json(mixed $data, int $status = 200): never
    {
        http_response_code($status);
        header('Content-Type: application/json; charset=utf-8');
        header('Cache-Control: no-store');
        echo json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
        exit;
    }

    public static function error(string $message, int $status, array $extra = []): never
    {
        self::json(['error' => $message] + $extra, $status);
    }

    public static function noContent(): never
    {
        http_response_code(204);
        header('Cache-Control: no-store');
        exit;
    }

    /** Decoded JSON request body or an error response when it is not an object. */
    public static function body(): array
    {
        $data = json_decode(self::rawBody(), true);
        if (!is_array($data)) {
            self::error('Request body must be a JSON object', 400);
        }
        return $data;
    }

    /**
     * The request body as bytes (uploads send images, not JSON).
     *
     * An empty body is answered here rather than by every caller, because PHP also reports
     * a body that exceeded `post_max_size` as empty – a truncated upload must not look like
     * a malformed one.
     */
    public static function rawBody(): string
    {
        $raw = file_get_contents('php://input');
        if ($raw === false || $raw === '') {
            self::error('Request body is empty or exceeds the upload limit', 400);
        }
        return $raw;
    }
}