export class RequestBodyTooLargeError extends Error {
    status = 413;
    constructor(max_bytes) {
        super(`Request body exceeds ${max_bytes} bytes`);
        this.name = "RequestBodyTooLargeError";
    }
}
/**
 * Reads the whole request body, aborting as soon as it grows past
 * `max_bytes` so oversized (or chunked, length-less) bodies are never fully
 * buffered. Returns `undefined` when the request has no body.
 */
export default async function readRequestBody({ req, max_bytes, }) {
    if (req.method == "GET" || req.method == "HEAD" || !req.body) {
        return undefined;
    }
    const content_length = Number(req.headers.get("content-length"));
    if (content_length > max_bytes) {
        throw new RequestBodyTooLargeError(max_bytes);
    }
    const reader = req.body.getReader();
    const chunks = [];
    let total = 0;
    while (true) {
        const { done, value } = await reader.read();
        if (done)
            break;
        total += value.byteLength;
        if (total > max_bytes) {
            await reader.cancel();
            throw new RequestBodyTooLargeError(max_bytes);
        }
        chunks.push(value);
    }
    const body = new Uint8Array(total);
    let offset = 0;
    for (const chunk of chunks) {
        body.set(chunk, offset);
        offset += chunk.byteLength;
    }
    return body;
}