import { toBase64 } from "../../util-base64/toBase64.browser";
import { isReadableStream } from "../stream-type-check";
import { ChecksumStream } from "./ChecksumStream.browser";
export const createChecksumStream = ({ expectedChecksum, checksum, source, checksumSourceLocation, base64Encoder, }) => {
    if (!isReadableStream(source)) {
        throw new Error(`@smithy/util-stream: unsupported source type ${source?.constructor?.name ?? source} in ChecksumStream.`);
    }
    const encoder = base64Encoder ?? toBase64;
    if (typeof TransformStream !== "function") {
        throw new Error("@smithy/util-stream: unable to instantiate ChecksumStream because API unavailable: ReadableStream/TransformStream.");
    }
    const transform = new TransformStream({
        start() { },
        async transform(chunk, controller) {
            checksum.update(chunk);
            controller.enqueue(chunk);
        },
        async flush(controller) {
            const digest = await checksum.digest();
            const received = encoder(digest);
            if (expectedChecksum !== received) {
                const error = new Error(`Checksum mismatch: expected "${expectedChecksum}" but received "${received}"` +
                    ` in response header "${checksumSourceLocation}".`);
                controller.error(error);
            }
            else {
                controller.terminate();
            }
        },
    });
    source.pipeThrough(transform);
    const readable = transform.readable;
    Object.setPrototypeOf(readable, ChecksumStream.prototype);
    return readable;
};