import { assertEquals } from "@std/assert/equals";

import { createHash } from "node:crypto";

import { decodeNixBase32 } from "./base32.ts";

import { splitOnce } from "./util.ts";

export class Hash {

raw: string;

algorithm: string;

hash: Uint8Array;

constructor(raw: string) {

this.raw = raw;

const [algorithm, encodedHash] = splitOnce(raw, ":");

this.algorithm = algorithm;

this.hash = decodeNixBase32(encodedHash);

}

createVerifierStream(): HashVerifierStream {

return new HashVerifierStream(this.algorithm, this.hash);

}

}

class HashVerifierStream extends TransformStream<Uint8Array, Uint8Array> {

constructor(

algorithm: string,

expectedHash: Uint8Array,

) {

const hasher = createHash(algorithm);

super({

transform(chunk, controller) {

hasher.update(chunk);

controller.enqueue(chunk);

},

flush() {

assertEquals(

new Uint8Array(hasher.digest()),

expectedHash,

`Hash mismatch`,

);

},

});

}

}