import { Transform } from "node:stream";
import { createHash } from "node:crypto";
import File from "vinyl";

function fileHash(buffer: Buffer) {
    const hash = createHash("sha256");
    hash.update(buffer.toString());
    return hash.digest("hex");
}

export default function (manifestName: string) {
    const mappings: { [path: string]: string } = {};

    return new Transform({
        readableObjectMode: true,
        writableObjectMode: true,
        transform(chunk: File, _, callback) {
            const hash = fileHash(chunk.contents as Buffer);
            const newName = `${chunk.basename.substring(0, chunk.basename.length - chunk.extname.length)}.${hash.substring(0, 8)}${chunk.extname}`;

            mappings[chunk.basename] = newName;
            chunk.basename = newName;

            callback(null, chunk);
        },
        final(callback) {
            const mappingFile = new File({
                path: manifestName,
                contents: Buffer.from(JSON.stringify(mappings)),
            });
            this.push(mappingFile);

            callback(null);
        },
    });
}