predict.ts

import { ObjectId } from "mongodb";
import { KMeans, StandardScaler } from "scikitjs";
import getDb, { getBucket } from "../db";
import { Song } from "../db/types";
import extractFeatures, { decodeAudio } from "./features";

export const predictFromGridFS = async (
    model: KMeans,
    filename: string
): Promise<number> => {
    const bucket = getBucket();
    const stream = bucket.openDownloadStreamByName(filename);

    // Decode file stream from GridFS
    const audioData = await decodeAudio(stream);
    const features = extractFeatures(audioData);

    // Standardize features
    const data = new StandardScaler().fitTransform([features]);
    
    const output = await model.predict(data).array();
    return output[0];
};