/**
 * Computes the cosine similarity between two vectors
 */
export function cosineSimilarity(a: Float32Array, b: Float32Array): number {
    if (a.length !== b.length) {
        throw new Error(`Vector dimensions don't match: ${a.length} vs ${b.length}`);
    }

    let dotProduct = 0;
    let aMagnitude = 0;
    let bMagnitude = 0;

    for (let i = 0; i < a.length; i++) {
        dotProduct += a[i] * b[i];
        aMagnitude += a[i] * a[i];
        bMagnitude += b[i] * b[i];
    }

    aMagnitude = Math.sqrt(aMagnitude);
    bMagnitude = Math.sqrt(bMagnitude);

    if (aMagnitude === 0 || bMagnitude === 0) {
        return 0;
    }

    return dotProduct / (aMagnitude * bMagnitude);
}

/**
 * Converts embedding Float32Array to Buffer for storage in SQLite
 */
export function embeddingToBuffer(embedding: Float32Array): Buffer {
    return Buffer.from(embedding.buffer);
}

/**
 * Converts Buffer from SQLite back to Float32Array
 */
export function bufferToEmbedding(buffer: Buffer, dimension: number): Float32Array {
    return new Float32Array(buffer.buffer, buffer.byteOffset, dimension);
}