ShieldAI/services/voiceprint/src/embedding/EmbeddingService.ts

import { spawn } from "child_process";
import { v4 as uuidv4 } from "uuid";
import { logger } from "../logger";

const EMBEDDING_DIM = 192;
const MODEL_VERSION = "ecapa-tdnn-0.1.0-mock";

export class EmbeddingService {
  private mlServiceUrl: string;
  private readonly maxRetries = 3;
  private readonly retryDelay = 1000;

  constructor() {
    this.mlServiceUrl = process.env.VOICEPRINT_ML_URL || "http://localhost:8001";
  }

  async extract(audioBuffer: Buffer): Promise<EmbeddingOutput> {
    const mlAvailable = await this.checkMLService();

    if (mlAvailable) {
      logger.info("Using ML service for embedding extraction", { mlUrl: this.mlServiceUrl });
      return this.extractViaML(audioBuffer);
    }

    logger.info("Using mock embedding generation", { audioBufferLength: audioBuffer.length });
    return this.generateMockFromBuffer(audioBuffer);
  }

  async classify(embedding: number[]): Promise<number> {
    const mlAvailable = await this.checkMLService();

    if (mlAvailable) {
      logger.info("Using ML service for classification", { embeddingLength: embedding.length });
      return this.classifyViaML(embedding);
    }

    logger.info("Using mock classification", { embeddingLength: embedding.length });
    const mean = embedding.reduce((s, v) => s + v, 0) / embedding.length;
    const variance = embedding.reduce((s, v) => s + (v - mean) ** 2, 0) / embedding.length;
    const stdDev = Math.sqrt(variance);

    const syntheticIndicators = [
      stdDev < 0.1 ? 0.8 : 0.2,
      Math.abs(mean) > 0.5 ? 0.7 : 0.3,
      this.hasArtifacts(embedding) ? 0.9 : 0.1,
    ];

    return syntheticIndicators.reduce((s, v) => s + v, 0) / syntheticIndicators.length;
  }

  getModelVersion(): string {
    return MODEL_VERSION;
  }

  private async extractViaML(audioBuffer: Buffer): Promise<EmbeddingOutput> {
    return new Promise((resolve, reject) => {
      const jsonInput = audioBuffer.toString("base64");
      const proc = spawn("python3", [
        "-c",
        `
import urllib.request, json, sys
req = urllib.request.Request(
    "${this.mlServiceUrl}/embedding",
    data=json.dumps({"audio": "${jsonInput.substring(0, 5000)}"}).encode(),
    headers={"Content-Type": "application/json"}
)
try:
    with urllib.request.urlopen(req, timeout=60) as resp:
        data = json.loads(resp.read())
        sys.stdout.write(json.dumps({"ok": True, "vector": data.get("embedding", []), "dim": data.get("dimension", ${EMBEDDING_DIM})}))
except Exception as e:
    sys.stdout.write(json.dumps({"ok": False, "error": str(e)}))
`,
      ]);

      let output = "";
      proc.stdout.on("data", (chunk) => { output += chunk.toString(); });
      proc.on("close", (code) => {
        try {
          const result = JSON.parse(output);
          if (result.ok && result.vector.length === EMBEDDING_DIM) {
            resolve({ vector: result.vector, dimension: EMBEDDING_DIM });
          } else {
            resolve(this.generateMockFromBuffer(audioBuffer));
          }
        } catch {
          resolve(this.generateMockFromBuffer(audioBuffer));
        }
      });
    });
  }

  private async classifyViaML(embedding: number[]): Promise<number> {
    return new Promise((resolve) => {
      const proc = spawn("python3", [
        "-c",
        `
import urllib.request, json, sys
req = urllib.request.Request(
    "${this.mlServiceUrl}/classify",
    data=json.dumps({"embedding": ${JSON.stringify(embedding)}}).encode(),
    headers={"Content-Type": "application/json"}
)
try:
    with urllib.request.urlopen(req, timeout=30) as resp:
        data = json.loads(resp.read())
        sys.stdout.write(json.dumps({"score": data.get("synthetic_score", 0.5)}))
except:
    sys.stdout.write(json.dumps({"score": 0.5}))
`,
      ]);

      let output = "";
      proc.stdout.on("data", (chunk) => { output += chunk.toString(); });
      proc.on("close", () => {
        try {
          const result = JSON.parse(output);
          resolve(result.score || 0.5);
        } catch {
          resolve(0.5);
        }
      });
    });
  }

  private hasArtifacts(embedding: number[]): boolean {
    const window = 16;
    let artifactCount = 0;

    for (let i = 0; i < embedding.length - window; i += window) {
      const slice = embedding.slice(i, i + window);
      const localMean = slice.reduce((s, v) => s + v, 0) / slice.length;
      const localVar = slice.reduce((s, v) => s + (v - localMean) ** 2, 0) / slice.length;

      if (localVar < 0.001) artifactCount++;
    }

    return artifactCount > embedding.length / window / 3;
  }

  private generateMockFromBuffer(audioBuffer: Buffer): EmbeddingOutput {
    let hash = 0;
    const sampleSize = Math.min(audioBuffer.length, 1024);
    for (let i = 0; i < sampleSize; i += 4) {
      hash = ((hash << 5) - hash + audioBuffer.readInt32LE(i)) | 0;
    }
    const seed = Math.abs(hash);
    
    const rng = this.createRNG(seed);
    const vector: number[] = [];

    for (let i = 0; i < EMBEDDING_DIM; i++) {
      const u1 = rng();
      const u2 = rng();
      const gauss = Math.sqrt(-2 * Math.log(u1)) * Math.cos(2 * Math.PI * u2);
      vector.push(parseFloat(gauss.toFixed(6)));
    }

    const norm = Math.sqrt(vector.reduce((s, v) => s + v * v, 0));
    const normalized = vector.map((v) => parseFloat((v / norm).toFixed(6)));

    return { vector: normalized, dimension: EMBEDDING_DIM };
  }

  private async checkMLService(): Promise<boolean> {
    logger.info("Checking ML service availability", { mlUrl: this.mlServiceUrl });
    return new Promise((resolve) => {
      const proc = spawn("python3", [
        "-c",
        `
import urllib.request, sys
try:
    urllib.request.urlopen("${this.mlServiceUrl}/health", timeout=2)
    sys.exit(0)
except:
    sys.exit(1)
`,
      ]);
      proc.on("close", (code) => resolve(code === 0));
    });
  }

  private createRNG(seed: number): () => number {
    return () => {
      seed = (seed * 1664525 + 1013904223) & 0xffffffff;
      return (seed >>> 0) / 0xffffffff;
    };
  }
}

export interface EmbeddingOutput {
  vector: number[];
  dimension: number;
}