FieldProcessingChain class exported ✓ 100.0%

export class FieldProcessingChain {
  private _classifiers: FieldClassifier[] = [];

  // ── Classify ─────────────────────────────────────────────────────────────────

  /**
   * Classifiers to run in order — each one is a named, injectable step.
   * The first classifier that returns a confident result wins.
   * Chrome AI (detectAsync) is called only in runAsync / stream.
   *
   * Each call to classify() REPLACES the previous list (no appending).
   */
  classify(...classifiers: FieldClassifier[]): this {
    this._classifiers = classifiers;
    return this;
  }

  // ── Helper ───────────────────────────────────────────────────────────────────

  private applyResult(field: FormField, result: PipelineResult): void {
    field.fieldType = result.type;
    field.detectionMethod = result.method;
    field.detectionConfidence = result.confidence;
    field.detectionDurationMs = result.durationMs;
    field.timings = result.timings;
    field.predictions = result.predictions;
    field.decisionTrace = result.decisionTrace;
  }

  // ── Execution modes ──────────────────────────────────────────────────────────

  /**
   * Async run — awaits every classifier (including Chrome AI) per field,
   * then returns all fields at once.
   */
  async runAsync(fields: FormField[]): Promise<FormField[]> {
    const pipeline = new DetectionPipeline(this._classifiers);
    for (const field of fields) {
      this.applyResult(field, await pipeline.runAsync(field));
    }
    return fields;
  }

  /**
   * Streaming run — yields each FormField immediately after it is classified.
   * Enables real-time UI updates while classification is still in progress.
   */
  async *stream(fields: FormField[]): AsyncGenerator<FormField> {
    const pipeline = new DetectionPipeline(this._classifiers);
    for (const field of fields) {
      this.applyResult(field, await pipeline.runAsync(field));
      yield field;
    }
  }
}