import { IdentityDBError } from '../core/errors';
import { normalizeTopicName } from '../core/utils';
import type { FactExtractor, ExtractedFact } from './types';

export async function extractFact(
  input: string,
  extractor: FactExtractor,
): Promise<ExtractedFact> {
  const extracted = await extractor.extract(input);
  const statement = extracted.statement?.trim() || input.trim();

  if (statement.length === 0) {
    throw new IdentityDBError('Extractor returned an empty statement.');
  }

  const dedupedTopics = new Map<string, ExtractedFact['topics'][number]>();

  for (const topic of extracted.topics) {
    const normalizedName = normalizeTopicName(topic.name);

    if (normalizedName.length === 0) {
      continue;
    }

    if (!dedupedTopics.has(normalizedName)) {
      dedupedTopics.set(normalizedName, topic);
    }
  }

  if (dedupedTopics.size === 0) {
    throw new IdentityDBError('Extractor returned no usable topics.');
  }

    return {
      statement,
      summary: extracted.summary ?? null,
      source: extracted.source ?? null,
      confidence: extracted.confidence ?? null,
      metadata: extracted.metadata ?? null,
      topics: Array.from(dedupedTopics.values()),
    };
}