market_screener/server/screener/ScreenerEngine.ts

import { YahooClient } from '../market/YahooClient.js';
import { BenchmarkProvider } from '../market/BenchmarkProvider.js';
import { mapToStandardFormat } from './DataMapper.js';
import { chunkArray } from './Chunker.js';
import { RuleMerger } from './RuleMerger.js';
import { Stock } from './assets/Stock.js';
import { Etf } from './assets/Etf.js';
import { Bond } from './assets/Bond.js';
import { StockScorer } from './scorers/StockScorer.js';
import { EtfScorer } from './scorers/EtfScorer.js';
import { BondScorer } from './scorers/BondScorer.js';
import { SIGNAL, SIGNAL_ORDER, SCORE_MODE, ASSET_TYPE } from '../config/constants.js';
import type { Logger, MarketContext, Signal, AssetType, ScreenerResult } from '../types.js';

const SCORERS: Record<AssetType, typeof StockScorer | typeof EtfScorer | typeof BondScorer> = {
  [ASSET_TYPE.STOCK]: StockScorer,
  [ASSET_TYPE.ETF]: EtfScorer,
  [ASSET_TYPE.BOND]: BondScorer,
};

interface ScreenerEngineOptions {
  logger?: Logger;
}

interface ErrorResult {
  isError: true;
  ticker: string;
  message: string;
}

type FetchResult = ReturnType<typeof mapToStandardFormat> | ErrorResult;

export class ScreenerEngine {
  private client: YahooClient;
  private benchmarkProvider: BenchmarkProvider;
  private logger: Logger;

  constructor({ logger }: ScreenerEngineOptions = {}) {
    this.client = new YahooClient();
    this.benchmarkProvider = new BenchmarkProvider({
      logger: logger ?? (console as unknown as Logger),
    });
    this.logger = logger ?? {
      write: (msg: string) => process.stdout.write(msg),
      log: (...args: unknown[]) => console.log(...args),
      warn: (...args: unknown[]) => console.warn(...args),
    };
  }

  // Pure data method — returns structured results. Safe to use in a server route.
  async screenTickers(tickers: string[]): Promise<ScreenerResult> {
    const marketContext = await this.benchmarkProvider.getMarketContext();
    const results: Omit<ScreenerResult, 'marketContext'> = {
      STOCK: [],
      ETF: [],
      BOND: [],
      ERROR: [],
    };

    for (const chunk of chunkArray(tickers, 5)) {
      const batch = await Promise.all(chunk.map((t) => this._fetch(t)));
      batch.forEach((data) => this._process(data, marketContext, results));
      await new Promise<void>((r) => setTimeout(r, 1000));
    }

    return { ...results, marketContext };
  }

  // CLI helper — emits progress to logger, returns structured results.
  async screenWithProgress(tickers: string[]): Promise<ScreenerResult> {
    this.logger.write('⏳ Fetching market context...');
    const marketContext = await this.benchmarkProvider.getMarketContext();
    this.logger.write(' done\n');

    const results: Omit<ScreenerResult, 'marketContext'> = {
      STOCK: [],
      ETF: [],
      BOND: [],
      ERROR: [],
    };
    const chunks = chunkArray(tickers, 5);
    let processed = 0;

    for (const chunk of chunks) {
      const batch = await Promise.all(chunk.map((t) => this._fetch(t)));
      batch.forEach((data) => this._process(data, marketContext, results));
      processed += chunk.length;
      this.logger.write(`\r⏳ Screening tickers... ${processed}/${tickers.length}`);
      await new Promise<void>((r) => setTimeout(r, 1000));
    }

    this.logger.write('\n');
    return { ...results, marketContext };
  }

  private async _fetch(ticker: string): Promise<FetchResult> {
    try {
      const summary = await this.client.fetchSummary(ticker);
      if (!summary?.price) throw new Error('Empty response from Yahoo');
      return mapToStandardFormat(ticker, summary);
    } catch (err) {
      return { isError: true, ticker: ticker.toUpperCase(), message: (err as Error).message };
    }
  }

  private _process(
    data: FetchResult,
    marketContext: MarketContext,
    results: Omit<ScreenerResult, 'marketContext'>,
  ): void {
    if ('isError' in data && data.isError) {
      results.ERROR.push({ ticker: data.ticker, message: data.message });
      return;
    }

    try {
      const asset = this._buildAsset(data as ReturnType<typeof mapToStandardFormat>);
      const scorer = SCORERS[asset.type as AssetType];
      if (!scorer) throw new Error(`No scorer for type: ${asset.type}`);

      const fundamental = scorer.score(
        asset.metrics as never,
        RuleMerger.getRulesForAsset(
          asset.type as AssetType,
          asset.metrics as { sector?: string },
          marketContext,
          SCORE_MODE.FUNDAMENTAL,
        ),
        marketContext,
      );
      const inflated = scorer.score(
        asset.metrics as never,
        RuleMerger.getRulesForAsset(
          asset.type as AssetType,
          asset.metrics as { sector?: string },
          marketContext,
          SCORE_MODE.INFLATED,
        ),
        marketContext,
      );

      (results[asset.type as AssetType] as unknown[]).push({
        asset,
        fundamental,
        inflated,
        signal: this._signal(fundamental.label, inflated.label),
      });
    } catch (err) {
      results.ERROR.push({
        ticker: ((data as { ticker?: string }).ticker || 'UNKNOWN').toUpperCase(),
        message: (err as Error).message,
      });
    }
  }

  private _buildAsset(data: Record<string, unknown>): Stock | Etf | Bond {
    switch (((data.type as string) || ASSET_TYPE.STOCK).toUpperCase()) {
      case ASSET_TYPE.BOND:
        return new Bond(data as never);
      case ASSET_TYPE.ETF:
        return new Etf(data as never);
      default:
        return new Stock(data as never);
    }
  }

  private _signal(fundamentalLabel: string, inflatedLabel: string): Signal {
    const green = (l: string) => l.startsWith('🟢');
    const yellow = (l: string) => l.startsWith('🟡');
    if (green(fundamentalLabel)) return SIGNAL.STRONG_BUY;
    if (green(inflatedLabel) && yellow(fundamentalLabel)) return SIGNAL.MOMENTUM;
    if (green(inflatedLabel) && !green(fundamentalLabel)) return SIGNAL.SPECULATION;
    if (yellow(fundamentalLabel) || yellow(inflatedLabel)) return SIGNAL.NEUTRAL;
    return SIGNAL.AVOID;
  }

  signalOrder(signal: Signal): number {
    return SIGNAL_ORDER[signal] ?? 5;
  }
}