backend/src/modules/investments/instruments/stocks/application/stock-income.service.ts

import { Injectable, NotFoundException } from '@nestjs/common';

import {
  decimalFromString,
  formatDecimal,
  multiply,
} from '../../../../../common/decimal';
import { ISO_DATE_LENGTH, ISO_DATE_START } from '../../../../../common/time';
import { decimal } from '../../../../../integrations/tbank/decimal';
import {
  TbankAccessService,
  type TbankDividend,
} from '../../../../../integrations/tbank/tbank.api';
import {
  ForecastService,
  PortfolioService,
} from '../../../portfolio/portfolio.api';
import { CatalogEnrichmentService } from '../../application/catalog-enrichment.service';
import { moscowDay, timestamp } from '../../application/instrument-market';
import { instrumentPosition } from '../../application/instrument-position';
import {
  StockDividendDto,
  StockDividendsDto,
  StockDividendsResourceDto,
  StockPositionDto,
} from '../presentation/stock.dto';

const INCOME_FORECAST_YEARS = 1;
const ZERO_QUANTITY = 0n;

const ISO_YEAR_LENGTH = 4;
const INCOME_HISTORY_YEARS = 5;
@Injectable()
export class StockIncomeService {
  constructor(
    private readonly portfolios: PortfolioService,
    private readonly sources: CatalogEnrichmentService,
    private readonly access: TbankAccessService,
    private readonly forecasts: ForecastService,
  ) {}

  async readPosition(userId: string, uid: string, observe = false) {
    const saved = await this.portfolios.read(userId, 'all', observe);
    return {
      data: saved.data ? instrumentPosition(saved.data, uid, 'STOCK') : null,
      meta: { ...saved.meta, resourceKey: `stock/position/${uid}` },
    };
  }

  async dividends(
    userId: string,
    uid: string,
    observe = false,
  ): Promise<StockDividendsResourceDto> {
    const connection = await this.access.local(userId);
    const today = moscowDay(new Date().toISOString());
    const from = `${Number(today.slice(ISO_DATE_START, ISO_YEAR_LENGTH)) - INCOME_HISTORY_YEARS}${today.slice(ISO_YEAR_LENGTH)}`;
    const to = `${Number(today.slice(ISO_DATE_START, ISO_YEAR_LENGTH)) + INCOME_FORECAST_YEARS}${today.slice(ISO_YEAR_LENGTH)}`;
    const portfolio = await this.portfolios.read(userId, 'all', observe);
    const sources = await this.sources.readMany(
      userId,
      'share',
      [uid],
      observe,
      ['detail', 'dividends'],
      { from, to },
    );
    if (sources[0].meta.availability === 'complete' && !sources[0].instrument) {
      throw new NotFoundException();
    }
    const events = sources[1].payload?.dividends;
    const position = portfolio.data ?
        instrumentPosition(portfolio.data, uid, 'STOCK') :
      null;
    const projected = events ?
        stockDividends(
          events,
          position,
          { from, to, today },
          sources[1].meta.lastSuccessfulAt ?? new Date().toISOString(),
          !portfolio.data,
        ) :
      undefined;
    const result = await this.forecasts.result({
      userId,
      revision: connection.revision,
      membershipRevision: connection.membershipRevision,
      scopeKey: `stock/dividends/${JSON.stringify([uid, from, to])}`,
      portfolio: portfolio.meta,
      sources,
      candidate:
        portfolio.data && sources[0].instrument ? projected : undefined,
    });
    return result.data || !projected ?
      result :
        {
          data: stockDividends(
            events ?? [],
            null,
            { from, to, today },
            projected.observedAt,
            true,
          ),
          meta: { ...result.meta, availability: 'partial' },
        };
  }
}

export function stockDividends(
  events: TbankDividend[],
  position: null | StockPositionDto,
  window: { from: string; to: string; today: string },
  observedAt: string,
  positionUnavailable: boolean,
): StockDividendsDto {
  const { from, to, today } = window;
  const quantity =
    position &&
    position.accounts.length &&
    position.accounts.every((p) => decimalFromString(p.quantity).value > ZERO_QUANTITY) ?
        decimalFromString(position.quantity) :
      null;
  const dividends: StockDividendDto[] = events
    .filter((event) => event.dividendType?.toLowerCase() !== 'cancelled')
    .map((event) => {
      const recordDate = timestamp(event.recordDate)?.slice(ISO_DATE_START, ISO_DATE_LENGTH) ?? null;
      const paymentDate = timestamp(event.paymentDate)?.slice(ISO_DATE_START, ISO_DATE_LENGTH) ?? null;
      const lastBuyDate = timestamp(event.lastBuyDate)?.slice(ISO_DATE_START, ISO_DATE_LENGTH) ?? null;
      const currency = event.dividendNet?.currency?.toUpperCase();
      const perShare =
        currency && event.dividendNet ?
            { currency, value: formatDecimal(decimal(event.dividendNet)) } :
          null;
      // A future payment can have an already-fixed register: keep the event, but do not estimate entitlement from today's holding.
      const eventDate = paymentDate ?? recordDate;
      const timing: StockDividendDto['timing'] = eventDate ?
        eventDate >= today ?
          'upcoming' :
          'past' :
        'undated';
      const estimatedAmount =
        quantity &&
        perShare &&
        recordDate &&
        recordDate >= today &&
        timing === 'upcoming' ?
            {
              currency: perShare.currency,
              value: formatDecimal(
                multiply(quantity, decimalFromString(perShare.value)),
              ),
            } :
          null;
      return {
        perShare,
        recordDate,
        lastBuyDate,
        paymentDate,
        timing,
        estimatedAmount,
      };
    })
    .sort((a, b) => (b.recordDate ?? '').localeCompare(a.recordDate ?? ''));
  return {
    dividends,
    from,
    to,
    observedAt: observedAt,
    positionAt: quantity ? (position?.observedAt ?? null) : null,
    estimateUnavailable: positionUnavailable,
    positionIsStale: position?.isStale ?? false,
  };
}