import { Injectable } from '@nestjs/common';
import assert from 'node:assert/strict';

import {
  add,
  compare,
  decimalFromString,
  formatDecimal,
  subtract,
} from '../../../common/decimal';
import { isTbankProtocolValue, TbankOperationType } from '../../../integrations/tbank/tbank-protocol';
import { DateOnlyRange, moscowDate } from '../investment-calendar';
import { investmentResourceMeta } from '../investment-resource.mapper';
import {
  BrokerageOperationDto,
  BrokerageOperationsService,
} from '../operations/operations.api';
import {
  IncomeAnalyticsEntryDto,
  IncomeAnalyticsResourceDto,
  IncomeComparisonDto,
  IncomeCurrencySummaryDto,
  IncomeDependencyDto,
  IncomeInstrumentDto,
  IncomeSummaryDto,
  IncomeSummaryResourceDto,
} from './income-analytics.dto';
import {
  IncomeBucketGranularity,
  planIncomePeriod,
  rangeBuckets,
} from './income-period';

const STALE_FRESHNESS_MS = 0;

type Total = {
  coupon: ReturnType<typeof decimalFromString>;
  dividend: ReturnType<typeof decimalFromString>;
};

@Injectable()
export class IncomeAnalyticsService {
  constructor(private readonly operations: BrokerageOperationsService) {}

  async summary(
    userId: string,
    accountId: string,
    observe = false,
  ): Promise<IncomeSummaryResourceDto> {
    let plan = planIncomePeriod(undefined, undefined);
    const [selected] = await this.operations.collectRanges(
      userId,
      accountId,
      (openedAt) => {
        plan = planIncomePeriod(undefined, undefined, openedAt);
        return [plan.selected];
      },
      observe,
    );
    if (selected.items === null) return { data: null, meta: selected.meta };
    assert(selected.meta.lastSuccessfulAt);
    return {
      data: summaryResponse(
        accountId,
        plan.selected,
        qualifying(selected.items),
        selected.meta.lastSuccessfulAt,
      ),
      meta: selected.meta,
    };
  }

  async analytics(
    userId: string,
    accountId: string,
    from: string | undefined,
    to: string | undefined,
    observe = false,
  ): Promise<IncomeAnalyticsResourceDto> {
    let plan = planIncomePeriod(from, to);
    const periods = await this.operations.collectRanges(
      userId,
      accountId,
      (openedAt) => {
        plan = planIncomePeriod(from, to, openedAt);
        return [
          plan.selected,
          plan.previous,
          ...(plan.yearAgo ? [plan.yearAgo] : []),
        ];
      },
      observe,
    );
    const [current, prior, year] = periods;
    // Preserve the legacy order while consumers migrate to explicit roles.
    const dependencies: IncomeDependencyDto[] = [
      { ...current.meta, role: 'selected' },
      { ...prior.meta, role: 'previous' },
      {
        ...(plan.yearAgo && year
          ? year.meta
          : investmentResourceMeta({
              resourceKey: 'income/yearAgo', // gitleaks:allow public resource identifier
              dataRevision: 'unavailable',
              availability: 'missing',
              fetchedAt: null,
              freshForMs: 0,
              work: null,
              unavailableReason: 'CALENDAR_OR_ACCOUNT_HISTORY',
            })),
        role: 'year',
      },
    ];
    const states = periods.map((period) => period.meta.sync);
    const work =
      states.find((state) => state.state === 'running') ??
      states.find((state) => state.state === 'failed');
    const meta = {
      ...investmentResourceMeta({
        resourceKey: `income/${accountId}/${plan.selected.from}/${plan.selected.to}`,
        dataRevision: current.meta.dataRevision,
        availability: current.meta.availability,
        fetchedAt: current.meta.lastSuccessfulAt
          ? new Date(current.meta.lastSuccessfulAt)
          : null,
        freshForMs: current.meta.freshness === 'fresh' ? Infinity : STALE_FRESHNESS_MS,
        work: work?.id ? { ...work, id: work.id } : null,
        coverage: current.meta.coverage,
        dependencies,
      }),
      dependencies,
    };
    if (current.items === null) return { data: null, meta };
    assert(current.meta.lastSuccessfulAt);
    const selected = qualifying(current.items).map((entry) => ({
      ...entry,
      instrumentKey: `${instrumentKey(entry)}:${entry.payment?.currency ?? ''}`,
    }));
    return {
      data: {
        ...summaryResponse(
          accountId,
          plan.selected,
          selected,
          current.meta.lastSuccessfulAt,
        ),
        previous:
          prior.items === null
            ? null
            : comparison(selected, plan.previous, qualifying(prior.items)),
        yearComparison:
          plan.yearAgo && year?.items !== null && year
            ? comparison(selected, plan.yearAgo, qualifying(year.items))
            : null,
        bucketGranularity: plan.granularity,
        buckets: buckets(plan.selected, plan.granularity, selected),
        instruments: instruments(selected),
        entries: selected,
      },
      meta,
    };
  }
}

function qualifying(entries: BrokerageOperationDto[]): BrokerageOperationDto[] {
  return entries.filter(
    (entry) =>
      Boolean(entry.payment) &&
      [TbankOperationType.Coupon, TbankOperationType.Dividend].some((type) => isTbankProtocolValue(entry.type, type)),
  );
}

function summaryResponse(
  accountId: string,
  period: DateOnlyRange,
  entries: BrokerageOperationDto[],
  calculatedAt: string,
): IncomeSummaryDto {
  return { accountId, period, totalsByCurrency: totals(entries), calculatedAt };
}

function totals(entries: BrokerageOperationDto[]): IncomeCurrencySummaryDto[] {
  const values = new Map<string, Total>();
  for (const entry of entries) {
    if (!entry.payment) continue;
    const total = values.get(entry.payment.currency) ?? zeroTotal();
    const value = decimalFromString(entry.payment.value);
    if (isTbankProtocolValue(entry.type, TbankOperationType.Coupon)) {
      total.coupon = add(total.coupon, value);
    } else total.dividend = add(total.dividend, value);
    values.set(entry.payment.currency, total);
  }
  return [...values]
    .sort(([left], [right]) => left.localeCompare(right))
    .map(([currency, total]) => presentTotal(currency, total));
}

function comparison(
  selectedEntries: BrokerageOperationDto[],
  comparedPeriod: DateOnlyRange,
  comparedEntries: BrokerageOperationDto[],
): IncomeComparisonDto {
  const selected = new Map(
    totals(selectedEntries).map((total) => [total.currency, total]),
  );
  const compared = new Map(
    totals(comparedEntries).map((total) => [total.currency, total]),
  );
  const currencies = [
    ...new Set([...selected.keys(), ...compared.keys()]),
  // eslint-disable-next-line sonarjs/no-alphabetical-sort -- Code-unit ordering is intentional for canonical keys and ISO dates; locale collation would change persisted bindings.
  ].sort();
  return {
    period: comparedPeriod,
    totalsByCurrency: currencies.map((currency) => {
      const current =
        selected.get(currency) ?? presentTotal(currency, zeroTotal());
      const prior =
        compared.get(currency) ?? presentTotal(currency, zeroTotal());
      return {
        currency,
        selected: current,
        compared: prior,
        difference: difference(current, prior),
      };
    }),
  };
}

function buckets(
  range: DateOnlyRange,
  granularity: IncomeBucketGranularity,
  entries: BrokerageOperationDto[],
) {
  const datedEntries = entries.map((entry) => ({
    entry,
    date: moscowDate(new Date(entry.occurredAt)),
  }));
  return rangeBuckets(range, granularity).map((period) => ({
    period,
    totalsByCurrency: totals(
      datedEntries
        .filter(({ date }) => date >= period.from && date <= period.to)
        .map(({ entry }) => entry),
    ),
  }));
}

function instruments(
  entries: IncomeAnalyticsEntryDto[],
): IncomeInstrumentDto[] {
  const groups = new Map<string, IncomeAnalyticsEntryDto[]>();
  for (const entry of entries) {
    const group = groups.get(entry.instrumentKey);
    if (group) group.push(entry);
    else groups.set(entry.instrumentKey, [entry]);
  }
  return [...groups]
    .map(([key, group]) => {
      const first = group[0];
      const [total] = totals(group);
      return {
        key,
        figi: first.figi,
        instrumentUid: first.instrumentUid,
        ticker: first.ticker,
        instrumentType: first.instrumentType,
        displayName: first.ticker ?? (first.description || first.type),
        coupon: total.coupon,
        dividend: total.dividend,
        total: total.total,
        receiptCount: group.length,
      };
    })
    .sort(
      (left, right) =>
        compare(
          decimalFromString(right.total.value),
          decimalFromString(left.total.value),
        ) || left.key.localeCompare(right.key),
    );
}

function instrumentKey(entry: BrokerageOperationDto): string {
  if (entry.instrumentUid) return `uid:${entry.instrumentUid}`;
  if (entry.figi) return `figi:${entry.figi}`;
  if (entry.ticker || entry.instrumentType) {
    return `ticker:${entry.ticker ?? ''}:${entry.instrumentType ?? ''}`;
  }
  return `operation:${entry.account ? `${entry.account.id}:` : ''}${entry.id}`;
}

function difference(
  left: IncomeCurrencySummaryDto,
  right: IncomeCurrencySummaryDto,
): IncomeCurrencySummaryDto {
  return presentTotal(left.currency, {
    coupon: subtract(
      decimalFromString(left.coupon.value),
      decimalFromString(right.coupon.value),
    ),
    dividend: subtract(
      decimalFromString(left.dividend.value),
      decimalFromString(right.dividend.value),
    ),
  });
}

function zeroTotal(): Total {
  return { coupon: { value: 0n, scale: 0 }, dividend: { value: 0n, scale: 0 } };
}

function presentTotal(
  currency: string,
  value: Total,
): IncomeCurrencySummaryDto {
  const total = add(value.coupon, value.dividend);
  return {
    currency,
    coupon: { currency, value: formatDecimal(value.coupon) },
    dividend: { currency, value: formatDecimal(value.dividend) },
    total: { currency, value: formatDecimal(total) },
  };
}