import { Injectable, ServiceUnavailableException } from '@nestjs/common';
import { LRUCache } from 'lru-cache';
import { RequestContextService } from '../common/logging/request-context.service';
import {
  BrokerageOperationsPageDto,
  BrokerageOperationsQueryDto,
} from './brokerage-operation.dto';
import {
  mapBrokerageOperation,
  operationCategory,
} from './brokerage-operation.mapper';
import { InstrumentMetadataService } from './instrument-metadata.service';
import { TbankAccessService } from './tbank-access.service';
import { TbankClient } from './tbank.client';
import { DateOnlyRange, dateOnlyBounds } from './income-period';

const freshForMs = 30_000;
const maxCachedPages = 100;

@Injectable()
export class BrokerageOperationsService {
  private readonly pages = new LRUCache<string, BrokerageOperationsPageDto>({
    max: maxCachedPages,
    ttl: freshForMs,
    ttlAutopurge: true,
  });

  constructor(
    private readonly access: TbankAccessService,
    private readonly tbank: TbankClient,
    private readonly requestContext: RequestContextService,
    private readonly metadata: InstrumentMetadataService,
  ) {}

  async get(
    userId: string,
    accountId: string,
    query: BrokerageOperationsQueryDto,
  ): Promise<BrokerageOperationsPageDto> {
    this.requestContext.set({ userId, brokerageAccountId: accountId });
    const range = this.range(query);

    return this.access.withAccount(userId, accountId, ({ token, generation }) =>
      this.page(token, generation, userId, accountId, query, range),
    );
  }

  async collectRanges(
    userId: string,
    accountId: string,
    ranges:
      | DateOnlyRange[]
      | ((accountOpenedAt: Date | undefined) => DateOnlyRange[]),
  ): Promise<{
    accountOpenedAt: Date | undefined;
    pages: BrokerageOperationsPageDto[][];
  }> {
    this.requestContext.set({ userId, brokerageAccountId: accountId });
    return this.access.withAccount(
      userId,
      accountId,
      async ({ token, generation, account }) => {
        const accountOpenedAt = account.openedDate?.seconds
          ? new Date(Number(account.openedDate.seconds) * 1000)
          : undefined;
        const selected =
          typeof ranges === 'function' ? ranges(accountOpenedAt) : ranges;
        return {
          accountOpenedAt,
          pages: await Promise.all(
            selected.map((range) =>
              this.collectRange(token, generation, userId, accountId, range),
            ),
          ),
        };
      },
    );
  }

  private async collectRange(
    token: string,
    generation: string,
    userId: string,
    accountId: string,
    range: DateOnlyRange,
  ): Promise<BrokerageOperationsPageDto[]> {
    const pages: BrokerageOperationsPageDto[] = [];
    const seen = new Set<string>();
    let cursor: string | undefined;
    do {
      const page = await this.page(
        token,
        generation,
        userId,
        accountId,
        {
          from: range.from,
          cursor,
          limit: 1000,
          categories: ['income'],
        },
        dateOnlyBounds(range),
      );
      pages.push(page);
      if (!page.hasNext) return pages;
      if (!page.nextCursor || seen.has(page.nextCursor))
        throw new ServiceUnavailableException({ code: 'TBANK_UNAVAILABLE' });
      seen.add(page.nextCursor);
      cursor = page.nextCursor;
    } while (cursor);
    return pages;
  }

  private async page(
    token: string,
    generation: string,
    userId: string,
    accountId: string,
    query: BrokerageOperationsQueryDto,
    range: { from: Date; to: Date },
  ): Promise<BrokerageOperationsPageDto> {
    const key = cacheKey(generation, userId, accountId, query, range);
    const cached = this.pages.get(key);
    if (cached) return cached;
    if (range.from > range.to) {
      const page = emptyPage(accountId);
      this.pages.set(key, page);
      return page;
    }
    const response = await this.tbank.getOperationsByCursor(token, {
      accountId,
      from: seconds(range.from),
      to: seconds(range.to, /^\d{4}-\d{2}-\d{2}$/.test(query.to ?? '')),
      cursor: query.cursor,
      limit: query.limit ?? 100,
      state: 'OPERATION_STATE_EXECUTED',
    });
    const items = (response.items ?? []).filter(
      (item) =>
        !query.categories?.length ||
        query.categories.includes(operationCategory(item.type)),
    );
    const logoNames = new Map<string, Promise<string | null>>();
    const page = {
      accountId,
      items: await Promise.all(
        items.map(async (item) => ({
          ...mapBrokerageOperation(item),
          logoName: await this.logoName(
            token,
            item.instrumentUid,
            item.figi,
            logoNames,
          ),
        })),
      ),
      nextCursor: response.nextCursor || null,
      hasNext: Boolean(response.hasNext),
      observedAt: new Date().toISOString(),
    };
    this.pages.set(key, page);
    return page;
  }

  private range(query: BrokerageOperationsQueryDto) {
    const now = new Date();
    return {
      from:
        dateBoundary(query.from, false) ??
        new Date(Date.UTC(now.getUTCFullYear(), 0, 1)),
      to: dateBoundary(query.to, true) ?? now,
    };
  }

  private async logoName(
    token: string,
    instrumentUid: string | undefined,
    figi: string | undefined,
    logoNames: Map<string, Promise<string | null>>,
  ): Promise<string | null> {
    const uid = instrumentUid?.trim() || null;
    const instrumentFigi = figi?.trim() || null;
    const key =
      uid || instrumentFigi
        ? JSON.stringify({ uid, figi: instrumentFigi })
        : null;
    if (!key) return Promise.resolve(null);
    const existing = logoNames.get(key);
    if (existing) return existing;
    const logoName = this.metadata
      .resolve(token, uid, instrumentFigi)
      .then((instrument) => instrument?.brand?.logoName?.trim() || null);
    logoNames.set(key, logoName);
    return logoName;
  }
}

function cacheKey(
  generation: string,
  userId: string,
  accountId: string,
  query: BrokerageOperationsQueryDto,
  range: { from: Date; to: Date },
): string {
  const categories = [...new Set(query.categories ?? [])].sort();
  const end = query.to
    ? range.to.toISOString()
    : Math.floor(range.to.valueOf() / freshForMs);
  return JSON.stringify({
    generation,
    userId,
    accountId,
    from: range.from.toISOString(),
    to: end,
    categories,
    cursor: query.cursor ?? null,
    limit: query.limit ?? 100,
  });
}

function dateBoundary(value: string | undefined, end: boolean): Date | null {
  if (!value) return null;
  if (/^\d{4}-\d{2}-\d{2}$/.test(value))
    return new Date(`${value}T${end ? '23:59:59.999' : '00:00:00.000'}Z`);
  return new Date(value);
}

function seconds(value: Date, endOfSecond = false) {
  return {
    seconds: Math.floor(value.valueOf() / 1000).toString(),
    ...(endOfSecond ? { nanos: 999_999_999 } : {}),
  };
}

function emptyPage(accountId: string): BrokerageOperationsPageDto {
  return {
    accountId,
    items: [],
    nextCursor: null,
    hasNext: false,
    observedAt: new Date().toISOString(),
  };
}