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

import { isZero } from '#src/common/decimal';
import { StructuredLogger } from '#src/common/logging/structured-logger.service';
import { MILLISECONDS_PER_DAY } from '#src/common/time';
import { decimal } from '#src/integrations/tbank/decimal';
import { isTbankErrorCode, TbankErrorCode } from '#src/integrations/tbank/tbank-error-code';
import { InstrumentIdType } from '#src/integrations/tbank/tbank-protocol';
import { metadataKey, TbankClient, type TbankPortfolio } from '#src/integrations/tbank/tbank.api';

import { PositionClassificationRepository } from '../infrastructure/position-classification.repository';

export type Classification = { issuer: null | { id: string; name: string }; sector: null | string };
type Position = NonNullable<TbankPortfolio['positions']>[number];
type Instrument = { assetUid?: string; figi?: string; sector?: string; uid?: string };
type Row = NonNullable<Awaited<ReturnType<PositionClassificationRepository['read']>>>;
type Update = Parameters<PositionClassificationRepository['save']>[1];

@Injectable()
export class PositionClassificationService {
  constructor(
    private readonly tbank: TbankClient,
    private readonly repository: PositionClassificationRepository,
    private readonly logger: StructuredLogger,
  ) {}

  async refresh(token: string, positions: Position[], walkStartedAt: Date): Promise<Map<string, Classification>> {
    const result = new Map<string, Classification>();
    const inFlight = new Map<string, Promise<unknown>>();
    for (const position of positions) {
      if (!['bond', 'etf', 'share'].includes((position.instrumentType ?? '').toLowerCase())) continue;
      if (isZero(decimal(position.quantity ?? {}))) continue;
      const key = metadataKey(position);
      if (result.has(key)) continue;
      result.set(key, await this.refreshOne(token, position, key, walkStartedAt, inFlight));
    }
    return result;
  }

  private async refreshOne(token: string, position: Position, key: string, startedAt: Date,
    inFlight: Map<string, Promise<unknown>>): Promise<Classification> {
    let saved: null | Row = null;
    const update: Update = {};
    try {
      saved = await this.repository.read(key);
      const due = (at: Date | null | undefined) => !at || startedAt.valueOf() - at.valueOf() >= MILLISECONDS_PER_DAY;
      const sectorDue = due(saved?.sectorFetchedAt);
      const brandDue = due(saved?.brandFetchedAt);
      let assetUid = saved?.assetUid ?? null;
      let instrumentFresh = false;
      if (sectorDue || (brandDue && !saved?.assetUid)) {
        const instrument = await this.refreshInstrument(token, position, sectorDue, assetUid, update, startedAt);
        assetUid = instrument.assetUid;
        instrumentFresh = instrument.fresh;
      }
      const assetChanged = 'assetUid' in update && update.assetUid !== saved?.assetUid;
      if (assetChanged) {
        update.brandUid = null;
        update.brandName = null;
        update.brandFetchedAt = null;
      }
      if (brandDue || assetChanged) {
        await this.refreshBrand(token, assetUid, update, startedAt, inFlight, instrumentFresh);
      }
      if (Object.keys(update).length) saved = await this.repository.save(key, update);
    } catch (error) {
      if (this.invalidToken(error)) throw error;
      this.failed(error);
    }
    const current = { ...saved, ...update };
    return {
      issuer: current.brandUid && current.brandName ? { id: current.brandUid, name: current.brandName } : null,
      sector: current.sector ?? null,
    };
  }

  private async refreshInstrument(token: string, position: Position, sectorDue: boolean, savedUid: null | string,
    update: Update, startedAt: Date): Promise<{ assetUid: null | string; fresh: boolean }> {
    try {
      const lookup = await this.instrument(token, position);
      if (lookup && !this.matches(lookup)) return { assetUid: savedUid, fresh: false };
      if (lookup) return { assetUid: this.acceptInstrument(lookup.found, savedUid, sectorDue, update, startedAt), fresh: true };
      if (sectorDue) this.clearSector(update, startedAt);
    } catch (error) {
      if (this.invalidToken(error)) throw error;
      if (error instanceof NotFoundException) {
        if (sectorDue) this.clearSector(update, startedAt);
      } else this.failed(error);
    }
    return { assetUid: savedUid, fresh: false };
  }

  private clearSector(update: Update, startedAt: Date) {
    update.sector = null;
    update.sectorFetchedAt = startedAt;
  }

  private acceptInstrument(found: Instrument, savedUid: null | string, sectorDue: boolean, update: Update, startedAt: Date) {
    const assetUid = found.assetUid?.trim() || null;
    if (assetUid !== savedUid) update.assetUid = assetUid;
    if (sectorDue) this.setSector(update, found.sector, startedAt);
    return assetUid;
  }

  private setSector(update: Update, sector: string | undefined, startedAt: Date) {
    update.sector = sector?.trim() || null;
    update.sectorFetchedAt = startedAt;
  }

  private async refreshBrand(token: string, assetUid: null | string, update: Update, startedAt: Date,
    inFlight: Map<string, Promise<unknown>>, instrumentFresh: boolean) {
    if (!assetUid) {
      if (instrumentFresh || 'assetUid' in update || 'sectorFetchedAt' in update) this.clearBrand(update, startedAt);
      return;
    }
    try {
      const asset = await this.dedupe(inFlight, assetUid, () => this.tbank.getAssetBrand(token, assetUid));
      if (asset && asset.assetUid !== assetUid) return;
      const uid = asset?.brand?.uid?.trim() || null;
      const name = asset?.brand?.name?.trim() || null;
      update.brandUid = uid && name ? uid : null;
      update.brandName = uid && name ? name : null;
      update.brandFetchedAt = startedAt;
    } catch (error) {
      if (this.invalidToken(error)) throw error;
      if (error instanceof NotFoundException) this.clearBrand(update, startedAt);
      else this.failed(error);
    }
  }

  private clearBrand(update: Update, startedAt: Date) {
    update.brandUid = null;
    update.brandName = null;
    update.brandFetchedAt = startedAt;
  }

  private matches(lookup: { found: Instrument; id: string; idType: InstrumentIdType }) {
    return (lookup.idType === InstrumentIdType.Uid ? lookup.found.uid : lookup.found.figi) === lookup.id;
  }

  private invalidToken(error: unknown) {
    return error instanceof Error && isTbankErrorCode(error.message, TbankErrorCode.InvalidToken);
  }

  private async instrument(token: string, position: Position) {
    const type = (position.instrumentType ?? '').toLowerCase();
    const lookup = (id: string, idType: InstrumentIdType) => {
      switch (type) {
        case 'bond': return this.tbank.getBond(token, id, idType, true);
        case 'share': return this.tbank.getShare(token, id, idType, true);
        default: return this.tbank.getEtf(token, id, idType, true);
      }
    };
    const uid = position.instrumentUid?.trim();
    const figi = position.figi?.trim();
    if (uid) {
      try {
        const found = await lookup(uid, InstrumentIdType.Uid);
        if (found) return { found, id: uid, idType: InstrumentIdType.Uid };
      } catch (error) {
        if (!(error instanceof NotFoundException)) throw error;
      }
    }
    if (figi) {
      const found = await lookup(figi, InstrumentIdType.Figi);
      return found ? { found, id: figi, idType: InstrumentIdType.Figi } : null;
    }
    return null;
  }

  private dedupe<T>(map: Map<string, Promise<unknown>>, key: string, run: () => Promise<T>): Promise<T> {
    const pending = map.get(key);
    if (pending) return pending as Promise<T>;
    const promise = run().catch((error: unknown) => {
      map.delete(key);
      throw error;
    });
    map.set(key, promise);
    return promise;
  }

  private failed(error: unknown) {
    this.logger.event('warn', 'portfolio.classification.failed', { code: error instanceof Error ? error.name : 'Unknown' });
  }
}