/**
 * Auction intelligence (§33–§35): a lot's current bid / estimate is compared with the RareIndex
 * Valuation only on a buyer-pays (all-in) basis — hammer + the house's buyer premium — and only
 * through the same gates as a marketplace ask (same variant, transaction-based RIV, ≥ 5 sales,
 * confidence ≥ 0.5, plausibility band, review threshold). Taxes, duties and shipping are out of
 * scope and are stated as such wherever an all-in figure is shown.
 */
import { assessAsk, type AskVerdict } from './scores.js';
import { allInPrice, type FeeBasis } from './fees.js';
import { round } from '@rareindex/shared';

export interface LotAssessmentInput {
  /** auction house name / connector id for the fee schedule */
  house: string | null | undefined;
  /** lot amounts already converted to USD (null when absent) */
  currentBidUsd: number | null;
  bidCount: number | null;
  estimateLowUsd: number | null;
  estimateHighUsd: number | null;
  hammerPriceUsd?: number | null;
  /** connector flag for the lot's quoted amounts; lots are hammer-basis unless the connector says otherwise */
  buyerPremiumIncluded?: boolean | null;
  /** rate converting USD into the schedule currency (for tier boundaries); 1 when unknown */
  fxUsdToScheduleCurrency?: number;
  /** valuation of the lot's own variant (or the asset when raw and representative) */
  riv: { rivUsd: number | null; confidence: number | null; sampleSize: number | null; basis?: 'transactions' | 'comps' | 'guide' | 'none' | null } | null;
  /** false when the lot's grade does not match the valuation's variant */
  sameVariant?: boolean;
}

export interface LotAssessment {
  buyerPremiumRate: number | null;
  feeBasis: FeeBasis;
  allInBidUsd: number | null;
  allInEstimateLowUsd: number | null;
  allInEstimateHighUsd: number | null;
  allInHammerUsd: number | null;
  rivUsd: number | null;
  /** (all-in bid − RIV) / RIV — null without a bid or when ungated/anomalous/review */
  bidVsRiv: number | null;
  /** (all-in low estimate − RIV) / RIV — null when ungated/anomalous/review */
  estimateVsRiv: number | null;
  /** verdict of the most informative comparison: the bid when there is one, else the low estimate */
  verdict: AskVerdict;
  reasons: string[];
  /** what the verdict is based on */
  basedOn: 'bid' | 'estimate' | 'none';
}

const allIn = (usd: number | null, i: LotAssessmentInput) => {
  if (usd === null || !(usd > 0)) return null;
  return allInPrice({ price: usd, buyerPremiumIncluded: i.buyerPremiumIncluded ?? false, house: i.house, saleType: 'auction', sourceType: 'auction_house', fxToScheduleCurrency: i.fxUsdToScheduleCurrency });
};

export function assessLot(i: LotAssessmentInput): LotAssessment {
  const hasBid = (i.bidCount ?? 0) > 0 && i.currentBidUsd !== null && i.currentBidUsd > 0;
  const bid = hasBid ? allIn(i.currentBidUsd, i) : null;
  const lo = allIn(i.estimateLowUsd, i);
  const hi = allIn(i.estimateHighUsd, i);
  const hammer = allIn(i.hammerPriceUsd ?? null, i);
  const ref = bid ?? lo ?? hi ?? hammer;
  const riv = i.riv?.rivUsd ?? null;
  const gate = (askUsd: number | null) =>
    assessAsk({ askUsd, rivUsd: riv, confidence: i.riv?.confidence ?? null, sampleSize: i.riv?.sampleSize ?? null, basis: i.riv?.basis ?? undefined, sameVariant: i.sameVariant });
  const bidA = bid ? gate(bid.allIn) : null;
  const loA = lo ? gate(lo.allIn) : null;
  const primary = bidA ?? loA;
  const usable = (a: ReturnType<typeof assessAsk> | null) => (a && (a.verdict === 'deal' || a.verdict === 'fair' || a.verdict === 'premium') ? a.discount : null);
  return {
    buyerPremiumRate: ref ? round(ref.rate, 4) : null,
    feeBasis: ref?.basis ?? 'unknown',
    allInBidUsd: bid?.allIn ?? null,
    allInEstimateLowUsd: lo?.allIn ?? null,
    allInEstimateHighUsd: hi?.allIn ?? null,
    allInHammerUsd: hammer?.allIn ?? null,
    rivUsd: riv,
    bidVsRiv: usable(bidA),
    estimateVsRiv: usable(loA),
    verdict: primary?.verdict ?? 'ungated',
    reasons: primary?.reasons ?? (riv === null ? ['no_riv'] : ['no_bid_or_estimate']),
    basedOn: bidA ? 'bid' : loA ? 'estimate' : 'none',
  };
}