/**
 * Pure helpers for the DXTrade client (lib/dxtrade-class.ts): account ids,
 * contract names, the firm-day clock, parsing the API's loosely typed
 * answers, and the instrument selector's volatility and cost scoring.
 *
 * No imports beyond node built-ins, so scripts/check-trading-logic.mjs can
 * test them directly.
 */

import { createHash } from 'crypto';

// ── account ids ──────────────────────────────────────────────────────────────

/**
 * A stable numeric id for a DXTrade account code ("clearing:account"). Every
 * account table, route and backup keys on a number, and DXTrade codes are
 * strings, so the code is hashed — deterministically, which is what lets a
 * backup restored onto a new machine find its manual assignments again (a
 * per-machine id table would renumber them).
 *
 * 52 bits of SHA-256 folded into [2^50, 2^53): safe integers, far above any
 * Tradovate or TopstepX id. The host is part of the key, so the same code on
 * two DXTrade servers never collides — and changing a firm's server URL
 * re-keys its accounts.
 */
export function dxAccountId(host: string, code: string): number {
    const digest = createHash('sha256').update(`dxtrade|${host.toLowerCase()}|${code}`).digest();
    return 2 ** 50 + digest.readUIntBE(0, 6) * 16 + (digest[6] >> 4);
}

/** "default:TFY-50K-123" → "TFY-50K-123": what the dashboard shows and what
 *  account-type prefixes match against. */
export function accountDisplayName(code: string): string {
    const i = code.indexOf(':');
    return i >= 0 && i < code.length - 1 ? code.slice(i + 1) : code;
}

/** DXTrade answers carry account codes either as "clearing:account" or as an
 *  {clearing, account} object, depending on the endpoint's serializer. */
export function accountCodeOf(raw: unknown): string | null {
    if (typeof raw === 'string' && raw) return raw;
    if (raw && typeof raw === 'object') {
        const r = raw as { clearing?: unknown; account?: unknown };
        if (typeof r.account === 'string') return typeof r.clearing === 'string' ? `${r.clearing}:${r.account}` : r.account;
    }
    return null;
}

// ── contract names ───────────────────────────────────────────────────────────

/** An engine "contract" on DXTrade is one quantity step of a symbol; the
 *  step rides in the name the engine hands back to sendOrder, which keeps
 *  order placement stateless. Symbols never contain '|' (the master refuses
 *  them). */
export function encodeContractName(symbol: string, step: number): string {
    return `${symbol}|${step}`;
}

export function decodeContractName(name: string): { symbol: string; step: number } | null {
    const i = name.lastIndexOf('|');
    if (i <= 0) return null;
    const step = Number(name.slice(i + 1));
    if (!Number.isFinite(step) || step <= 0) return null;
    return { symbol: name.slice(0, i), step };
}

/** Decimal places of a step like 0.001 (or 1e-7), for exact rounding. */
export function decimalsOf(step: number): number {
    if (!Number.isFinite(step) || step <= 0) return 0;
    const s = step.toString();
    const exp = s.match(/e-(\d+)$/);
    if (exp) return Number(exp[1]) + (s.split('e')[0].split('.')[1]?.length ?? 0);
    return s.split('.')[1]?.length ?? 0;
}

/** A multiple of `step` without float fuzz (0.1 + 0.2 style). */
export function roundToStep(value: number, step: number, mode: 'nearest' | 'down' | 'up' = 'nearest'): number {
    if (!(step > 0)) return value;
    const n = value / step;
    const k = mode === 'down' ? Math.floor(n + 1e-9) : mode === 'up' ? Math.ceil(n - 1e-9) : Math.round(n);
    return Number((k * step).toFixed(decimalsOf(step)));
}

// ── clocks ───────────────────────────────────────────────────────────────────

/** The most recent 22:00 UTC at or before `now` — when Tradeify (and DXtrade
 *  brokers generally) snapshot the closed balance and start a new day. */
export function lastUtcReset(now: Date, hourUtc = 22): Date {
    const reset = new Date(Date.UTC(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate(), hourUtc));
    if (reset.getTime() > now.getTime()) reset.setUTCDate(reset.getUTCDate() - 1);
    return reset;
}

/** The trading day the firm books a moment to: the day that began at the
 *  reset before it, labelled by the calendar date that follows — the label
 *  currentTradeDateCT gives the same day. In summer the two roll together
 *  (22:00 UTC = 5 PM CDT); in winter the firm's rolls an hour earlier, and a
 *  close in that hour belongs to the new day, as the firm counts it. */
export function firmDayOf(at: Date, hourUtc = 22): string {
    return new Date(at.getTime() + (24 - hourUtc) * 3_600_000).toISOString().slice(0, 10);
}

/** When the current Central trade date began (5 PM CT) — the window today's
 *  realized P&L covers, matching currentTradeDateCT. */
export function ctTradeDayStart(now: Date): Date {
    const parts = new Intl.DateTimeFormat('en-US', {
        hour: 'numeric', minute: 'numeric', second: 'numeric', hour12: false, timeZone: 'America/Chicago',
    }).formatToParts(now);
    const get = (t: string) => Number(parts.find((p) => p.type === t)?.value ?? '0');
    const secondsIntoDay = (get('hour') % 24) * 3600 + get('minute') * 60 + get('second');
    const sinceRoll = (secondsIntoDay - 17 * 3600 + 86_400) % 86_400;
    return new Date(Math.floor(now.getTime() / 1000) * 1000 - sinceRoll * 1000);
}

/** DXTrade timestamps: ISO strings on the wire (the schema calls them
 *  objects); epoch ms tolerated. NaN when unreadable. */
export function timeOf(raw: unknown): number {
    if (typeof raw === 'number') return raw;
    if (typeof raw === 'string') return Date.parse(raw);
    return NaN;
}

/** The login answer's inactivity timeout, in ms: "PT30M", "01:05:08", a
 *  {seconds} object or a number of seconds. Falls back to 30 minutes. */
export function parseDurationMs(raw: unknown): number {
    const fallback = 30 * 60_000;
    if (typeof raw === 'number' && raw > 0) return raw * 1000;
    if (raw && typeof raw === 'object') {
        const s = (raw as { seconds?: unknown }).seconds;
        if (typeof s === 'number' && s > 0) return s * 1000;
    }
    if (typeof raw === 'string') {
        const iso = raw.match(/^P(?:T)?(?:(\d+(?:\.\d+)?)H)?(?:(\d+(?:\.\d+)?)M)?(?:(\d+(?:\.\d+)?)S)?$/i);
        if (iso && (iso[1] || iso[2] || iso[3])) {
            return ((Number(iso[1] ?? 0) * 60 + Number(iso[2] ?? 0)) * 60 + Number(iso[3] ?? 0)) * 1000;
        }
        const hms = raw.match(/^(\d+):(\d{2}):(\d{2})$/);
        if (hms) return ((Number(hms[1]) * 60 + Number(hms[2])) * 60 + Number(hms[3])) * 1000;
    }
    return fallback;
}

// ── loose parsing ────────────────────────────────────────────────────────────

/** A number field read case-insensitively — the live server says openPL
 *  where the docs say openPl. */
export function ciNum(obj: unknown, key: string): number | undefined {
    if (!obj || typeof obj !== 'object') return undefined;
    const want = key.toLowerCase();
    for (const [k, v] of Object.entries(obj as Record<string, unknown>)) {
        if (k.toLowerCase() === want && typeof v === 'number' && Number.isFinite(v)) return v;
    }
    return undefined;
}

/** Deposits and withdrawals move money in or out; every other cash
 *  transaction (SETTLEMENT, COMMISSION, FINANCING, ADJUSTMENT…) is trading. */
export function isFundType(type: unknown): boolean {
    return type === 'DEPOSIT' || type === 'WITHDRAWAL';
}

/** A withdrawal always takes money out, whatever sign the server files it with. */
export function signedFundValue(type: string, value: number): number {
    return type === 'WITHDRAWAL' ? -Math.abs(value) : Math.abs(value);
}

export interface DxTxn {
    key: string;
    account: string;
    type: string;
    value: number;
    time: number;
    orderCode: string | undefined;
}

/**
 * The cash transactions in a /transfers answer, flattened. A close books its
 * SETTLEMENT (the trade's P&L) and its COMMISSION under one transaction code,
 * so the key carries the type — and a running count, should a transfer ever
 * hold two of one type — or one would overwrite the other.
 */
export function parseTransfers(body: unknown): DxTxn[] {
    const transfers = (body as { cashTransfers?: unknown[] })?.cashTransfers ?? [];
    const out: DxTxn[] = [];
    for (const t of transfers) {
        const transfer = t as Record<string, unknown>;
        const txns = Array.isArray(transfer.cashTransactions) ? transfer.cashTransactions : [];
        const seen = new Map<string, number>();
        for (const x of txns) {
            const tx = x as Record<string, unknown>;
            const account = accountCodeOf(tx.account) ?? accountCodeOf(transfer.account);
            const value = ciNum(tx, 'value');
            const time = timeOf(tx.transactionTime ?? transfer.transactionTime);
            if (!account || value === undefined || !Number.isFinite(time) || typeof tx.type !== 'string') continue;
            const code = typeof tx.transactionCode === 'string' ? tx.transactionCode : '';
            const base = code
                ? `${code}|${tx.type}`
                : `${transfer.transferCode ?? ''}|${tx.type}|${time}|${value}|${tx.orderCode ?? ''}|${tx.tradeCode ?? ''}`;
            const n = seen.get(base) ?? 0;
            seen.set(base, n + 1);
            out.push({
                key: n === 0 ? base : `${base}|${n}`,
                account,
                type: tx.type,
                value,
                time,
                orderCode: typeof tx.orderCode === 'string' ? tx.orderCode : undefined,
            });
        }
    }
    return out;
}

/**
 * The margin an account posts per dollar of notional on an instrument — its
 * leverage cap, inverted (0.2 = 5:1). A tiered rate reads as its steepest
 * tier. undefined when the details don't say.
 */
export function marginRateOf(details: unknown): number | undefined {
    const rate = (details as { marginRate?: { tiers?: { value?: unknown }[]; value?: unknown } } | undefined)?.marginRate;
    const values = [...(rate?.tiers ?? []).map((t) => Number(t?.value)), Number(rate?.value)]
        .filter((v) => Number.isFinite(v) && v > 0 && v <= 1);
    return values.length > 0 ? Math.max(...values) : undefined;
}

/** A client order code: unique, ≤ 64 chars, and recognisably ours. */
export function newOrderCode(tag: string): string {
    const rand = Math.random().toString(36).slice(2, 8);
    return `af-${Date.now().toString(36)}-${rand}-${tag}`.slice(0, 64);
}

// ── trading hours ────────────────────────────────────────────────────────────

const WEEKDAYS = ['SUNDAY', 'MONDAY', 'TUESDAY', 'WEDNESDAY', 'THURSDAY', 'FRIDAY', 'SATURDAY'];

/**
 * Whether an instrument's sessions have it open at `now`. Sessions are
 * SESSION_OPEN / SESSION_CLOSE events on a UTC week; the latest event at or
 * before now (wrapping around the week) decides. No sessions, or any it
 * can't read, means always open — 24/7 crypto lists none.
 */
export function inTradingHours(sessions: unknown, now: Date): boolean {
    if (!Array.isArray(sessions) || sessions.length === 0) return true;
    const events: { at: number; open: boolean }[] = [];
    for (const s of sessions) {
        const e = s as { eventType?: unknown; weekDay?: { dayOfWeek?: unknown; time?: { hour?: unknown; minute?: unknown } } };
        const day = WEEKDAYS.indexOf(String(e.weekDay?.dayOfWeek ?? ''));
        const hour = Number(e.weekDay?.time?.hour ?? NaN);
        const minute = Number(e.weekDay?.time?.minute ?? 0);
        if (day < 0 || !Number.isFinite(hour) || (e.eventType !== 'SESSION_OPEN' && e.eventType !== 'SESSION_CLOSE')) return true;
        events.push({ at: day * 1440 + hour * 60 + minute, open: e.eventType === 'SESSION_OPEN' });
    }
    events.sort((a, b) => a.at - b.at);
    const t = now.getUTCDay() * 1440 + now.getUTCHours() * 60 + now.getUTCMinutes();
    const past = events.filter((e) => e.at <= t);
    const latest = past.length > 0 ? past[past.length - 1] : events[events.length - 1];
    return latest.open;
}

// ── instrument selector ──────────────────────────────────────────────────────

/** Fewest hourly candles a volatility estimate is trusted on. */
export const MIN_VOL_CANDLES = 24;

/**
 * σ of hourly log returns (per √hour) from hourly closes, oldest first, in
 * wall-clock time — flat hours count, so an instrument that sits still all
 * weekend really does read as quiet on a weekend. null on too few candles.
 */
export function realizedVolPerHour(closes: number[]): number | null {
    const clean = closes.filter((c) => Number.isFinite(c) && c > 0);
    if (clean.length < MIN_VOL_CANDLES + 1) return null;
    const returns: number[] = [];
    for (let i = 1; i < clean.length; i++) returns.push(Math.log(clean[i] / clean[i - 1]));
    const mean = returns.reduce((s, r) => s + r, 0) / returns.length;
    const variance = returns.reduce((s, r) => s + (r - mean) ** 2, 0) / (returns.length - 1);
    return Math.sqrt(variance);
}

/**
 * A candidate's cost score — lower is better.
 *
 * A leg sized for a hold of T hours needs notional ∝ 1/σ, so its cost —
 * spread plus both commissions plus financing over the hold, all
 * proportional to notional — is proportional to (spread + 2c + f·T/24) / σ.
 * A volatile instrument reaches the take-profit with less notional, which is
 * what makes a tight spread alone not enough.
 *
 * null = can't be scored (no σ).
 */
export function scoreCandidate(o: {
    spreadFraction: number;
    commissionPct: number;
    financingPctPerDay: number;
    targetHoldHours: number;
    volatilityPerHour: number | null;
}): number | null {
    if (!o.volatilityPerHour || !(o.volatilityPerHour > 0)) return null;
    const financing = (o.financingPctPerDay / 100) * (Math.max(0, o.targetHoldHours) / 24);
    return (o.spreadFraction + 2 * (o.commissionPct / 100) + financing) / o.volatilityPerHour;
}

/** Most a spread may be, as a share of the mid price, for a candidate to trade. */
export const MAX_SPREAD_FRACTION = 0.005;
/** A quote older than this doesn't count as live. */
export const MAX_QUOTE_AGE_MS = 5 * 60_000;

/** Why a candidate can't trade right now, or null when it can. */
export function candidateRejection(o: {
    tradingStatus: string | undefined;
    bid: number | undefined;
    ask: number | undefined;
    quoteAgeMs: number | null;
    inHours: boolean;
    candles: number;
    minContractsOk: boolean;
    currency: string | undefined;
    accountCurrency: string;
}): string | null {
    if (o.tradingStatus !== undefined && o.tradingStatus !== 'FULL') return `trading status ${o.tradingStatus}`;
    if (!o.inHours) return 'outside trading hours';
    if (!(typeof o.bid === 'number' && o.bid > 0 && typeof o.ask === 'number' && o.ask >= o.bid)) return 'no live quote';
    if (o.quoteAgeMs !== null && o.quoteAgeMs > MAX_QUOTE_AGE_MS) return `quote ${Math.round(o.quoteAgeMs / 60_000)}m old`;
    const mid = (o.bid + o.ask) / 2;
    if ((o.ask - o.bid) / mid > MAX_SPREAD_FRACTION) return `spread ${(((o.ask - o.bid) / mid) * 100).toFixed(2)}%`;
    if (o.candles < MIN_VOL_CANDLES + 1) return `only ${o.candles} hourly candles`;
    if (!o.minContractsOk) return 'minimum order size out of reach';
    if (o.currency && o.currency !== o.accountCurrency) return `priced in ${o.currency}`;
    return null;
}

// ── trades ───────────────────────────────────────────────────────────────────

/** A filled order off /orders/history, as the trades record needs it. */
export interface DxHistoryOrder {
    orderCode: string;
    orderId: number | undefined;
    /** MARKET, LIMIT, STOP. */
    type: string;
    instrument: string;
    positionCode: string | undefined;
    effect: 'OPEN' | 'CLOSE' | undefined;
    side: 'BUY' | 'SELL' | undefined;
    /** Filled. */
    qty: number;
    /** Average fill price. */
    price: number | undefined;
    /** The last fill, else the order's own time. */
    at: number;
}

/** null for an order that never filled. */
export function parseHistoryOrder(raw: unknown): DxHistoryOrder | null {
    const o = raw as Record<string, unknown>;
    if (!o || typeof o !== 'object' || typeof o.orderCode !== 'string') return null;
    const legs = Array.isArray(o.legs) ? (o.legs as Record<string, unknown>[]) : [];
    const leg = legs[0] ?? {};
    const qty = Math.abs(ciNum(leg, 'filledQuantity') ?? ciNum(o, 'filledQuantity') ?? 0);
    if (!(qty > 0)) return null;
    const executions = Array.isArray(o.executions) ? (o.executions as Record<string, unknown>[]) : [];
    const fillTimes = executions
        .filter((e) => (ciNum(e, 'lastQuantity') ?? ciNum(e, 'filledQuantity') ?? 0) > 0)
        .map((e) => timeOf(e.transactionTime))
        .filter(Number.isFinite);
    const at = fillTimes.length > 0 ? Math.max(...fillTimes) : [timeOf(o.transactionTime), timeOf(o.issueTime)].find(Number.isFinite) ?? NaN;
    if (!Number.isFinite(at)) return null;
    const effect = leg.positionEffect === 'OPEN' || leg.positionEffect === 'CLOSE' ? leg.positionEffect : undefined;
    const sideRaw = leg.side ?? o.side;
    return {
        orderCode: o.orderCode,
        orderId: ciNum(o, 'orderId'),
        type: String(o.type ?? ''),
        instrument: String(leg.instrument ?? o.instrument ?? ''),
        positionCode: typeof leg.positionCode === 'string' && leg.positionCode ? leg.positionCode : undefined,
        effect,
        side: sideRaw === 'BUY' || sideRaw === 'SELL' ? sideRaw : undefined,
        qty,
        price: ciNum(leg, 'averagePrice')
            ?? [...executions].reverse().map((e) => ciNum(e, 'averagePrice')).find((p) => p !== undefined && p > 0),
        at,
    };
}

/** One position, from the orders that opened and closed it. */
export interface DxTrade {
    positionCode: string;
    symbol: string;
    side: 'long' | 'short';
    quantity: number;
    openPrice: number | null;
    closePrice: number | null;
    /** The SETTLEMENT its closes booked; null while open or unseen. */
    pnl: number | null;
    /** Its COMMISSION, opens and closes; null when none was seen. */
    fee: number | null;
    openedAt: number;
    closedAt: number | null;
    /** The opening order's code; null when it opened before the history. */
    openCode: string | null;
    /** The order that closed it, and its type. */
    closeCode: string | null;
    closeType: string | null;
}

/** What the record knows of a position already: the open one on the
 *  account now, or one stored from an earlier pass. */
export interface DxKnownPosition {
    symbol: string;
    side: 'long' | 'short';
    quantity: number;
    openPrice: number | null;
    openedAt: number;
}

const vwap = (orders: DxHistoryOrder[]): number | null => {
    const priced = orders.filter((o) => o.price !== undefined);
    const qty = priced.reduce((s, o) => s + o.qty, 0);
    return qty > 0 ? priced.reduce((s, o) => s + o.price! * o.qty, 0) / qty : null;
};

/**
 * The account's positions, out of its filled orders (one account) and its
 * cash transactions. On a position-based account an opening order's position
 * code is its order id, so an OPEN leg without one takes that. A position the
 * account still holds (`open`) stays open whatever closed part of it; one
 * whose opening is older than the orders at hand is completed from `known`,
 * and left out when nothing knows it.
 */
export function dxTrades(orders: DxHistoryOrder[], txns: DxTxn[], open: Map<string, DxKnownPosition>, known: Map<string, DxKnownPosition>): DxTrade[] {
    const groups = new Map<string, DxHistoryOrder[]>();
    for (const o of orders) {
        const code = o.positionCode ?? (o.effect === 'OPEN' && o.orderId !== undefined ? String(o.orderId) : undefined);
        if (!code) continue;
        groups.set(code, [...(groups.get(code) ?? []), o]);
    }
    for (const code of open.keys()) if (!groups.has(code)) groups.set(code, []);

    const settled = new Map<string, number>();
    const commission = new Map<string, number>();
    for (const t of txns) {
        if (!t.orderCode) continue;
        if (t.type === 'SETTLEMENT') settled.set(t.orderCode, (settled.get(t.orderCode) ?? 0) + t.value);
        else if (t.type === 'COMMISSION') commission.set(t.orderCode, (commission.get(t.orderCode) ?? 0) + Math.abs(t.value));
    }

    const out: DxTrade[] = [];
    for (const [code, list] of groups) {
        const sorted = [...list].sort((a, b) => a.at - b.at);
        const now = open.get(code);
        const before = now ?? known.get(code);
        // An OPEN leg, or one on the same side as the opening.
        const firstOpen = sorted.find((o) => o.effect === 'OPEN') ?? (before ? undefined : sorted.find((o) => o.effect === undefined));
        const openSide = firstOpen?.side ?? (before ? (before.side === 'long' ? 'BUY' : 'SELL') : undefined);
        if (!openSide) continue;
        const opens = sorted.filter((o) => o.effect === 'OPEN' || (o.effect === undefined && o.side === openSide));
        const closes = sorted.filter((o) => !opens.includes(o));
        if (opens.length === 0 && !before) continue;

        const openPrice = opens.length > 0 ? vwap(opens) : before!.openPrice;
        const closeQty = closes.reduce((s, o) => s + o.qty, 0);
        const closed = !now && closeQty > 0;
        const last = closed ? closes[closes.length - 1] : undefined;
        const codes = sorted.map((o) => o.orderCode);
        const fees = codes.filter((c) => commission.has(c));
        const pnlCodes = closes.map((o) => o.orderCode).filter((c) => settled.has(c));
        out.push({
            positionCode: code,
            symbol: opens[0]?.instrument || before?.symbol || closes[0]?.instrument || '',
            side: openSide === 'BUY' ? 'long' : 'short',
            quantity: Math.max(opens.reduce((s, o) => s + o.qty, 0), now?.quantity ?? 0, before?.quantity ?? 0),
            openPrice: openPrice ?? now?.openPrice ?? null,
            closePrice: closed ? vwap(closes) : null,
            pnl: closed && pnlCodes.length > 0 ? Math.round(pnlCodes.reduce((s, c) => s + settled.get(c)!, 0) * 100) / 100 : null,
            fee: fees.length > 0 ? Math.round(fees.reduce((s, c) => s + commission.get(c)!, 0) * 100) / 100 : null,
            openedAt: opens.length > 0 ? opens[0].at : before!.openedAt,
            closedAt: last ? last.at : null,
            openCode: opens.length > 0 ? opens[0].orderCode : null,
            closeCode: last?.orderCode ?? null,
            closeType: last?.type ?? null,
        });
    }
    return out;
}