/**
 * 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;
}

/** 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);
}

/** 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;
}