/**
 * Resolve the effective profit target and consistency for an account based on its withdrawal strategy.
 *
 * Mode A (targetSameEquity=true): the account must reach the same cumulative equity level.
 *   remainingProfit = priorProfit + totalWithdrawals (profit still in the account after payouts)
 *   effectiveProfitTarget = profitTarget − remainingProfit
 *
 * Mode B (withdrawalStages non-empty): Stage 1 (no withdrawals yet) uses base profitTarget/consistency.
 *   After the Nth withdrawal, use withdrawalStages[N-1]; last stage repeats.
 * Fallback: returns base profitTarget and consistency unchanged.
 */
export function resolveEffectiveConfig(
    profitTarget: number,
    consistency: number,
    minTradingDays: number,
    targetSameEquity: boolean,
    withdrawalStages: { profit: number; consistency: number; minTradingDays: number }[],
    priorProfit: number,
    fundTransactions: { date: string; amount: number }[]
): { profitTarget: number; consistency: number; minTradingDays: number } {
    if (targetSameEquity) {
        // Simple Mode A: effective target = profitTarget - equityProfit, computed in computeDailyTarget.
        // Since computeDailyTarget already compares (amount - accountSize) against profitTarget,
        // no adjustment needed here — just return the base values.
        return { profitTarget, consistency, minTradingDays };
    }
    if (withdrawalStages.length > 0) {
        const withdrawalCount = fundTransactions.filter((f) => f.amount < 0).length;
        if (withdrawalCount === 0) {
            return { profitTarget, consistency, minTradingDays }; // Stage 1 = base values
        }
        const idx = Math.min(withdrawalCount - 1, withdrawalStages.length - 1);
        const stage = withdrawalStages[idx];
        // Fall back to base minTradingDays when the stage doesn't specify one (0 or missing)
        return { profitTarget: stage.profit, consistency: stage.consistency, minTradingDays: stage.minTradingDays || minTradingDays };
    }
    return { profitTarget, consistency, minTradingDays };
}

/** @deprecated Use resolveEffectiveConfig instead */
export function resolveEffectiveProfitTarget(
    profitTarget: number,
    targetSameEquity: boolean,
    withdrawalStages: { profit: number; consistency: number; minTradingDays: number }[],
    priorProfit: number,
    fundTransactions: { date: string; amount: number }[]
): number {
    return resolveEffectiveConfig(profitTarget, 0, 0, targetSameEquity, withdrawalStages, priorProfit, fundTransactions).profitTarget;
}

// ── randomized targets / split legs ──────────────────────────────────────────

/** Split a day's target into multiple legs when it exceeds this. */
export const BIG_DAY_THRESHOLD = 1700;
/** Every split leg must be at least this. */
export const MIN_LEG = 500;
/** After at least one trade, a residual at or below this counts as "day done". */
export const LEG_COMPLETION_EPSILON = 25;
/** Safety valve: never fire more than this many legs per account per trade date. */
export const MAX_LEGS_PER_DAY = 8;

const round2 = (n: number) => Math.round(n * 100) / 100;

/**
 * Deterministic random bump in {0, 5, 10, 15, 20, 25} for an (account, trade date) pair.
 * Seeded (FNV-1a) rather than Math.random() so the dashboard, reporter, and trade path —
 * which each compute the target independently — always agree on the same number.
 */
export function dailyBump(accountId: number, tradeDate: string): number {
    const key = `${accountId}|${tradeDate}`;
    let hash = 0x811c9dc5;
    for (let i = 0; i < key.length; i++) {
        hash ^= key.charCodeAt(i);
        hash = Math.imul(hash, 0x01000193) >>> 0;
    }
    return (hash % 6) * 5;
}

/**
 * Current Tradovate trade date as YYYY-MM-DD: the Chicago calendar date, rolled to the
 * next day once the evening session opens (≥ 5:00 PM CT) — matching when Tradovate
 * resets realizedPnL.
 */
export function currentTradeDateCT(now: Date = new Date()): string {
    const parts = new Intl.DateTimeFormat('en-US', {
        timeZone: 'America/Chicago',
        year: 'numeric', month: '2-digit', day: '2-digit', hour: '2-digit', hour12: false,
    }).formatToParts(now);
    const get = (t: string) => parts.find((p) => p.type === t)?.value ?? '0';
    let date = Date.UTC(Number(get('year')), Number(get('month')) - 1, Number(get('day')));
    if (Number(get('hour')) % 24 >= 17) date += 24 * 60 * 60 * 1000;
    return new Date(date).toISOString().slice(0, 10);
}

/**
 * Deterministic fraction in [0, 1) for a (prefix group, trade date, leg index) triple.
 * Like accounts (same account-type prefix) carving the same leg of the same day draw the
 * same fraction, so pickLegAmount splits their targets identically when their remaining
 * amounts match and proportionally close when they differ (bumps, epsilon leftovers).
 */
export function groupLegFraction(prefix: string, tradeDate: string, legIndex: number): number {
    const key = `${prefix}|${tradeDate}|${legIndex}`;
    let hash = 0x811c9dc5;
    for (let i = 0; i < key.length; i++) {
        hash ^= key.charCodeAt(i);
        hash = Math.imul(hash, 0x01000193) >>> 0;
    }
    return hash / 0x100000000;
}

/**
 * Pick the next leg to trade toward today's remaining target.
 * remaining ≤ BIG_DAY_THRESHOLD → trade it all in one final leg; otherwise carve a random
 * $5-rounded piece from [MIN_LEG, remaining − MIN_LEG] so the remainder also stays ≥ MIN_LEG.
 *
 * minLegsLeft (an account's min-legs setting minus the legs already fired
 * today) forces a carve even below the big-day threshold and reserves MIN_LEG
 * for each leg still owed after this one. It is clamped to what MIN_LEG-sized
 * pieces make possible, so a small coast day is never forced into impossible
 * splits.
 */
export function pickLegAmount(remainingToday: number, rand: () => number = Math.random, minLegsLeft = 0): number {
    const owedAfter = Math.min(minLegsLeft, Math.floor(remainingToday / MIN_LEG)) - 1;
    if (owedAfter > 0) {
        const lo = MIN_LEG;
        const hi = remainingToday - owedAfter * MIN_LEG;
        if (hi <= lo) return lo;
        const leg = Math.round((lo + rand() * (hi - lo)) / 5) * 5;
        return Math.min(Math.max(leg, lo), hi);
    }
    if (remainingToday <= BIG_DAY_THRESHOLD) return round2(remainingToday);
    const lo = MIN_LEG;
    const hi = remainingToday - MIN_LEG;
    const leg = Math.round((lo + rand() * (hi - lo)) / 5) * 5;
    return Math.min(Math.max(leg, lo), hi);
}

// ── CME holiday session combining ────────────────────────────────────────────

const fmtUTC = (d: Date) => d.toISOString().slice(0, 10);

/** The nth given weekday of a month, e.g. (2026, 8, 1, 1) = first Monday of September. */
function nthWeekday(year: number, month: number, weekday: number, n: number): string {
    const first = new Date(Date.UTC(year, month, 1));
    const offset = (weekday - first.getUTCDay() + 7) % 7;
    return fmtUTC(new Date(Date.UTC(year, month, 1 + offset + (n - 1) * 7)));
}

/** The last given weekday of a month, e.g. (2026, 4, 1) = last Monday of May. */
function lastWeekday(year: number, month: number, weekday: number): string {
    const last = new Date(Date.UTC(year, month + 1, 0));
    const offset = (last.getUTCDay() - weekday + 7) % 7;
    return fmtUTC(new Date(Date.UTC(year, month + 1, 0 - offset)));
}

/** A fixed-date holiday as observed: Saturday moves to Friday, Sunday to Monday. */
function observed(year: number, month: number, day: number): string {
    const d = new Date(Date.UTC(year, month, day));
    if (d.getUTCDay() === 6) d.setUTCDate(d.getUTCDate() - 1);
    else if (d.getUTCDay() === 0) d.setUTCDate(d.getUTCDate() + 1);
    return fmtUTC(d);
}

const holidayCache = new Map<number, Set<string>>();

/**
 * Trade dates in the given year whose CME session does not clear on its own:
 * the exchange runs a shortened holiday session (opened the prior evening) and
 * clearing folds it into the next full trading day. Firms that follow CME
 * reporting count the whole stretch as ONE trading day — e.g. Apex on Labor
 * Day 2026: "Sunday, Monday, and Tuesday trading activity will be combined
 * and recorded as a single trading day on Tuesday, September 8."
 *
 * Computed from the federal-holiday rules rather than a hand-kept table so
 * every year works. Full-closure days (Good Friday, Christmas, New Year's
 * Day) have no session and produce no P&L rows, so they aren't included.
 */
function cmeUnsettledDates(year: number): Set<string> {
    let dates = holidayCache.get(year);
    if (!dates) {
        dates = new Set([
            nthWeekday(year, 0, 1, 3),   // MLK Day — 3rd Monday of January
            nthWeekday(year, 1, 1, 3),   // Presidents' Day — 3rd Monday of February
            lastWeekday(year, 4, 1),     // Memorial Day — last Monday of May
            observed(year, 5, 19),       // Juneteenth
            observed(year, 6, 4),        // Independence Day
            nthWeekday(year, 8, 1, 1),   // Labor Day — 1st Monday of September
            nthWeekday(year, 10, 4, 4),  // Thanksgiving — 4th Thursday of November
        ]);
        holidayCache.set(year, dates);
    }
    return dates;
}

/** Weekends never clear either — a weekend-dated Cash History row (Sunday
 *  evening activity attributed to its calendar date) belongs to the next
 *  settling day, which is precisely why Apex's holiday notices say "Sunday,
 *  Monday, and Tuesday" and not just the holiday itself. */
function isUnsettledTradeDate(date: string, dayOfWeek: number): boolean {
    if (dayOfWeek === 0 || dayOfWeek === 6) return true;
    return cmeUnsettledDates(Number(date.slice(0, 4))).has(date);
}

/** The trade date a session clears under: weekend- and holiday-dated activity
 *  rolls forward, through any consecutive unsettled dates, to the next date
 *  that settles. */
export function combinedTradeDate(date: string): string {
    if (!/^\d{4}-\d{2}-\d{2}$/.test(date)) return date;
    const d = new Date(`${date}T00:00:00Z`);
    if (!isUnsettledTradeDate(date, d.getUTCDay())) return date;
    for (let i = 0; i < 7; i++) {
        d.setUTCDate(d.getUTCDate() + 1);
        const next = fmtUTC(d);
        if (!isUnsettledTradeDate(next, d.getUTCDay())) return next;
    }
    return date; // unreachable: no unsettled stretch spans a week
}

export interface CombinedSessionView {
    /** Daily P&L with holiday-session entries folded into their clearing date. */
    dailyPnL: { date: string; pnl: number }[];
    /** The trade date mapped to its clearing date. */
    tradeDate: string;
    /** Live realizedPnL plus P&L already booked on earlier sessions of the same combined day. */
    realizedPnL: number;
    /** Trading days as the firm counts them (nonzero combined entries). */
    daysTraded: number;
}

/**
 * The account's day-based state as its firm records it. With `enabled` false
 * this is the identity view, so callers can apply it unconditionally.
 *
 * On the later sessions of a combined day (e.g. the Tuesday after a Monday
 * holiday), Tradovate's live realizedPnL covers only the current session; the
 * earlier sessions' booked P&L is added back so day targets, already-traded
 * gates and the day's displayed P&L all treat the stretch as one day. Entries
 * dated `tradeDate` itself are never added — computeDayPlan excludes that row
 * and live realizedPnL already covers it.
 */
export function combineCmeSessions(
    enabled: boolean,
    dailyPnL: { date: string; pnl: number }[],
    tradeDate: string,
    realizedPnL: number,
): CombinedSessionView {
    if (!enabled) {
        return {
            dailyPnL, tradeDate, realizedPnL,
            daysTraded: dailyPnL.filter((d) => d.pnl !== 0).length,
        };
    }

    const merged = new Map<string, number>();
    for (const entry of dailyPnL) {
        const date = combinedTradeDate(entry.date);
        merged.set(date, round2((merged.get(date) ?? 0) + entry.pnl));
    }
    const combined = [...merged.entries()]
        .map(([date, pnl]) => ({ date, pnl }))
        .sort((a, b) => a.date.localeCompare(b.date));

    const effectiveTradeDate = combinedTradeDate(tradeDate);
    const carry = dailyPnL
        .filter((d) => d.date !== tradeDate && combinedTradeDate(d.date) === effectiveTradeDate)
        .reduce((sum, d) => sum + d.pnl, 0);

    return {
        dailyPnL: combined,
        tradeDate: effectiveTradeDate,
        realizedPnL: round2(realizedPnL + carry),
        daysTraded: combined.filter((d) => d.pnl !== 0).length,
    };
}

/** Dollar-per-point value for common futures products. */
export const POINT_VALUES: { [symbol: string]: number } = {
    NQ: 20, MNQ: 2, ES: 50, MES: 5,
    YM: 5, MYM: 0.5, RTY: 50, M2K: 10,
    GC: 100, MGC: 10, SI: 50, CL: 1000,
    MCL: 100, NG: 10000, ZB: 1000, ZN: 1000,
    ZF: 1000, '6E': 125000, '6J': 12500000, '6B': 62500,
};

/**
 * Compute the next trading day's profit target for an account.
 *
 * Path 1 – No positive trading days yet:
 *   target = profitTarget × consistency
 *
 * Path 2 – At least one positive day exists:
 *   maxDay     = highest single-day P&L so far
 *   realTarget = maxDay / consistency  (the total profit at which maxDay ≤ consistency% of total)
 *   needed     = realTarget − totalProfit
 *
 *   if needed > maxDay  → target maxDay (still a long way from the real target; trade a normal day)
 *   else                → target needed (close to the real target; aim for exactly what's left)
 *
 * Min-day reservation (only when minDayPnL > 0):
 *   When there are still mandatory trading days remaining, today's target is capped so that
 *   enough profit is reserved for each future mandatory day to meet minDayPnL.
 *   Cap = (profitTarget - totalProfit) − (remainingDaysAfterToday × minDayPnL)
 *   Floor = minDayPnL (we must make at least this today)
 */
export function computeDailyTarget(
    profitTarget: number,
    consistency: number,
    dailyPnL: { date: string; pnl: number }[],
    minDayPnL: number,          // 0 = no minimum per day
    minTradingDays: number,     // 0 = no minimum trading days
    equityProfit: number | null | undefined, // amount − accountSize. Null/undefined → skip (return null). 0 is valid.
    bump: number = 0                         // random extra target. No consistency rule: applied when the min-day floor binds. Strict consistency: first trade ever only.
): { amount: number; path: 'first_day' | 'normal_day' | 'reduced_day' } | null {
    // Don't run if we don't have a real account balance to compute against — 0 is valid.
    if (typeof equityProfit !== 'number' || !Number.isFinite(equityProfit)) {
        return null;
    }

    const qualifyingDays = minDayPnL === 0 ? dailyPnL : dailyPnL.filter((d) => d.pnl >= minDayPnL);
    const daysTraded = qualifyingDays.length;
    const effectiveMinDay = Math.max(0, minDayPnL);
    const tradingProfit = dailyPnL.reduce((s, d) => s + d.pnl, 0); // cycle-local trading profit

    // Shortfall to hit profitTarget (measured in equity terms — accounts for deposits/withdrawals)
    const equityShortfall = Math.max(0, profitTarget - equityProfit);

    // Shortfall to satisfy consistency rule: total trading profit must be ≥ maxDay / consistency,
    // otherwise the biggest day would exceed the consistency ratio.
    let consistencyShortfall = 0;
    if (consistency > 0 && consistency < 1 && qualifyingDays.length > 0) {
        const maxDay = Math.max(...qualifyingDays.map((d) => d.pnl));
        const realTarget = maxDay / consistency;
        consistencyShortfall = Math.max(0, realTarget - tradingProfit);
    }

    const remaining = Math.max(equityShortfall, consistencyShortfall);

    const noConsistencyRule = consistency === 0 || consistency >= 1;

    // 1. Both target and consistency already satisfied — coast on min-day if mandatory days remain.
    if (remaining <= 0) {
        const needsMoreDays = minTradingDays > daysTraded;
        let coastAmount = needsMoreDays ? effectiveMinDay : 0;
        if (coastAmount > 0 && noConsistencyRule) coastAmount += bump;
        return { amount: coastAmount, path: 'reduced_day' };
    }

    // 2. Min-day reservation: future mandatory days each reserve minDayPnL.
    //    cappedByFuture = remaining profit available after reserving.
    const daysLeft = Math.max(1, minTradingDays - daysTraded); // includes today
    const futureReserve = (daysLeft - 1) * effectiveMinDay;
    const cappedByFuture = remaining - futureReserve;

    // 3. Consistency cap.
    //    cycleStartEquity = equityProfit − tradingProfit (equity at the start of this cycle).
    //    cycleNetTarget   = profitTarget − cycleStartEquity (cycle's net P&L needed to hit target).
    //    maxConsistencyDay = cycleNetTarget × consistency — the largest day the rule allows
    //    measured against the cycle's net total (not against profitTarget directly), so prior
    //    losses don't artificially expand the cap.
    //
    //    Day 1: min(remaining × consistency, maxConsistencyDay).
    //    Day 2+: max(maxDay, maxConsistencyDay).
    //      - If maxDay ≤ maxConsistencyDay: room to grow days up to that ceiling.
    //      - If maxDay > maxConsistencyDay: consistency already broken at target, total must
    //        grow to at least maxDay / consistency. Each day can be up to maxDay (going higher
    //        creates a new maxDay requiring even more total).
    let consistencyCap: number;
    let path: 'first_day' | 'normal_day' | 'reduced_day';

    if (noConsistencyRule) {
        consistencyCap = Infinity;
        path = daysTraded === 0 ? 'first_day' : 'reduced_day';
    } else {
        const cycleStartEquity = equityProfit - tradingProfit;
        const cycleNetTarget = Math.max(0, profitTarget - cycleStartEquity);
        const maxConsistencyDay = cycleNetTarget * consistency;
        if (daysTraded === 0) {
            consistencyCap = Math.min(remaining * consistency, maxConsistencyDay);
            path = 'first_day';
        } else {
            const maxDay = Math.max(...qualifyingDays.map((d) => d.pnl));
            consistencyCap = Math.max(maxDay, maxConsistencyDay);
            path = 'normal_day';
        }
    }

    // 4. Combine caps and apply min-day floor when mandatory days remain.
    const raw = Math.min(consistencyCap, cappedByFuture);
    const mustFloor = minTradingDays > daysTraded;
    let amount = mustFloor ? Math.max(effectiveMinDay, raw) : Math.max(0, raw);

    // 5. Random bump. Without a consistency rule, bump the days where the min-day floor is
    //    what set the target (big days get their randomness from leg splitting instead).
    //    With a strict consistency rule, only the first trade ever gets a bump — a slight
    //    overshoot there just raises consistencyShortfall, which later days self-correct.
    if (bump > 0) {
        if (noConsistencyRule) {
            if (mustFloor && raw <= effectiveMinDay && effectiveMinDay > 0) amount = effectiveMinDay + bump;
        } else if (daysTraded === 0) {
            amount += bump;
        }
    }

    return { amount: Math.round(amount * 100) / 100, path };
}

export interface DayPlan {
    /** Full target for this trade date (bump included) — a fixed anchor all day. */
    dayTarget: number;
    /** dayTarget minus what's already realized today; what's left to trade. */
    remainingToday: number;
    path: 'first_day' | 'normal_day' | 'reduced_day';
    /** False when the account type disables splitting, or for strict-consistency
     *  accounts past their first trade ever — single unsplit trade. */
    splitAllowed: boolean;
}

/**
 * Compute today's full target and what's still left of it, as of right now.
 *
 * Unlike calling computeDailyTarget directly, this anchors the day: today's PnL row (which
 * the hourly Cash History refresh may write mid-day) is excluded, and day-start equity is
 * reconstructed as equityProfit − realizedPnL. So the same (account, trade date) always
 * yields the same dayTarget no matter when or where it's computed — the dashboard, the
 * reporter, and the trade path agree, and completed legs only move remainingToday.
 */
export function computeDayPlan(
    accountId: number,
    tradeDate: string,
    profitTarget: number,
    consistency: number,
    dailyPnL: { date: string; pnl: number }[],
    minDayPnL: number,
    minTradingDays: number,
    equityProfit: number | null | undefined,
    realizedPnL: number,
    splitEnabled: boolean = true
): DayPlan | null {
    if (typeof equityProfit !== 'number' || !Number.isFinite(equityProfit)) return null;

    const priorDays = dailyPnL.filter((d) => d.date !== tradeDate);
    const dayStartEquity = equityProfit - realizedPnL;
    const target = computeDailyTarget(
        profitTarget, consistency, priorDays, minDayPnL, minTradingDays,
        dayStartEquity, dailyBump(accountId, tradeDate)
    );
    if (!target) return null;

    const qualifyingDays = minDayPnL === 0 ? priorDays : priorDays.filter((d) => d.pnl >= minDayPnL);
    const splitAllowed = splitEnabled && (consistency === 0 || consistency >= 1 || qualifyingDays.length === 0);

    return {
        dayTarget: target.amount,
        remainingToday: round2(target.amount - realizedPnL),
        path: target.path,
        splitAllowed,
    };
}