Combined odds = o₁ × o₂ × ... × oₙ
Payout = stake × combined odds
Profit = payout - stake

Combined = 1.90 × 2.10 × 1.75 = 6.9825
Payout = $10 × 6.9825 = $69.83
Profit = $69.83 - $10.00 = $59.83

function calculateParlay(legs) {
  const combinedOdds = legs.reduce((acc, leg) => acc * leg.odds, 1);

  return {
    legs: legs.length,
    combinedOdds: Math.round(combinedOdds * 100) / 100,
    impliedProbability: (1 / combinedOdds * 100).toFixed(1) + "%",
  };
}

// Example
const myParlay = calculateParlay([
  { name: "Arsenal Win", odds: 1.90 },
  { name: "Over 2.5 Goals", odds: 2.10 },
  { name: "BTTS Yes", odds: 1.75 },
]);

console.log(myParlay);
// { legs: 3, combinedOdds: 6.98, impliedProbability: "14.3%" }

function parlayPayout(stake, legs) {
  const combined = legs.reduce((acc, leg) => acc * leg.odds, 1);

  return {
    stake,
    combinedOdds: Math.round(combined * 100) / 100,
    payout: Math.round(combined * stake * 100) / 100,
    profit: Math.round((combined * stake - stake) * 100) / 100,
  };
}

console.log(parlayPayout(25, [
  { name: "Lakers Win", odds: 1.45 },
  { name: "Celtics Win", odds: 1.60 },
  { name: "Warriors Win", odds: 2.20 },
]));
// { stake: 25, combinedOdds: 5.10, payout: 127.60, profit: 102.60 }

function parlayWithRefunds(stake, legs) {
  let combined = 1;
  let activeLegCount = 0;
  let refundLegCount = 0;

  for (const leg of legs) {
    if (leg.status === "refund" || leg.status === "void") {
      combined *= 1.00; // Refund leg = odds 1.00
      refundLegCount++;
    } else {
      combined *= leg.odds;
      activeLegCount++;
    }
  }

  return {
    totalLegs: legs.length,
    activeLegs: activeLegCount,
    refundedLegs: refundLegCount,
    combinedOdds: Math.round(combined * 100) / 100,
    payout: Math.round(combined * stake * 100) / 100,
  };
}

// One leg refunded — parlay becomes a double
const result = parlayWithRefunds(50, [
  { name: "Arsenal Win", odds: 1.90, status: "won" },
  { name: "Chelsea Win", odds: 2.10, status: "refund" },  // Postponed
  { name: "Liverpool Win", odds: 1.75, status: "won" },
]);

console.log(result);
// { totalLegs: 3, activeLegs: 2, refundedLegs: 1,
//   combinedOdds: 3.33, payout: 166.25 }

function decimalToAmerican(decimal) {
  if (decimal >= 2.0) return `+${Math.round((decimal - 1) * 100)}`;
  return `-${Math.round(100 / (decimal - 1))}`;
}

function decimalToFractional(decimal) {
  const fraction = decimal - 1;
  // Simple fraction approximation
  const denominator = 100;
  const numerator = Math.round(fraction * denominator);
  const gcd = (a, b) => (b === 0 ? a : gcd(b, a % b));
  const d = gcd(numerator, denominator);
  return `${numerator / d}/${denominator / d}`;
}

console.log(decimalToAmerican(2.50));    // "+150"
console.log(decimalToAmerican(1.40));    // "-250"
console.log(decimalToFractional(2.50));  // "3/2"
console.log(decimalToFractional(1.75));  // "3/4"

const API_KEY = "your_api_key_here";

async function settleParlay(stake, legs) {
  const response = await fetch(
    "https://api.fieldfunded.com/v1/bets/check-parlay",
    {
      method: "POST",
      headers: {
        "X-API-Key": API_KEY,
        "Content-Type": "application/json",
      },
      body: JSON.stringify({ stake, legs }),
    }
  );

  return response.json();
}

// Submit a 3-leg parlay for settlement
const settlement = await settleParlay(50, [
  {
    event_id: "evt_abc123",
    market: "Match Winner",
    selection: "Arsenal",
    odds: 1.90,
    market_id: "mkt_001",
    selection_id: "sel_001",
  },
  {
    event_id: "evt_def456",
    market: "Over/Under 2.5",
    selection: "Over 2.5",
    odds: 2.10,
    market_id: "mkt_002",
    selection_id: "sel_002",
  },
  {
    event_id: "evt_ghi789",
    market: "BTTS",
    selection: "Yes",
    odds: 1.75,
    market_id: "mkt_003",
    selection_id: "sel_003",
  },
]);

console.log(`Status: ${settlement.status}`);
console.log(`Payout: $${settlement.payout}`);
// Status: won
// Payout: $348.25