전체적인 리팩토링

lib/autotrade/execution-cost.ts

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+export interface AutotradeExecutionCostProfile {
+  buyFeeRate: number;
+  sellFeeRate: number;
+  sellTaxRate: number;
+}
+
+export interface AutotradeEstimatedOrderCost {
+  side: "buy" | "sell";
+  price: number;
+  quantity: number;
+  grossAmount: number;
+  feeAmount: number;
+  taxAmount: number;
+  netAmount: number;
+}
+
+export function resolveExecutionCostProfile(): AutotradeExecutionCostProfile {
+  return {
+    buyFeeRate: readRateFromEnv("AUTOTRADE_BUY_FEE_RATE", 0.00015),
+    sellFeeRate: readRateFromEnv("AUTOTRADE_SELL_FEE_RATE", 0.00015),
+    sellTaxRate: readRateFromEnv("AUTOTRADE_SELL_TAX_RATE", 0.0018),
+  };
+}
+
+export function estimateBuyUnitCost(
+  price: number,
+  profile: AutotradeExecutionCostProfile,
+) {
+  const safePrice = Math.max(0, price);
+  if (safePrice <= 0) return 0;
+  return safePrice * (1 + Math.max(0, profile.buyFeeRate));
+}
+
+export function estimateSellNetUnit(
+  price: number,
+  profile: AutotradeExecutionCostProfile,
+) {
+  const safePrice = Math.max(0, price);
+  if (safePrice <= 0) return 0;
+  const totalRate = Math.max(0, profile.sellFeeRate) + Math.max(0, profile.sellTaxRate);
+  return safePrice * (1 - totalRate);
+}
+
+export function estimateOrderCost(params: {
+  side: "buy" | "sell";
+  price: number;
+  quantity: number;
+  profile: AutotradeExecutionCostProfile;
+}): AutotradeEstimatedOrderCost {
+  const safePrice = Math.max(0, params.price);
+  const safeQuantity = Math.max(0, Math.floor(params.quantity));
+  const grossAmount = safePrice * safeQuantity;
+
+  if (params.side === "buy") {
+    const feeAmount = grossAmount * Math.max(0, params.profile.buyFeeRate);
+    return {
+      side: params.side,
+      price: safePrice,
+      quantity: safeQuantity,
+      grossAmount,
+      feeAmount,
+      taxAmount: 0,
+      netAmount: grossAmount + feeAmount,
+    };
+  }
+
+  const feeAmount = grossAmount * Math.max(0, params.profile.sellFeeRate);
+  const taxAmount = grossAmount * Math.max(0, params.profile.sellTaxRate);
+  return {
+    side: params.side,
+    price: safePrice,
+    quantity: safeQuantity,
+    grossAmount,
+    feeAmount,
+    taxAmount,
+    netAmount: grossAmount - feeAmount - taxAmount,
+  };
+}
+
+function readRateFromEnv(envName: string, fallback: number) {
+  const raw = Number.parseFloat(process.env[envName] ?? "");
+  if (!Number.isFinite(raw)) return fallback;
+
+  if (raw >= 1 && raw <= 100) {
+    return clamp(raw / 100, 0, 0.5);
+  }
+
+  return clamp(raw, 0, 0.5);
+}
+
+function clamp(value: number, min: number, max: number) {
+  if (!Number.isFinite(value)) return min;
+  return Math.min(max, Math.max(min, value));
+}