export type ExecutableOrderSide = "buy" | "sell";

export interface ClampExecutableOrderQuantityParams {
  side: ExecutableOrderSide;
  requestedQuantity: number;
  maxBuyQuantity?: number;
  holdingQuantity?: number;
  sellableQuantity?: number;
}

export interface ClampExecutableOrderQuantityResult {
  ok: boolean;
  quantity: number;
  adjusted: boolean;
}

/**
 * [목적]
 * 주문 전 계좌 제약(매수가능/보유/매도가능)에 맞춰 최종 실행 수량을 순수 계산합니다.
 *
 * [입력 -> 처리 -> 결과]
 * 요청 수량/사이드/제약값 -> 가능 최대 수량으로 clamp -> 실행 가능 여부와 수량 반환
 */
export function clampExecutableOrderQuantity(
  params: ClampExecutableOrderQuantityParams,
): ClampExecutableOrderQuantityResult {
  const requestedQuantity = Math.max(0, Math.floor(params.requestedQuantity));
  if (requestedQuantity <= 0) {
    return {
      ok: false,
      quantity: 0,
      adjusted: false,
    };
  }

  if (params.side === "buy") {
    const maxBuyQuantity = Math.max(0, Math.floor(params.maxBuyQuantity ?? 0));
    const quantity = Math.min(requestedQuantity, maxBuyQuantity);
    return {
      ok: quantity > 0,
      quantity,
      adjusted: quantity !== requestedQuantity,
    };
  }

  const holdingQuantity = Math.max(0, Math.floor(params.holdingQuantity ?? 0));
  const sellableQuantity = Math.max(0, Math.floor(params.sellableQuantity ?? 0));
  const maxSellQuantity = Math.min(holdingQuantity, sellableQuantity);
  const quantity = Math.min(requestedQuantity, maxSellQuantity);
  return {
    ok: quantity > 0,
    quantity,
    adjusted: quantity !== requestedQuantity,
  };
}