ADOFAIRenderer/Data/DoubleLimit.cs

namespace ADOFAIRenderer.Data
{
    /// <summary>
    /// Base class for double input validation limits.
    /// Multiple limits can be composed on a single input field — all are checked in order.
    /// </summary>
    public abstract class DoubleLimit
    {
        /// <summary>
        /// Validates the given double value against this limit.
        /// </summary>
        /// <param name="value">The parsed double value to validate.</param>
        /// <param name="errorMessage">
        /// When validation fails, set to a human-readable error message.
        /// When validation succeeds, set to null.
        /// </param>
        /// <returns>true if the value satisfies this limit; false otherwise.</returns>
        public abstract bool Validate(double value, out string errorMessage);
    }

    /// <summary>
    /// Requires the double value to be strictly positive (> 0).
    /// </summary>
    public class PositiveOnlyDoubleLimit : DoubleLimit
    {
        public override bool Validate(double value, out string errorMessage)
        {
            if (value > 0)
            {
                errorMessage = null!;
                return true;
            }

            errorMessage = "값은 0보다 큰 양수여야 합니다.";
            return false;
        }
    }

    /// <summary>
    /// Requires the double value to be within an inclusive [Min, Max] range.
    /// Either bound can be null to represent an unbounded side.
    /// </summary>
    public class RangeDoubleLimit : DoubleLimit
    {
        public double? Min { get; }
        public double? Max { get; }

        /// <param name="min">Inclusive lower bound, or null for no lower bound.</param>
        /// <param name="max">Inclusive upper bound, or null for no upper bound.</param>
        public RangeDoubleLimit(double? min, double? max)
        {
            Min = min;
            Max = max;
        }

        public override bool Validate(double value, out string errorMessage)
        {
            if (Min.HasValue && value < Min.Value)
            {
                errorMessage = Max.HasValue
                    ? $"값은 {Min.Value}에서 {Max.Value} 사이의 숫자여야 합니다."
                    : $"값은 {Min.Value} 이상의 숫자여야 합니다.";
                return false;
            }

            if (Max.HasValue && value > Max.Value)
            {
                errorMessage = Min.HasValue
                    ? $"값은 {Min.Value}에서 {Max.Value} 사이의 숫자여야 합니다."
                    : $"값은 {Max.Value} 이하의 숫자여야 합니다.";
                return false;
            }

            errorMessage = null!;
            return true;
        }
    }
}