using System;

namespace Unosquare.Swan.Models {
  /// <summary>
  /// Represents a Ok value or Error value.
  /// </summary>
  /// <typeparam name="T">The type of OK value.</typeparam>
  /// <typeparam name="TError">The type of the error.</typeparam>
  public class OkOrError<T, TError> {
    /// <summary>
    /// Gets or sets a value indicating whether this instance is Ok.
    /// </summary>
    /// <value>
    ///   <c>true</c> if this instance is ok; otherwise, <c>false</c>.
    /// </value>
    public Boolean IsOk => !Equals(this.Ok, default(T));

    /// <summary>
    /// Gets or sets the ok.
    /// </summary>
    /// <value>
    /// The ok.
    /// </value>
    public T Ok {
      get; set;
    }

    /// <summary>
    /// Gets or sets the error.
    /// </summary>
    /// <value>
    /// The error.
    /// </value>
    public TError Error {
      get; set;
    }

    /// <summary>
    /// Creates a new OkOrError from the specified Ok object.
    /// </summary>
    /// <param name="ok">The ok.</param>
    /// <returns>OkOrError instance.</returns>
    public static OkOrError<T, TError> FromOk(T ok) => new OkOrError<T, TError> { Ok = ok };

    /// <summary>
    /// Creates a new OkOrError from the specified Error object.
    /// </summary>
    /// <param name="error">The error.</param>
    /// <returns>OkOrError instance.</returns>
    public static OkOrError<T, TError> FromError(TError error) => new OkOrError<T, TError> { Error = error };
  }
}