Mccn/src/Common/Mccn.Common.Domain/Abstractions/Result.cs

namespace Mccn.Common.Domain.Abstractions;

public class Result
{
    protected Result(bool isSuccess, Error error)
    {
        if (isSuccess && error != Error.None)
            throw new InvalidOperationException();
        if (!isSuccess && error == Error.None)
            throw new InvalidOperationException();

        IsSuccess = isSuccess;
        Error = error;
    }

    public bool IsSuccess { get; }
    public bool IsFailure => !IsSuccess;
    public Error Error { get; }

    public static Result Success()
    {
        return new Result(true, Error.None);
    }

    public static Result Failure(Error error)
    {
        return new Result(false, error);
    }

    public static Result<TValue> Success<TValue>(TValue value)
    {
        return new Result<TValue>(value, true, Error.None);
    }

    public static Result<TValue> Failure<TValue>(Error error)
    {
        return new Result<TValue>(default, false, error);
    }
}

public sealed class Result<TValue> : Result
{
    private readonly TValue? _value;

    internal Result(TValue? value, bool isSuccess, Error error) : base(isSuccess, error)
    {
        _value = value;
    }

    public TValue Value => IsSuccess
        ? _value!
        : throw new InvalidOperationException("The value of a failure result cannot be accessed.");

    public static implicit operator Result<TValue>(TValue? value)
    {
        return value is not null ? Success(value) : Failure<TValue>(Error.NullValue);
    }
}