using System;

namespace Umbraco.Core
{
    /// <summary>
    /// Represents the result of an operation attempt.
    /// </summary>
    /// <typeparam name="TResult">The type of the attempted operation result.</typeparam>
    /// <typeparam name="TStatus">The type of the attempted operation status.</typeparam>
    [Serializable]
    public struct Attempt<TResult, TStatus>
    {
        /// <summary>
        /// Gets a value indicating whether this <see cref="Attempt{TResult,TStatus}"/> was successful.
        /// </summary>
        public bool Success { get; }

        /// <summary>
        /// Gets the exception associated with an unsuccessful attempt.
        /// </summary>
        public Exception Exception { get; }

        /// <summary>
        /// Gets the attempt result.
        /// </summary>
        public TResult Result { get; }

        /// <summary>
        /// Gets the attempt status.
        /// </summary>
        public TStatus Status { get; }

        // private - use Succeed() or Fail() methods to create attempts
        private Attempt(bool success, TResult result, TStatus status, Exception exception)
        {
            Success = success;
            Result = result;
            Status = status;
            Exception = exception;
        }

        /// <summary>
        /// Creates a successful attempt.
        /// </summary>
        /// <param name="status">The status of the attempt.</param>
        /// <returns>The successful attempt.</returns>
        public static Attempt<TResult, TStatus> Succeed(TStatus status)
        {
            return new Attempt<TResult, TStatus>(true, default(TResult), status, null);
        }

        /// <summary>
        /// Creates a successful attempt with a result.
        /// </summary>
        /// <param name="status">The status of the attempt.</param>
        /// <param name="result">The result of the attempt.</param>
        /// <returns>The successful attempt.</returns>
        public static Attempt<TResult, TStatus> Succeed(TStatus status, TResult result)
        {
            return new Attempt<TResult, TStatus>(true, result, status, null);
        }

        /// <summary>
        /// Creates a failed attempt.
        /// </summary>
        /// <param name="status">The status of the attempt.</param>
        /// <returns>The failed attempt.</returns>
        public static Attempt<TResult, TStatus> Fail(TStatus status)
        {
            return new Attempt<TResult, TStatus>(false, default(TResult), status, null);
        }

        /// <summary>
        /// Creates a failed attempt with an exception.
        /// </summary>
        /// <param name="status">The status of the attempt.</param>
        /// <param name="exception">The exception causing the failure of the attempt.</param>
        /// <returns>The failed attempt.</returns>
        public static Attempt<TResult, TStatus> Fail(TStatus status, Exception exception)
        {
            return new Attempt<TResult, TStatus>(false, default(TResult), status, exception);
        }

        /// <summary>
        /// Creates a failed attempt with a result.
        /// </summary>
        /// <param name="status">The status of the attempt.</param>
        /// <param name="result">The result of the attempt.</param>
        /// <returns>The failed attempt.</returns>
        public static Attempt<TResult, TStatus> Fail(TStatus status, TResult result)
        {
            return new Attempt<TResult, TStatus>(false, result, status, null);
        }

        /// <summary>
        /// Creates a failed attempt with a result and an exception.
        /// </summary>
        /// <param name="status">The status of the attempt.</param>
        /// <param name="result">The result of the attempt.</param>
        /// <param name="exception">The exception causing the failure of the attempt.</param>
        /// <returns>The failed attempt.</returns>
        public static Attempt<TResult, TStatus> Fail(TStatus status, TResult result, Exception exception)
        {
            return new Attempt<TResult, TStatus>(false, result, status, exception);
        }

        /// <summary>
        /// Creates a successful or a failed attempt.
        /// </summary>
        /// <param name="condition">A value indicating whether the attempt is successful.</param>
        /// <param name="succStatus">The status of the successful attempt.</param>
        /// <param name="failStatus">The status of the failed attempt.</param>
        /// <returns>The attempt.</returns>
        public static Attempt<TResult, TStatus> If(bool condition, TStatus succStatus, TStatus failStatus)
        {
            return new Attempt<TResult, TStatus>(condition, default(TResult), condition ? succStatus : failStatus, null);
        }

        /// <summary>
        /// Creates a successful or a failed attempt, with a result.
        /// </summary>
        /// <param name="condition">A value indicating whether the attempt is successful.</param>
        /// <param name="succStatus">The status of the successful attempt.</param>
        /// <param name="failStatus">The status of the failed attempt.</param>
        /// <param name="result">The result of the attempt.</param>
        /// <returns>The attempt.</returns>
        public static Attempt<TResult, TStatus> If(bool condition, TStatus succStatus, TStatus failStatus, TResult result)
        {
            return new Attempt<TResult, TStatus>(condition, result, condition ? succStatus : failStatus, null);
        }

        /// <summary>
        /// Implicitly operator to check if the attempt was successful without having to access the 'success' property
        /// </summary>
        /// <param name="a"></param>
        /// <returns></returns>
        public static implicit operator bool(Attempt<TResult, TStatus> a)
        {
            return a.Success;
        }
    }
}