// Copyright (c) The Geekeey Authors
// SPDX-License-Identifier: EUPL-1.2

using System.Diagnostics.Contracts;

namespace Geekeey.Extensions.Result;

/// <summary>
/// A class containing various utility methods, a 'prelude' to the rest of the library.
/// </summary>
/// <remarks>
/// This class is meant to be imported statically, e.g. <c>using static Geekeey.Extensions.Result.Prelude;</c>.
/// Recommended to be imported globally via a global using statement.
/// </remarks>
public static class Prelude
{
	/// <summary>
	/// Creates a result containing an success value.
	/// </summary>
	/// <typeparam name="T">The type of the success value.</typeparam>
	/// <param name="value">The success value to create the result from.</param>
	[Pure]
	public static Result<T> Success<T>(T value) => new(value);

	/// <summary>
	/// Creates a result containing a failure value.
	/// </summary>
	/// <typeparam name="T">The type of an success value in the result.</typeparam>
	/// <param name="error">The failure value to create the result from.</param>
	[Pure]
	public static Result<T> Failure<T>(Error error) => new(error);

	/// <summary>
	/// Tries to execute a function and return the result. If the function throws an exception, the exception will be
	/// returned wrapped in an <see cref="ExceptionError"/>.
	/// </summary>
	/// <typeparam name="T">The type the function returns.</typeparam>
	/// <param name="function">The function to try execute.</param>
	/// <returns>A result containing the return value of the function or an <see cref="ExceptionError"/> containing the
	/// exception thrown by the function.</returns>
	[Pure]
	public static Result<T> Try<T>(Func<T> function)
	{
		try
		{
			return new Result<T>(function());
		}
		catch (Exception exception)
		{
			return new Result<T>(new ExceptionError(exception));
		}
	}

	/// <summary>
	/// Tries to execute an asynchronous function and return the result. If the function throws an exception, the
	/// exception will be returned wrapped in an <see cref="ExceptionError"/>.
	/// </summary>
	/// <typeparam name="T">The type the function returns.</typeparam>
	/// <param name="function">The function to try execute.</param>
	/// <returns>A result containing the return value of the function or an <see cref="ExceptionError"/> containing the
	/// exception thrown by the function.</returns>
	[Pure]
	public static async ValueTask<Result<T>> TryAsync<T>(Func<ValueTask<T>> function)
	{
		try
		{
			return new Result<T>(await function());
		}
		catch (Exception exception)
		{
			return new Result<T>(new ExceptionError(exception));
		}
	}

	/// <summary>
	/// Tries to execute an asynchronous function and return the result. If the function throws an exception, the
	/// exception will be returned wrapped in an <see cref="ExceptionError"/>.
	/// </summary>
	/// <typeparam name="T">The type the function returns.</typeparam>
	/// <param name="function">The function to try execute.</param>
	/// <returns>A result containing the return value of the function or an <see cref="ExceptionError"/> containing the
	/// exception thrown by the function.</returns>
	[Pure]
	public static async Task<Result<T>> TryAsync<T>(Func<Task<T>> function)
	{
		try
		{
			return new Result<T>(await function());
		}
		catch (Exception exception)
		{
			return new Result<T>(new ExceptionError(exception));
		}
	}
}