// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
 
namespace Microsoft.AspNetCore.Components.Forms;
 
internal static class InputExtensions
{
    public static bool TryParseSelectableValueFromString<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] TValue>(
        this InputBase<TValue> input, string? value,
        [MaybeNullWhen(false)] out TValue result,
        [NotNullWhen(false)] out string? validationErrorMessage)
    {
        try
        {
            // We special-case bool values because BindConverter reserves bool conversion for conditional attributes.
            if (typeof(TValue) == typeof(bool))
            {
                if (TryConvertToBool(value, out result))
                {
                    validationErrorMessage = null;
                    return true;
                }
            }
            else if (typeof(TValue) == typeof(bool?))
            {
                if (TryConvertToNullableBool(value, out result))
                {
                    validationErrorMessage = null;
                    return true;
                }
            }
            else if (BindConverter.TryConvertTo<TValue>(value, CultureInfo.CurrentCulture, out var parsedValue))
            {
                result = parsedValue;
                validationErrorMessage = null;
                return true;
            }
 
            result = default;
            validationErrorMessage = $"The {input.DisplayName ?? input.FieldIdentifier.FieldName} field is not valid.";
            return false;
        }
        catch (InvalidOperationException ex)
        {
            throw new InvalidOperationException($"{input.GetType()} does not support the type '{typeof(TValue)}'.", ex);
        }
    }
 
    private static bool TryConvertToBool<TValue>(string? value, out TValue result)
    {
        if (bool.TryParse(value, out var @bool))
        {
            result = (TValue)(object)@bool;
            return true;
        }
 
        result = default!;
        return false;
    }
 
    private static bool TryConvertToNullableBool<TValue>(string? value, out TValue result)
    {
        if (string.IsNullOrEmpty(value))
        {
            result = default!;
            return true;
        }
 
        return TryConvertToBool(value, out result);
    }
}