spectre.console/src/Spectre.Console/Cli/Internal/Binding/CommandConstructorBinder.cs

using System;
using System.Collections.Generic;
using System.Reflection;

namespace Spectre.Console.Cli;

internal static class CommandConstructorBinder
{
    public static CommandSettings CreateSettings(CommandValueLookup lookup, ConstructorInfo constructor, ITypeResolver resolver)
    {
        if (constructor.DeclaringType == null)
        {
            throw new InvalidOperationException("Cannot create settings since constructor have no declaring type.");
        }

        var parameters = new List<object?>();
        var mapped = new HashSet<Guid>();
        foreach (var parameter in constructor.GetParameters())
        {
            if (lookup.TryGetParameterWithName(parameter.Name, out var result))
            {
                parameters.Add(result.Value);
                mapped.Add(result.Parameter.Id);
            }
            else
            {
                var value = resolver.Resolve(parameter.ParameterType);
                if (value == null)
                {
                    throw CommandRuntimeException.CouldNotResolveType(parameter.ParameterType);
                }

                parameters.Add(value);
            }
        }

        // Create the settings.
        if (!(Activator.CreateInstance(constructor.DeclaringType, parameters.ToArray()) is CommandSettings settings))
        {
            throw new InvalidOperationException("Could not create settings");
        }

        // Try to do property injection for parameters that wasn't injected.
        foreach (var (parameter, value) in lookup)
        {
            if (!mapped.Contains(parameter.Id) && parameter.Property.SetMethod != null)
            {
                parameter.Property.SetValue(settings, value);
            }
        }

        return settings;
    }
}