// Copyright 2009-2022 Josh Close
// This file is a part of CsvHelper and is dual licensed under MS-PL and Apache 2.0.
// See LICENSE.txt for details or visit http://www.opensource.org/licenses/ms-pl.html for MS-PL and http://opensource.org/licenses/Apache-2.0 for Apache 2.0.
// https://github.com/JoshClose/CsvHelper
using System;
using System.Reflection;
using System.Linq.Expressions;
using System.Runtime.CompilerServices;
using System.Linq;

namespace CsvHelper
{
	/// <summary>
	/// Extensions to help with reflection.
	/// </summary>
	public static class ReflectionExtensions
	{
		/// <summary>
		/// Gets the type from the member.
		/// </summary>
		/// <param name="member">The member to get the type from.</param>
		/// <returns>The type.</returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static Type MemberType(this MemberInfo member)
		{
			var property = member as PropertyInfo;
			if (property != null)
			{
				return property.PropertyType;
			}

			var field = member as FieldInfo;
			if (field != null)
			{
				return field.FieldType;
			}

			throw new InvalidOperationException("Member is not a property or a field.");
		}

		/// <summary>
		/// Gets a member expression for the member.
		/// </summary>
		/// <param name="member">The member to get the expression for.</param>
		/// <param name="expression">The member expression.</param>
		/// <returns>The member expression.</returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static MemberExpression GetMemberExpression(this MemberInfo member, Expression expression)
		{
			var property = member as PropertyInfo;
			if (property != null)
			{
				return Expression.Property(expression, property);
			}

			var field = member as FieldInfo;
			if (field != null)
			{
				return Expression.Field(expression, field);
			}

			throw new InvalidOperationException("Member is not a property or a field.");
		}

		/// <summary>
		/// Gets a value indicating if the given type is anonymous.
		/// True for anonymous, otherwise false.
		/// </summary>
		/// <param name="type">The type.</param>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static bool IsAnonymous(this Type type)
		{
			if (type == null)
			{
				throw new ArgumentNullException(nameof(type));
			}

			// https://stackoverflow.com/a/2483054/68499
			var isAnonymous = Attribute.IsDefined(type, typeof(CompilerGeneratedAttribute), false)
				&& type.IsGenericType
				&& type.Name.Contains("AnonymousType")
				&& (type.Name.StartsWith("<>") || type.Name.StartsWith("VB$"))
				&& (type.Attributes & TypeAttributes.Public) != TypeAttributes.Public;

			return isAnonymous;
		}

		/// <summary>
		/// Gets a value indicating if the given type has a parameterless constructor.
		/// True if it has a parameterless constructor, otherwise false.
		/// </summary>
		/// <param name="type">The type.</param>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static bool HasParameterlessConstructor(this Type type)
		{
			return type.GetConstructor(new Type[0]) != null;
		}

		/// <summary>
		/// Gets a value indicating if the given type has any constructors.
		/// </summary>
		/// <param name="type">The type.</param>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static bool HasConstructor(this Type type)
		{
			return type.GetConstructors().Length > 0;
		}

		/// <summary>
		/// Gets the constructor that contains the most parameters.
		/// </summary>
		/// <param name="type">The type.</param>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static ConstructorInfo GetConstructorWithMostParameters(this Type type)
		{
			return type.GetConstructors()
				.OrderByDescending(c => c.GetParameters().Length)
				.First();
		}

		/// <summary>
		/// Gets a value indicating if the type is a user defined struct.
		/// True if it is a user defined struct, otherwise false.
		/// </summary>
		/// <param name="type">The type.</param>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static bool IsUserDefinedStruct(this Type type)
		{
			return type.IsValueType && !type.IsPrimitive && !type.IsEnum;
		}

		/// <summary>
		/// Gets a string representation of the constructor.
		/// </summary>
		/// <param name="constructor">The constructor.</param>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static string GetDefinition(this ConstructorInfo constructor)
		{
			var parameters = constructor.GetParameters();
			var definition = $"{constructor.Name}({string.Join(", ", parameters.Select(p => p.GetDefinition()))})";

			return definition;
		}

		/// <summary>
		/// Gets a string representation of the parameter.
		/// </summary>
		/// <param name="parameter">The parameter.</param>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static string GetDefinition(this ParameterInfo parameter)
		{
			return $"{parameter.ParameterType.Name} {parameter.Name}";
		}
	}
}