using System;
using System.Collections.Generic;
using System.Linq;
using Mono.CecilX;

namespace Mirror.Weaver
{
    public static class Extensions
    {
        public static bool Is(this TypeReference td, Type t)
        {
            if (t.IsGenericType)
            {
                return td.GetElementType().FullName == t.FullName;
            }
            return td.FullName == t.FullName;
        }

        public static bool Is<T>(this TypeReference td) => Is(td, typeof(T));

        public static bool IsDerivedFrom<T>(this TypeDefinition td) => IsDerivedFrom(td, typeof(T));

        public static bool IsDerivedFrom(this TypeDefinition td, Type baseClass)
        {

            if (!td.IsClass)
                return false;

            // are ANY parent classes of baseClass?
            TypeReference parent = td.BaseType;

            if (parent == null)
                return false;

            if (parent.Is(baseClass))
                return true;

            if (parent.CanBeResolved())
                return IsDerivedFrom(parent.Resolve(), baseClass);

            return false;
        }

        public static TypeReference GetEnumUnderlyingType(this TypeDefinition td)
        {
            foreach (FieldDefinition field in td.Fields)
            {
                if (!field.IsStatic)
                    return field.FieldType;
            }
            throw new ArgumentException($"Invalid enum {td.FullName}");
        }

        public static bool ImplementsInterface<TInterface>(this TypeDefinition td)
        {
            TypeDefinition typedef = td;

            while (typedef != null)
            {
                foreach (InterfaceImplementation iface in typedef.Interfaces)
                {
                    if (iface.InterfaceType.Is<TInterface>())
                        return true;
                }

                try
                {
                    TypeReference parent = typedef.BaseType;
                    typedef = parent?.Resolve();
                }
                catch (AssemblyResolutionException)
                {
                    // this can happen for pluins.
                    //Console.WriteLine("AssemblyResolutionException: "+ ex.ToString());
                    break;
                }
            }

            return false;
        }

        public static bool IsMultidimensionalArray(this TypeReference tr)
        {
            return tr is ArrayType arrayType && arrayType.Rank > 1;
        }

        public static bool CanBeResolved(this TypeReference parent)
        {
            while (parent != null)
            {
                if (parent.Scope.Name == "Windows")
                {
                    return false;
                }

                if (parent.Scope.Name == "mscorlib")
                {
                    TypeDefinition resolved = parent.Resolve();
                    return resolved != null;
                }

                try
                {
                    parent = parent.Resolve().BaseType;
                }
                catch
                {
                    return false;
                }
            }
            return true;
        }


        /// <summary>
        /// Given a method of a generic class such as ArraySegment`T.get_Count,
        /// and a generic instance such as ArraySegment`int
        /// Creates a reference to the specialized method  ArraySegment`int`.get_Count
        /// <para> Note that calling ArraySegment`T.get_Count directly gives an invalid IL error </para>
        /// </summary>
        /// <param name="self"></param>
        /// <param name="instanceType"></param>
        /// <returns></returns>
        public static MethodReference MakeHostInstanceGeneric(this MethodReference self, GenericInstanceType instanceType)
        {
            MethodReference reference = new MethodReference(self.Name, self.ReturnType, instanceType)
            {
                CallingConvention = self.CallingConvention,
                HasThis = self.HasThis,
                ExplicitThis = self.ExplicitThis
            };

            foreach (ParameterDefinition parameter in self.Parameters)
                reference.Parameters.Add(new ParameterDefinition(parameter.ParameterType));

            foreach (GenericParameter generic_parameter in self.GenericParameters)
                reference.GenericParameters.Add(new GenericParameter(generic_parameter.Name, reference));

            return Weaver.CurrentAssembly.MainModule.ImportReference(reference);
        }

        /// <summary>
        /// Given a field of a generic class such as Writer<T>.write,
        /// and a generic instance such as ArraySegment`int
        /// Creates a reference to the specialized method  ArraySegment`int`.get_Count
        /// <para> Note that calling ArraySegment`T.get_Count directly gives an invalid IL error </para>
        /// </summary>
        /// <param name="self"></param>
        /// <param name="instanceType">Generic Instance eg Writer<int></param>
        /// <returns></returns>
        public static FieldReference SpecializeField(this FieldReference self, GenericInstanceType instanceType)
        {
            FieldReference reference = new FieldReference(self.Name, self.FieldType, instanceType);

            return Weaver.CurrentAssembly.MainModule.ImportReference(reference);
        }

        public static CustomAttribute GetCustomAttribute<TAttribute>(this ICustomAttributeProvider method)
        {
            foreach (CustomAttribute ca in method.CustomAttributes)
            {
                if (ca.AttributeType.Is<TAttribute>())
                    return ca;
            }
            return null;
        }

        public static bool HasCustomAttribute<TAttribute>(this ICustomAttributeProvider attributeProvider)
        {
            // Linq allocations don't matter in weaver
            return attributeProvider.CustomAttributes.Any(attr => attr.AttributeType.Is<TAttribute>());
        }

        public static T GetField<T>(this CustomAttribute ca, string field, T defaultValue)
        {
            foreach (CustomAttributeNamedArgument customField in ca.Fields)
            {
                if (customField.Name == field)
                {
                    return (T)customField.Argument.Value;
                }
            }

            return defaultValue;
        }

        public static MethodDefinition GetMethod(this TypeDefinition td, string methodName)
        {
            // Linq allocations don't matter in weaver
            return td.Methods.FirstOrDefault(method => method.Name == methodName);
        }

        public static List<MethodDefinition> GetMethods(this TypeDefinition td, string methodName)
        {
            // Linq allocations don't matter in weaver
            return td.Methods.Where(method => method.Name == methodName).ToList();
        }

        public static MethodDefinition GetMethodInBaseType(this TypeDefinition td, string methodName)
        {
            TypeDefinition typedef = td;
            while (typedef != null)
            {
                foreach (MethodDefinition md in typedef.Methods)
                {
                    if (md.Name == methodName)
                        return md;
                }

                try
                {
                    TypeReference parent = typedef.BaseType;
                    typedef = parent?.Resolve();
                }
                catch (AssemblyResolutionException)
                {
                    // this can happen for plugins.
                    break;
                }
            }

            return null;
        }

        /// <summary>
        /// Finds public fields in type and base type
        /// </summary>
        /// <param name="variable"></param>
        /// <returns></returns>
        public static IEnumerable<FieldDefinition> FindAllPublicFields(this TypeReference variable)
        {
            return FindAllPublicFields(variable.Resolve());
        }

        /// <summary>
        /// Finds public fields in type and base type
        /// </summary>
        /// <param name="variable"></param>
        /// <returns></returns>
        public static IEnumerable<FieldDefinition> FindAllPublicFields(this TypeDefinition typeDefinition)
        {
            while (typeDefinition != null)
            {
                foreach (FieldDefinition field in typeDefinition.Fields)
                {
                    if (field.IsStatic || field.IsPrivate)
                        continue;

                    if (field.IsNotSerialized)
                        continue;

                    yield return field;
                }

                try
                {
                    typeDefinition = typeDefinition.BaseType?.Resolve();
                }
                catch (AssemblyResolutionException)
                {
                    break;
                }
            }
        }
    }
}