using System;
using System.Collections.Generic;
using System.Linq;
using SharpGen.CppModel;
using SharpGen.Transform;

namespace SharpGen.Model
{
    public abstract class CsCallable : CsBase, IExpiring
    {
        private CsBaseItemListCache<CsParameter> _parameters;
        private Dictionary<PlatformDetectionType, InteropMethodSignature> interopSignatures;
        protected readonly Ioc Ioc;

        protected abstract int MaxSizeReturnParameter { get; }

        protected CsCallable(Ioc ioc, CppCallable callable, string name) : base(callable, name)
        {
            Ioc = ioc ?? throw new ArgumentNullException(nameof(ioc));

            if (callable == null)
                return;

            var tag = callable.Rule;
            CheckReturnType = tag.MethodCheckReturnType ?? CheckReturnType;
            ForceReturnType = tag.ParameterUsedAsReturnType ?? ForceReturnType;
            AlwaysReturnHResult = tag.AlwaysReturnHResult ?? AlwaysReturnHResult;
            RequestRawPtr = tag.RawPtr ?? RequestRawPtr;

            CppSignature = callable.ToString();
            ShortName = callable.ToShortString();
            CppCallingConvention = callable.CallingConvention;
        }

        public CppCallingConvention CppCallingConvention { get; } = CppCallingConvention.Unknown;
        public bool RequestRawPtr { get; }
        private string CppSignature { get; }
        private string ShortName { get; }
        public bool CheckReturnType { get; }
        public bool ForceReturnType { get; }
        private bool AlwaysReturnHResult { get; }
        public CsReturnValue ReturnValue { get; set; }
        public bool SignatureOnly => GetParent<CsInterface>()?.IsCallback ?? false;
        public override string DocUnmanagedName => CppSignature ?? "Unknown";
        public override string DocUnmanagedShortName => ShortName;

        public IReadOnlyList<CsParameter> Parameters => _parameters.GetList(this);

        public IEnumerable<CsParameter> PublicParameters => _parameters.Enumerate(this)
           .Where(param => !param.UsedAsReturn && param.Relations.Count == 0);

        public IEnumerable<CsParameter> InRefInRefParameters => _parameters.Enumerate(this)
           .Where(param => !param.IsOut);

        public IEnumerable<CsParameter> LocalManagedReferenceParameters => _parameters.Enumerate(this)
           .Where(param => param.IsLocalManagedReference);

        public CsMarshalCallableBase ActualReturnValue
        {
            get
            {
                foreach (var param in _parameters.Enumerate(this).Where(param => param.UsedAsReturn))
                {
                    return param;
                }

                return ReturnValue;
            }
        }

        public override void FillDocItems(IList<string> docItems, IDocumentationLinker manager)
        {
            foreach (var param in PublicParameters)
                docItems.Add("<param name=\"" + param.Name + "\">" + manager.GetSingleDoc(param) + "</param>");

            if (HasReturnType)
                docItems.Add("<returns>" + manager.GetSingleDoc(ActualReturnValue) + "</returns>");
        }

        public bool IsReturnStructLarge
        {
            get
            {
                // Workaround for https://github.com/dotnet/coreclr/issues/19474. This workaround is sufficient
                // for DirectX on Windows x86 and x64. It may produce incorrect code on other platforms depending
                // on the calling convention details.
                if (ReturnValue.MarshalType is CsStruct csStruct)
                {
                    return !csStruct.IsNativePrimitive && csStruct.Size > MaxSizeReturnParameter;
                }

                return false;
            }
        }

        public Dictionary<PlatformDetectionType, InteropMethodSignature> InteropSignatures
        {
            get => interopSignatures ?? throw new InvalidOperationException($"Accessing non-initialized {nameof(InteropSignatures)}");
            set
            {
                if (interopSignatures != null)
                    throw new InvalidOperationException($"Setting initialized {nameof(InteropSignatures)}");

                interopSignatures = value;
            }
        }

        // Hide return type only if it is a HRESULT and AlwaysReturnHResult is false
        public bool IsReturnTypeHidden => CheckReturnType && IsReturnTypeResult && !AlwaysReturnHResult;
        public bool IsReturnTypeResult => ReturnValue.PublicType.IsWellKnownType(Ioc.GlobalNamespace, WellKnownName.Result);
        public bool HasReturnType => ReturnValue.PublicType != TypeRegistry.Void;
        internal bool HasReturnStatement => HasReturnTypeParameter || HasReturnTypeValue;
        internal bool HasReturnTypeValue => HasReturnType && (ForceReturnType || !IsReturnTypeHidden);

        /// <summary>
        /// Returns true if a parameter is marked to be used as the return type.
        /// </summary>
        public bool HasReturnTypeParameter => _parameters.Enumerate(this).Any(param => param.UsedAsReturn);

        /// <summary>
        /// Return the Public return type. If a out parameter is used as a public return type
        /// then use the type of the out parameter for the public API.
        /// </summary>
        public string PublicReturnTypeQualifiedName
        {
            get
            {
                var returnValue = ActualReturnValue;
                if (returnValue is CsParameter)
                    return returnValue.PublicType.QualifiedName;

                if (IsReturnTypeHidden && !ForceReturnType)
                    return "void";

                return returnValue.PublicType.QualifiedName;
            }
        }

        /// <summary>
        /// Return the name of the variable used to return the value
        /// </summary>
        public string ReturnName => ActualReturnValue.Name;

        private protected override IEnumerable<IExpiring> ExpiringOnItemsChange
        {
            get
            {
                yield return _parameters.Expiring;
                yield return this;
            }
        }

        public virtual CsCallable Clone()
        {
            var method = (CsCallable) MemberwiseClone();

            // Clear cached parameters
            method.Expire();
            method.ResetItems();
            foreach (var parameter in Parameters)
                method.Add(parameter.Clone());
            method.ResetParentAfterClone();
            return method;
        }

        public void Expire()
        {
            interopSignatures = null;
        }

        public override IEnumerable<CsBase> AdditionalItems => AppendNonNull(base.AdditionalItems, ReturnValue);
    }
}