#region License
// Copyright (c) 2007 James Newton-King
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
#endregion

#if HAVE_FSHARP_TYPES
using System.Threading;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using LC.Newtonsoft.Json.Serialization;
using System.Diagnostics;

namespace LC.Newtonsoft.Json.Utilities
{
    internal class FSharpFunction
    {
        private readonly object? _instance;
        private readonly MethodCall<object?, object> _invoker;

        public FSharpFunction(object? instance, MethodCall<object?, object> invoker)
        {
            _instance = instance;
            _invoker = invoker;
        }

        public object Invoke(params object[] args)
        {
            object o = _invoker(_instance, args);

            return o;
        }
    }

    internal class FSharpUtils
    {
        private FSharpUtils(Assembly fsharpCoreAssembly)
        {
            FSharpCoreAssembly = fsharpCoreAssembly;

            Type fsharpType = fsharpCoreAssembly.GetType("Microsoft.FSharp.Reflection.FSharpType");

            MethodInfo isUnionMethodInfo = GetMethodWithNonPublicFallback(fsharpType, "IsUnion", BindingFlags.Public | BindingFlags.Static);
            IsUnion = JsonTypeReflector.ReflectionDelegateFactory.CreateMethodCall<object?>(isUnionMethodInfo)!;

            MethodInfo getUnionCasesMethodInfo = GetMethodWithNonPublicFallback(fsharpType, "GetUnionCases", BindingFlags.Public | BindingFlags.Static);
            GetUnionCases = JsonTypeReflector.ReflectionDelegateFactory.CreateMethodCall<object?>(getUnionCasesMethodInfo)!;

            Type fsharpValue = fsharpCoreAssembly.GetType("Microsoft.FSharp.Reflection.FSharpValue");

            PreComputeUnionTagReader = CreateFSharpFuncCall(fsharpValue, "PreComputeUnionTagReader");
            PreComputeUnionReader = CreateFSharpFuncCall(fsharpValue, "PreComputeUnionReader");
            PreComputeUnionConstructor = CreateFSharpFuncCall(fsharpValue, "PreComputeUnionConstructor");

            Type unionCaseInfo = fsharpCoreAssembly.GetType("Microsoft.FSharp.Reflection.UnionCaseInfo");

            GetUnionCaseInfoName = JsonTypeReflector.ReflectionDelegateFactory.CreateGet<object>(unionCaseInfo.GetProperty("Name")!)!;
            GetUnionCaseInfoTag = JsonTypeReflector.ReflectionDelegateFactory.CreateGet<object>(unionCaseInfo.GetProperty("Tag")!)!;
            GetUnionCaseInfoDeclaringType = JsonTypeReflector.ReflectionDelegateFactory.CreateGet<object>(unionCaseInfo.GetProperty("DeclaringType")!)!;
            GetUnionCaseInfoFields = JsonTypeReflector.ReflectionDelegateFactory.CreateMethodCall<object>(unionCaseInfo.GetMethod("GetFields"));

            Type listModule = fsharpCoreAssembly.GetType("Microsoft.FSharp.Collections.ListModule");
            _ofSeq = listModule.GetMethod("OfSeq");

            _mapType = fsharpCoreAssembly.GetType("Microsoft.FSharp.Collections.FSharpMap`2");
        }

        private static readonly object Lock = new object();
        private static FSharpUtils? _instance;

        public static FSharpUtils Instance
        {
            get
            {
                MiscellaneousUtils.Assert(_instance != null);
                return _instance;
            }
        }

        private MethodInfo _ofSeq;
        private Type _mapType;

        public Assembly FSharpCoreAssembly { get; private set; }
        public MethodCall<object?, object> IsUnion { get; private set; }
        public MethodCall<object?, object> GetUnionCases { get; private set; }
        public MethodCall<object?, object> PreComputeUnionTagReader { get; private set; }
        public MethodCall<object?, object> PreComputeUnionReader { get; private set; }
        public MethodCall<object?, object> PreComputeUnionConstructor { get; private set; }
        public Func<object, object> GetUnionCaseInfoDeclaringType { get; private set; }
        public Func<object, object> GetUnionCaseInfoName { get; private set; }
        public Func<object, object> GetUnionCaseInfoTag { get; private set; }
        public MethodCall<object, object?> GetUnionCaseInfoFields { get; private set; }

        public const string FSharpSetTypeName = "FSharpSet`1";
        public const string FSharpListTypeName = "FSharpList`1";
        public const string FSharpMapTypeName = "FSharpMap`2";

        public static void EnsureInitialized(Assembly fsharpCoreAssembly)
        {
            if (_instance == null)
            {
                lock (Lock)
                {
                    if (_instance == null)
                    {
                        _instance = new FSharpUtils(fsharpCoreAssembly);
                    }
                }
            }
        }

        private static MethodInfo GetMethodWithNonPublicFallback(Type type, string methodName, BindingFlags bindingFlags)
        {
            MethodInfo methodInfo = type.GetMethod(methodName, bindingFlags);

            // if no matching method then attempt to find with nonpublic flag
            // this is required because in WinApps some methods are private but always using NonPublic breaks medium trust
            // https://github.com/JamesNK/Newtonsoft.Json/pull/649
            // https://github.com/JamesNK/Newtonsoft.Json/issues/821
            if (methodInfo == null && (bindingFlags & BindingFlags.NonPublic) != BindingFlags.NonPublic)
            {
                methodInfo = type.GetMethod(methodName, bindingFlags | BindingFlags.NonPublic);
            }

            return methodInfo!;
        }

        private static MethodCall<object?, object> CreateFSharpFuncCall(Type type, string methodName)
        {
            MethodInfo innerMethodInfo = GetMethodWithNonPublicFallback(type, methodName, BindingFlags.Public | BindingFlags.Static);
            MethodInfo invokeFunc = innerMethodInfo.ReturnType.GetMethod("Invoke", BindingFlags.Public | BindingFlags.Instance);

            MethodCall<object?, object?> call = JsonTypeReflector.ReflectionDelegateFactory.CreateMethodCall<object?>(innerMethodInfo);
            MethodCall<object?, object> invoke = JsonTypeReflector.ReflectionDelegateFactory.CreateMethodCall<object?>(invokeFunc)!;

            MethodCall<object?, object> createFunction = (target, args) =>
            {
                object? result = call(target, args);

                FSharpFunction f = new FSharpFunction(result, invoke);
                return f;
            };

            return createFunction;
        }

        public ObjectConstructor<object> CreateSeq(Type t)
        {
            MethodInfo seqType = _ofSeq.MakeGenericMethod(t);

            return JsonTypeReflector.ReflectionDelegateFactory.CreateParameterizedConstructor(seqType);
        }

        public ObjectConstructor<object> CreateMap(Type keyType, Type valueType)
        {
            MethodInfo creatorDefinition = typeof(FSharpUtils).GetMethod("BuildMapCreator");

            MethodInfo creatorGeneric = creatorDefinition.MakeGenericMethod(keyType, valueType);

            return (ObjectConstructor<object>)creatorGeneric.Invoke(this, null);
        }

        public ObjectConstructor<object> BuildMapCreator<TKey, TValue>()
        {
            Type genericMapType = _mapType.MakeGenericType(typeof(TKey), typeof(TValue));
            ConstructorInfo ctor = genericMapType.GetConstructor(new[] { typeof(IEnumerable<Tuple<TKey, TValue>>) });
            ObjectConstructor<object> ctorDelegate = JsonTypeReflector.ReflectionDelegateFactory.CreateParameterizedConstructor(ctor);

            ObjectConstructor<object> creator = args =>
            {
                // convert dictionary KeyValuePairs to Tuples
                IEnumerable<KeyValuePair<TKey, TValue>> values = (IEnumerable<KeyValuePair<TKey, TValue>>)args[0]!;
                IEnumerable<Tuple<TKey, TValue>> tupleValues = values.Select(kv => new Tuple<TKey, TValue>(kv.Key, kv.Value));

                return ctorDelegate(tupleValues);
            };

            return creator;
        }
    }
}

#endif