using System;
using System.Collections;
using System.Collections.Generic;
using UnityFusion.CLR.Method;
using UnityFusion.Runtime.Enviorment;
using UnityFusion.Runtime.Intepreter;

namespace UnityFusion.CLRBinding.Adapter
{
    /// <summary>
    /// Adapter for serializing and managing coroutines across the domain boundary.
    /// Supports <see cref="IEnumerator"/> and <see cref="IDisposable"/>.
    /// </summary>
    public class CoroutineAdapter : CrossBindingAdaptor
    {
        public override Type BaseCLRType => null;

        public override Type[] BaseCLRTypes => new Type[] { typeof(IEnumerator<object>), typeof(IEnumerator), typeof(IDisposable) };

        public override Type AdaptorType => typeof(CoroutineAdaptor);

        public override object CreateCLRInstance(UnityFusion.Runtime.Enviorment.AppDomain appdomain, ILTypeInstance instance)
        {
            return new CoroutineAdaptor(appdomain, instance);
        }
        //Coroutine生成的类实现了IEnumerator<System.Object>, IEnumerator, IDisposable,所以都要实现，这个可以通过reflector之类的IL反编译软件得知
        /// <summary>
        /// Internal implementation of the coroutine adapter.
        /// Coroutine generated classes implement <see cref="IEnumerator{object}"/>, <see cref="IEnumerator"/>, and <see cref="IDisposable"/>.
        /// </summary>
        public class CoroutineAdaptor : IEnumerator<System.Object>, IEnumerator, IDisposable, CrossBindingAdaptorType
        {
            ILTypeInstance instance;
            UnityFusion.Runtime.Enviorment.AppDomain appdomain;

            public CoroutineAdaptor()
            {

            }

            public CoroutineAdaptor(UnityFusion.Runtime.Enviorment.AppDomain appdomain, ILTypeInstance instance)
            {
                this.appdomain = appdomain;
                this.instance = instance;
            }

            public ILTypeInstance ILInstance { get { return instance; } }

            IMethod mCurrentMethod;
            bool mCurrentMethodGot;
            public object Current
            {
                get
                {
                    if (!mCurrentMethodGot)
                    {
                        mCurrentMethod = instance.Type.GetMethod("get_Current", 0);
                        if (mCurrentMethod == null)
                        {
                            //这里写System.Collections.IEnumerator.get_Current而不是直接get_Current是因为coroutine生成的类是显式实现这个接口的，通过Reflector等反编译软件可得知
                            //为了兼容其他只实现了单一Current属性的，所以上面先直接取了get_Current
                            mCurrentMethod = instance.Type.GetMethod("System.Collections.IEnumerator.get_Current", 0);
                        }
                        mCurrentMethodGot = true;
                    }

                    if (mCurrentMethod != null)
                    {
                        var res = appdomain.Invoke(mCurrentMethod, instance, null);
                        return res;
                    }
                    else
                    {
                        return null;
                    }
                }
            }

            IMethod mDisposeMethod;
            bool mDisposeMethodGot;
            public void Dispose()
            {
                if (!mDisposeMethodGot)
                {
                    mDisposeMethod = instance.Type.GetMethod("Dispose", 0);
                    if (mDisposeMethod == null)
                    {
                        mDisposeMethod = instance.Type.GetMethod("System.IDisposable.Dispose", 0);
                    }
                    mDisposeMethodGot = true;
                }

                if (mDisposeMethod != null)
                {
                    appdomain.Invoke(mDisposeMethod, instance, null);
                }
            }

            IMethod mMoveNextMethod;
            bool mMoveNextMethodGot;
            public bool MoveNext()
            {
                if (!mMoveNextMethodGot)
                {
                    mMoveNextMethod = instance.Type.GetMethod("MoveNext", 0);
                    mMoveNextMethodGot = true;
                }

                if (mMoveNextMethod != null)
                {
                    return (bool)appdomain.Invoke(mMoveNextMethod, instance, null);
                }
                else
                {
                    return false;
                }
            }

            IMethod mResetMethod;
            bool mResetMethodGot;
            public void Reset()
            {
                if (!mResetMethodGot)
                {
                    mResetMethod = instance.Type.GetMethod("Reset", 0);
                    mResetMethodGot = true;
                }

                if (mResetMethod != null)
                {
                    appdomain.Invoke(mResetMethod, instance, null);
                }
            }

            public override string ToString()
            {
                IMethod m = appdomain.ObjectType.GetMethod("ToString", 0);
                m = instance.Type.GetVirtualMethod(m);
                if (m == null || m is ILMethod)
                {
                    return instance.ToString();
                }
                else
                    return instance.Type.FullName;
            }
        }
    }
}