NamedMethodCall.cs

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Threading.Tasks;
using System.Xml.Linq;
using Waher.Runtime.Collections;
using Waher.Runtime.Inventory;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
using Waher.Script.Objects;
using Waher.Script.Operators.Vectors;
 
namespace Waher.Script.Operators.Membership
{
    public class NamedMethodCall : NullCheckUnaryOperator
    {
        private readonly string name;
        private readonly ScriptNode[] parameters;
        private readonly int nrParameters;
 
        public NamedMethodCall(ScriptNode Operand, string Name, ScriptNode[] Parameters, bool NullCheck,
            int Start, int Length, Expression Expression)
            : base(Operand, NullCheck, Start, Length, Expression)
        {
            this.name = Name;
 
            this.parameters = Parameters;
            this.parameters?.SetParent(this);
 
            this.nrParameters = Parameters.Length;
            this.isAsync = true;
        }
 
        public string Name => this.name;
 
        public ScriptNode[] Parameters => this.parameters;
 
        public override bool IsAsynchronous => true;
 
        public override IElement Evaluate(IElement Operand, Variables Variables)
        {
            return this.EvaluateAsync(Operand, Variables).Result;
        }
 
        public override async Task<IElement> EvaluateAsync(IElement Operand, Variables Variables)
        {
            object Object = Operand.AssociatedObjectValue;
            Type T;
            IElement[] Arguments;
            object Instance;
            int i;
 
            if (Object is null && this.nullCheck)
                return ObjectValue.Null;
 
            T = Object as Type;
            if (T is null)
            {
                T = Object?.GetType() ?? typeof(object);
                Instance = Object;
            }
            else
                Instance = null;
 
            Arguments = new IElement[this.nrParameters];
            for (i = 0; i < this.nrParameters; i++)
                Arguments[i] = await this.parameters[i].EvaluateAsync(Variables);
 
            IElement Result = await this.EvaluateAsync(T, Instance, Arguments, Variables);
 
            if (Result is null)
            {
                if (Operand.IsScalar)
                    throw new ScriptRuntimeException("Invalid number or type of parameters.", this);
 
                ChunkedList<IElement> Elements = new ChunkedList<IElement>();
 
                foreach (IElement Item in Operand.ChildElements)
                    Elements.Add(await this.EvaluateAsync(Item, Variables));
 
                return Operand.Encapsulate(Elements, this);
            }
 
            return Result;
        }
 
        public async Task<IElement> EvaluateAsync(Type T, object Instance, IElement[] Arguments, Variables Variables)
        {
            Type PT;
            object[] ParameterValues;
            bool[] Extend;
            object Value;
            bool DoExtend = false;
            int i;
 
            lock (this.synchObject)
            {
                if (this.lastType != T)
                {
                    this.method = null;
                    this.methodType = MethodType.Method;
                    this.methods = null;
                    this.byReference = null;
                    this.lastType = T;
                }
 
                if (!(this.method is null) && this.methodType == MethodType.Method)
                {
                    if (this.methodParametersTypes.Length != this.nrParameters)
                    {
                        this.method = null;
                        this.methodType = MethodType.Method;
                        this.methods = null;
                        this.byReference = null;
                    }
                    else
                    {
                        for (i = 0; i < this.methodParametersTypes.Length; i++)
                        {
                            PT = this.methodParametersTypes[i].ParameterType;
 
                            if (PT.IsByRef && Arguments[i].TryConvertTo(PT.GetElementType(), out Value))
                            {
                                this.methodArgumentExtensions[i] = false;
                                this.methodArguments[i] = Value;
                            }
                            else if (Arguments[i].TryConvertTo(PT, out Value))
                            {
                                this.methodArgumentExtensions[i] = false;
                                this.methodArguments[i] = Value;
                            }
                            else
                            {
                                if (Arguments[i].IsScalar || Variables is null)
                                    break;
 
                                this.methodArgumentExtensions[i] = true;
                                this.methodArguments[i] = null;
                                DoExtend = true;
                            }
                        }
 
                        if (i < this.methodParametersTypes.Length)
                        {
                            this.method = null;
                            this.methodType = MethodType.Method;
                            this.methods = null;
                            this.byReference = null;
                        }
                    }
                }
 
                if (this.method is null)
                {
                    if (this.methods is null)
                        this.methods = this.GetMethods(T);
 
                    ChunkedList<KeyValuePair<string, int>> ByRef = null;
                    ParameterValues = null;
                    Extend = null;
 
                    foreach (MethodRec Rec in this.methods)
                    {
                        DoExtend = false;
 
                        if (Instance is null)
                        {
                            if (!Rec.Method.IsStatic)
                                continue;
                        }
                        else
                        {
                            if (Rec.Method.IsStatic)
                                continue;
                        }
 
                        if (Rec.MethodType == MethodType.Method)
                        {
                            for (i = 0; i < this.nrParameters; i++)
                            {
                                PT = Rec.Parameters[i].ParameterType;
                                IElement Argument = Arguments[i];
 
                                if (PT.IsByRef && ((Value = Argument.AssociatedObjectValue) is null ||
                                    Argument.TryConvertTo(PT.GetElementType(), out Value)))
                                {
                                    if (ParameterValues is null)
                                    {
                                        Extend = new bool[this.nrParameters];
                                        ParameterValues = new object[this.nrParameters];
                                    }
 
                                    Extend[i] = false;
                                    ParameterValues[i] = Value;
 
                                    if (ByRef is null)
                                        ByRef = new ChunkedList<KeyValuePair<string, int>>();
 
                                    if (this.parameters[i] is VariableReference Ref)
                                        ByRef.Add(new KeyValuePair<string, int>(Ref.VariableName, i));
                                    else
                                        ByRef.Add(new KeyValuePair<string, int>(null, i));
                                }
                                else if (Argument.TryConvertTo(PT, out Value))
                                {
                                    if (ParameterValues is null)
                                    {
                                        Extend = new bool[this.nrParameters];
                                        ParameterValues = new object[this.nrParameters];
                                    }
 
                                    Extend[i] = false;
                                    ParameterValues[i] = Value;
                                }
                                else
                                {
                                    if (Argument.IsScalar || Variables is null)
                                        break;
 
                                    if (Extend is null)
                                    {
                                        Extend = new bool[this.nrParameters];
                                        ParameterValues = new object[this.nrParameters];
                                    }
 
                                    Extend[i] = true;
                                    ParameterValues[i] = null;
                                    DoExtend = true;
                                }
                            }
 
                            if (i < this.nrParameters)
                            {
                                ByRef?.Clear();
                                continue;
                            }
                        }
 
                        this.method = Rec.Method;
                        this.methodType = Rec.MethodType;
                        this.methodParametersTypes = Rec.Parameters;
                        this.methodArguments = ParameterValues;
                        this.methodArgumentExtensions = Extend;
 
                        if (!(ByRef is null) && ByRef.Count > 0)
                            this.byReference = ByRef.ToArray();
                        else
                            this.byReference = null;
 
                        break;
                    }
 
                    if (this.method is null)
                        return null;
                }
            }
 
            if (DoExtend)
            {
                if (!(this.byReference is null))
                    throw new ScriptException("Canonical extensions of method calls having reference type arguments not supported.");   // TODO
 
                return await this.EvaluateCanonicalAsync(Instance, this.method, this.methodType, this.methodParametersTypes, 
                    Arguments, this.methodArguments, this.methodArgumentExtensions, Variables);
            }
            else
            {
                Value = await this.EvaluateAsync(Instance, this.method, this.methodType, Arguments, this.methodArguments, Variables);
                return Expression.Encapsulate(Value);
            }
        }
 
        private async Task<IElement> EvaluateAsync(object Instance, MethodInfo Method, MethodType MethodType,
            IElement[] Arguments, object[] ArgumentValues, Variables Variables)
        {
            object Value;
 
            switch (MethodType)
            {
                case MethodType.Method:
                default:
                    Value = Method.Invoke(Instance, ArgumentValues);
                    Value = await WaitPossibleTask(Value);
 
                    if (!(this.byReference is null))
                    {
                        int i, j, c = this.byReference.Length;
                        string s;
 
                        for (i = 0; i < c; i++)
                        {
                            j = this.byReference[i].Value;
                            if (string.IsNullOrEmpty(s = this.byReference[i].Key))
                                Operators.PatternMatch.Match(this.parameters[j], Expression.Encapsulate(this.methodArguments[j]), Variables, this);
                            else
                                Variables[s] = this.methodArguments[j];
                        }
                    }
 
                    break;
 
                case MethodType.LambdaProperty:
                    Value = Method.Invoke(Instance, Types.NoParameters);
                    Value = await WaitPossibleTask(Value);
 
                    if (!(Value is ILambdaExpression LambdaExpression))
                        throw new ScriptRuntimeException("Lambda expression property expected.", this);
 
                    Value = await LambdaExpression.EvaluateAsync(Arguments, Variables);
                    break;
 
                case MethodType.LambdaIndexProperty:
                    object[] Index;
 
                    if (this.methodParametersTypes[0].ParameterType == typeof(string))
                        Index = new object[] { this.name };
                    else
                        Index = new object[] { Expression.ConvertTo(this.name, this.methodParametersTypes[0].ParameterType, this) };
 
                    Value = Method.Invoke(Instance, Index);
 
                    Value = await WaitPossibleTask(Value);
 
                    LambdaExpression = Value as ILambdaExpression;
                    if (LambdaExpression is null)
                        throw new ScriptRuntimeException("Lambda expression property expected.", this);
 
                    Value = await LambdaExpression.EvaluateAsync(Arguments, Variables);
                    break;
            }
 
            return Expression.Encapsulate(Value);
        }
 
        private async Task<IElement> EvaluateCanonicalAsync(object Object, MethodInfo Method, MethodType MethodType,
            ParameterInfo[] ParametersTypes, IElement[] Arguments, object[] ArgumentValues, bool[] Extend, Variables Variables)
        {
            IEnumerator<IElement>[] Enumerators = null;
            ICollection<IElement> Children;
            IEnumerator<IElement> e;
            IElement First = null;
            int i, c = 0;
 
            for (i = 0; i < this.nrParameters; i++)
            {
                if (Extend[i])
                {
                    if (Arguments[i].IsScalar)
                    {
                        if (!Arguments[i].TryConvertTo(ParametersTypes[i].ParameterType, out ArgumentValues[i]))
                            throw new ScriptRuntimeException("Inconsistent argument types.", this);
                    }
                    else
                    {
                        Children = Arguments[i].ChildElements;
                        if (First is null)
                        {
                            Enumerators = new IEnumerator<IElement>[this.nrParameters];
                            First = Arguments[i];
                            c = Children.Count;
                        }
                        else if (c != Children.Count)
                            throw new ScriptRuntimeException("Incompatible dimensions.", this);
 
                        Enumerators[i] = Children.GetEnumerator();
                    }
                }
            }
 
            if (First is null)
            {
                object Value = await this.EvaluateAsync(Object, Method, MethodType, Arguments, ArgumentValues, Variables);
                return Expression.Encapsulate(Value);
            }
 
            ChunkedList<IElement> Elements = new ChunkedList<IElement>();
            Arguments = (IElement[])Arguments.Clone();
 
            while (true)
            {
                for (i = 0; i < this.nrParameters; i++)
                {
                    if (!Extend[i])
                        continue;
 
                    if (!(e = Enumerators[i]).MoveNext())
                        break;
 
                    Arguments[i] = e.Current;
                }
 
                if (i < this.nrParameters)
                    break;
 
                Elements.Add(await this.EvaluateCanonicalAsync(Object, Method, MethodType, ParametersTypes, Arguments, 
                    ArgumentValues, Extend, Variables));
            }
 
            for (i = 0; i < this.nrParameters; i++)
            {
                if (Extend[i])
                    Enumerators[i].Dispose();
            }
 
            return First.Encapsulate(Elements, this);
        }
 
        private MethodRec[] GetMethods(Type Type)
        {
            ChunkedList<MethodRec> Result = new ChunkedList<MethodRec>();
            ParameterInfo[] ParameterInfo;
            IEnumerable<MethodInfo> Methods = Type.GetRuntimeMethods();
 
            foreach (MethodInfo MI in Methods)
            {
                if (MI.IsAbstract || !MI.IsPublic || MI.Name != this.name)
                    continue;
 
                ParameterInfo = MI.GetParameters();
                if (ParameterInfo.Length != this.nrParameters)
                    continue;
 
                Result.Add(new MethodRec()
                {
                    Method = MI,
                    Parameters = ParameterInfo,
                    MethodType = MethodType.Method
                });
            }
 
            if (Result.Count == 0)
            {
                PropertyInfo PI = Type.GetRuntimeProperty(this.name);
                if (!(PI is null) && PI.GetIndexParameters().Length == 0)
                {
                    if (!PI.CanRead)
                        throw new ScriptRuntimeException("Property cannot be read: " + this.name, this);
                    else if (!PI.GetMethod.IsPublic)
                        throw new ScriptRuntimeException("Property not accessible: " + this.name, this);
                    else
                    {
                        Result.Add(new MethodRec()
                        {
                            Method = PI.GetMethod,
                            Parameters = Array.Empty<ParameterInfo>(),
                            MethodType = MethodType.LambdaProperty
                        });
                    }
                }
                else if (VectorIndex.TryGetIndexProperty(Type, true, false, out PI, out ParameterInfo[] Parameters))
                {
                    Result.Add(new MethodRec()
                    {
                        Method = PI.GetMethod,
                        Parameters = Parameters,
                        MethodType = MethodType.LambdaIndexProperty
                    });
                }
            }
 
            return Result.ToArray();
        }
 
        private enum MethodType
        {
            Method,
            LambdaProperty,
            LambdaIndexProperty
        }
 
        private class MethodRec
        {
            public MethodInfo Method;
            public ParameterInfo[] Parameters;
            public MethodType MethodType;
        }
 
        private Type lastType = null;
        private MethodInfo method = null;
        private MethodType methodType = MethodType.Method;
        private ParameterInfo[] methodParametersTypes = null;
        private MethodRec[] methods = null;
        private KeyValuePair<string, int>[] byReference = null;
        private object[] methodArguments = null;
        private bool[] methodArgumentExtensions = null;
        private readonly object synchObject = new object();
 
        public override bool ForAllChildNodes(ScriptNodeEventHandler Callback, object State, SearchMethod Order)
        {
            int i;
 
            if (Order == SearchMethod.DepthFirst)
            {
                if (!this.parameters.ForAllChildNodes(Callback, State, Order))
                    return false;
            }
 
            ScriptNode Node;
 
            for (i = 0; i < this.nrParameters; i++)
            {
                Node = this.parameters[i];
                if (!(Node is null))
                {
                    bool b = !Callback(Node, out ScriptNode NewNode, State);
                    if (!(NewNode is null))
                    {
                        this.parameters[i] = Node = NewNode;
                        NewNode.SetParent(this);
                    }
 
                    if (b || (Order == SearchMethod.TreeOrder && !Node.ForAllChildNodes(Callback, State, Order)))
                        return false;
                }
            }
 
            if (Order == SearchMethod.BreadthFirst)
            {
                if (!this.parameters.ForAllChildNodes(Callback, State, Order))
                    return false;
            }
 
            return true;
        }
 
        public override bool Equals(object obj)
        {
            return obj is NamedMethodCall O &&
                this.name == O.name &&
                AreEqual(this.parameters, O.parameters) &&
                base.Equals(obj);
        }
 
        public override int GetHashCode()
        {
            int Result = base.GetHashCode();
            Result ^= Result << 5 ^ GetHashCode(this.name);
            Result ^= Result << 5 ^ GetHashCode(this.parameters);
            return Result;
        }
    }
}