// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Reflection;
using System.Diagnostics;
using System.Globalization;
using System.Collections.Generic;
using System.Reflection.Runtime.General;
using System.Reflection.Runtime.TypeInfos;
using System.Reflection.Runtime.TypeInfos.NativeFormat;
using System.Reflection.Runtime.Assemblies;
using System.Reflection.Runtime.FieldInfos;
using System.Reflection.Runtime.FieldInfos.NativeFormat;
using System.Reflection.Runtime.MethodInfos;
using System.Reflection.Runtime.BindingFlagSupport;
using System.Reflection.Runtime.Modules;

using Internal.Runtime.Augments;
using Internal.Reflection.Augments;
using Internal.Reflection.Core.Execution;
using Internal.Metadata.NativeFormat;

namespace System.Reflection.Runtime.General
{
    internal sealed class ReflectionCoreCallbacksImplementation : ReflectionCoreCallbacks
    {
        internal ReflectionCoreCallbacksImplementation()
        {
        }

        public sealed override Assembly Load(AssemblyName assemblyRef, bool throwOnFileNotFound)
        {
            if (assemblyRef == null)
                throw new ArgumentNullException(nameof(assemblyRef));
            if (throwOnFileNotFound)
                return RuntimeAssembly.GetRuntimeAssembly(assemblyRef.ToRuntimeAssemblyName());
            else
                return RuntimeAssembly.GetRuntimeAssemblyIfExists(assemblyRef.ToRuntimeAssemblyName());
        }

        public sealed override Assembly Load(byte[] rawAssembly, byte[] pdbSymbolStore)
        {
            if (rawAssembly == null)
                throw new ArgumentNullException(nameof(rawAssembly));

            return RuntimeAssembly.GetRuntimeAssemblyFromByteArray(rawAssembly, pdbSymbolStore);
        }

        //
        // This overload of GetMethodForHandle only accepts handles for methods declared on non-generic types (the method, however,
        // can be an instance of a generic method.) To resolve handles for methods declared on generic types, you must pass
        // the declaring type explicitly using the two-argument overload of GetMethodFromHandle.
        //
        // This is a vestige from desktop generic sharing that got itself enshrined in the code generated by the C# compiler for Linq Expressions.
        //
        public sealed override MethodBase GetMethodFromHandle(RuntimeMethodHandle runtimeMethodHandle)
        {
            ExecutionEnvironment executionEnvironment = ReflectionCoreExecution.ExecutionEnvironment;
            QMethodDefinition methodHandle;
            RuntimeTypeHandle declaringTypeHandle;
            RuntimeTypeHandle[] genericMethodTypeArgumentHandles;
            if (!executionEnvironment.TryGetMethodFromHandle(runtimeMethodHandle, out declaringTypeHandle, out methodHandle, out genericMethodTypeArgumentHandles))
                throw new ArgumentException(SR.Argument_InvalidHandle);

            MethodBase methodBase = ReflectionCoreExecution.ExecutionDomain.GetMethod(declaringTypeHandle, methodHandle, genericMethodTypeArgumentHandles);
            if (methodBase.DeclaringType.IsConstructedGenericType)  // For compat with desktop, insist that the caller pass us the declaring type to resolve members of generic types.
                throw new ArgumentException(SR.Format(SR.Argument_MethodDeclaringTypeGeneric, methodBase));
            return methodBase;
        }

        //
        // This overload of GetMethodHandle can handle all method handles.
        //
        public sealed override MethodBase GetMethodFromHandle(RuntimeMethodHandle runtimeMethodHandle, RuntimeTypeHandle declaringTypeHandle)
        {
            ExecutionEnvironment executionEnvironment = ReflectionCoreExecution.ExecutionEnvironment;
            QMethodDefinition methodHandle;
            RuntimeTypeHandle[] genericMethodTypeArgumentHandles;
            if (!executionEnvironment.TryGetMethodFromHandleAndType(runtimeMethodHandle, declaringTypeHandle, out methodHandle, out genericMethodTypeArgumentHandles))
            {
                // This may be a method declared on a non-generic type: this api accepts that too so try the other table.
                RuntimeTypeHandle actualDeclaringTypeHandle;
                if (!executionEnvironment.TryGetMethodFromHandle(runtimeMethodHandle, out actualDeclaringTypeHandle, out methodHandle, out genericMethodTypeArgumentHandles))
                    throw new ArgumentException(SR.Argument_InvalidHandle);
                if (!actualDeclaringTypeHandle.Equals(declaringTypeHandle))
                    throw new ArgumentException(SR.Format(SR.Argument_ResolveMethodHandle,
                        declaringTypeHandle.GetTypeForRuntimeTypeHandle(),
                        actualDeclaringTypeHandle.GetTypeForRuntimeTypeHandle()));
            }

            MethodBase methodBase = ReflectionCoreExecution.ExecutionDomain.GetMethod(declaringTypeHandle, methodHandle, genericMethodTypeArgumentHandles);
            return methodBase;
        }

        //
        // This overload of GetFieldForHandle only accepts handles for fields declared on non-generic types. To resolve handles for fields
        // declared on generic types, you must pass the declaring type explicitly using the two-argument overload of GetFieldFromHandle.
        //
        // This is a vestige from desktop generic sharing that got itself enshrined in the code generated by the C# compiler for Linq Expressions.
        //
        public sealed override FieldInfo GetFieldFromHandle(RuntimeFieldHandle runtimeFieldHandle)
        {
            ExecutionEnvironment executionEnvironment = ReflectionCoreExecution.ExecutionEnvironment;
            FieldHandle fieldHandle;
            RuntimeTypeHandle declaringTypeHandle;
            if (!executionEnvironment.TryGetFieldFromHandle(runtimeFieldHandle, out declaringTypeHandle, out fieldHandle))
                throw new ArgumentException(SR.Argument_InvalidHandle);

            FieldInfo fieldInfo = GetFieldInfo(declaringTypeHandle, fieldHandle);
            if (fieldInfo.DeclaringType.IsConstructedGenericType) // For compat with desktop, insist that the caller pass us the declaring type to resolve members of generic types.
                throw new ArgumentException(SR.Format(SR.Argument_FieldDeclaringTypeGeneric, fieldInfo));
            return fieldInfo;
        }

        //
        // This overload of GetFieldHandle can handle all field handles.
        //
        public sealed override FieldInfo GetFieldFromHandle(RuntimeFieldHandle runtimeFieldHandle, RuntimeTypeHandle declaringTypeHandle)
        {
            ExecutionEnvironment executionEnvironment = ReflectionCoreExecution.ExecutionEnvironment;
            FieldHandle fieldHandle;
            if (!executionEnvironment.TryGetFieldFromHandleAndType(runtimeFieldHandle, declaringTypeHandle, out fieldHandle))
            {
                // This may be a field declared on a non-generic type: this api accepts that too so try the other table.
                RuntimeTypeHandle actualDeclaringTypeHandle;
                if (!executionEnvironment.TryGetFieldFromHandle(runtimeFieldHandle, out actualDeclaringTypeHandle, out fieldHandle))
                    throw new ArgumentException(SR.Argument_InvalidHandle);
                if (!actualDeclaringTypeHandle.Equals(declaringTypeHandle))
                    throw new ArgumentException(SR.Format(SR.Argument_ResolveFieldHandle,
                        declaringTypeHandle.GetTypeForRuntimeTypeHandle(),
                        actualDeclaringTypeHandle.GetTypeForRuntimeTypeHandle()));
            }

            FieldInfo fieldInfo = GetFieldInfo(declaringTypeHandle, fieldHandle);
            return fieldInfo;
        }

        public sealed override EventInfo GetImplicitlyOverriddenBaseClassEvent(EventInfo e)
        {
            return e.GetImplicitlyOverriddenBaseClassMember();
        }

        public sealed override MethodInfo GetImplicitlyOverriddenBaseClassMethod(MethodInfo m)
        {
            return m.GetImplicitlyOverriddenBaseClassMember();
        }

        public sealed override PropertyInfo GetImplicitlyOverriddenBaseClassProperty(PropertyInfo p)
        {
            return p.GetImplicitlyOverriddenBaseClassMember();
        }

        private FieldInfo GetFieldInfo(RuntimeTypeHandle declaringTypeHandle, FieldHandle fieldHandle)
        {
            RuntimeTypeInfo contextTypeInfo = declaringTypeHandle.GetTypeForRuntimeTypeHandle();
            NativeFormatRuntimeNamedTypeInfo definingTypeInfo = contextTypeInfo.AnchoringTypeDefinitionForDeclaredMembers.CastToNativeFormatRuntimeNamedTypeInfo();
            MetadataReader reader = definingTypeInfo.Reader;

            // RuntimeFieldHandles always yield FieldInfo's whose ReflectedType equals the DeclaringType.
            RuntimeTypeInfo reflectedType = contextTypeInfo;
            return NativeFormatRuntimeFieldInfo.GetRuntimeFieldInfo(fieldHandle, definingTypeInfo, contextTypeInfo, reflectedType);
        }

        [DebuggerHidden]
        [DebuggerStepThrough]
        public sealed override object ActivatorCreateInstance(Type type, bool nonPublic)
        {
            return ActivatorImplementation.CreateInstance(type, nonPublic);
        }

        [DebuggerHidden]
        [DebuggerStepThrough]
        public sealed override object ActivatorCreateInstance(Type type, BindingFlags bindingAttr, Binder binder, object[] args, CultureInfo culture, object[] activationAttributes)
        {
            return ActivatorImplementation.CreateInstance(type, bindingAttr, binder, args, culture, activationAttributes);
        }

        // V2 api: Creates open or closed delegates to static or instance methods - relaxed signature checking allowed. 
        public sealed override Delegate CreateDelegate(Type type, object firstArgument, MethodInfo method, bool throwOnBindFailure)
        {
            return CreateDelegateWorker(type, firstArgument, method, throwOnBindFailure, allowClosed: true);
        }

        // V1 api: Creates open delegates to static or instance methods - relaxed signature checking allowed.
        public sealed override Delegate CreateDelegate(Type type, MethodInfo method, bool throwOnBindFailure)
        {
            // This API existed in v1/v1.1 and only expected to create open
            // instance delegates, so we forbid closed delegates for backward compatibility. 
            // But we'll allow relaxed signature checking and open static delegates because
            // there's no ambiguity there (the caller would have to explicitly
            // pass us a static method or a method with a non-exact signature
            // and the only change in behavior from v1.1 there is that we won't
            // fail the call).
            return CreateDelegateWorker(type, null, method, throwOnBindFailure, allowClosed: false);
        }

        private static Delegate CreateDelegateWorker(Type type, object firstArgument, MethodInfo method, bool throwOnBindFailure, bool allowClosed)
        {
            if (type == null)
                throw new ArgumentNullException(nameof(type));
            if (method == null)
                throw new ArgumentNullException(nameof(method));

            if (!(type is RuntimeTypeInfo runtimeDelegateType))
                throw new ArgumentException(SR.Argument_MustBeRuntimeType, nameof(type));

            if (!(method is RuntimeMethodInfo runtimeMethodInfo))
                throw new ArgumentException(SR.Argument_MustBeRuntimeMethodInfo, nameof(method));

            if (!runtimeDelegateType.IsDelegate)
                throw new ArgumentException(SR.Arg_MustBeDelegate, nameof(type));

            Delegate result = runtimeMethodInfo.CreateDelegateNoThrowOnBindFailure(runtimeDelegateType, firstArgument, allowClosed);
            if (result == null)
            {
                if (throwOnBindFailure)
                    throw new ArgumentException(SR.Arg_DlgtTargMeth);
                return null;
            }
            return result;
        }

        // V1 api: Creates closed delegates to instance methods only, relaxed signature checking disallowed.
        public sealed override Delegate CreateDelegate(Type type, object target, string method, bool ignoreCase, bool throwOnBindFailure)
        {
            if (type == null)
                throw new ArgumentNullException(nameof(type));
            if (target == null)
                throw new ArgumentNullException(nameof(target));
            if (method == null)
                throw new ArgumentNullException(nameof(method));

            if (!(type is RuntimeTypeInfo runtimeDelegateType))
                throw new ArgumentException(SR.Argument_MustBeRuntimeType, nameof(type));
            if (!runtimeDelegateType.IsDelegate)
                throw new ArgumentException(SR.Arg_MustBeDelegate);

            RuntimeTypeInfo runtimeContainingType = target.GetType().CastToRuntimeTypeInfo();
            RuntimeMethodInfo runtimeMethodInfo = LookupMethodForCreateDelegate(runtimeDelegateType, runtimeContainingType, method, isStatic: false, ignoreCase: ignoreCase);
            if (runtimeMethodInfo == null)
            {
                if (throwOnBindFailure)
                    throw new ArgumentException(SR.Arg_DlgtTargMeth);
                return null;
            }
            return runtimeMethodInfo.CreateDelegateWithoutSignatureValidation(type, target, isStatic: false, isOpen: false);
        }

        // V1 api: Creates open delegates to static methods only, relaxed signature checking disallowed.
        public sealed override Delegate CreateDelegate(Type type, Type target, string method, bool ignoreCase, bool throwOnBindFailure)
        {
            if (type == null)
                throw new ArgumentNullException(nameof(type));
            if (target == null)
                throw new ArgumentNullException(nameof(target));
            if (target.ContainsGenericParameters)
                throw new ArgumentException(SR.Arg_UnboundGenParam);
            if (method == null)
                throw new ArgumentNullException(nameof(method));

            if (!(type is RuntimeTypeInfo runtimeDelegateType))
                throw new ArgumentException(SR.Argument_MustBeRuntimeType, nameof(type));

            if (!(target is RuntimeTypeInfo runtimeContainingType))
                throw new ArgumentException(SR.Argument_MustBeRuntimeType, nameof(target));

            if (!runtimeDelegateType.IsDelegate)
                throw new ArgumentException(SR.Arg_MustBeDelegate);

            RuntimeMethodInfo runtimeMethodInfo = LookupMethodForCreateDelegate(runtimeDelegateType, runtimeContainingType, method, isStatic: true, ignoreCase: ignoreCase);
            if (runtimeMethodInfo == null)
            {
                if (throwOnBindFailure)
                    throw new ArgumentException(SR.Arg_DlgtTargMeth);
                return null;
            }
            return runtimeMethodInfo.CreateDelegateWithoutSignatureValidation(type, target: null, isStatic: true, isOpen: true);
        }

        //
        // Helper for the V1/V1.1 Delegate.CreateDelegate() api. These apis take method names rather than MethodInfo and only expect to create open static delegates 
        // or closed instance delegates. For backward compatibility, they don't allow relaxed signature matching (which could make the choice of target method ambiguous.)
        //
        private static RuntimeMethodInfo LookupMethodForCreateDelegate(RuntimeTypeInfo runtimeDelegateType, RuntimeTypeInfo containingType, string method, bool isStatic, bool ignoreCase)
        {
            Debug.Assert(runtimeDelegateType.IsDelegate);

            BindingFlags bindingFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.ExactBinding;
            if (isStatic)
            {
                bindingFlags |= BindingFlags.Static;
            }
            else
            {
                bindingFlags |= BindingFlags.Instance | BindingFlags.DeclaredOnly;
            }
            if (ignoreCase)
            {
                bindingFlags |= BindingFlags.IgnoreCase;
            }
            RuntimeMethodInfo invokeMethod = runtimeDelegateType.GetInvokeMethod();
            ParameterInfo[] parameters = invokeMethod.GetParametersNoCopy();
            int numParameters = parameters.Length;
            Type[] parameterTypes = new Type[numParameters];
            for (int i = 0; i < numParameters; i++)
            {
                parameterTypes[i] = parameters[i].ParameterType;
            }

            while (containingType != null)
            {
                MethodInfo methodInfo = containingType.GetMethod(method, 0, bindingFlags, null, parameterTypes, null);
                if (methodInfo != null && methodInfo.ReturnType.Equals(invokeMethod.ReturnType))
                    return (RuntimeMethodInfo)methodInfo; // This cast is safe since we already verified that containingType is runtime implemented.

                containingType = (RuntimeTypeInfo)(containingType.BaseType);
            }
            return null;
        }

        public sealed override Type GetTypeFromCLSID(Guid clsid, string server, bool throwOnError)
        {
            // Note: "throwOnError" is a vacuous parameter. Any errors due to the CLSID not being registered or the server not being found will happen
            // on the Activator.CreateInstance() call. GetTypeFromCLSID() merely wraps the data in a Type object without any validation.
            return RuntimeCLSIDTypeInfo.GetRuntimeCLSIDTypeInfo(clsid, server);
        }

        public sealed override IntPtr GetFunctionPointer(RuntimeMethodHandle runtimeMethodHandle, RuntimeTypeHandle declaringTypeHandle)
        {
            MethodBase method = GetMethodFromHandle(runtimeMethodHandle, declaringTypeHandle);

            switch (method)
            {
                case RuntimeMethodInfo methodInfo:
                    return methodInfo.LdFtnResult;
                case RuntimeConstructorInfo constructorInfo:
                    return constructorInfo.LdFtnResult;
                default:
                    Debug.Fail("RuntimeMethodHandle should only return a methodbase implemented by the runtime.");
                    throw new NotSupportedException();
            }
        }

        public sealed override void RunModuleConstructor(Module module)
        {
            RuntimeAssembly assembly = (RuntimeAssembly)module.Assembly;
            assembly.RunModuleConstructor();
        }

        public sealed override void MakeTypedReference(object target, FieldInfo[] flds, out Type type, out int offset)
        {
            if (target == null)
                throw new ArgumentNullException(nameof(target));
            if (flds == null)
                throw new ArgumentNullException(nameof(flds));
            if (flds.Length == 0)
                throw new ArgumentException(SR.Arg_ArrayZeroError);

            offset = 0;
            Type targetType = target.GetType();
            for (int i = 0; i < flds.Length; i++)
            {
                if (!(flds[i] is RuntimeFieldInfo field))
                    throw new ArgumentException(SR.Argument_MustBeRuntimeFieldInfo);
                if (field.IsInitOnly || field.IsStatic)
                    throw new ArgumentException(SR.Argument_TypedReferenceInvalidField);

                // For proper handling of Nullable<T> don't change to something like 'IsAssignableFrom'
                // Currently we can't make a TypedReference to fields of Nullable<T>, which is fine.
                Type declaringType = field.DeclaringType;
                if (targetType != declaringType && !targetType.IsSubclassOf(declaringType))
                    throw new MissingMemberException(SR.MissingMemberTypeRef); // MissingMemberException is a strange exception to throw, but it is the compatible exception.

                Type fieldType = field.FieldType;
                if (fieldType.IsPrimitive)
                    throw new ArgumentException(SR.Arg_TypeRefPrimitve);  // This check exists for compatibility (why such an ad-hoc restriction?)
                if (i < (flds.Length - 1) && !fieldType.IsValueType)
                    throw new MissingMemberException(SR.MissingMemberNestErr); // MissingMemberException is a strange exception to throw, but it is the compatible exception.

                targetType = fieldType;
                offset = checked(offset + field.Offset);
            }

            type = targetType;
        }

        public sealed override Assembly[] GetLoadedAssemblies() => RuntimeAssembly.GetLoadedAssemblies();

        public sealed override EnumInfo GetEnumInfo(Type type) => type.CastToRuntimeTypeInfo().EnumInfo;
    }
}
