using System;
using System.Reflection;
using System.Globalization;
using System.Runtime.Serialization;

namespace system.reflection
{

    [System.Serializable]
    public sealed class RuntimeMethodInfo : MethodInfo, ISerializable
    {
        #pragma warning disable 0436
        [java.attr.RetainType] public java.lang.reflect.Method JavaMethod;
        #pragma warning restore 0436
        [java.attr.RetainType] public string originalName;
        [java.attr.RetainType] public string strippedName;
        [java.attr.RetainType] public system.RuntimeType reflectedType;
        [java.attr.RetainType] public object[] typeArguments;

        [java.attr.RetainType] public int genericFlags;
        const int flgGenericMethod             = 0x10;
        const int flgGenericMethodDefinition   = 0x20;
        const int flgContainsGenericParameters = 0x40;
        const int flgCombineGenericArguments   = 0x80;

        //
        // GetMethod (called by system.RuntimeType.GetMethodImpl)
        //

        public static MethodInfo GetMethod(string name, BindingFlags bindingAttr,
                                           Binder binder, CallingConventions callConvention,
                                           Type[] types, ParameterModifier[] modifiers,
                                           RuntimeType initialType)
        {
            //
            // validate parameters
            //

            if (name == null)
                throw new ArgumentNullException("name");
            if (binder != null)
                throw new PlatformNotSupportedException("non-null binder");
            if (callConvention != CallingConventions.Any)
                throw new PlatformNotSupportedException("calling convention must be Any");
            if (types != null)
                throw new PlatformNotSupportedException("non-null types");
            if (modifiers != null)
                throw new PlatformNotSupportedException("non-null modifiers");

            //
            // calculate modifier AND mask and result for matches
            //

            int modifierMask = 0;
            int modifierValue = 0;

            BindingFlags chk = bindingAttr & (BindingFlags.Public | BindingFlags.NonPublic);
            if (chk != (BindingFlags.Public | BindingFlags.NonPublic))
            {
                if (chk == 0)       // if neither, no methods will match
                    return null;
                // methods with internal access are converted to public access,
                // so we cannot honor the distinction between Public and NonPublic
                /*
                modifierMask |= java.lang.reflect.Modifier.PUBLIC;
                if (chk == BindingFlags.Public)
                    modifierValue |= java.lang.reflect.Modifier.PUBLIC;
                */
                bindingAttr &= ~chk;
            }

            chk = bindingAttr & (BindingFlags.Static | BindingFlags.Instance);
            if (chk != (BindingFlags.Static | BindingFlags.Instance))
            {
                if (chk == 0)       // if neither, no methods will match
                    return null;
                modifierMask |= java.lang.reflect.Modifier.STATIC;
                if (chk == BindingFlags.Static)
                    modifierValue |= java.lang.reflect.Modifier.STATIC;
                bindingAttr &= ~chk;
            }

            RuntimeType stopAtType = null;
            if ((bindingAttr & BindingFlags.DeclaredOnly) != 0)
            {
                stopAtType = initialType;
                bindingAttr &= ~BindingFlags.DeclaredOnly;
            }

            if (bindingAttr != 0)
                throw new PlatformNotSupportedException("bad binding flags " + bindingAttr);

            //
            // collect methods from class and base classes
            //

            var currentType = initialType;
            for (;;)
            {
                #pragma warning disable 0436
                java.lang.reflect.Method[] javaMethods =
                    (java.lang.reflect.Method[]) (object)
                            currentType.JavaClassForArray().getDeclaredMethods();
                #pragma warning restore 0436

                foreach (var javaMethod in javaMethods)
                {
                    int jmodifiers = javaMethod.getModifiers();
                    if ((jmodifiers & modifierMask) == modifierValue)
                    {
                        string originalName = javaMethod.getName();
                        // note the actual suffix character below is configured
                        // in CilMain.cs, with special considerations for Android.
                        // we list all possible characters here, just in case.
                        int idx = originalName.IndexOf('\u00AB'); // U+00AB Left-Pointing Double Angle Quotation Mark
                        if (idx == -1)
                            idx = originalName.IndexOf('\u00A1'); // U+00A1 Inverted Exclamation Mark
                        if (idx == -1)
                            idx = originalName.IndexOf('(');
                        if (idx == -1)
                            idx = originalName.IndexOf('!');
                        var compareName =
                            (idx == -1) ? originalName : originalName.Substring(0, idx);

                        if (name == compareName)
                        {
                            javaMethod.setAccessible(true);
                            return new RuntimeMethodInfo(javaMethod, jmodifiers, initialType,
                                                         originalName, compareName);
                        }
                    }
                }

                currentType = (system.RuntimeType) currentType.BaseType;
                if (currentType == stopAtType)
                    break;
            }

            return null;
        }

        //
        // constructor
        //

        #pragma warning disable 0436
        private RuntimeMethodInfo(java.lang.reflect.Method javaMethod, int modifiers,
                                  system.RuntimeType reflectedType,
                                  string originalName, string strippedName)
        #pragma warning restore 0436
        {
            this.JavaMethod = javaMethod;
            this.reflectedType = reflectedType;
            this.originalName = originalName;
            this.strippedName = strippedName;

            if (modifiers == -1)    // if called from MakeGenericMethod
                return;

            // analyze the method and the declaring type in order to decide what
            // type of a generic method this is.  the general idea is:
            // if the method takes more generic parameters, than the number of
            // arguments in the type, then it is a generic method definition.

            int originalNameLen = originalName.Length;
            char lastChar = (originalNameLen > 0)
                          ? originalName[originalNameLen - 1]
                          : (char) 0;
            // the actual suffix character is configured in CilMain.cs
            if (lastChar == '\u00A1' || lastChar == '!') // U+00A1 Inverted Exclamation Mark
            {
                if ((modifiers & java.lang.reflect.Modifier.STATIC) == 0)
                {
                    // if an instance method takes any type arguments at all,
                    // then it must be a generic method definition
                    genericFlags |= flgGenericMethod
                                 |  flgGenericMethodDefinition
                                 |  flgContainsGenericParameters;
                }
                else
                {
                    // count the number of type arguments in the declaring type
                    var typeArgsInType = reflectedType.GetGenericArguments();
                    int numTypeArgsInType = typeArgsInType.Length;

                    // count the number of type parameters in the method signature
                    int numTypeArgsInMethod = 0;
                    var paramTypes = javaMethod.getParameterTypes();
                    int paramIndex = paramTypes.Length;
                    while (paramIndex-- > 0)
                    {
                        var paramType = paramTypes[paramIndex];
                        if (paramType != (java.lang.Class) typeof(System.Type))
                            break;
                        numTypeArgsInMethod++;
                    }

                    if (numTypeArgsInMethod == numTypeArgsInType)
                    {
                        // a static method that takes a number of type parameters
                        // equal to the number of arguments in the declaring type.
                        // this means it is not a generic method, but it may not
                        // be invokable, if the declaring type is not concrete.

                        if (reflectedType.ContainsGenericParameters)
                            genericFlags |= flgContainsGenericParameters;

                        else if (reflectedType.IsGenericType)
                            genericFlags |= flgCombineGenericArguments;
                    }

                    else if (numTypeArgsInMethod > numTypeArgsInType)
                    {
                        // a static method that takes more parameters than the
                        // declaring type, i.e. it is a generic method definition.
                        genericFlags |= flgGenericMethod
                                     |  flgGenericMethodDefinition
                                     |  flgContainsGenericParameters;
                    }

                    else
                        throw new TypeLoadException(originalName);
                }
            }
            else
            {
                // a method that does not take any type argument may still be
                // not invokable, if the reflected type is not a concrete type.
                // note that this is true only for instance methods, as static
                // methods in a generic type will always take type arguments.

                if ((modifiers & java.lang.reflect.Modifier.STATIC) == 0)
                {
                    if (reflectedType.ContainsGenericParameters)
                        genericFlags |= flgContainsGenericParameters;

                    else if (reflectedType.IsGenericType)
                        genericFlags |= flgCombineGenericArguments;
                }
            }
        }

        //
        // MakeGenericMethod
        //

        public override MethodInfo MakeGenericMethod(Type[] typeArguments)
        {
            if (! IsGenericMethodDefinition)
                throw new InvalidOperationException();
            if (typeArguments == null)
                throw new ArgumentNullException();

            var implicitTypeArgs      = reflectedType.GetGenericArguments();
            int implicitTypeArgsCount = implicitTypeArgs.Length;
            var explicitTypeArgsCount = typeArguments.Length;
            int combinedTypeArgsCount = implicitTypeArgsCount + explicitTypeArgsCount;

            var combinedTypeArgs = new object[combinedTypeArgsCount];
            java.lang.System.arraycopy(
                            /* from  */ implicitTypeArgs, 0,
                            /* into  */ combinedTypeArgs, 0,
                            /* count */ implicitTypeArgsCount);
            java.lang.System.arraycopy(
                            /* from */ typeArguments, 0,
                            /* into */ combinedTypeArgs, implicitTypeArgsCount,
                            /* count */ explicitTypeArgsCount);

            var newMethod = new RuntimeMethodInfo(JavaMethod, -1, reflectedType,
                                                  originalName, strippedName);
            newMethod.typeArguments = combinedTypeArgs;
            newMethod.genericFlags = flgGenericMethod;

            for (int i = 0; i < combinedTypeArgsCount; i++)
            {
                var arg = combinedTypeArgs[i] as RuntimeType;
                if (arg == null)
                    throw new ArgumentNullException();
                if (arg.IsGenericParameter || arg.ContainsGenericParameters)
                    newMethod.genericFlags |= flgContainsGenericParameters;
            }

            return newMethod;
        }

        //
        // Invoke
        //

        public override object Invoke(object obj, BindingFlags invokeAttr, Binder binder,
                                      object[] parameters, CultureInfo culture)
        {
            if (ContainsGenericParameters)
                throw new InvalidOperationException();
            if (invokeAttr != BindingFlags.Default)
                throw new PlatformNotSupportedException("bad binding flags " + invokeAttr);
            if (binder != null)
                throw new PlatformNotSupportedException("non-null binder");
            if (culture != null)
                throw new PlatformNotSupportedException("non-null culture");

            // combine the provided parameters and any suffix type arguments
            // that were previously injected by MakeGenericMethod

            var typeArgs = typeArguments;
            if (typeArgs == null && (genericFlags & flgCombineGenericArguments) != 0)
                typeArgs = typeArguments = reflectedType.GetGenericArguments();

            if (typeArgs != null)
            {
                if (parameters == null)
                    parameters = typeArgs;
                else
                {
                    int nParams = parameters.Length;
                    int nTypes = typeArgs.Length;
                    var newParams = new object[nParams + nTypes];
                    java.lang.System.arraycopy(parameters, 0, newParams, 0,       nParams);
                    java.lang.System.arraycopy(typeArgs,   0, newParams, nParams, nTypes);
                    parameters = newParams;
                }
            }

            int numParameters = (parameters != null) ? parameters.Length : 0;
            if (JavaMethod.getParameterTypes().Length != numParameters)
                throw new TargetParameterCountException();

            return JavaMethod.invoke(obj, parameters);
        }

        //
        //
        //

        public override bool IsGenericMethod
            => (genericFlags & flgGenericMethod) != 0;

        public override bool IsGenericMethodDefinition
            => (genericFlags & flgGenericMethodDefinition) != 0;

        public override bool ContainsGenericParameters
            => (genericFlags & flgContainsGenericParameters) != 0;

        //
        //
        //

        public override Type ReflectedType => reflectedType;

        public override Type DeclaringType
            => system.RuntimeType.GetType(JavaMethod.getDeclaringClass());

        public override MethodAttributes Attributes
            => throw new PlatformNotSupportedException();

        public override string Name => strippedName;

        public override RuntimeMethodHandle MethodHandle
            => throw new PlatformNotSupportedException();

        public override ParameterInfo[] GetParameters()
            => throw new PlatformNotSupportedException();

        public override MethodInfo GetBaseDefinition()
            => throw new PlatformNotSupportedException();

        public override MethodImplAttributes GetMethodImplementationFlags()
            => throw new PlatformNotSupportedException();

        //
        //
        //

        public override string ToString() => strippedName;

        //
        // custom attributes
        //

        public override bool IsDefined(Type attributeType, bool inherit)
            => throw new PlatformNotSupportedException();

        public override object[] GetCustomAttributes(bool inherit)
            => throw new PlatformNotSupportedException();

        public override object[] GetCustomAttributes(Type attributeType, bool inherit)
            => throw new PlatformNotSupportedException();

        public override ICustomAttributeProvider ReturnTypeCustomAttributes
            => throw new PlatformNotSupportedException();

        //
        // ISerializable
        //

        public void GetObjectData(SerializationInfo info, StreamingContext context)
            => throw new PlatformNotSupportedException();

    }

}

//
// declaration of java.lang.reflect.Method and java.lang.reflect.Constructor.
// this is needed because java 1.8 inserts a new java.lang.reflect.Executable
// class as the base class for Method and Constructor.
// this causes an error on Android, because the Executable class is missing.
//

namespace java.lang.reflect
{
    [java.attr.Discard] // discard in output
    public abstract class Constructor : AccessibleObject
    {
        public abstract object newInstance(object[] initargs);
        public abstract Class[] getParameterTypes();
        public abstract int getModifiers();
    }

    [java.attr.Discard] // discard in output
    public abstract class Method : AccessibleObject
    {
        public abstract Class getDeclaringClass();
        public abstract string getName();
        public abstract Class[] getParameterTypes();
        public abstract Class getReturnType();
        public abstract int getModifiers();
        public abstract object invoke(object obj, object[] args);
    }
}