/*
 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.lang.reflect;

import dalvik.annotation.optimization.FastNative;

import java.lang.annotation.Annotation;
import java.util.Objects;
import libcore.reflect.AnnotatedElements;
import libcore.reflect.GenericSignatureParser;
import libcore.reflect.ListOfTypes;
import libcore.reflect.Types;
import libcore.util.EmptyArray;

/**
 * A shared superclass for the common functionality of {@link Method}
 * and {@link Constructor}.
 *
 * @since 1.8
 */
public abstract class Executable extends AccessibleObject
    implements Member, GenericDeclaration {
    /*
     * Only grant package-visibility to the constructor.
     */
    Executable() {}

    /**
     * Does the Executable have generic information.
     */
    abstract boolean hasGenericInformation();

    boolean equalParamTypes(Class<?>[] params1, Class<?>[] params2) {
        /* Avoid unnecessary cloning */
        if (params1.length == params2.length) {
            for (int i = 0; i < params1.length; i++) {
                if (params1[i] != params2[i])
                    return false;
            }
            return true;
        }
        return false;
    }

    void separateWithCommas(Class<?>[] types, StringBuilder sb) {
        for (int j = 0; j < types.length; j++) {
            sb.append(types[j].getTypeName());
            if (j < (types.length - 1))
                sb.append(",");
        }

    }

    void printModifiersIfNonzero(StringBuilder sb, int mask, boolean isDefault) {
        int mod = getModifiers() & mask;

        if (mod != 0 && !isDefault) {
            sb.append(Modifier.toString(mod)).append(' ');
        } else {
            int access_mod = mod & Modifier.ACCESS_MODIFIERS;
            if (access_mod != 0)
                sb.append(Modifier.toString(access_mod)).append(' ');
            if (isDefault)
                sb.append("default ");
            mod = (mod & ~Modifier.ACCESS_MODIFIERS);
            if (mod != 0)
                sb.append(Modifier.toString(mod)).append(' ');
        }
    }

    String sharedToString(int modifierMask,
                          boolean isDefault,
                          Class<?>[] parameterTypes,
                          Class<?>[] exceptionTypes) {
        try {
            StringBuilder sb = new StringBuilder();

            printModifiersIfNonzero(sb, modifierMask, isDefault);
            specificToStringHeader(sb);

            sb.append('(');
            separateWithCommas(parameterTypes, sb);
            sb.append(')');
            if (exceptionTypes.length > 0) {
                sb.append(" throws ");
                separateWithCommas(exceptionTypes, sb);
            }
            return sb.toString();
        } catch (Exception e) {
            return "<" + e + ">";
        }
    }

    /**
     * Generate toString header information specific to a method or
     * constructor.
     */
    abstract void specificToStringHeader(StringBuilder sb);

    String sharedToGenericString(int modifierMask, boolean isDefault) {
        try {
            StringBuilder sb = new StringBuilder();

            printModifiersIfNonzero(sb, modifierMask, isDefault);

            TypeVariable<?>[] typeparms = getTypeParameters();
            if (typeparms.length > 0) {
                boolean first = true;
                sb.append('<');
                for(TypeVariable<?> typeparm: typeparms) {
                    if (!first)
                        sb.append(',');
                    // Class objects can't occur here; no need to test
                    // and call Class.getName().
                    sb.append(typeparm.toString());
                    first = false;
                }
                sb.append("> ");
            }

            specificToGenericStringHeader(sb);

            sb.append('(');
            Type[] params = getGenericParameterTypes();
            for (int j = 0; j < params.length; j++) {
                String param = params[j].getTypeName();
                if (isVarArgs() && (j == params.length - 1)) // replace T[] with T...
                    param = param.replaceFirst("\\[\\]$", "...");
                sb.append(param);
                if (j < (params.length - 1))
                    sb.append(',');
            }
            sb.append(')');
            Type[] exceptions = getGenericExceptionTypes();
            if (exceptions.length > 0) {
                sb.append(" throws ");
                for (int k = 0; k < exceptions.length; k++) {
                    sb.append((exceptions[k] instanceof Class)?
                              ((Class)exceptions[k]).getName():
                              exceptions[k].toString());
                    if (k < (exceptions.length - 1))
                        sb.append(',');
                }
            }
            return sb.toString();
        } catch (Exception e) {
            return "<" + e + ">";
        }
    }

    /**
     * Generate toGenericString header information specific to a
     * method or constructor.
     */
    abstract void specificToGenericStringHeader(StringBuilder sb);

    /**
     * Returns the {@code Class} object representing the class or interface
     * that declares the executable represented by this object.
     */
    public abstract Class<?> getDeclaringClass();

    /**
     * Returns the name of the executable represented by this object.
     */
    public abstract String getName();

    /**
     * Returns the Java language {@linkplain Modifier modifiers} for
     * the executable represented by this object.
     */
    public abstract int getModifiers();

    /**
     * Returns an array of {@code TypeVariable} objects that represent the
     * type variables declared by the generic declaration represented by this
     * {@code GenericDeclaration} object, in declaration order.  Returns an
     * array of length 0 if the underlying generic declaration declares no type
     * variables.
     *
     * @return an array of {@code TypeVariable} objects that represent
     *     the type variables declared by this generic declaration
     * @throws GenericSignatureFormatError if the generic
     *     signature of this generic declaration does not conform to
     *     the format specified in
     *     <cite>The Java&trade; Virtual Machine Specification</cite>
     */
    public abstract TypeVariable<?>[] getTypeParameters();

    /**
     * Returns an array of {@code Class} objects that represent the formal
     * parameter types, in declaration order, of the executable
     * represented by this object.  Returns an array of length
     * 0 if the underlying executable takes no parameters.
     *
     * @return the parameter types for the executable this object
     * represents
     */
    public abstract Class<?>[] getParameterTypes();

    /**
     * Returns the number of formal parameters (whether explicitly
     * declared or implicitly declared or neither) for the executable
     * represented by this object.
     *
     * @since 1.8
     * @return The number of formal parameters for the executable this
     * object represents
     */
    public int getParameterCount() {
        throw new AbstractMethodError();
    }

    /**
     * Returns an array of {@code Type} objects that represent the formal
     * parameter types, in declaration order, of the executable represented by
     * this object. Returns an array of length 0 if the
     * underlying executable takes no parameters.
     *
     * <p>If a formal parameter type is a parameterized type,
     * the {@code Type} object returned for it must accurately reflect
     * the actual type parameters used in the source code.
     *
     * <p>If a formal parameter type is a type variable or a parameterized
     * type, it is created. Otherwise, it is resolved.
     *
     * @return an array of {@code Type}s that represent the formal
     *     parameter types of the underlying executable, in declaration order
     * @throws GenericSignatureFormatError
     *     if the generic method signature does not conform to the format
     *     specified in
     *     <cite>The Java&trade; Virtual Machine Specification</cite>
     * @throws TypeNotPresentException if any of the parameter
     *     types of the underlying executable refers to a non-existent type
     *     declaration
     * @throws MalformedParameterizedTypeException if any of
     *     the underlying executable's parameter types refer to a parameterized
     *     type that cannot be instantiated for any reason
     */
    public Type[] getGenericParameterTypes() {
        // Android-changed: Changed to use Types / getMethodOrConstructorGenericInfoInternal()
        return Types.getTypeArray(
                getMethodOrConstructorGenericInfoInternal().genericParameterTypes, false);
    }

    /**
     * Behaves like {@code getGenericParameterTypes}, but returns type
     * information for all parameters, including synthetic parameters.
     */
    Type[] getAllGenericParameterTypes() {
        final boolean genericInfo = hasGenericInformation();

        // Easy case: we don't have generic parameter information.  In
        // this case, we just return the result of
        // getParameterTypes().
        if (!genericInfo) {
            return getParameterTypes();
        } else {
            final boolean realParamData = hasRealParameterData();
            final Type[] genericParamTypes = getGenericParameterTypes();
            final Type[] nonGenericParamTypes = getParameterTypes();
            final Type[] out = new Type[nonGenericParamTypes.length];
            final Parameter[] params = getParameters();
            int fromidx = 0;
            // If we have real parameter data, then we use the
            // synthetic and mandate flags to our advantage.
            if (realParamData) {
                for (int i = 0; i < out.length; i++) {
                    final Parameter param = params[i];
                    if (param.isSynthetic() || param.isImplicit()) {
                        // If we hit a synthetic or mandated parameter,
                        // use the non generic parameter info.
                        out[i] = nonGenericParamTypes[i];
                    } else {
                        // Otherwise, use the generic parameter info.
                        out[i] = genericParamTypes[fromidx];
                        fromidx++;
                    }
                }
            } else {
                // Otherwise, use the non-generic parameter data.
                // Without method parameter reflection data, we have
                // no way to figure out which parameters are
                // synthetic/mandated, thus, no way to match up the
                // indexes.
                return genericParamTypes.length == nonGenericParamTypes.length ?
                    genericParamTypes : nonGenericParamTypes;
            }
            return out;
        }
    }

    /**
     * Returns an array of {@code Parameter} objects that represent
     * all the parameters to the underlying executable represented by
     * this object.  Returns an array of length 0 if the executable
     * has no parameters.
     *
     * <p>The parameters of the underlying executable do not necessarily
     * have unique names, or names that are legal identifiers in the
     * Java programming language (JLS 3.8).
     *
     * @since 1.8
     * @throws MalformedParametersException if the class file contains
     * a MethodParameters attribute that is improperly formatted.
     * @return an array of {@code Parameter} objects representing all
     * the parameters to the executable this object represents.
     */
    public Parameter[] getParameters() {
        // TODO: This may eventually need to be guarded by security
        // mechanisms similar to those in Field, Method, etc.
        //
        // Need to copy the cached array to prevent users from messing
        // with it.  Since parameters are immutable, we can
        // shallow-copy.
        return privateGetParameters().clone();
    }

    private Parameter[] synthesizeAllParams() {
        final int realparams = getParameterCount();
        final Parameter[] out = new Parameter[realparams];
        for (int i = 0; i < realparams; i++)
            // TODO: is there a way to synthetically derive the
            // modifiers?  Probably not in the general case, since
            // we'd have no way of knowing about them, but there
            // may be specific cases.
            out[i] = new Parameter("arg" + i, 0, this, i);
        return out;
    }

    private void verifyParameters(final Parameter[] parameters) {
        final int mask = Modifier.FINAL | Modifier.SYNTHETIC | Modifier.MANDATED;

        if (getParameterTypes().length != parameters.length)
            throw new MalformedParametersException("Wrong number of parameters in MethodParameters attribute");

        for (Parameter parameter : parameters) {
            final String name = parameter.getRealName();
            final int mods = parameter.getModifiers();

            if (name != null) {
                if (name.isEmpty() || name.indexOf('.') != -1 ||
                    name.indexOf(';') != -1 || name.indexOf('[') != -1 ||
                    name.indexOf('/') != -1) {
                    throw new MalformedParametersException("Invalid parameter name \"" + name + "\"");
                }
            }

            if (mods != (mods & mask)) {
                throw new MalformedParametersException("Invalid parameter modifiers");
            }
        }
    }

    private Parameter[] privateGetParameters() {
        // Use tmp to avoid multiple writes to a volatile.
        Parameter[] tmp = parameters;

        if (tmp == null) {
            // Otherwise, go to the JVM to get them
            try {
                tmp = getParameters0();
            } catch(IllegalArgumentException e) {
                // Rethrow ClassFormatErrors
                // Android-changed: Exception changed to be more descriptive.
                MalformedParametersException e2 =
                        new MalformedParametersException(
                                "Invalid parameter metadata in class file");
                e2.initCause(e);
                throw e2;
            }

            // If we get back nothing, then synthesize parameters
            if (tmp == null) {
                hasRealParameterData = false;
                tmp = synthesizeAllParams();
            } else {
                hasRealParameterData = true;
                verifyParameters(tmp);
            }

            parameters = tmp;
        }

        return tmp;
    }

    boolean hasRealParameterData() {
        // If this somehow gets called before parameters gets
        // initialized, force it into existence.
        if (parameters == null) {
            privateGetParameters();
        }
        return hasRealParameterData;
    }

    private transient volatile boolean hasRealParameterData;
    private transient volatile Parameter[] parameters;

    @FastNative
    private native Parameter[] getParameters0();

    /**
     * Returns an array of {@code Class} objects that represent the
     * types of exceptions declared to be thrown by the underlying
     * executable represented by this object.  Returns an array of
     * length 0 if the executable declares no exceptions in its {@code
     * throws} clause.
     *
     * @return the exception types declared as being thrown by the
     * executable this object represents
     */
    public abstract Class<?>[] getExceptionTypes();

    /**
     * Returns an array of {@code Type} objects that represent the
     * exceptions declared to be thrown by this executable object.
     * Returns an array of length 0 if the underlying executable declares
     * no exceptions in its {@code throws} clause.
     *
     * <p>If an exception type is a type variable or a parameterized
     * type, it is created. Otherwise, it is resolved.
     *
     * @return an array of Types that represent the exception types
     *     thrown by the underlying executable
     * @throws GenericSignatureFormatError
     *     if the generic method signature does not conform to the format
     *     specified in
     *     <cite>The Java&trade; Virtual Machine Specification</cite>
     * @throws TypeNotPresentException if the underlying executable's
     *     {@code throws} clause refers to a non-existent type declaration
     * @throws MalformedParameterizedTypeException if
     *     the underlying executable's {@code throws} clause refers to a
     *     parameterized type that cannot be instantiated for any reason
     */
    public Type[] getGenericExceptionTypes() {
        // Android-changed: Changed to use Types / getMethodOrConstructorGenericInfoInternal()
        return Types.getTypeArray(
                getMethodOrConstructorGenericInfoInternal().genericExceptionTypes, false);
    }

    /**
     * Returns a string describing this {@code Executable}, including
     * any type parameters.
     * @return a string describing this {@code Executable}, including
     * any type parameters
     */
    public abstract String toGenericString();

    /**
     * Returns {@code true} if this executable was declared to take a
     * variable number of arguments; returns {@code false} otherwise.
     *
     * @return {@code true} if an only if this executable was declared
     * to take a variable number of arguments.
     */
    public boolean isVarArgs()  {
        // Android-changed: Slightly more efficient.
        return (accessFlags & Modifier.VARARGS) != 0;
    }

    /**
     * Returns {@code true} if this executable is a synthetic
     * construct; returns {@code false} otherwise.
     *
     * @return true if and only if this executable is a synthetic
     * construct as defined by
     * <cite>The Java&trade; Language Specification</cite>.
     * @jls 13.1 The Form of a Binary
     */
    public boolean isSynthetic() {
        // Android-changed: Slightly more efficient.
        return (accessFlags & Modifier.SYNTHETIC) != 0;
    }

    /**
     * Returns an array of arrays of {@code Annotation}s that
     * represent the annotations on the formal parameters, in
     * declaration order, of the {@code Executable} represented by
     * this object.  Synthetic and mandated parameters (see
     * explanation below), such as the outer "this" parameter to an
     * inner class constructor will be represented in the returned
     * array.  If the executable has no parameters (meaning no formal,
     * no synthetic, and no mandated parameters), a zero-length array
     * will be returned.  If the {@code Executable} has one or more
     * parameters, a nested array of length zero is returned for each
     * parameter with no annotations. The annotation objects contained
     * in the returned arrays are serializable.  The caller of this
     * method is free to modify the returned arrays; it will have no
     * effect on the arrays returned to other callers.
     *
     * A compiler may add extra parameters that are implicitly
     * declared in source ("mandated"), as well as parameters that
     * are neither implicitly nor explicitly declared in source
     * ("synthetic") to the parameter list for a method.  See {@link
     * java.lang.reflect.Parameter} for more information.
     *
     * @see java.lang.reflect.Parameter
     * @see java.lang.reflect.Parameter#getAnnotations
     * @return an array of arrays that represent the annotations on
     *    the formal and implicit parameters, in declaration order, of
     *    the executable represented by this object
     */
    public abstract Annotation[][] getParameterAnnotations();

    /**
     * {@inheritDoc}
     * @throws NullPointerException  {@inheritDoc}
     */
    public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
        Objects.requireNonNull(annotationClass);
        // Android-changed: Implemented natively.
        return getAnnotationNative(annotationClass);
    }
    @FastNative
    private native <T extends Annotation> T getAnnotationNative(Class<T> annotationClass);

    /**
     * {@inheritDoc}
     * @throws NullPointerException {@inheritDoc}
     * @since 1.8
     */
    @Override
    public <T extends Annotation> T[] getAnnotationsByType(Class<T> annotationClass) {
        // Android-changed: Uses AnnotatedElements instead.
        return AnnotatedElements.getDirectOrIndirectAnnotationsByType(this, annotationClass);
    }

    /**
     * {@inheritDoc}
     */
    public Annotation[] getDeclaredAnnotations()  {
        // Android-changed: Implemented natively.
        return getDeclaredAnnotationsNative();
    }
    @FastNative
    private native Annotation[] getDeclaredAnnotationsNative();

    // Android-changed: Additional ART-related fields and logic below that is shared between
    // Method and Constructor.

    /** Bits encoding access (e.g. public, private) as well as other runtime specific flags */
    @SuppressWarnings("unused") // set by runtime
    private int accessFlags;

    /**
     * The ArtMethod associated with this Executable, required for dispatching due to entrypoints
     * Classloader is held live by the declaring class.
     */
    @SuppressWarnings("unused") // set by runtime
    private long artMethod;

    /** Executable's declaring class */
    @SuppressWarnings("unused") // set by runtime
    private Class<?> declaringClass;

    /**
     * Overriden method's declaring class (same as declaringClass unless declaringClass is a proxy
     * class).
     */
    @SuppressWarnings("unused") // set by runtime
    private Class<?> declaringClassOfOverriddenMethod;

    /** The method index of this method within its defining dex file */
    @SuppressWarnings("unused") // set by runtime
    private int dexMethodIndex;

    /**
     * We insert native method stubs for abstract methods so we don't have to
     * check the access flags at the time of the method call.  This results in
     * "native abstract" methods, which can't exist.  If we see the "abstract"
     * flag set, clear the "native" flag.
     *
     * We also move the DECLARED_SYNCHRONIZED flag into the SYNCHRONIZED
     * position, because the callers of this function are trying to convey
     * the "traditional" meaning of the flags to their callers.
     */
    private static int fixMethodFlags(int flags) {
        if ((flags & Modifier.ABSTRACT) != 0) {
            flags &= ~Modifier.NATIVE;
        }
        flags &= ~Modifier.SYNCHRONIZED;
        int ACC_DECLARED_SYNCHRONIZED = 0x00020000;
        if ((flags & ACC_DECLARED_SYNCHRONIZED) != 0) {
            flags |= Modifier.SYNCHRONIZED;
        }
        return flags & 0xffff;  // mask out bits not used by Java
    }

    final int getModifiersInternal() {
        return fixMethodFlags(accessFlags);
    }

    final Class<?> getDeclaringClassInternal() {
        return declaringClass;
    }

    /**
     * Returns an array of {@code Class} objects associated with the parameter types of this
     * Executable. If the Executable was declared with no parameters, {@code null} will be
     * returned.
     *
     * @return the parameter types, or {@code null} if no parameters were declared.
     */
    @FastNative
    final native Class<?>[] getParameterTypesInternal();

    @FastNative
    final native int getParameterCountInternal();

    // Android provides a more efficient implementation of this method for Executable than the one
    // implemented in AnnotatedElement.
    @Override
    public final boolean isAnnotationPresent(Class<? extends Annotation> annotationType) {
        Objects.requireNonNull(annotationType);
        return isAnnotationPresentNative(annotationType);
    }
    @FastNative
    private native boolean isAnnotationPresentNative(Class<? extends Annotation> annotationType);

    final Annotation[][] getParameterAnnotationsInternal() {
        Annotation[][] parameterAnnotations = getParameterAnnotationsNative();
        if (parameterAnnotations == null) {
            parameterAnnotations = new Annotation[getParameterTypes().length][0];
        }
        return parameterAnnotations;
    }
    @FastNative
    private native Annotation[][] getParameterAnnotationsNative();

    /**
     * @hide - exposed for use by {@link Class}.
     */
    public final int getAccessFlags() {
        return accessFlags;
    }

    /**
     * @hide - exposed for use by {@code java.lang.invoke.*}.
     */
    public final long getArtMethod() {
        return artMethod;
    }

    static final class GenericInfo {
        final ListOfTypes genericExceptionTypes;
        final ListOfTypes genericParameterTypes;
        final Type genericReturnType;
        final TypeVariable<?>[] formalTypeParameters;

        GenericInfo(ListOfTypes exceptions, ListOfTypes parameters, Type ret,
                TypeVariable<?>[] formal) {
            genericExceptionTypes = exceptions;
            genericParameterTypes = parameters;
            genericReturnType = ret;
            formalTypeParameters = formal;
        }
    }

    final boolean hasGenericInformationInternal() {
        return getSignatureAnnotation() != null;
    }

    /**
     * Returns generic information associated with this method/constructor member.
     */
    final GenericInfo getMethodOrConstructorGenericInfoInternal() {
        String signatureAttribute = getSignatureAttribute();
        Class<?>[] exceptionTypes = this.getExceptionTypes();
        GenericSignatureParser parser =
                new GenericSignatureParser(this.getDeclaringClass().getClassLoader());
        if (this instanceof Method) {
            parser.parseForMethod(this, signatureAttribute, exceptionTypes);
        } else {
            parser.parseForConstructor(this, signatureAttribute, exceptionTypes);
        }
        return new GenericInfo(parser.exceptionTypes, parser.parameterTypes,
                parser.returnType, parser.formalTypeParameters);
    }

    private String getSignatureAttribute() {
        String[] annotation = getSignatureAnnotation();
        if (annotation == null) {
            return null;
        }
        StringBuilder result = new StringBuilder();
        for (String s : annotation) {
            result.append(s);
        }
        return result.toString();
    }
    @FastNative
    private native String[] getSignatureAnnotation();

    final boolean equalNameAndParametersInternal(Method m) {
        return getName().equals(m.getName()) && (compareMethodParametersInternal(m) == 0);
    }

    @FastNative
    native int compareMethodParametersInternal(Method meth);

    @FastNative
    final native String getMethodNameInternal();

    @FastNative
    final native Class<?> getMethodReturnTypeInternal();

    /** A cheap implementation for {@link Method#isDefault()}. */
    final boolean isDefaultMethodInternal() {
        return (accessFlags & Modifier.DEFAULT) != 0;
    }

    /** A cheap implementation for {@link Method#isBridge()}. */
    final boolean isBridgeMethodInternal() {
        return (accessFlags & Modifier.BRIDGE) != 0;
    }
}