/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */
package org.apache.bcel.generic;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

import org.apache.bcel.Const;
import org.apache.bcel.classfile.AnnotationEntry;
import org.apache.bcel.classfile.Annotations;
import org.apache.bcel.classfile.Attribute;
import org.apache.bcel.classfile.Constant;
import org.apache.bcel.classfile.ConstantObject;
import org.apache.bcel.classfile.ConstantPool;
import org.apache.bcel.classfile.ConstantValue;
import org.apache.bcel.classfile.Field;
import org.apache.bcel.classfile.Utility;
import org.apache.bcel.util.BCELComparator;

Template class for building up a field.  The only extraordinary thing
one can do is to add a constant value attribute to a field (which must of
course be compatible with to the declared type).
See Also:
Field/**
 * Template class for building up a field.  The only extraordinary thing
 * one can do is to add a constant value attribute to a field (which must of
 * course be compatible with to the declared type).
 *
 * @see Field
 */
public class FieldGen extends FieldGenOrMethodGen {

    private Object value = null;
    private static BCELComparator bcelComparator = new BCELComparator() {

        @Override
        public boolean equals( final Object o1, final Object o2 ) {
            final FieldGen THIS = (FieldGen) o1;
            final FieldGen THAT = (FieldGen) o2;
            return Objects.equals(THIS.getName(), THAT.getName())
                    && Objects.equals(THIS.getSignature(), THAT.getSignature());
        }


        @Override
        public int hashCode( final Object o ) {
            final FieldGen THIS = (FieldGen) o;
            return THIS.getSignature().hashCode() ^ THIS.getName().hashCode();
        }
    };


    
Declare a field. If it is static (isStatic() == true) and has a
basic type like int or String it may have an initial value
associated with it as defined by setInitValue().
Params:
access_flags – access qualifiers
type –  field type
name – field name
cp – constant pool/**
     * Declare a field. If it is static (isStatic() == true) and has a
     * basic type like int or String it may have an initial value
     * associated with it as defined by setInitValue().
     *
     * @param access_flags access qualifiers
     * @param type  field type
     * @param name field name
     * @param cp constant pool
     */
    public FieldGen(final int access_flags, final Type type, final String name, final ConstantPoolGen cp) {
        super(access_flags);
        setType(type);
        setName(name);
        setConstantPool(cp);
    }


    
Instantiate from existing field.
Params:
field – Field object
cp – constant pool (must contain the same entries as the field's constant pool)/**
     * Instantiate from existing field.
     *
     * @param field Field object
     * @param cp constant pool (must contain the same entries as the field's constant pool)
     */
    public FieldGen(final Field field, final ConstantPoolGen cp) {
        this(field.getAccessFlags(), Type.getType(field.getSignature()), field.getName(), cp);
        final Attribute[] attrs = field.getAttributes();
        for (final Attribute attr : attrs) {
            if (attr instanceof ConstantValue) {
                setValue(((ConstantValue) attr).getConstantValueIndex());
            } else if (attr instanceof Annotations) {
                final Annotations runtimeAnnotations = (Annotations)attr;
                final AnnotationEntry[] annotationEntries = runtimeAnnotations.getAnnotationEntries();
                for (final AnnotationEntry element : annotationEntries) {
                    addAnnotationEntry(new AnnotationEntryGen(element,cp,false));
                }
            } else {
                addAttribute(attr);
            }
        }
    }


    private void setValue( final int index ) {
        final ConstantPool cp = super.getConstantPool().getConstantPool();
        final Constant c = cp.getConstant(index);
        value = ((ConstantObject) c).getConstantValue(cp);
    }


    
Set (optional) initial value of field, otherwise it will be set to null/0/false
by the JVM automatically.
/**
     * Set (optional) initial value of field, otherwise it will be set to null/0/false
     * by the JVM automatically.
     */
    public void setInitValue( final String str ) {
        checkType(  ObjectType.getInstance("java.lang.String"));
        if (str != null) {
            value = str;
        }
    }


    public void setInitValue( final long l ) {
        checkType(Type.LONG);
        if (l != 0L) {
            value = Long.valueOf(l);
        }
    }


    public void setInitValue( final int i ) {
        checkType(Type.INT);
        if (i != 0) {
            value = Integer.valueOf(i);
        }
    }


    public void setInitValue( final short s ) {
        checkType(Type.SHORT);
        if (s != 0) {
            value = Integer.valueOf(s);
        }
    }


    public void setInitValue( final char c ) {
        checkType(Type.CHAR);
        if (c != 0) {
            value = Integer.valueOf(c);
        }
    }


    public void setInitValue( final byte b ) {
        checkType(Type.BYTE);
        if (b != 0) {
            value = Integer.valueOf(b);
        }
    }


    public void setInitValue( final boolean b ) {
        checkType(Type.BOOLEAN);
        if (b) {
            value = Integer.valueOf(1);
        }
    }


    public void setInitValue( final float f ) {
        checkType(Type.FLOAT);
        if (f != 0.0) {
            value = new Float(f);
        }
    }


    public void setInitValue( final double d ) {
        checkType(Type.DOUBLE);
        if (d != 0.0) {
            value = new Double(d);
        }
    }


    
Remove any initial value.
/** Remove any initial value.
     */
    public void cancelInitValue() {
        value = null;
    }


    private void checkType( final Type atype ) {
        final Type superType = super.getType();
        if (superType == null) {
            throw new ClassGenException("You haven't defined the type of the field yet");
        }
        if (!isFinal()) {
            throw new ClassGenException("Only final fields may have an initial value!");
        }
        if (!superType.equals(atype)) {
            throw new ClassGenException("Types are not compatible: " + superType + " vs. " + atype);
        }
    }


    
Get field object after having set up all necessary values.
/**
     * Get field object after having set up all necessary values.
     */
    public Field getField() {
        final String signature = getSignature();
        final int name_index = super.getConstantPool().addUtf8(super.getName());
        final int signature_index = super.getConstantPool().addUtf8(signature);
        if (value != null) {
            checkType(super.getType());
            final int index = addConstant();
            addAttribute(new ConstantValue(super.getConstantPool().addUtf8("ConstantValue"), 2, index,
                    super.getConstantPool().getConstantPool())); // sic
        }
        addAnnotationsAsAttribute(super.getConstantPool());
        return new Field(super.getAccessFlags(), name_index, signature_index, getAttributes(),
                super.getConstantPool().getConstantPool()); // sic
    }

    private void addAnnotationsAsAttribute(final ConstantPoolGen cp) {
          final Attribute[] attrs = AnnotationEntryGen.getAnnotationAttributes(cp, super.getAnnotationEntries());
        for (final Attribute attr : attrs) {
            addAttribute(attr);
        }
      }


    private int addConstant() {
        switch (super.getType().getType()) { // sic
            case Const.T_INT:
            case Const.T_CHAR:
            case Const.T_BYTE:
            case Const.T_BOOLEAN:
            case Const.T_SHORT:
                return super.getConstantPool().addInteger(((Integer) value).intValue());
            case Const.T_FLOAT:
                return super.getConstantPool().addFloat(((Float) value).floatValue());
            case Const.T_DOUBLE:
                return super.getConstantPool().addDouble(((Double) value).doubleValue());
            case Const.T_LONG:
                return super.getConstantPool().addLong(((Long) value).longValue());
            case Const.T_REFERENCE:
                return super.getConstantPool().addString((String) value);
            default:
                throw new RuntimeException("Oops: Unhandled : " + super.getType().getType()); // sic
        }
    }


    @Override
    public String getSignature() {
        return super.getType().getSignature();
    }

    private List<FieldObserver> observers;


    
Add observer for this object.
/** Add observer for this object.
     */
    public void addObserver( final FieldObserver o ) {
        if (observers == null) {
            observers = new ArrayList<>();
        }
        observers.add(o);
    }


    
Remove observer for this object.
/** Remove observer for this object.
     */
    public void removeObserver( final FieldObserver o ) {
        if (observers != null) {
            observers.remove(o);
        }
    }


    
Call notify() method on all observers. This method is not called
automatically whenever the state has changed, but has to be
called by the user after he has finished editing the object.
/** Call notify() method on all observers. This method is not called
     * automatically whenever the state has changed, but has to be
     * called by the user after he has finished editing the object.
     */
    public void update() {
        if (observers != null) {
            for (final FieldObserver observer : observers ) {
                observer.notify(this);
            }
        }
    }


    public String getInitValue() {
        if (value != null) {
            return value.toString();
        }
        return null;
    }


    
Return string representation close to declaration format,
`public static final short MAX = 100', e.g..
Returns:
String representation of field/**
     * Return string representation close to declaration format,
     * `public static final short MAX = 100', e.g..
     *
     * @return String representation of field
     */
    @Override
    public final String toString() {
        String name;
        String signature;
        String access; // Short cuts to constant pool
        access = Utility.accessToString(super.getAccessFlags());
        access = access.isEmpty() ? "" : (access + " ");
        signature = super.getType().toString();
        name = getName();
        final StringBuilder buf = new StringBuilder(32); // CHECKSTYLE IGNORE MagicNumber
        buf.append(access).append(signature).append(" ").append(name);
        final String value = getInitValue();
        if (value != null) {
            buf.append(" = ").append(value);
        }
        return buf.toString();
    }


    
Returns:
deep copy of this field/** @return deep copy of this field
     */
    public FieldGen copy( final ConstantPoolGen cp ) {
        final FieldGen fg = (FieldGen) clone();
        fg.setConstantPool(cp);
        return fg;
    }


    
Returns:
Comparison strategy object/**
     * @return Comparison strategy object
     */
    public static BCELComparator getComparator() {
        return bcelComparator;
    }


    
Params:
comparator – Comparison strategy object/**
     * @param comparator Comparison strategy object
     */
    public static void setComparator( final BCELComparator comparator ) {
        bcelComparator = comparator;
    }


    
Return value as defined by given BCELComparator strategy.
By default two FieldGen objects are said to be equal when
their names and signatures are equal.
See Also:
equals.equals(Object)/**
     * Return value as defined by given BCELComparator strategy.
     * By default two FieldGen objects are said to be equal when
     * their names and signatures are equal.
     *
     * @see java.lang.Object#equals(java.lang.Object)
     */
    @Override
    public boolean equals( final Object obj ) {
        return bcelComparator.equals(this, obj);
    }


    
Return value as defined by given BCELComparator strategy.
By default return the hashcode of the field's name XOR signature.
See Also:
hashCode.hashCode()/**
     * Return value as defined by given BCELComparator strategy.
     * By default return the hashcode of the field's name XOR signature.
     *
     * @see java.lang.Object#hashCode()
     */
    @Override
    public int hashCode() {
        return bcelComparator.hashCode(this);
    }
}