package nl.tudelft.simulation.dsol.interpreter;

import nl.tudelft.simulation.dsol.interpreter.classfile.LocalVariableDescriptor;

/**
 * Each frame (<a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-2.html#jvms-2.6">par 2.6</a>) contains
 * an array of variables known as its local variables. The length of the local variable array of a frame is determined
 * at compile time and supplied in the binary representation of a class or interface along with the code for the method
 * associated with the frame (<a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.3">par
 * 4.7.3</a>). A single local variable can hold a value of type boolean, byte, char, short, int, float, reference, or
 * returnAddress. A pair of local variables can hold a value of type long or double.
 * <p>
 * Local variables are addressed by indexing. The index of the first local variable is zero. An integer is be considered
 * to be an index into the local variable array if and only if that integer is between zero and one less than the size
 * of the local variable array.
 * </p>
 * <p>
 * Copyright (c) 2002-2018 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights
 * reserved. See for project information <a href="https://simulation.tudelft.nl/" target="_blank">
 * https://simulation.tudelft.nl</a>. The DSOL project is distributed under a three-clause BSD-style license, which can
 * be found at <a href="https://simulation.tudelft.nl/dsol/3.0/license.html" target="_blank">
 * https://simulation.tudelft.nl/dsol/3.0/license.html</a>.
 * </p>
 * @author <a href="https://www.linkedin.com/in/peterhmjacobs">Peter Jacobs</a>
 * @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
 * @since 1.5
 */
public class LocalVariable implements Cloneable
{
    /** the localVariableDescriptor. */
    private final LocalVariableDescriptor localVariableDescriptor;

    /** the runtime value of the localVariable. */
    private Object value = null;

    /**
     * constructs a new LocalVariable.
     * @param localVariableDescriptor LocalVariableDescriptor; the descriptor
     */
    public LocalVariable(final LocalVariableDescriptor localVariableDescriptor)
    {
        this.localVariableDescriptor = localVariableDescriptor;
    }

    /**
     * @return Returns the localVariableDescriptor.
     */
    public final LocalVariableDescriptor getLocalVariableDescriptor()
    {
        return this.localVariableDescriptor;
    }

    /**
     * @return Returns the value.
     */
    public final synchronized Object getValue()
    {
        return this.value;
    }

    /**
     * @param value Object; The value to set.
     */
    public final synchronized void setValue(final Object value)
    {
        this.value = value;
    }

    /** {@inheritDoc} */
    @Override
    public String toString()
    {
        String result = "variable";
        if (this.localVariableDescriptor != null)
        {
            result = result + " descriptor=" + this.localVariableDescriptor.toString();
        }
        if (this.value != null)
        {
            String valueString = null;
            if (this.value instanceof StringBuffer)
            {
                valueString = StringBuffer.class.getName();
            }
            else
            {
                valueString = this.value.toString();
            }
            result = result + valueString;
        }
        return result;
    }

    /**
     * creates a new array of local variables.
     * @param descriptors LocalVariableDescriptor[]; the descriptors
     * @return LocalVariable[]
     */
    public static LocalVariable[] newInstance(final LocalVariableDescriptor[] descriptors)
    {
        LocalVariable[] result = new LocalVariable[descriptors.length];
        for (int i = 0; i < result.length; i++)
        {
            result[i] = new LocalVariable(descriptors[i]);
        }
        return result;
    }

    /**
     * replaces the value of a local variable.
     * @param localVariables LocalVariable[]; the set to introspect
     * @param oldValue Object; the oldValue
     * @param newValue Object; the new value
     */
    public static void replace(final LocalVariable[] localVariables, final Object oldValue, final Object newValue)
    {
        synchronized (localVariables)
        {
            for (int i = 0; i < localVariables.length; i++)
            {
                if (oldValue.equals(localVariables[i].getValue()))
                {
                    localVariables[i].setValue(newValue);
                }
            }
        }
    }

    /**
     * parses the localVariables to string.
     * @param localVariables LocalVariable[]; the localVariables
     * @return String the result
     */
    public static String toString(final LocalVariable[] localVariables)
    {
        String result = "";
        for (int i = 0; i < localVariables.length; i++)
        {
            result = result + i + ": " + localVariables[i].toString() + "\n";
        }
        return result;
    }

    /** {@inheritDoc} */
    @Override
    public Object clone()
    {
        LocalVariable result = new LocalVariable(this.localVariableDescriptor);
        result.value = this.value;
        return result;
    }

}