/*******************************************************************************
 * Copyright (c) 2011 University of Illinois All rights reserved. This program
 * and the accompanying materials are made available under the terms of the
 * Eclipse Public License v1.0 which accompanies this distribution, and is
 * available at http://www.eclipse.org/legal/epl-v10.html 
 * 	
 * Contributors: 
 * 	Albert L. Rossi - design and implementation
 ******************************************************************************/

package org.eclipse.ptp.rm.jaxb.core.data.impl;

import java.lang.reflect.Method;
import java.math.BigInteger;
import java.util.List;

import org.eclipse.ptp.rm.jaxb.core.IAssign;
import org.eclipse.ptp.rm.jaxb.core.IJAXBNonNLSConstants;
import org.eclipse.ptp.rm.jaxb.core.data.AddType;
import org.eclipse.ptp.rm.jaxb.core.data.AppendType;
import org.eclipse.ptp.rm.jaxb.core.data.EntryType;
import org.eclipse.ptp.rm.jaxb.core.data.PutType;
import org.eclipse.ptp.rm.jaxb.core.data.SetType;
import org.eclipse.ptp.rm.jaxb.core.variables.RMVariableMap;

/**
 * Base class for the wrappers around the data objects providing information as
 * to the operations on a target property to be undertaken when there is a
 * match.
 * 
 * @author arossi
 * 
 */
public abstract class AbstractAssign implements IAssign, IJAXBNonNLSConstants {

	protected String uuid;
	protected String field;
	protected Object target;
	protected int index;

	protected AbstractAssign() {
		uuid = null;
		field = null;
		target = null;
		index = 0;
	}

	/**
	 * Applies the assignment.
	 * 
	 * @param values
	 *            from the expression parsing (groups or segments)
	 * @throws Throwable
	 */
	public void assign(String[] values) throws Throwable {
		Object previous = get(target, field);
		set(target, field, getValue(previous, values));
		index++;
	}

	/**
	 * Used in the case of references to targets constructed in connection with
	 * the tokenization. The assumption is that an Assign action will be applied
	 * only once to any given target, in the order of their construction; this
	 * index keeps track of where this particular assign action is in the list.
	 * 
	 * @return the index of the current target
	 */
	public int getIndex() {
		return index;
	}

	/**
	 * @param target
	 *            the current property or attribute
	 */
	public void setTarget(Object target) {
		this.target = target;
	}

	/**
	 * Decides whether the index of the map key is a segment (from
	 * regex.split()) or a regex group number.
	 * 
	 * @param entry
	 *            from the target map
	 * @return the key index
	 */
	protected int determineKeyIndex(EntryType entry) {
		int index = entry.getKeyIndex();
		int group = entry.getKeyGroup();
		if (index == 0 && group != 0) {
			index = group;
		}
		return index;
	}

	/**
	 * Decides whether the index of the map value is a segment (from
	 * regex.split()) or a regex group number.
	 * 
	 * @param entry
	 *            carries the key and value indices
	 * @see org.eclipse.ptp.rm.jaxb.core.data.Entry
	 * @return the value index
	 */
	protected int determineValueIndex(EntryType entry) {
		int index = entry.getValueIndex();
		int group = entry.getValueGroup();
		if (index == 0 && group != 0) {
			index = group;
		}
		return index;
	}

	/**
	 * Find the map key
	 * 
	 * @param entry
	 *            carries the key and value indices
	 * @see org.eclipse.ptp.rm.jaxb.core.data.Entry
	 * @param values
	 *            the parsed result of the expression match
	 * @return key
	 * @throws Throwable
	 */
	protected String getKey(EntryType entry, String[] values) throws Throwable {
		String k = entry.getKey();
		if (k != null) {
			return (String) normalizedValue(target, uuid, k, false);
		}
		int index = determineKeyIndex(entry);
		if (values != null) {
			return values[index];
		}
		return null;
	}

	/**
	 * Find the map value
	 * 
	 * @param entry
	 *            carries the key and value indices
	 * @see org.eclipse.ptp.rm.jaxb.core.data.Entry
	 * @param values
	 *            the parsed result of the expression match
	 * @return value
	 * @throws Throwable
	 */
	protected Object getValue(EntryType entry, String[] values) throws Throwable {
		String v = entry.getValue();
		if (v != null) {
			return normalizedValue(target, uuid, v, true);
		}
		int index = determineValueIndex(entry);
		if (values != null) {
			return values[index];
		}
		return null;
	}

	/**
	 * Method specific to the assign type for retrieving the values from the
	 * matched expression.
	 * 
	 * @param previous
	 *            the value currently assigned to the field of the target in
	 *            question.
	 * @param values
	 *            the parsed result of the expression match
	 * @return the value(s) retrieved from the parsed result
	 * @throws Throwable
	 */
	protected abstract Object[] getValue(Object previous, String[] values) throws Throwable;

	/**
	 * Auxiliary for adding a wrapper implementation.
	 * 
	 * @param uuid
	 *            unique id associated with this resource manager operation (can
	 *            be <code>null</code>).
	 * @param assign
	 *            the JAXB element class.
	 * @param list
	 *            the list of wrappers
	 */
	static void add(String uuid, Object assign, List<IAssign> list) {
		if (assign instanceof AddType) {
			AddType add = (AddType) assign;
			list.add(new AddImpl(uuid, add));
			return;
		}
		if (assign instanceof AppendType) {
			AppendType append = (AppendType) assign;
			list.add(new AppendImpl(uuid, append));
			return;
		}
		if (assign instanceof PutType) {
			PutType put = (PutType) assign;
			list.add(new PutImpl(uuid, put));
			return;
		}
		if (assign instanceof SetType) {
			SetType set = (SetType) assign;
			list.add(new SetImpl(uuid, set));
			return;
		}
	}

	/**
	 * Auxiliary using Java reflection to perform a get on the target.
	 * 
	 * @param target
	 *            Property or Attribute
	 * @param field
	 *            on the target from which to retrieve the value.
	 * @return value of the field
	 * @throws Throwable
	 */
	static Object get(Object target, String field) throws Throwable {
		String name = GET + field.substring(0, 1).toUpperCase() + field.substring(1);
		Method method = null;
		try {
			method = target.getClass().getMethod(name, (Class[]) null);
		} catch (Throwable t) {
			name = IS + field.substring(0, 1).toUpperCase() + field.substring(1);
			method = target.getClass().getMethod(name, (Class[]) null);
		}
		return method.invoke(target, (Object[]) null);
	}

	/**
	 * Determines whether the input represents an object field or a resolvable
	 * expression. Also converts string to int or boolean, if applicable,
	 * 
	 * @param target
	 *            on which to apply the getter.
	 * @param uuid
	 *            unique id associated with this resource manager operation (can
	 *            be <code>null</code>).
	 * @param expression
	 *            input to be interpreted
	 * @param convert
	 *            expression to boolean or int, if applicable.
	 * 
	 * @return value after dereferencing or normalization
	 * @throws Throwable
	 */
	static Object normalizedValue(Object target, String uuid, String expression, boolean convert) throws Throwable {
		if (expression.startsWith(PD)) {
			if (target == null) {
				return null;
			}
			String field = expression.substring(1);
			return AbstractAssign.get(target, field);
		} else if (expression.indexOf(OPENV) >= 0) {
			expression = RMVariableMap.getActiveInstance().getString(uuid, expression);
			return RMVariableMap.getActiveInstance().getString(uuid, expression);
		} else if (convert) {
			if (TRUE.equalsIgnoreCase(expression)) {
				return true;
			}
			if (FALSE.equalsIgnoreCase(expression)) {
				return false;
			}
			try {
				if (expression.indexOf(DOT) >= 0) {
					return new Double(expression);
				}
				return new Integer(expression);
			} catch (NumberFormatException nfe) {
				return expression;
			}
		}
		return expression;
	}

	/**
	 * Auxiliary using Java reflection to perform a set on the target.
	 * 
	 * @param target
	 *            Property or Attribute
	 * @param field
	 *            on the target on which to set the value.
	 * @param values
	 *            corresonding to the parameter(s) of the set method (usually a
	 *            single one)
	 * @throws Throwable
	 */
	static void set(Object target, String field, Object[] values) throws Throwable {
		String name = SET + field.substring(0, 1).toUpperCase() + field.substring(1);
		Method[] methods = target.getClass().getMethods();
		Method setter = null;
		for (Method m : methods) {
			if (m.getName().equals(name)) {
				setter = m;
			}
		}
		if (setter == null) {
			throw new NoSuchMethodException(name + CO + SP + target);
		}
		if (values[0] != null) {
			Class<?>[] mclzz = setter.getParameterTypes();
			// better have 1 parameter
			Class<?> param = mclzz[0];
			Class<?> valueClass = values[0].getClass();
			Throwable t = new IllegalArgumentException(name + SP + valueClass);
			if (!param.equals(Object.class) && !param.isAssignableFrom(values[0].getClass())) {
				if (valueClass.equals(String.class)) {
					if (param.equals(Boolean.class)) {
						values[0] = new Boolean(values[0].toString());
					} else if (param.equals(Integer.class)) {
						values[0] = new Integer(values[0].toString());
					} else if (param.equals(BigInteger.class)) {
						values[0] = new BigInteger(values[0].toString());
					} else {
						throw t;
					}
				} else if (valueClass.equals(Integer.class) || valueClass.equals(BigInteger.class)
						|| valueClass.equals(Boolean.class)) {
					if (param.equals(String.class)) {
						values[0] = values[0].toString();
					} else {
						throw t;
					}
				} else {
					throw t;
				}
			}
		}
		setter.invoke(target, values);
	}
}