/*******************************************************************************
 * Copyright (c) 2005, 2007 IBM Corporation and others.
 * 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
 *
 
 *******************************************************************************/
package org.eclipse.dltk.internal.core;

import java.util.ArrayList;
import java.util.HashMap;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.PlatformObject;
import org.eclipse.dltk.core.IScriptProject;
import org.eclipse.dltk.core.IField;
import org.eclipse.dltk.core.IModelElement;
import org.eclipse.dltk.core.IModelElementVisitor;
import org.eclipse.dltk.core.IModelStatus;
import org.eclipse.dltk.core.IModelStatusConstants;
import org.eclipse.dltk.core.IOpenable;
import org.eclipse.dltk.core.IParent;
import org.eclipse.dltk.core.IScriptModel;
import org.eclipse.dltk.core.ISourceModule;
import org.eclipse.dltk.core.ISourceRange;
import org.eclipse.dltk.core.ISourceReference;
import org.eclipse.dltk.core.ModelException;
import org.eclipse.dltk.core.WorkingCopyOwner;
import org.eclipse.dltk.internal.core.util.MementoTokenizer;
import org.eclipse.dltk.internal.core.util.Util;
import org.eclipse.dltk.utils.CorePrinter;


/**
 * Root of model element handle hierarchy.
 * 
 * @see IModelElement
 */

public abstract class ModelElement extends PlatformObject implements
		IModelElement {
	
	
	public static final char JEM_ESCAPE = '\\';
	public static final char JEM_SCRIPTPROJECT = '=';
	public static final char JEM_PROJECTFRAGMENT = '/';	
	public static final char JEM_SCRIPTFOLDER = '<';	
	public static final char JEM_FIELD = '^';
	public static final char JEM_METHOD = '~';	
	public static final char JEM_SOURCEMODULE = '{';		
	public static final char JEM_TYPE = '[';	
	public static final char JEM_IMPORTDECLARATION = '#';
	public static final char JEM_COUNT = '!';
	public static final char JEM_LOCALVARIABLE = '@';
	public static final char JEM_TYPE_PARAMETER = ']';
	public static final char JEM_PACKAGEDECLARATION = '%';
	
	// Used to replace path / or \\ symbols in external package names and archives.
	public static final char JEM_SKIP_DELIMETER= '>';


	/**
	 * This element's parent, or <code>null</code> if this element does not
	 * have a parent.
	 */
	protected ModelElement parent;
	
	protected static final ModelElement[] NO_ELEMENTS = new ModelElement[0];
	protected static final Object NO_INFO = new Object();
	

	/**
	 * Constructs a handle for a model element with
	 * the given parent element.
	 *
	 * @param parent The parent of model element
	 *
	 * @exception IllegalArgumentException if the type is not one of the valid
	 *		model element type constants
	 *
	 */
	protected ModelElement(ModelElement parent) throws IllegalArgumentException {
		this.parent = parent;
	}
	

	/**
	 * @see IModelElement
	 */
	public boolean exists() {
		
		try {
			getElementInfo();
			return true;
		} catch (ModelException e) {
			// element doesn't exist: return false
		}
		return false;
	}
	
	/**
	 * @see IModelElement
	 */
	public IModelElement getAncestor(int ancestorType) {
		
		IModelElement element = this;
		while (element != null) {
			if (element.getElementType() == ancestorType)  return element;
			element= element.getParent();
		}
		return null;				
	}	
	
	/**
	 * @see IOpenable
	 */
	public void close() throws ModelException {
		ModelManager.getModelManager().removeInfoAndChildren(this);
	}
	
	/**
	 * This element is being closed.  Do any necessary cleanup.
	 */
	protected abstract void closing(Object info) throws ModelException;
	
	/**
	 * Returns the info for this handle.  
	 * If this element is not already open, it and all of its parents are opened.
	 * Does not return null.
	 * NOTE: BinaryType infos are NOT rooted under ModelElementInfo.
	 * @exception ModelException if the element is not present or not accessible
	 */
	public Object getElementInfo() throws ModelException {
		return getElementInfo(null);
	}
	
	/**
	 * Returns the info for this handle.  
	 * If this element is not already open, it and all of its parents are opened.
	 * Does not return null.
	 * NOTE: BinaryType infos are NOT rooted under ModelElementInfo.
	 * @exception ModelException if the element is not present or not accessible
	 */
	public Object getElementInfo(IProgressMonitor monitor) throws ModelException {

		ModelManager manager = ModelManager.getModelManager();
		Object info = manager.getInfo(this);
		if (info != null) return info;
		return openWhenClosed(createElementInfo(), monitor);
	}
	
	/*
	 * Opens an <code>Openable</code> that is known to be closed (no check for <code>isOpen()</code>).
	 * Returns the created element info.
	 */
	protected Object openWhenClosed(Object info, IProgressMonitor monitor) throws ModelException {
		ModelManager manager = ModelManager.getModelManager();
		boolean hadTemporaryCache = manager.hasTemporaryCache();
		try {
			HashMap newElements = manager.getTemporaryCache();
			generateInfos(info, newElements, monitor);
			if (info == null) {
				info = newElements.get(this);
			}
			if (info == null) { // a source ref element could not be opened
				// close the buffer that was opened for the openable parent
			    // close only the openable's buffer (see https://bugs.eclipse.org/bugs/show_bug.cgi?id=62854)
			    Openable openable = (Openable) getOpenable();
			    if (newElements.containsKey(openable)) {
			        openable.closeBuffer();
			    }
				throw newNotPresentException();
			}
			if (!hadTemporaryCache) {
				manager.putInfos(this, newElements);
			}
		} finally {
			if (!hadTemporaryCache) {
				manager.resetTemporaryCache();
			}
		}
		return info;
	}
	
	/*
	 * @see IModelElement
	 */
	public IOpenable getOpenable() {
		return this.getOpenableParent();	
	}
	
	
	/**
	 * Return the first instance of IOpenable in the parent
	 * hierarchy of this element.
	 *
	 * <p>Subclasses that are not IOpenable's must override this method.
	 */
	public IOpenable getOpenableParent() {
		return (IOpenable)this.parent;
	}
	
	/**
	 * @see IModelElement
	 */
	public IModelElement getParent() {
		return this.parent;
	}
	
	/*
	 * Returns a new element info for this element.
	 */
	protected abstract Object createElementInfo();
	
	/**
	 * Generates the element infos for this element, its ancestors (if they are not opened) and its children (if it is an Openable).
	 * Puts the newly created element info in the given map.
	 */
	protected abstract void generateInfos(Object info, HashMap newElements, IProgressMonitor pm) throws ModelException;
	
	/**
	 * @see IAdaptable
	 */
	public String getElementName() {
		return ""; //$NON-NLS-1$
	}
	
	/**
	 * Creates and returns a new not present exception for this element.
	 */
	public ModelException newNotPresentException() {
		return new ModelException(new ModelStatus(IModelStatusConstants.ELEMENT_DOES_NOT_EXIST, this));
	}
	
	/**
	 * Returns true if this handle represents the same model element
	 * as the given handle. By default, two handles represent the same
	 * element if they are identical or if they represent the same type
	 * of element, have equal names, parents, and occurrence counts.
	 *
	 * <p>If a subclass has other requirements for equality, this method
	 * must be overridden.
	 *
	 * @see Object#equals
	 */
	public boolean equals(Object o) {
		
		if (this == o) return true;
	
		// model parent is null
		if (this.parent == null) return super.equals(o);
	
		// assume instanceof check is done in subclass
		ModelElement other = (ModelElement) o;		
		return getElementName().equals(other.getElementName()) &&
				this.parent.equals(other.parent);
	}
	
	/**
	 * Returns the hash code for this model element. By default,
	 * the hash code for an element is a combination of its name
	 * and parent's hash code. Elements with other requirements must
	 * override this method.
	 */
	public int hashCode() {
		if (this.parent == null) return super.hashCode();
		return Util.combineHashCodes(getElementName().hashCode(), this.parent.hashCode());
	}
	
	/**
	 * Returns true if this element is an ancestor of the given element,
	 * otherwise false.
	 */
	public boolean isAncestorOf(IModelElement e) {
		IModelElement parentElement= e.getParent();
		while (parentElement != null && !parentElement.equals(this)) {
			parentElement= parentElement.getParent();
		}
		return parentElement != null;
	}
	
	/**
	 * @see IModelElement
	 */
	public boolean isReadOnly() {
		return false;
	}
	
	/**
	 * Returns a collection of (immediate) children of this node of the
	 * specified type.
	 *
	 * @param type - one of the EM_* constants defined by ModelElement
	 */
	protected ArrayList getChildrenOfType(int type) throws ModelException {
		IModelElement[] children = getChildren();
		int size = children.length;
		ArrayList list = new ArrayList(size);
		for (int i = 0; i < size; ++i) {
			ModelElement elt = (ModelElement)children[i];
			if (elt.getElementType() == type) {
				list.add(elt);
			}
		}
		return list;
	}
	
	/**
	 * @see IParent 
	 */
	public IModelElement[] getChildren() throws ModelException {
		Object elementInfo = getElementInfo();
		if (elementInfo instanceof ModelElementInfo) {
			return ((ModelElementInfo)elementInfo).getChildren();
		} else {
			return NO_ELEMENTS;
		}
	}	
	
	/**
	 * @see IModelElement
	 */
	public IScriptModel getModel() {
		IModelElement current = this;
		do {
			if (current instanceof IScriptModel) return (IScriptModel) current;
		} while ((current = current.getParent()) != null);
		return null;
	}

	/**
	 * Creates and returns a new model exception for this element with the given status.
	 */
	public ModelException newModelException(IStatus status) {
		if (status instanceof IModelStatus)
			return new ModelException((IModelStatus) status);
		else
			return new ModelException(new ModelStatus(status.getSeverity(), status.getCode(), status.getMessage()));
	}
	
	/**
	 * @see IModelElement
	 */
	public IScriptProject getScriptProject() {
		IModelElement current = this;
		do {
			if (current instanceof IScriptProject) return (IScriptProject) current;
		} while ((current = current.getParent()) != null);
		return null;
	}
	
	public boolean hasChildren() throws ModelException {
		// if I am not open, return true to avoid opening (case of a project, a source module or a binary file).
		Object elementInfo = ModelManager.getModelManager().getInfo(this);
		if (elementInfo instanceof ModelElementInfo) {
			return ((ModelElementInfo)elementInfo).getChildren().length > 0;
		} else {
			return true;
		}
	}
	
	/**
	 * Debugging purposes
	 */	
	protected String tabString(int tab) {
		StringBuffer buffer = new StringBuffer();
		for (int i = tab; i > 0; i--)
			buffer.append("  "); //$NON-NLS-1$
		return buffer.toString();
	}
	
	/**
	 * Debugging purposes
	 */
	public String toDebugString() {
		StringBuffer buffer = new StringBuffer();
		this.toStringInfo(0, buffer, NO_INFO, true/*show resolved info*/);
		return buffer.toString();
	}
	/**
	 *  Debugging purposes
	 */
	public String toString() {
		StringBuffer buffer = new StringBuffer();
		toString(0, buffer);
		return buffer.toString();
	}
	/**
	 *  Debugging purposes
	 */
	protected void toString(int tab, StringBuffer buffer) {
		Object info = this.toStringInfo(tab, buffer);
		if (tab == 0) {
			this.toStringAncestors(buffer);
		}
		this.toStringChildren(tab, buffer, info);
	}
	/**
	 *  Debugging purposes
	 */
	public String toStringWithAncestors() {
		return toStringWithAncestors(true/*show resolved info*/);
	}
		/**
	 *  Debugging purposes
	 */
	public String toStringWithAncestors(boolean showResolvedInfo) {
		StringBuffer buffer = new StringBuffer();
		this.toStringInfo(0, buffer, NO_INFO, showResolvedInfo);
		this.toStringAncestors(buffer);
		return buffer.toString();
	}
	/**
	 *  Debugging purposes
	 */
	protected void toStringAncestors(StringBuffer buffer) {
		ModelElement parentElement = (ModelElement)this.getParent();
		if (parentElement != null && parentElement.getParent() != null) {
			buffer.append(" [in "); //$NON-NLS-1$
			parentElement.toStringInfo(0, buffer, NO_INFO, false/*don't show resolved info*/);
			parentElement.toStringAncestors(buffer);
			buffer.append("]"); //$NON-NLS-1$
		}
	}
	/**
	 *  Debugging purposes
	 */
	protected void toStringChildren(int tab, StringBuffer buffer, Object info) {
		if (info == null || !(info instanceof ModelElementInfo)) return;
		IModelElement[] children = ((ModelElementInfo)info).getChildren();
		for (int i = 0; i < children.length; i++) {
			buffer.append("\n"); //$NON-NLS-1$
			((ModelElement)children[i]).toString(tab + 1, buffer);
		}
	}
	/**
	 *  Debugging purposes
	 */
	public Object toStringInfo(int tab, StringBuffer buffer) {
		Object info = ModelManager.getModelManager().peekAtInfo(this);
		this.toStringInfo(tab, buffer, info, true/*show resolved info*/);
		return info;
	}
	/**
	 *  Debugging purposes
	 * @param showResolvedInfo TODO
	 */
	protected void toStringInfo(int tab, StringBuffer buffer, Object info, boolean showResolvedInfo) {
		buffer.append(this.tabString(tab));
		toStringName(buffer);
		if (info == null) {
			buffer.append(" (not open)"); //$NON-NLS-1$
		}
	}
	/**
	 *  Debugging purposes
	 */
	protected void toStringName(StringBuffer buffer) {
		buffer.append(getElementName());
	}
	
	/**
	 * Returns the element that is located at the given source position
	 * in this element.  This is a helper method for <code>ISourceModule#getElementAt</code>,
	 * and only works on compilation units and types. The position given is
	 * known to be within this element's source range already, and if no finer
	 * grained element is found at the position, this element is returned.
	 */
	protected IModelElement getSourceElementAt(int position) throws ModelException {
		IModelElement res = getSourceElementAtTop(position);
		if (res != this)
			return res;
		
		if (this instanceof ISourceReference) {
			IModelElement[] children = getChildren();
			for (int i = children.length-1; i >= 0; i--) {
				IModelElement aChild = children[i];
				if (aChild instanceof SourceRefElement) {
					SourceRefElement child = (SourceRefElement) children[i];
					if (child instanceof IParent) {
						res =  child.getSourceElementAt(position);
						if (res != child)
							return res;
					}
				}
			}
		} else {
			// should not happen
			Assert.isTrue(false);
		}
		return this;
	}
	
	/**
	 * Returns the element that is located at the given source position
	 * in this element.  This is a helper method for <code>ISourceModule#getElementAt</code>,
	 * and only works on compilation units and types. The position given is
	 * known to be within this element's source range already, and if no finer
	 * grained element is found at the position, this element is returned.
	 */
	protected IModelElement getSourceElementAtTop(int position) throws ModelException {
		if (this instanceof ISourceReference) {
			IModelElement[] children = getChildren();
			for (int i = children.length-1; i >= 0; i--) {
				IModelElement aChild = children[i];
				if (aChild instanceof SourceRefElement) {
					SourceRefElement child = (SourceRefElement) children[i];
					ISourceRange range = child.getSourceRange();
					int start = range.getOffset();
					int end = start + range.getLength();
					if (start <= position && position <= end) {
						if (child instanceof IField) {
							// check muti-declaration case (see https://bugs.eclipse.org/bugs/show_bug.cgi?id=39943)
							int declarationStart = start;
							SourceRefElement candidate = null;
							do {
								// check name range
								range = ((IField)child).getNameRange();
								if (position <= range.getOffset() + range.getLength()) {
									candidate = child;
								} else {
									return candidate == null ? child.getSourceElementAt(position) : candidate.getSourceElementAt(position);
								}
								child = --i>=0 ? (SourceRefElement) children[i] : null;
							} while (child != null && child.getSourceRange().getOffset() == declarationStart);
							// position in field's type: use first field
							return candidate.getSourceElementAt(position);
						} else if (child instanceof IParent) {
							return child.getSourceElementAt(position);
						} else {
							return child;
						}
					}
				}
			}
		} else {
			// should not happen
			Assert.isTrue(false);
		}
		return this;
	}
	
	/**
	 * Only for testing.
	 * 
	 * Used to print this node with all sub childs.
	 * @param output
	 */
	public abstract void printNode( CorePrinter output );
	
	/*
	 * @see IModelElement#getPrimaryElement()
	 */
	public IModelElement getPrimaryElement() {
		return getPrimaryElement(true);
	}
	/*
	 * Returns the primary element. If checkOwner, and the cu owner is primary,
	 * return this element.
	 */
	public IModelElement getPrimaryElement(boolean checkOwner) {
		return this;
	}
	
	public IModelElement getHandleFromMemento(MementoTokenizer memento, WorkingCopyOwner owner) {
		if (!memento.hasMoreTokens()) return this;
		String token = memento.nextToken();
		return getHandleFromMemento(token, memento, owner);
	}
	public abstract IModelElement getHandleFromMemento(String token, MementoTokenizer memento, WorkingCopyOwner owner);
	
	public String getHandleIdentifier() {
		return getHandleMemento();
	}
	public String getHandleMemento(){
		StringBuffer buff = new StringBuffer();
		getHandleMemento(buff);
		return buff.toString();
	}
	protected void getHandleMemento(StringBuffer buff) {
		((ModelElement)getParent()).getHandleMemento(buff);
		buff.append(getHandleMementoDelimiter());
		escapeMementoName(buff, getElementName());
	}
	protected abstract char getHandleMementoDelimiter();
	protected void escapeMementoName(StringBuffer buffer, String mementoName) {
		for (int i = 0, length = mementoName.length(); i < length; i++) {
			char character = mementoName.charAt(i);
			switch (character) {
				case JEM_ESCAPE:
				case JEM_COUNT:
				case JEM_SCRIPTPROJECT:
				case JEM_PROJECTFRAGMENT:
				case JEM_SCRIPTFOLDER:
				case JEM_FIELD:
				case JEM_METHOD:				
				case JEM_SOURCEMODULE:	
				case JEM_TYPE:				
				case JEM_IMPORTDECLARATION:
				case JEM_LOCALVARIABLE:
				case JEM_TYPE_PARAMETER:
					buffer.append(JEM_ESCAPE);
			}
			buffer.append(character);
		}
	}
	public ISourceModule getSourceModule() {
		return null;
	}
	public void accept( IModelElementVisitor visitor ) throws ModelException {
		if( visitor.visit(this) ) {
			IModelElement[] elements = getChildren();
			for( int i = 0; i < elements.length; ++i ) {
				elements[i].accept(visitor);
			}
		}
	}
}
