/*******************************************************************************
 * Copyright (c) 2010 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
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.wst.sse.ui.internal.comment;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITypedRegion;
import org.eclipse.jface.text.Region;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocument;
import org.eclipse.wst.sse.ui.internal.Logger;

/**
 * <p>Defines a commenting strategy defined by the <code>org.eclipse.wst.sse.ui.commentinStrategy</code>
 * extension point and tracked by the {@link CommentingStrategyRegistry}.  Though it is important to
 * note it is not a one to one relationship of {@link CommentingStrategy}s to extensions, there is actually
 * one {@link CommentingStrategy} for each content type defined for each 
 * <code>org.eclipse.wst.sse.ui.commentinStrategy</code> extension.<p>
 * 
 * <p>The expected use case is that a {@link CommentingStrategy} is created off the basic configuration
 * of the extension point and then cloned for each associated content type and then each clone has
 * its partition information set using {@link #setPartitionInformation}.
 * Then the {@link CommentingStrategyRegistry} can be used to retrieve applicable {@link CommentingStrategy}s
 * and apply them to documents.</p>
 * 
 * <p>It is important to note that any instance of a {@link CommentingStrategy} is only valid for a specific
 * content type ID but this relationship is tracked by the {@link CommentingStrategyRegistry} and not by
 * the strategy itself.  Thus any reference to the strategy being valid for specific or general partition
 * types is implying it is already only valid for a specific content type</p>
 */
public abstract class CommentingStrategy {
	/** <code>true</code> if this strategy has any required partition types, <code>false</code> otherwise */
	private boolean fHasRequiredPartitionTypes;
	
	/**
	 * <p>required partition type IDs that must be seen for this strategy to be valid, the number of them
	 * that must be seen for the strategy to be valid is determined by {@link #fRequireAllRequiredPartitionTypes}
	 * this requirement is waved if the optional {@link #fAssociatedCommentPartitionTypeID} is specified and
	 * present because this strategy must be valid if its {@link #fAssociatedCommentPartitionTypeID} is present</p>
	 * 
	 * @see #fRequireAllRequiredPartitionTypes
	 * @see #fAssociatedCommentPartitionTypeID
	 */
	private List fRequriedPartitionTypeIDs;
	
	/**
	 * <p>if <code>true</code> then {@link #fAllowablePartitionTypeIDs} is ignored because
	 * this strategy is valid for any partition type, if <code>false</code> then this
	 * strategy is only valid for those partition types listed in {@link #fAllowablePartitionTypeIDs}</p>
	 * 
	 * @see #fAllowablePartitionTypeIDs
	 */
	private boolean fAllPartitionTypesAllowable;
	
	/**
	 * <p>the partition types that this strategy is valid for, it is also automatically valid for
	 * any partition types listed in {@link #fRequriedPartitionTypeIDs} and the optionally
	 * specified {@link #fAssociatedCommentPartitionTypeID}</p>
	 * 
	 * @see #fAllPartitionTypesAllowable
	 * @see #fRequriedPartitionTypeIDs
	 * @see #fAssociatedCommentPartitionTypeID
	 */
	private List fAllowablePartitionTypeIDs;
	
	/**
	 * an optional associated comment partition type ID, if this partition type is seen then the
	 * the {@link #fRequriedPartitionTypeIDs} requirement is waved as to weather this strategy is
	 * valid or not
	 * 
	 * @see #fRequriedPartitionTypeIDs
	 */
	private String fAssociatedCommentPartitionTypeID;
	
	/**
	 * <p>Default constructor, the specific initialization is done by
	 * {@link #setPartitionInformation}</p>
	 */
	public CommentingStrategy() {
		this.fAssociatedCommentPartitionTypeID = null;
		this.fRequriedPartitionTypeIDs = Collections.EMPTY_LIST;
		this.fAllowablePartitionTypeIDs = Collections.EMPTY_LIST;
		this.fHasRequiredPartitionTypes = false;
		this.fAllPartitionTypesAllowable = false;
	}
	
	/**
	 * <p>Used to set up the partition information for this strategy</p>
	 * <p>This information is used to determine if a strategy is valid for a set of
	 * {@link ITypedRegion}s.</p>
	 * 
	 * @param allowablePartitionTypeIDs the partition types this strategy is valid for, the strategy will also
	 * be considered valid for any of the required partition types
	 * @param allPartitionTypesAllowable if <code>true</code> then this strategy is valid for any partition types
	 * thus ignoring the <code>allowablePartitionTypeIDs</code>, <code>false</code> otherwise
	 * @param requiredPartitionTypeIDs partition type IDs that must be seen for this strategy to be valid, there
	 * are exceptions to this rule, see {@link #isApplicableFor(ITypedRegion[])}
	 * @param requireAllRequiredPartitionTypes <code>true</code> if all of the <code>requiredPartitionTypeIDs must
	 * be seen for this strategy to be valid, <code>false</code> otherwise, there are exceptions to these rules, see
	 * {@link #isApplicableFor(ITypedRegion[])}
	 * @param associatedCommentPartitionTypeID optional comment partition type associated with this strategy,
	 * maybe <code>null</code>
	 * 
	 * @see #isApplicableFor(ITypedRegion[])
	 */
	protected final void setPartitionInformation(List allowablePartitionTypeIDs, boolean allPartitionTypesAllowable,
			List requiredPartitionTypeIDs, String associatedCommentPartitionTypeID) {
		
		this.fAllPartitionTypesAllowable = allPartitionTypesAllowable;
		
		this.fRequriedPartitionTypeIDs = requiredPartitionTypeIDs;
		if(this.fRequriedPartitionTypeIDs == null) {
			this.fRequriedPartitionTypeIDs = Collections.EMPTY_LIST;
		}
		
		this.fHasRequiredPartitionTypes = this.fRequriedPartitionTypeIDs.size() != 0;
		
		this.fAllowablePartitionTypeIDs = allowablePartitionTypeIDs;
		if(this.fAllowablePartitionTypeIDs == null) {
			this.fAllowablePartitionTypeIDs = Collections.EMPTY_LIST;
		}
		
		this.fAssociatedCommentPartitionTypeID = associatedCommentPartitionTypeID;
	}
	
	/**
	 * <p>Applies this strategy to the given model starting at the given offset for the given length</p>
	 * 
	 * @param document {@link IStructuredDocument} to apply this strategy too
	 * @param offset the offset to start this comment at
	 * @param length the length of the region to apply this comment too
	 * 
	 * @throws BadLocationException it is not the fault of the strategy if callers passes a bad
	 * <code>offset</code> and/or <code>length</code> for the given <code>model</code>
	 */
	public abstract void apply(IStructuredDocument document, int offset, int length) throws BadLocationException;
	
	/**
	 * <p>Remove any comments associated with this strategy from the given model for the given offset to
	 * the given length.  Weather a comment surrounding the given range should be removed can also be
	 * specified</p>
	 * 
	 * @param document {@link IStructuredDocument} to remove comments associated with this strategy from
	 * @param offset the location to start removing comments associated with this strategy from
	 * @param length the length of the region to remove associated comments from
	 * @param removeEnclosing weather a comment should be removed if it incloses the region specified
	 * by the given <code>offset</code> and <code>length</code>
	 * 
	 * @throws BadLocationException it is not the fault of the strategy if callers passes a bad
	 * <code>offset</code> and/or <code>length</code> for the given <code>model</code>
	 */
	public abstract void remove(IStructuredDocument document, int offset, int length, boolean removeEnclosing) throws BadLocationException;
	
	/**
	 * <p>Determines if the given region is a comment region commented by this strategy.</p>
	 * 
	 * @param document {@link IStructuredDocument} containing the given <code>region</code>
	 * @param region determine if this region is a comment region commented by this strategy
	 * @return <code>true</code> if the given <code>region</code> has already been
	 * commented by this strategy, <code>false</code> otherwise
	 * 
	 * @throws BadLocationException it is not the fault of the strategy if callers passes a bad
	 * <code>offset</code> and/or <code>length</code> for the given <code>model</code>
	 */
	public abstract boolean alreadyCommenting(IStructuredDocument document, IRegion region) throws BadLocationException;
	
	/** 
	 * <p>Implementers should return a copy of themselves</p>
	 * <p>Allows the {@link CommentingStrategyRegistry} to create a {@link CommentingStrategy} for
	 * each of its associated content types.</p>
	 * 
	 * @return implementers should return an object of type {@link CommentingStrategy}
	 * 
	 * @see java.lang.Object#clone()
	 */
	public abstract Object clone();
	
	/**
	 * <p>Determines if this strategy is applicable for the given regions for either commenting or un-commenting. 
	 * For this strategy to be applicable the given regions must contain at least one or all of the
	 * {@link #fRequriedPartitionTypeIDs} (depending on the value of {@link #fRequireAllRequiredPartitionTypes})
	 * or contain at least one region of type {@link #fAssociatedCommentPartitionTypeID}.  Also if the value of
	 * {@link #fAllPartitionTypesAllowable} is <code>false</code> the given regions must all be of type
	 * {@link #fAllowablePartitionTypeIDs} and/or {@link #fRequriedPartitionTypeIDs} and/or
	 * {@link #fAssociatedCommentPartitionTypeID} otherwise the regions can be of any type except for they still
	 * must beet the required partition type requirements</p>
	 * 
	 * @param regions determine if this strategy is applicable for these regions
	 * @return <code>true</code> if this strategy is applicable for the given <code>regions</code>
	 * <code>false</code> otherwise.
	 */
	public final boolean isApplicableFor(ITypedRegion[] regions) {
		List partitionTypeIDs = getPartitionTypeIDs(regions);
		
		boolean foundAssociatedCommentPartitions = false;
		if(this.fAssociatedCommentPartitionTypeID != null) {
			foundAssociatedCommentPartitions = partitionTypeIDs.contains(this.fAssociatedCommentPartitionTypeID);
			if(foundAssociatedCommentPartitions) {
				//remove all instances of the comment partition type
				boolean removed;
				do {
					removed = partitionTypeIDs.remove(this.fAssociatedCommentPartitionTypeID);
				} while(removed);
			}
		}
		
		//determine if required partitions requirements are met
		boolean requiredPartitionsRequirementsMet = !this.fHasRequiredPartitionTypes ||
			partitionTypeIDs.removeAll(this.fRequriedPartitionTypeIDs);
		
		//determine if allowable partitions requirements are met
		boolean allowablePartitionsRequirementsMet = false;
		if(this.fAllPartitionTypesAllowable) {
			allowablePartitionsRequirementsMet = true;
		} else {
			partitionTypeIDs.removeAll(this.fAllowablePartitionTypeIDs);
			
			//at this point all required partitions and allowable partitions have been removed
			allowablePartitionsRequirementsMet = partitionTypeIDs.size() == 0;
		}
		
		return (requiredPartitionsRequirementsMet || foundAssociatedCommentPartitions) && allowablePartitionsRequirementsMet;
	}
	
	/**
	 * <p>Convenience method to take a list of regions and create one encompassing region to pass to
	 * {@link #alreadyCommenting(IDocument, IRegion)}</p>
	 * 
	 * @param document {@link IDocument} that contains the given <code>regions</code>
	 * @param regions {@link IRegion}s to combine into one region and pass onto
	 * {@link #alreadyCommenting(IDocument, IRegion)}
	 * 
	 * @return the result of a call to {@link #alreadyCommenting(IDocument, IRegion)} combining
	 * all of the given <code>regions</code> into one region
	 * 
	 * @throws BadLocationException it is not the fault of the strategy if callers passes a bad
	 * <code>offset</code> and/or <code>length</code> for the given <code>model</code>
	 */
	public final boolean alreadyCommenting(IStructuredDocument document, IRegion[] regions) throws BadLocationException {
		boolean alreadyCommenting = false;
		if(regions != null && regions.length > 0) {
			//create one region spanning all the given regions
			int offset = regions[0].getOffset();
			int length = regions[regions.length-1].getOffset() +
					regions[regions.length-1].getLength() - offset;
		
			IRegion region = new Region(offset, length);
			alreadyCommenting = this.alreadyCommenting(document, region);
		}
		
		return alreadyCommenting;
	}
	/**
	 * <p>Given a list of {@link ITypedRegion}s returns the sub set of that list that
	 * are of the comment region type associated with this strategy</p>
	 * 
	 * @param typedRegions {@link ITypedRegion}s to filter down to only the comment regions
	 * associated with this strategy
	 * 
	 * @return {@link List} of {@link ITypedRegion}s from the given <code>typedRegions</code>
	 * that are of the comment partition type associated with this strategy
	 */
	protected List getAssociatedCommentedRegions(ITypedRegion[] typedRegions) {
		List commentedRegions = new ArrayList();
		
		for(int i = 0; i < typedRegions.length; ++i) {
			if(typedRegions[i].getType().equals(this.fAssociatedCommentPartitionTypeID)) {
				commentedRegions.add(typedRegions[i]);
			}
		}
		
		return commentedRegions;
	}
	
	/**
	 * <p>Given a list of {@link ITypedRegion}s returns a list of the partition
	 * type IDs taken from the given regions.</p>
	 * 
	 * @param regions {@link ITypedRegion}s to get the partition type IDs from
	 * @return {@link List} of the partition type IDs taken from the given <code>regions</code>
	 */
	private static List getPartitionTypeIDs(ITypedRegion[] regions) {
		List partitionTypes = new ArrayList(regions.length);
		for(int i = 0; i < regions.length; ++i) {
			partitionTypes.add(regions[i].getType());
		}
		
		return partitionTypes;
	}
	
	/**
	 * <p>This method modifies the given document to remove the given comment
	 * prefix at the given comment prefix offset and the given comment
	 * suffix at the given comment suffix offset.  In the case of removing
	 * a line comment that does not have a suffix, pass <code>null</code>
	 * for the comment suffix and it and its associated offset will
	 * be ignored.</p>
	 * 
	 * <p><b>NOTE:</b> it is a good idea if a model is at hand when calling this to
	 * warn the model of an impending update</p>
	 * 
	 * @param document the document to remove the comment from
	 * @param commentPrefixOffset the offset of the comment prefix
	 * @param commentSuffixOffset the offset of the comment suffix
	 * (ignored if <code>commentSuffix</code> is <code>null</code>)
	 * @param commentPrefix the prefix of the comment to remove from its associated given offset
	 * @param commentSuffix the suffix of the comment to remove from its associated given offset,
	 * or null if there is not suffix to remove for this comment
	 */
	protected static void uncomment(IDocument document, int commentPrefixOffset, String commentPrefix,
			int commentSuffixOffset,  String commentSuffix) {
		
		try {
			//determine if there is a space after the comment prefix that should also be removed
			int commentPrefixLength = commentPrefix.length();
			String postCommentPrefixChar = document.get(commentPrefixOffset + commentPrefix.length(), 1);
			if(postCommentPrefixChar.equals(" ")) {
				commentPrefixLength++;
			}
			
			//remove the comment prefix
			document.replace(commentPrefixOffset, commentPrefixLength, ""); //$NON-NLS-1$
			
			if(commentSuffix != null) {
				commentSuffixOffset -= commentPrefixLength;
				
				//determine if there is a space before the comment suffix that should also be removed
				int commentSuffixLength = commentSuffix.length();
				String preCommentSuffixChar = document.get(commentSuffixOffset-1, 1);
				if(preCommentSuffixChar.equals(" ")) {
					commentSuffixLength++;
					commentSuffixOffset--;
				}
				
				//remove the comment suffix
				document.replace(commentSuffixOffset, commentSuffixLength, ""); //$NON-NLS-1$
			}
		}
		catch (BadLocationException e) {
			Logger.log(Logger.WARNING_DEBUG, e.getMessage(), e);
		}
	}
}