package org.drools.eclipse.dsl.editor.completion;



import java.io.BufferedReader;

import java.io.IOException;

import java.io.StringReader;

import java.util.Iterator;

import java.util.List;



import org.drools.eclipse.DroolsPluginImages;

import org.drools.eclipse.dsl.editor.DSLAdapter;

import org.drools.eclipse.dsl.editor.DSLRuleEditor;

import org.drools.eclipse.editors.AbstractRuleEditor;

import org.drools.eclipse.editors.completion.RuleCompletionProcessor;

import org.drools.eclipse.editors.completion.RuleCompletionProposal;

import org.drools.lang.Location;

import org.eclipse.swt.graphics.Image;



/**

 * For handling DSL rules.

 * 

 * @author <a href="mailto:kris_verlaenen@hotmail.com">Kris Verlaenen</a>

 */

public class DSLRuleCompletionProcessor extends RuleCompletionProcessor {



	private static final Image DSL_ICON = 

		DroolsPluginImages.getImage(DroolsPluginImages.DSL_EXPRESSION);



	public DSLRuleCompletionProcessor(AbstractRuleEditor editor) {

		super(editor);

	}



    protected DSLRuleEditor getDSLRuleEditor() {

    	return (DSLRuleEditor) getEditor();

    }

    

	protected void addRHSCompletionProposals(List list, int documentOffset, String prefix, String backText,

			String conditions, String consequence) {

		// super.addRHSCompletionProposals(list, documentOffset, prefix, backText, conditions, consequence);

		DSLAdapter adapter = getDSLRuleEditor().getDSLAdapter();

		if (adapter != null) {

			List dslConsequences = adapter.getDSLTree().getConsequenceChildrenList(prefix, true);

			addDSLProposals(list, documentOffset, prefix, dslConsequences);

		}

	}

	

	protected void addLHSCompletionProposals(List list, int documentOffset,

			Location location, String prefix, String backText) {

		// super.addLHSCompletionProposals(list, documentOffset, location, prefix, backText);

		DSLAdapter adapter = getDSLRuleEditor().getDSLAdapter();

		if (adapter != null) {

			String lastobj = this.getLastNonDashLine(backText);

			String last = this.getLastLine(backText);

			// we have to check if the last line is when. if it is we set

			// the last line to zero length string

			if (last.equals("when")) {

				last = "";

				lastobj = "*";

			}

			// pass the last string in the backText to getProposals

			List dslConditions = this.getProposals(adapter, lastobj, last);

			// if we couldn't find any matches, we add the list from

			// the DSLAdapter so that there's something

			if (dslConditions.size() == 0) {

				dslConditions.addAll(adapter.listConditionItems());

			}

			addDSLProposals(list, documentOffset, prefix, dslConditions);

		}

	}

	

	private void addDSLProposals(final List list, int documentOffset, final String prefix, List dslItems) {

		Iterator iterator = dslItems.iterator();

		while (iterator.hasNext()) {

			String consequence = (String) iterator.next();

			RuleCompletionProposal p = new RuleCompletionProposal(

				documentOffset - prefix.length(), prefix.length(), consequence);

			p.setImage(DSL_ICON);

			list.add(p);

		}

	}



	/**

	 * because of how the backText works, we need to get the last line, so that

	 * we can pass it to the DSLUtility

	 * 

	 * @param backText

	 * @return

	 */

	public String getLastLine(String backText) {

		BufferedReader breader = new BufferedReader(new StringReader(backText));

		String last = "";

		String line = null;

		try {

			while ((line = breader.readLine()) != null) {

				// only if the line has text do we set last to it

				if (line.length() > 0) {

					last = line;

				}

			}

		} catch (IOException e) {

			// TODO need to log this.

			// I'm leaving this for mic_hat, so he has something to do

		}

		// now that all the conditions for a single object are on the same line

		// we need to check for the left parenthesis

		if (last.indexOf("(") > -1) {

			last = last.substring(last.lastIndexOf("(") + 1);

		}

		// if the string has a comma "," we get the substring starting from

		// the index after the last comma

		if (last.indexOf(",") > -1) {

			last = last.substring(last.lastIndexOf(",") + 1);

		}

		// if the line ends with right parenthesis, we change it to zero length

		// string

		if (last.endsWith(")")) {

			last = "";

		}

		return last;

	}



	/**

	 * Returns the last line that doesn't start with a dash

	 * 

	 * @param backText

	 * @return

	 */

	public String getLastNonDashLine(String backText) {

		BufferedReader breader = new BufferedReader(new StringReader(backText));

		String last = "";

		String line = null;

		try {

			while ((line = breader.readLine()) != null) {

				// there may be blank lines, so we trim first

				line = line.trim();

				// only if the line has text do we set last to it

				if (line.length() > 0 && !line.startsWith("-")) {

					last = line;

				}

			}

		} catch (IOException e) {

			// TODO need to log this.

			// I'm leaving this for mic_hat, so he has something to do

		}

		if (last.indexOf("(") > -1 && !last.endsWith(")")) {

			last = last.substring(0, last.indexOf("("));

		} else if (last.indexOf("(") > -1 && last.endsWith(")")) {

			last = "";

		}

		return last;

	}



	/**

	 * The DSLTree is configurable. It can either return just the child of the

	 * last token found, or it can traverse the tree and generate all the

	 * combinations beneath the last matching node. TODO I don't know how to add

	 * configuration to the editor, so it needs to be hooked up to the

	 * configuration for the editor later.

	 * 

	 * @param last

	 * @return

	 */

	protected List getProposals(DSLAdapter adapter, String obj, String last) {

		if (last.length() == 0) {

			last = " ";

		}

		return adapter.getDSLTree().getChildrenList(obj, last, true);

	}

}