/*******************************************************************************
 * Copyright (c) 2007, 2011 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.che.ide.ext.java.jdt.templates;

import org.eclipse.che.ide.ext.java.jdt.templates.CompilationUnitCompletion.Variable;
import org.eclipse.che.ide.ext.java.jdt.templates.api.TemplateContext;
import org.eclipse.che.ide.ext.java.jdt.templates.api.TemplateVariable;
import org.eclipse.che.ide.ext.java.jdt.templates.api.TemplateVariableResolver;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

/**
 * Resolves template variables to variables which are assignment-compatible with the variable instance class parameters.
 *
 * @since 3.4
 */
public abstract class AbstractVariableResolver extends TemplateVariableResolver {

    protected final String fDefaultType;

    private Variable[] fVariables;

    /**
     * Create a variable resolver resolving to <code>defaultType</code> if no types specified as parameter
     *
     * @param defaultType
     *         the default type to resolve to
     */
    protected AbstractVariableResolver(String defaultType) {
        fDefaultType = defaultType;
    }

    /**
     * Returns a set of variables of <code>type</code> visible in the given <code>context</code>.
     *
     * @param type
     *         the type name to search variables for
     * @param context
     *         context within to search for variables
     * @return the visible variables of <code>type</code> in <code>context</code>, empty array if no visible variables
     */
    protected abstract Variable[] getVisibleVariables(String type, JavaContext context);

    /*
     * (non-Javadoc)
     * @see org.eclipse.jface.text.templates.TemplateVariableResolver#resolve(org.eclipse.jface.text.templates.TemplateVariable,
     * org.eclipse.jface.text.templates.TemplateContext)
     */
    @Override
    public void resolve(TemplateVariable variable, TemplateContext context) {

        if (variable instanceof JavaVariable) {
            JavaContext jc = (JavaContext)context;
            JavaVariable jv = (JavaVariable)variable;

            List<String> params = variable.getVariableType().getParams();
            if (params.size() == 0) {
                fVariables = getVisibleVariables(fDefaultType, jc);
                jv.setParamType(fDefaultType);
            } else if (params.size() == 1) {
                String type = params.get(0);
                fVariables = getVisibleVariables(type, jc);
                jv.setParamType(type);
            } else {
                ArrayList<Variable> variables = new ArrayList<Variable>();
                for (Iterator<String> iterator = params.iterator(); iterator.hasNext(); ) {
                    variables.addAll(Arrays.asList(getVisibleVariables(iterator.next(), jc)));
                }
                fVariables = variables.toArray(new Variable[variables.size()]);

                // set to default type, a template which references to the type
                // of _the_ parameter will not correctly work anyway
                jv.setParamType(fDefaultType);
            }

            if (fVariables.length > 0) {
                jv.setChoices(fVariables);
                jc.markAsUsed(jv.getDefaultValue());
            } else {
                super.resolve(variable, context);
                return;
            }
            if (fVariables.length > 1)
                variable.setUnambiguous(false);
            else
                variable.setUnambiguous(isUnambiguous(context));
        } else
            super.resolve(variable, context);
    }

    /*
     * (non-Javadoc)
     * @see org.eclipse.jface.text.templates.TemplateVariableResolver#resolveAll(org.eclipse.jface.text.templates.TemplateContext)
     */
    @Override
    protected String[] resolveAll(TemplateContext context) {

        String[] names = new String[fVariables.length];
        for (int i = 0; i < fVariables.length; i++)
            names[i] = fVariables[i].getName();

        if (names.length > 0)
            ((JavaContext)context).markAsUsed(names[0]);

        return names;
    }

}