/*
 * DBeaver - Universal Database Manager
 * Copyright (C) 2010-2017 Serge Rider (serge@jkiss.org)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.jkiss.dbeaver.ui.editors.sql.util;

import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.Region;

public class SQLWordFinder
{

    public static IRegion findWord(IDocument document, int offset)
    {

        int start;
        int end;

        start = getWordStartOffset(document.get(), offset);
        end = getWordEndOffset(document.get(), offset);

        if (start > -1 && end > -1)
        {
            if (start == offset && end == offset)
            {
                return new Region(offset, 0);
            }
            else if (start == offset)
            {
                return new Region(start, end - start);
            }
            else
            {
                return new Region(start + 1, end - start - 1);
            }
        }

        return null;
    }

    public static int getWordStartOffset(String text, int startIndex)
    {
        if (text == null || startIndex >= text.length())
        {
            return -1;
        }
        for (int offset = startIndex; offset >= 0; offset--)
        {
            char c = text.charAt(offset);
            if (isWhiteSpace(c))
            {
                return offset;
            }
        }
        return -1;
    }

    public static int getWordEndOffset(String text, int startIndex)
    {
        int pos = startIndex;
        char c;
        int length = text.length();

        while (pos < length)
        {
            c = text.charAt(pos);
            if (isWhiteSpace(c))
            {
                break;
            }
            ++pos;
        }

        return pos;
    }

    public static boolean isWhiteSpace(char c)
    {
        return Character.isWhitespace(c) || c == '(' || c == ')' || c == ',' || c == ';' || c == '\n' || c == '\r'
                || c == '=' || c == '>' || c == '<' || c == '+' || c == '-' || c == '*' || c == '/';
    }

}