/**
 * DataCleaner (community edition)
 * Copyright (C) 2014 Neopost - Customer Information Management
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.datacleaner.components.convert;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.sql.Clob;
import java.util.Arrays;

import javax.inject.Inject;
import javax.inject.Named;

import org.apache.metamodel.util.FileHelper;
import org.datacleaner.api.Categorized;
import org.datacleaner.api.Configured;
import org.datacleaner.api.Description;
import org.datacleaner.api.InputColumn;
import org.datacleaner.api.InputRow;
import org.datacleaner.api.OutputColumns;
import org.datacleaner.api.StringProperty;
import org.datacleaner.api.Transformer;
import org.datacleaner.components.categories.ConversionCategory;

/**
 * Attempts to convert anything to a String value.
 */
@Named("Convert to string")
@Description("Converts anything to a string (or null).")
@Categorized(ConversionCategory.class)
public class ConvertToStringTransformer implements Transformer {

    @Inject
    @Configured
    InputColumn<?>[] input;

    @StringProperty(multiline = true)
    @Configured(required = false)
    String nullReplacement;

    public static String transformValue(Object value) {
        if (value == null) {
            return null;
        }
        if (value instanceof InputStream) {
            value = new InputStreamReader(new BufferedInputStream((InputStream) value));
        }
        final String stringValue;
        if (value instanceof Reader) {
            final char[] buffer = new char[1024];

            final Reader reader = (Reader) value;

            final StringBuilder sb = new StringBuilder();
            try {
                for (int read = reader.read(buffer); read != -1; read = reader.read(buffer)) {
                    char[] charsToWrite = buffer;
                    if (read != buffer.length) {
                        charsToWrite = Arrays.copyOf(charsToWrite, read);
                    }
                    sb.append(charsToWrite);
                }
            } catch (final IOException e) {
                throw new IllegalStateException(e);
            } finally {
                FileHelper.safeClose(reader);
            }
            stringValue = sb.toString();
        } else if (value instanceof Clob) {
            try {
                final Clob clob = (Clob) value;
                stringValue = clob.getSubString(1, (int) clob.length());
            } catch (final Exception e) {
                throw new IllegalStateException("Failed to read CLOB value", e);
            }
        } else {
            stringValue = value.toString();
        }
        return stringValue;
    }

    @Override
    public OutputColumns getOutputColumns() {
        final String[] names = new String[input.length];
        for (int i = 0; i < names.length; i++) {
            names[i] = input[i].getName() + " (as string)";
        }
        return new OutputColumns(String.class, names);
    }

    @Override
    public String[] transform(final InputRow inputRow) {
        final String[] result = new String[input.length];
        for (int i = 0; i < input.length; i++) {
            final Object value = inputRow.getValue(input[i]);
            String stringValue = transformValue(value);
            if (stringValue == null) {
                stringValue = nullReplacement;
            }
            result[i] = stringValue;
        }
        return result;
    }

    public void setInput(final InputColumn<?>[] input) {
        this.input = input;
    }

    public void setNullReplacement(final String nullReplacement) {
        this.nullReplacement = nullReplacement;
    }
}