/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.camel.dataformat.bindy.csv;


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Consumer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Stream;

import org.apache.camel.Exchange;
import org.apache.camel.dataformat.bindy.BindyAbstractDataFormat;
import org.apache.camel.dataformat.bindy.BindyAbstractFactory;
import org.apache.camel.dataformat.bindy.BindyCsvFactory;
import org.apache.camel.dataformat.bindy.FormatFactory;
import org.apache.camel.dataformat.bindy.WrappedException;
import org.apache.camel.dataformat.bindy.util.ConverterUtils;
import org.apache.camel.spi.DataFormat;
import org.apache.camel.util.IOHelper;
import org.apache.camel.util.ObjectHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A <a href="http://camel.apache.org/data-format.html">data format</a> (
 * {@link DataFormat}) using Bindy to marshal to and from CSV files
 */
public class BindyCsvDataFormat extends BindyAbstractDataFormat {
    private static final Logger LOG = LoggerFactory.getLogger(BindyCsvDataFormat.class);

    public BindyCsvDataFormat() {
    }

    public BindyCsvDataFormat(Class<?> type) {
        super(type);
    }

    @Override
    public String getDataFormatName() {
        return "bindy-csv";
    }

    @SuppressWarnings("unchecked")
    public void marshal(Exchange exchange, Object body, OutputStream outputStream) throws Exception {

        BindyCsvFactory factory = (BindyCsvFactory)getFactory();
        ObjectHelper.notNull(factory, "not instantiated");

        // Get CRLF
        byte[] bytesCRLF = ConverterUtils.getByteReturn(factory.getCarriageReturn());

        if (factory.getGenerateHeaderColumnNames()) {

            String result = factory.generateHeader();
            byte[] bytes = exchange.getContext().getTypeConverter().convertTo(byte[].class, exchange, result);
            outputStream.write(bytes);

            // Add a carriage return
            outputStream.write(bytesCRLF);
        }

        List<Map<String, Object>> models = new ArrayList<>();

        // the body is not a prepared list of map that bindy expects so help a
        // bit here and create one for us
        Iterator<Object> it = ObjectHelper.createIterator(body);
        while (it.hasNext()) {
            Object model = it.next();
            if (model instanceof Map) {
                models.add((Map<String, Object>)model);
            } else {
                String name = model.getClass().getName();
                Map<String, Object> row = new HashMap<>(1);
                row.put(name, model);
                row.putAll(createLinkedFieldsModel(model));
                models.add(row);
            }
        }

        Iterator<Map<String, Object>> modelsMap = models.iterator();
        while (modelsMap.hasNext()) {
            String result = factory.unbind(getCamelContext(), modelsMap.next());

            byte[] bytes = exchange.getContext().getTypeConverter().convertTo(byte[].class, exchange, result);
            outputStream.write(bytes);

            if (factory.isEndWithLineBreak() || modelsMap.hasNext()) {
                // Add a carriage return
                outputStream.write(bytesCRLF);
            }
        }
    }

    /**
     * check emptyStream and if CVSRecord is allow to process emptyStreams avoid
     * IllegalArgumentException and return empty list when unmarshalling
     */
    private boolean checkEmptyStream(BindyCsvFactory factory, InputStream inputStream) throws IOException {
        boolean allowEmptyStream = factory.isAllowEmptyStream();
        boolean isStreamEmpty = false;
        boolean canReturnEmptyListOfModels = false;

        if (inputStream == null || inputStream.available() == 0) {
            isStreamEmpty = true;
        }

        if (isStreamEmpty && allowEmptyStream) {
            canReturnEmptyListOfModels = true;
        }

        return canReturnEmptyListOfModels;
    }

    public Object unmarshal(Exchange exchange, InputStream inputStream) throws Exception {
        BindyCsvFactory factory = (BindyCsvFactory)getFactory();
        ObjectHelper.notNull(factory, "not instantiated");

        // List of Pojos
        List<Map<String, Object>> models = new ArrayList<>();

        InputStreamReader in = null;
        try {
            if (checkEmptyStream(factory, inputStream)) {
                return models;
            }

            in = new InputStreamReader(inputStream, IOHelper.getCharsetName(exchange));

            // Retrieve the separator defined to split the record
            String separator = factory.getSeparator();
            String quote = factory.getQuote();
            ObjectHelper.notNull(separator, "The separator has not been defined in the annotation @CsvRecord or not instantiated during initModel.");
            Boolean removeQuotes = factory.getRemoveQuotes();
            AtomicInteger count = new AtomicInteger(0);

            // Use a Stream to stream a file across.
            try (Stream<String> lines = new BufferedReader(in).lines()) {
                int linesToSkip = 0;

                // If the first line of the CSV file contains columns name, then we
                // skip this line
                if (factory.getSkipFirstLine()) {
                    linesToSkip = 1;
                }

                // Consume the lines in the file via a consumer method, passing in state as necessary.
                // If the internals of the consumer fail, we unrap the checked exception upstream.
                try {
                    lines.skip(linesToSkip)
                            .forEachOrdered(consumeFile(factory, models, separator, removeQuotes, quote, count));
                } catch (WrappedException e) {
                    throw e.getWrappedException();
                }

                // BigIntegerFormatFactory if models list is empty or not
                // If this is the case (correspond to an empty stream, ...)
                if (models.size() == 0) {
                    throw new java.lang.IllegalArgumentException("No records have been defined in the CSV");
                } else {
                    return extractUnmarshalResult(models);
                }
            }
        } finally {
            if (in != null) {
                IOHelper.close(in, "in", LOG);
            }
        }

    }

    private Consumer<String> consumeFile(BindyCsvFactory factory, List<Map<String, Object>> models,
                                         String separator, Boolean removeQuotes, String quote, AtomicInteger count) {
        return line -> {
            try {
                // Trim the line coming in to remove any trailing whitespace
                String trimmedLine;

                // if separator is a tab, don't trim any leading whitespaces (could be empty values separated by tabs)
                if (separator.equals("\t")) {
                    // trim only trailing whitespaces
                    trimmedLine = line.replaceAll("\\s+$", "");
                } else {
                    trimmedLine = line.trim();
                }

                // Increment counter
                count.incrementAndGet();
                Map<String, Object> model;

                // Create POJO where CSV data will be stored
                model = factory.factory();

                // Split the CSV record according to the separator defined in
                // annotated class @CSVRecord
                Pattern pattern = Pattern.compile(separator);
                Matcher matcher = pattern.matcher(trimmedLine);
                List<String> separators = new ArrayList<>();

                // Retrieve separators for each match
                while (matcher.find()) {
                    separators.add(matcher.group());
                }
                // Add terminal separator
                if (separators.size() > 0) {
                    separators.add(separators.get(separators.size() - 1));
                }

                String[] tokens = pattern.split(trimmedLine, factory.getAutospanLine() ? factory.getMaxpos() : -1);

                List<String> result = Arrays.asList(tokens);

                // must unquote tokens before use
                if (removeQuotes) {
                    result = unquoteTokens(result, separators, quote);
                }

                if (result.isEmpty()) {
                    throw new IllegalArgumentException("No records have been defined in the CSV");
                } else {
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("Size of the record splitted : {}", result.size());
                    }

                    // Bind data from CSV record with model classes

                    factory.bind(getCamelContext(), result, model, count.get());

                    // Link objects together
                    factory.link(model);

                    // Add objects graph to the list
                    models.add(model);

                    LOG.debug("Graph of objects created: {}", model);
                }
            } catch (Exception e) {
                throw new WrappedException(e);
            }
        };
    }

    /**
     * Unquote the tokens, by removing leading and trailing quote chars, as will
     * handling fixing broken tokens which may have been split by a separator
     * inside a quote.
     */
    private List<String> unquoteTokens(List<String> result, List<String> separators, String quote) {
        // a current quoted token which we assemble from the broken pieces
        // we need to do this as we use the split method on the String class
        // to split the line using regular expression, and it does not handle
        // if the separator char is also inside a quoted token, therefore we
        // need
        // to fix this afterwards
        StringBuilder current = new StringBuilder();
        boolean inProgress = false;
        List<String> answer = new ArrayList<>();
        int idxSeparator = 0;

        // parsing assumes matching close and end quotes
        for (String s : result) {
            boolean canStart = false;
            boolean canClose = false;
            boolean cutStart = false;
            boolean cutEnd = false;
            if (s.startsWith(quote)) {
                // token is just a quote
                if (s.length() == 1) {
                    s = "";
                    // if token is a quote then it can only close processing if
                    // it has begun
                    if (inProgress) {
                        canClose = true;
                    } else {
                        canStart = true;
                    }
                } else {
                    // quote+"not empty"
                    cutStart = true;
                    canStart = true;
                }
            }

            // "not empty"+quote
            if (s.endsWith(quote)) {
                cutEnd = true;
                canClose = true;
            }

            // optimize to only substring once
            if (cutEnd || cutStart) {
                s = s.substring(cutStart ? 1 : 0, cutEnd ? s.length() - 1 : s.length());
            }

            // are we in progress of rebuilding a broken token
            if (inProgress) {
                current.append(separators.get(idxSeparator));
                current.append(s);

                if (canClose) {
                    answer.add(current.toString());
                    current.setLength(0);
                    inProgress = false;
                }
            } else {
                if (canStart && !canClose) {
                    current.append(s);
                    inProgress = true;
                } else {
                    // case where no quotes
                    answer.add(s);
                }
            }
            idxSeparator++;
        }

        // any left over from current?
        if (current.length() > 0) {
            answer.add(current.toString());
            current.setLength(0);
        }

        return answer;
    }

    @Override
    protected BindyAbstractFactory createModelFactory(FormatFactory formatFactory) throws Exception {
        BindyCsvFactory bindyCsvFactory = new BindyCsvFactory(getClassType());
        bindyCsvFactory.setFormatFactory(formatFactory);
        return bindyCsvFactory;
    }
}
