/*
 * 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.jmeter.report.core;

import java.io.BufferedReader;
import java.io.Closeable;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.nio.charset.StandardCharsets;

import org.apache.commons.lang3.tuple.Pair;
import org.apache.jmeter.samplers.SampleEvent;
import org.apache.jmeter.samplers.SampleSaveConfiguration;
import org.apache.jmeter.save.CSVSaveService;
import org.apache.jmeter.save.SaveService;
import org.apache.jmeter.util.JMeterUtils;
import org.apache.jorphan.util.JOrphanUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * Reader class for reading CSV files.
 * <p>
 * Handles {@link SampleMetadata} reading and sample extraction.
 *
 * @since 3.0
 */
public class CsvSampleReader implements Closeable{

    private static final Logger log = LoggerFactory.getLogger(CsvSampleReader.class);

    private static final int BUF_SIZE = 1024 * 1024;
    private static final String CHARSET = SaveService.getFileEncoding(StandardCharsets.UTF_8.displayName());
    private static final char DEFAULT_SEPARATOR =
            // Cannot use JMeterUtils#getPropDefault as it trims the value
            JMeterUtils.getDelimiter(
                    JMeterUtils.getJMeterProperties().getProperty(
                            SampleSaveConfiguration.DEFAULT_DELIMITER_PROP,
                            SampleSaveConfiguration.DEFAULT_DELIMITER))
                    .charAt(0);

    private final File file;
    private InputStream fis;
    private Reader isr;
    private BufferedReader reader;
    private final char separator;
    private long row;
    private final SampleMetadata metadata;
    private final int columnCount;
    private Sample lastSampleRead;
    /**
     * Number of sample_variables if csv file has no header
     */
    private final int numberOfSampleVariablesInCsv;

    /**
     * Instantiates a new csv sample reader.
     *
     * @param inputFile        the input file (must not be {@code null})
     * @param separator        the separator
     * @param useSaveSampleCfg indicates whether the reader uses jmeter
     *                         SampleSaveConfiguration to define metadata
     */
    public CsvSampleReader(File inputFile, char separator, boolean useSaveSampleCfg) {
        this(inputFile, null, separator, useSaveSampleCfg);
    }

    /**
     * Instantiates a new csv sample reader.
     *
     * @param inputFile the input file (must not be {@code null})
     * @param metadata  the metadata
     */
    public CsvSampleReader(File inputFile, SampleMetadata metadata) {
        this(inputFile, metadata, DEFAULT_SEPARATOR, false);
    }

    private CsvSampleReader(File inputFile, SampleMetadata metadata,
            char separator, boolean useSaveSampleCfg) {
        if (!(inputFile.isFile() && inputFile.canRead())) {
            throw new IllegalArgumentException(inputFile.getAbsolutePath()
                    + " does not exist or is not readable");
        }
        this.file = inputFile;
        try {
            this.fis = new FileInputStream(file);
            this.isr = new InputStreamReader(fis, CHARSET);
            this.reader = new BufferedReader(isr, BUF_SIZE);
        } catch (FileNotFoundException | UnsupportedEncodingException ex) {
            JOrphanUtils.closeQuietly(isr);
            JOrphanUtils.closeQuietly(fis);
            JOrphanUtils.closeQuietly(this.reader);
            throw new SampleException("Could not create file reader !", ex);
        }
        boolean usingHeadersInCsv = true;
        if (metadata == null) {
            Pair<Boolean, SampleMetadata> localMd = readMetadata(separator, useSaveSampleCfg);
            this.metadata = localMd.getRight();
            usingHeadersInCsv = localMd.getLeft();
        } else {
            this.metadata = metadata;
        }
        this.columnCount = this.metadata.getColumnCount();
        this.separator = this.metadata.getSeparator();
        this.row = 0;
        if(!usingHeadersInCsv) {
            String vars = JMeterUtils.getProperty(SampleEvent.SAMPLE_VARIABLES);
            String[] variableNames=vars != null ? vars.split(",") : new String[0];
            this.numberOfSampleVariablesInCsv = variableNames.length;
        } else {
            this.numberOfSampleVariablesInCsv = 0;
        }
        this.lastSampleRead = nextSample();
    }

    private Pair<Boolean, SampleMetadata> readMetadata(char separator, boolean useSaveSampleCfg) {
        try {
            SampleMetadata result;
            // Read first line
            String line = reader.readLine();
            this.row++;
            if (line == null) {
                throw new IllegalArgumentException("File is empty");
            }
            boolean hasHeaders = false;
            // When we can use sample save config and there is no header in csv file
            if (useSaveSampleCfg
                    && CSVSaveService.getSampleSaveConfiguration(
                            line, file.getAbsolutePath()) == null) {
                // Build metadata from default save config
                String warnMessage = "File '" + file.getAbsolutePath() + "' does not contain the field names header, "
                        + "ensure the jmeter.save.saveservice.* properties are the same "
                        + "as when the CSV file was created or the file may be read incorrectly "
                        + "when generating report";
                if (log.isWarnEnabled()) {
                    log.warn(warnMessage);
                }
                System.out.println(warnMessage);
                result = new SampleMetadata(
                        SampleSaveConfiguration.staticConfig());

            } else {
                // Build metadata from headers
                result = new SampleMetaDataParser(separator).parse(line);
                hasHeaders = true;
            }
            return Pair.of(hasHeaders, result);
        } catch (Exception e) {
            throw new SampleException("Could not read metadata !", e);
        }
    }

    public SampleMetadata getMetadata() {
        return metadata;
    }

    private Sample nextSample() {
        String[] data;
        try {
            data = CSVSaveService.csvReadFile(reader, separator);
            Sample sample = null;
            if (data.length > 0) {
                assertCorrectColumns(data);
                sample = new Sample(row++, metadata, data);
            }
            return sample;
        } catch (IOException e) {
            throw new SampleException("Could not read sample <" + row + ">", e);
        }
    }

    private void assertCorrectColumns(String[] data) {
        if (data.length != columnCount + numberOfSampleVariablesInCsv) {
            if (log.isWarnEnabled()) {
                log.warn("Short CSV read around line {} of file '{}'. Could only read {} elements of {} expected. Data is [{}]",
                        row + 2, file, data.length, columnCount,
                        String.join(", ", data));
            }
            throw new SampleException(
                    "Mismatch between expected number of columns:" + columnCount + " and columns in CSV file:"
                            + data.length + ", check your jmeter.save.saveservice.* configuration or check if line "
                            + (row + 2) + " in '" + file + "' is complete");
        }
    }

    /**
     * @return next sample from the file.
     */
    public Sample readSample() {
        Sample out = lastSampleRead;
        lastSampleRead = nextSample();
        return out;
    }

    /**
     * @return next sample from file but keep the reading file position.
     */
    public Sample peek() {
        return lastSampleRead;
    }

    /**
     * @return flag, that indicates whether the file contains more samples
     */
    public boolean hasNext() {
        return lastSampleRead != null;
    }

    @Override
    public void close() {
        JOrphanUtils.closeQuietly(isr);
        JOrphanUtils.closeQuietly(fis);
        JOrphanUtils.closeQuietly(reader);
    }
}
