/*
 * Copyright (c) nosqlbench
 *
 * 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 io.nosqlbench.virtdata.library.basics.shared.from_long.to_string;

import io.nosqlbench.nb.api.nbio.NBIO;
import io.nosqlbench.virtdata.api.annotations.Categories;
import io.nosqlbench.virtdata.api.annotations.Category;
import io.nosqlbench.virtdata.api.annotations.Example;
import io.nosqlbench.virtdata.api.annotations.ThreadSafeMapper;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.function.LongFunction;

/**
 * Select a value from a CSV file line by modulo division against the number
 * of lines in the file. The second parameter is the field name, and this must
 * be provided in the CSV header line as written.
 */
@ThreadSafeMapper
@Categories({Category.general})
public class ModuloCSVLineToString implements LongFunction<String> {
    private final static Logger logger  = LogManager.getLogger(ModuloLineToString.class);

    private final List<String> lines = new ArrayList<>();

    private final String filename;

    @Example({"ModuloCSVLineToString('data/myfile.csv','lat')","load values for 'lat' from the CSV file myfile.csv."})
    public ModuloCSVLineToString(String filename, String fieldname) {
        this.filename = filename;
        CSVParser csvp = NBIO.readFileCSV(filename);
        Map<String, Integer> headerMap = csvp.getHeaderMap();

        if (headerMap==null || headerMap.isEmpty()) {
            throw new RuntimeException("There were not headers for file "+ filename + ". " + ModuloCSVLineToString.class.getSimpleName() + " requires headers.");
        }

        Integer column = headerMap.get(fieldname);
        if (column==null) {
            throw new RuntimeException("Could not find the named column header '" + fieldname + "' in file " + filename);
        }

        for (CSVRecord strings : csvp) {
            if (strings.get(column) != null) {
                lines.add(strings.get(column));
            }
        }
    }

    @Override
    public String apply(long input) {
        int itemIdx = (int) (input % lines.size()) % Integer.MAX_VALUE;
        String item = lines.get(itemIdx);
        return item;
    }

    public String toString() {
        return getClass().getSimpleName() + ":" + filename;
    }


}
