/*
 * Copyright OpenSearch Contributors
 * SPDX-License-Identifier: Apache-2.0
 */

package org.opensearch.performanceanalyzer.reader;


import com.google.common.annotations.VisibleForTesting;
import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.opensearch.performanceanalyzer.commons.config.PluginSettings;
import org.opensearch.performanceanalyzer.commons.event_process.Event;

public abstract class FileHandler {
    private static final String[] EMPTY_STRING_ARRAY = new String[0];

    private String rootLocation;

    // find all relevant files for a metric
    public abstract List<File> findFiles4Metric(long timeBucket);

    public abstract List<Event> getMetricData(Map<String, List<Event>> metricDataMap);

    FileHandler() {
        this.rootLocation = PluginSettings.instance().getMetricsLocation();
    }

    public String[] processExtraDimensions(File file) throws IOException {
        if (filePathRegex().isEmpty()) {
            return EMPTY_STRING_ARRAY;
        }

        // Note the question mark in the 1st group is reluctant
        // quantifier.
        Pattern pattern = Pattern.compile(filePathRegex());
        // our regex uses '/' as file separator
        Matcher matcher = pattern.matcher(file.getCanonicalPath());
        if (matcher.find()) {
            int groupCount = matcher.groupCount();
            String[] extraDimensions = new String[groupCount];
            // group 0 is the entire match
            for (int i = 1; i <= groupCount; i++) {
                extraDimensions[i - 1] = matcher.group(i);
            }
            return extraDimensions;
        }
        throw new IOException(
                String.format("Cannot find a matching path %s", file.getCanonicalPath()));
    }

    // For something like
    // indices/nyc_taxis/9
    // The intention of this method to get:
    // [nyc_taxis, 9]
    String[] processExtraDimensions(String key) {
        if (filePathRegex().isEmpty()) {
            return EMPTY_STRING_ARRAY;
        }
        String[] temp = key.split(File.separatorChar == '\\' ? "\\\\" : File.separator);
        return Arrays.copyOfRange(temp, 1, temp.length);
    }

    // override this method if we need to extra dimensions from the file
    // path
    protected String filePathRegex() {
        return "";
    }

    public String getRootLocation() {
        return rootLocation;
    }

    @VisibleForTesting
    void setRootLocation(String location) {
        rootLocation = location;
    }
}