/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

package org.elasticsearch.ingest.common;

import org.elasticsearch.ingest.AbstractProcessor;
import org.elasticsearch.ingest.ConfigurationUtils;
import org.elasticsearch.ingest.IngestDocument;
import org.elasticsearch.ingest.Processor;

import java.util.List;
import java.util.Map;

import static org.elasticsearch.ingest.ConfigurationUtils.newConfigurationException;

/**
 * A processor that breaks line from CSV file into separate fields.
 * If there's more fields requested than there is in the CSV, extra field will not be present in the document after processing.
 * In the same way this processor will skip any field that is empty in CSV.
 * <p>
 * By default it uses rules according to <a href="https://tools.ietf.org/html/rfc4180">RCF 4180</a> with one exception: whitespaces are
 * allowed before or after quoted field. Processor can be tweaked with following parameters:
 * <p>
 * quote: set custom quote character (defaults to ")
 * separator: set custom separator (defaults to ,)
 * trim: trim leading and trailing whitespaces in unquoted fields
 * empty_value: sets custom value to use for empty fields (field is skipped if null)
 */
public final class CsvProcessor extends AbstractProcessor {

    public static final String TYPE = "csv";

    // visible for testing
    final String field;
    final String[] headers;
    final boolean trim;
    final char quote;
    final char separator;
    final boolean ignoreMissing;
    final Object emptyValue;

    CsvProcessor(
        String tag,
        String description,
        String field,
        String[] headers,
        boolean trim,
        char separator,
        char quote,
        boolean ignoreMissing,
        Object emptyValue
    ) {
        super(tag, description);
        this.field = field;
        this.headers = headers;
        this.trim = trim;
        this.quote = quote;
        this.separator = separator;
        this.ignoreMissing = ignoreMissing;
        this.emptyValue = emptyValue;
    }

    @Override
    public IngestDocument execute(IngestDocument ingestDocument) {
        if (headers.length == 0) {
            return ingestDocument;
        }

        String line = ingestDocument.getFieldValue(field, String.class, ignoreMissing);
        if (line == null && ignoreMissing) {
            return ingestDocument;
        } else if (line == null) {
            throw new IllegalArgumentException("field [" + field + "] is null, cannot process it.");
        }
        new CsvParser(ingestDocument, quote, separator, trim, headers, emptyValue).process(line);
        return ingestDocument;
    }

    @Override
    public String getType() {
        return TYPE;
    }

    public static final class Factory implements org.elasticsearch.ingest.Processor.Factory {
        @Override
        public CsvProcessor create(
            Map<String, Processor.Factory> registry,
            String processorTag,
            String description,
            Map<String, Object> config
        ) {
            String field = ConfigurationUtils.readStringProperty(TYPE, processorTag, config, "field");
            String quote = ConfigurationUtils.readStringProperty(TYPE, processorTag, config, "quote", "\"");
            if (quote.length() != 1) {
                throw newConfigurationException(TYPE, processorTag, "quote", "quote has to be single character like \" or '");
            }
            String separator = ConfigurationUtils.readStringProperty(TYPE, processorTag, config, "separator", ",");
            if (separator.length() != 1) {
                throw newConfigurationException(TYPE, processorTag, "separator", "separator has to be single character like , or ;");
            }
            boolean trim = ConfigurationUtils.readBooleanProperty(TYPE, processorTag, config, "trim", false);
            Object emptyValue = null;
            if (config.containsKey("empty_value")) {
                emptyValue = ConfigurationUtils.readObject(TYPE, processorTag, config, "empty_value");
            }
            boolean ignoreMissing = ConfigurationUtils.readBooleanProperty(TYPE, processorTag, config, "ignore_missing", false);
            List<String> targetFields = ConfigurationUtils.readList(TYPE, processorTag, config, "target_fields");
            if (targetFields.isEmpty()) {
                throw newConfigurationException(TYPE, processorTag, "target_fields", "target fields list can't be empty");
            }
            return new CsvProcessor(
                processorTag,
                description,
                field,
                targetFields.toArray(String[]::new),
                trim,
                separator.charAt(0),
                quote.charAt(0),
                ignoreMissing,
                emptyValue
            );
        }
    }
}
