// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.searchdefinition.derived;

import com.yahoo.searchdefinition.Search;
import com.yahoo.searchdefinition.document.Attribute;
import com.yahoo.searchdefinition.document.ImmutableSDField;
import com.yahoo.searchdefinition.document.ImportedField;
import com.yahoo.vespa.config.search.ImportedFieldsConfig;

import java.util.Optional;

/**
 * This class derives imported fields from search definition and produces imported-fields.cfg as needed by the search backend.
 *
 * @author geirst
 */
public class ImportedFields extends Derived implements ImportedFieldsConfig.Producer {

    private Optional<com.yahoo.searchdefinition.document.ImportedFields> importedFields = Optional.empty();

    public ImportedFields(Search search) {
        derive(search);
    }

    @Override
    protected void derive(Search search) {
        importedFields = search.importedFields();
    }

    @Override
    protected String getDerivedName() {
        return "imported-fields";
    }

    @Override
    public void getConfig(ImportedFieldsConfig.Builder builder) {
        if (importedFields.isPresent()) {
            importedFields.get().fields().forEach( (name, field) -> considerField(builder, field));
        }
    }

    private static void considerField(ImportedFieldsConfig.Builder builder, ImportedField field) {
        ImmutableSDField targetField = field.targetField();
        String targetFieldName = targetField.getName();
        if (targetFieldName.indexOf('.') == -1) {
            if (field.targetField().doesAttributing()) {
                builder.attribute.add(createAttributeBuilder(field));
            }
        } else {
            Attribute attribute = targetField.getAttributes().get(targetFieldName);
            if (attribute != null) {
                builder.attribute.add(createAttributeBuilder(field));
            }
        }
    }

    private static ImportedFieldsConfig.Attribute.Builder createAttributeBuilder(ImportedField field) {
        ImportedFieldsConfig.Attribute.Builder result = new ImportedFieldsConfig.Attribute.Builder();
        result.name(field.fieldName());
        result.referencefield(field.reference().referenceField().getName());
        result.targetfield(field.targetField().getName());
        return result;
    }

}