/*-
 * ============LICENSE_START=======================================================
 *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
 *  Modifications Copyright (C) 2020 Nordix Foundation.
 * ================================================================================
 * 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.
 *
 * SPDX-License-Identifier: Apache-2.0
 * ============LICENSE_END=========================================================
 */

package org.onap.policy.apex.plugins.context.schema.avro;

import com.google.gson.GsonBuilder;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import java.util.Map.Entry;

/**
 * This static final class contains utility methods for Avro schemas.
 *
 * @author Liam Fallon (liam.fallon@ericsson.com)
 */
public final class AvroSchemaKeyTranslationUtilities {
    // Constants for key replacements
    private static final String DOT_STRING = ".";
    private static final String DOT_STRING_REPLACEMENT = "_DoT_";
    private static final String DASH_STRING = "-";
    private static final String DASH_STRING_REPLACEMENT = "_DasH_";

    /**
     * Default constructor to avoid subclassing.
     */
    private AvroSchemaKeyTranslationUtilities() {
        // Private constructor to prevent subclassing
    }

    /**
     * Translate characters in JSON keys to values that are legal in Avro. Avro names must start with [A-Za-z_] and
     * subsequently contain only [A-Za-z0-9_]
     *
     * @param jsonString The JSON string to translate
     * @param revert True if we want to revert the field names to their original values
     * @return the translated JSON string
     */
    public static String translateIllegalKeys(final String jsonString, final boolean revert) {
        if (jsonString == null) {
            return jsonString;
        }

        // Create a JSON element for the incoming JSON string
        final JsonElement jsonElement = new GsonBuilder().serializeNulls().create().fromJson(jsonString,
                JsonElement.class);

        final JsonElement translatedJsonElement = translateIllegalKeys(jsonElement, revert);

        return new GsonBuilder().serializeNulls().create().toJson(translatedJsonElement);
    }

    /**
     * Translate characters in JSON keys to values that are legal in Avro. Avro names must start with [A-Za-z_] and
     * subsequently contain only [A-Za-z0-9_]
     *
     * @param jsonElement The JSON element to translate
     * @param revert True if we want to revert the field names to their original values
     * @return the translated JSON element
     */
    public static JsonElement translateIllegalKeys(final JsonElement jsonElement, final boolean revert) {
        // We only act on JSON objects and arrays
        if (jsonElement.isJsonObject()) {
            return translateIllegalKeys(jsonElement.getAsJsonObject(), revert);
        } else if (jsonElement.isJsonArray()) {
            return translateIllegalKeys(jsonElement.getAsJsonArray(), revert);
        } else {
            return jsonElement;
        }
    }

    /**
     * Translate characters in JSON keys to values that are legal in Avro. Avro names must start with [A-Za-z_] and
     * subsequently contain only [A-Za-z0-9_]
     *
     * @param jsonObject The JSON object to translate
     * @param revert True if we want to revert the field names to their original values
     * @return the translated JSON element
     */
    public static JsonElement translateIllegalKeys(final JsonObject jsonObject, final boolean revert) {
        final JsonObject newJsonObject = new JsonObject();

        for (final Entry<String, JsonElement> jsonObjectEntry : jsonObject.entrySet()) {
            newJsonObject.add(translateIllegalKey(jsonObjectEntry.getKey(), revert),
                    translateIllegalKeys(jsonObjectEntry.getValue(), revert));
        }

        return newJsonObject;
    }

    /**
     * Translate characters in JSON keys to values that are legal in Avro. Avro names must start with [A-Za-z_] and
     * subsequently contain only [A-Za-z0-9_]
     *
     * @param jsonArray The JSON array to translate
     * @param revert True if we want to revert the field names to their original values
     * @return the translated JSON element
     */
    public static JsonElement translateIllegalKeys(final JsonArray jsonArray, final boolean revert) {
        final JsonArray newJsonArray = new JsonArray();

        for (int i = 0; i < jsonArray.size(); i++) {
            newJsonArray.add(translateIllegalKeys(jsonArray.get(i), revert));
        }

        return newJsonArray;
    }

    /**
     * Translate characters in a single JSON key to values that are legal in Avro. Avro names must start with [A-Za-z_]
     * and subsequently contain only [A-Za-z0-9_]
     *
     * @param key The key to translate
     * @param revert True if we want to revert the field names to their original values
     * @return the translated key
     */
    private static String translateIllegalKey(final String key, final boolean revert) {
        if (revert) {
            return key.replace(DOT_STRING_REPLACEMENT, DOT_STRING).replace(DASH_STRING_REPLACEMENT, DASH_STRING);
        } else {
            return key.replace(DOT_STRING, DOT_STRING_REPLACEMENT).replace(DASH_STRING, DASH_STRING_REPLACEMENT);
        }
    }
}