/*-
 * ========================LICENSE_START=================================
 * O-RAN-SC
 * %%
 * Copyright (C) 2019 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.
 * ========================LICENSE_END===================================
 */

package org.oransc.policyagent.tasks;

import java.util.Optional;
import java.util.Properties;

import org.onap.dcaegen2.services.sdk.rest.services.cbs.client.model.EnvProperties;
import org.onap.dcaegen2.services.sdk.rest.services.cbs.client.model.ImmutableEnvProperties;
import org.oransc.policyagent.exceptions.EnvironmentLoaderException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import reactor.core.publisher.Mono;

class EnvironmentProcessor {

    private static final int DEFAULT_CONSUL_PORT = 8500;
    private static final Logger logger = LoggerFactory.getLogger(EnvironmentProcessor.class);

    private EnvironmentProcessor() {
    }

    static Mono<EnvProperties> readEnvironmentVariables(Properties systemEnvironment) {

        EnvProperties envProperties;
        try {
            envProperties = ImmutableEnvProperties.builder() //
                .consulHost(getConsulHost(systemEnvironment)) //
                .consulPort(getConsultPort(systemEnvironment)) //
                .cbsName(getConfigBindingService(systemEnvironment)) //
                .appName(getService(systemEnvironment)) //
                .build();
        } catch (EnvironmentLoaderException e) {
            return Mono.error(e);
        }
        logger.trace("Evaluated environment system variables {}", envProperties);
        return Mono.just(envProperties);
    }

    private static String getConsulHost(Properties systemEnvironments) throws EnvironmentLoaderException {
        return Optional.ofNullable(systemEnvironments.getProperty("CONSUL_HOST"))
            .orElseThrow(() -> new EnvironmentLoaderException("$CONSUL_HOST environment has not been defined"));
    }

    private static Integer getConsultPort(Properties systemEnvironments) {
        return Optional.ofNullable(systemEnvironments.getProperty("CONSUL_PORT")) //
            .map(Integer::valueOf) //
            .orElseGet(EnvironmentProcessor::getDefaultPortOfConsul);
    }

    private static String getConfigBindingService(Properties systemEnvironments) throws EnvironmentLoaderException {
        return Optional.ofNullable(systemEnvironments.getProperty("CONFIG_BINDING_SERVICE")) //
            .orElseThrow(
                () -> new EnvironmentLoaderException("$CONFIG_BINDING_SERVICE environment has not been defined"));
    }

    private static String getService(Properties systemEnvironments) throws EnvironmentLoaderException {
        return Optional
            .ofNullable(Optional.ofNullable(systemEnvironments.getProperty("HOSTNAME"))
                .orElse(systemEnvironments.getProperty("SERVICE_NAME")))
            .orElseThrow(() -> new EnvironmentLoaderException(
                "Neither $HOSTNAME/$SERVICE_NAME have not been defined as system environment"));
    }

    private static Integer getDefaultPortOfConsul() {
        logger.warn("$CONSUL_PORT variable will be set to default port {}", DEFAULT_CONSUL_PORT);
        return DEFAULT_CONSUL_PORT;
    }
}