import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.event.ApplicationPreparedEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.EnumerablePropertySource;
import org.springframework.core.env.PropertySource;

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

@SpringBootApplication
public class Application {

    public static void main(String[] args) {

        SpringApplication springApplication = new SpringApplication(Application.class);
        // For development purposes only. DO NOT log system properties in live envs.
        springApplication.addListeners(new PropertiesLogger());
        springApplication.run(args);
    }

    @Slf4j
    private static class PropertiesLogger  implements ApplicationListener<ApplicationPreparedEvent> {

        private ConfigurableEnvironment environment;
        private boolean isFirstRun = true;

        @Override
        public void onApplicationEvent(ApplicationPreparedEvent event) {

            if (isFirstRun) {
                environment = event.getApplicationContext().getEnvironment();
                printProperties();
            }
            isFirstRun = false;
        }
        public void printProperties() {
            for (EnumerablePropertySource propertySource : findPropertiesPropertySources()) {
                log.info("******* " + propertySource.getName() + " *******");
                String[] propertyNames = propertySource.getPropertyNames();
                Arrays.sort(propertyNames);
                for (String propertyName : propertyNames) {
                    String resolvedProperty = environment.getProperty(propertyName);
                    String sourceProperty = propertySource.getProperty(propertyName).toString();
                    if(resolvedProperty.equals(sourceProperty)) {
                        log.info("{}={}", propertyName, resolvedProperty);
                    }else {
                        log.info("{}={} OVERRIDDEN to {}", propertyName, sourceProperty, resolvedProperty);
                    }
                }
            }
        }

        private List<EnumerablePropertySource> findPropertiesPropertySources() {
            List<EnumerablePropertySource> propertiesPropertySources = new LinkedList<>();
            for (PropertySource<?> propertySource : environment.getPropertySources()) {
                if (propertySource instanceof EnumerablePropertySource) {
                    propertiesPropertySources.add((EnumerablePropertySource) propertySource);
                }
            }
            return propertiesPropertySources;
        }
    }
}