package org.simantics.logging;

import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceReference;
import org.simantics.logging.internal.Activator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public final class LogCollector {

    private static final Logger LOGGER = LoggerFactory.getLogger(LogCollector.class);

    public static Map<String, List<Path>> allLogs() {
        Map<String, List<Path>> results = new HashMap<>();
        if (LOGGER.isDebugEnabled())
            LOGGER.debug("Collecting all logs from declarative services");

        Collection<LogProvider> logProviders = getLogProviders();
        for (LogProvider logProvider : logProviders) {
            List<Path> logs = logProvider.get();
            String key = logProvider.getClass().getSimpleName();
            Collection<Path> existing = results.get(key);
            if (existing != null) {
                LOGGER.info("Duplicate log providers with name {} exist, merging logs", key);
                logs.addAll(existing);
            }
            results.put(key, logs);
        }
        if (LOGGER.isDebugEnabled())
            LOGGER.debug("Found logs from {} providers", results.keySet());
        return results;
    }

    private static List<LogProvider> getLogProviders() {
        ServiceReference<?>[] serviceReferences = new ServiceReference<?>[0];
        String key = LogProvider.class.getName();
        try {
            serviceReferences = Activator.getContext().getAllServiceReferences(key, null);
        } catch (InvalidSyntaxException e) {
            LOGGER.error("Could not get service references for {}!", key, e);
        }
        if (serviceReferences.length == 0) {
            if (LOGGER.isDebugEnabled())
                LOGGER.debug("No service references found for {}", key);
            return Collections.emptyList();
        }

        List<LogProvider> logProviders = new ArrayList<>(serviceReferences.length);
        for (ServiceReference<?> reference : serviceReferences) {
            LogProvider logProvider = (LogProvider) Activator.getContext().getService(reference);
            logProviders.add(logProvider);
        }
        if (LOGGER.isDebugEnabled())
            LOGGER.debug("Found {} log providers", logProviders);
        return logProviders;
    }
}