com.sap.cloud.mt.subscription.SqLiteFileResolver Maven / Gradle / Ivy

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/**************************************************************************
 * (C) 2019-2022 SAP SE or an SAP affiliate company. All rights reserved. *
 **************************************************************************/
package com.sap.cloud.mt.subscription;

import java.io.File;
import java.io.IOException;
import java.nio.file.FileVisitOption;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.function.Consumer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class SqLiteFileResolver {

	private static final Logger logger = LoggerFactory.getLogger(SqLiteFileResolver.class);

	private static final Pattern SQLITE_FILE_NAME = Pattern.compile("sqlite[_|-]([\\w-]+)\\.db");
	private static final Pattern SQLITE_ALTERNATIVE_FILE_NAME = Pattern.compile("db[_|-]([\\w-]+)\\.sqlite");

	private final List directories = Arrays.asList("mtx/sidecar/gen", "mtx/sidecar/", "../mtx/sidecar/", "../mtx/sidecar/gen", ".", "../");

	private final Path root;

	public SqLiteFileResolver(Path root) {
		this.root = root;
	}

	public Map get() {
		for (String variant : directories) {
			Path path = root.resolve(variant);
			Map result = find(path);
			if (!result.isEmpty()) {
				if (logger.isDebugEnabled()) {
					logger.debug("Picked up tenants: {}", String.join(", ", result.keySet()));
				}
				return result;
			}
		}
		logger.debug("No tenant databases found.");
		return Collections.emptyMap();
	}

	private static Map find(Path root) {
		try (Stream stream = Files.find(root, 1,
			(path, attributes) -> attributes.isRegularFile() && isFileUsable(path.toFile()),
			FileVisitOption.FOLLOW_LINKS)) {

			List potentialFiles = stream.toList();
			if (!potentialFiles.isEmpty()) {
				Map result = new HashMap<>();
				potentialFiles.forEach(item -> {
					ifMatch(item.getFileName().toString(), SQLITE_ALTERNATIVE_FILE_NAME,
						matcher -> result.putIfAbsent(matcher.group(1), item));
					ifMatch(item.getFileName().toString(), SQLITE_FILE_NAME,
						matcher -> result.putIfAbsent(matcher.group(1), item));
				});
				logger.debug("Found {} tenant databases at {}", result.size(), root);
				return Collections.unmodifiableMap(result);
			}
		} catch (NoSuchFileException e) {
			logger.debug("Skipped missing path at {}", e.getFile());
		} catch (IOException e) {
			logger.error("There was an error during file access. No tenants will be returned", e);
		}
		return Collections.emptyMap();
	}

	private static boolean isFileUsable(File file) {
		return file.exists() && file.canRead() && file.canWrite() && (
			SQLITE_FILE_NAME.matcher(file.getName()).matches() ||
			SQLITE_ALTERNATIVE_FILE_NAME.matcher(file.getName()).matches() );
	}

	private static void ifMatch(String text, Pattern pattern, Consumer action) {
		Matcher matcher = pattern.matcher(text);
		if (matcher.find()) {
			action.accept(matcher);
		}
	}
}