com.exasol.containers.slc.fileprovider.CachingUrlFileProvider Maven / Gradle / Ivy

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package com.exasol.containers.slc.fileprovider;

import java.io.IOException;
import java.io.UncheckedIOException;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;

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

import com.exasol.containers.ExasolContainerConstants;

// [impl->dsn~install-custom-slc.url~1]
class CachingUrlFileProvider implements FileProvider {
    private static final Logger LOGGER = LoggerFactory.getLogger(CachingUrlFileProvider.class);
    private final UrlDownloader urlDownloader;
    private final Path localCacheDir;
    private final URL url;

    CachingUrlFileProvider(final URL url) {
        this(new UrlDownloader(), getDefaultCacheDir(), url);
    }

    CachingUrlFileProvider(final UrlDownloader urlDownloader, final Path localCacheDir, final URL url) {
        this.urlDownloader = urlDownloader;
        this.localCacheDir = localCacheDir;
        this.url = url;
    }

    private static Path getDefaultCacheDir() {
        return ExasolContainerConstants.CACHE_DIRECTORY.resolve("slcs");
    }

    @Override
    public Path getLocalFile() {
        final Path localPath = localCacheDir.resolve(getFileName());
        if (Files.exists(localPath)) {
            LOGGER.debug("Using cached file {}", localPath);
            return localPath;
        }
        createDirectories();
        urlDownloader.download(url, localPath);
        return localPath;
    }

    private void createDirectories() {
        if (Files.exists(localCacheDir)) {
            return;
        }
        createDirectories(localCacheDir);
    }

    private static void createDirectories(final Path dir) {
        try {
            Files.createDirectories(dir);
        } catch (final IOException exception) {
            throw new UncheckedIOException("Unable to create cache directory '" + dir + "'", exception);
        }
    }

    @Override
    public String getFileName() {
        final String path = url.getPath();
        return url.getPath().substring(path.lastIndexOf('/') + 1);
    }
}