FileHandler.java

package uk.ac.ic.wlgitbridge.server;

import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.handler.ResourceHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import uk.ac.ic.wlgitbridge.bridge.BridgeAPI;
import uk.ac.ic.wlgitbridge.snapshot.push.exception.InvalidPostbackKeyException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Serve files referenced by the snapshot that we send to the Overleaf API.
 *
 * Requests must include the postback key.
 */
public class FileHandler extends ResourceHandler {
    private static final Logger LOG = LoggerFactory.getLogger(FileHandler.class);

    private final BridgeAPI writeLatexDataSource;
    private final Pattern DOC_KEY_PATTERN = Pattern.compile("^/(\\w+)/.+$");

    public FileHandler(BridgeAPI writeLatexDataSource) {
        this.writeLatexDataSource = writeLatexDataSource;
    }

    @Override
    public void handle(String target,
                       Request baseRequest,
                       HttpServletRequest request,
                       HttpServletResponse response) throws IOException, ServletException {
        if (!"GET".equals(baseRequest.getMethod())) return;
        LOG.info("GET <- {}", baseRequest.getRequestURI());

        Matcher docKeyMatcher = DOC_KEY_PATTERN.matcher(target);
        if (!docKeyMatcher.matches()) return;
        String docKey = docKeyMatcher.group(1);

        String apiKey = request.getParameter("key");
        if (apiKey == null) return;

        try {
            writeLatexDataSource.checkPostbackKey(docKey, apiKey);
        } catch (InvalidPostbackKeyException e) {
            LOG.warn("INVALID POST BACK KEY: docKey={} apiKey={}", docKey, apiKey);
            return;
        }

        super.handle(target, baseRequest, request, response);
    }
}