package org.kohsuke.github;

import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.HttpURLConnection;

/**
 * Pluggable strategy to determine what to do when the API abuse limit is hit.
 *
 * @author Kohsuke Kawaguchi
 * @see GitHubBuilder#withAbuseLimitHandler(AbuseLimitHandler) GitHubBuilder#withAbuseLimitHandler(AbuseLimitHandler)
 * @see <a href="https://developer.github.com/v3/#abuse-rate-limits">documentation</a>
 * @see RateLimitHandler
 */
public abstract class AbuseLimitHandler {
    /**
     * Called when the library encounters HTTP error indicating that the API abuse limit is reached.
     *
     * <p>
     * Any exception thrown from this method will cause the request to fail, and the caller of github-api will receive
     * an exception. If this method returns normally, another request will be attempted. For that to make sense, the
     * implementation needs to wait for some time.
     *
     * @param e
     *            Exception from Java I/O layer. If you decide to fail the processing, you can throw this exception (or
     *            wrap this exception into another exception and throw it).
     * @param uc
     *            Connection that resulted in an error. Useful for accessing other response headers.
     * @throws IOException
     *             on failure
     * @see <a href="https://developer.github.com/v3/#abuse-rate-limits">API documentation from GitHub</a>
     * @see <a href=
     *      "https://developer.github.com/v3/guides/best-practices-for-integrators/#dealing-with-abuse-rate-limits">Dealing
     *      with abuse rate limits</a>
     *
     */
    public abstract void onError(IOException e, HttpURLConnection uc) throws IOException;

    /**
     * Wait until the API abuse "wait time" is passed.
     */
    public static final AbuseLimitHandler WAIT = new AbuseLimitHandler() {
        @Override
        public void onError(IOException e, HttpURLConnection uc) throws IOException {
            try {
                Thread.sleep(parseWaitTime(uc));
            } catch (InterruptedException ex) {
                throw (InterruptedIOException) new InterruptedIOException().initCause(e);
            }
        }

        private long parseWaitTime(HttpURLConnection uc) {
            String v = uc.getHeaderField("Retry-After");
            if (v == null)
                return 60 * 1000; // can't tell, return 1 min

            return Math.max(1000, Long.parseLong(v) * 1000);
        }
    };

    /**
     * Fail immediately.
     */
    public static final AbuseLimitHandler FAIL = new AbuseLimitHandler() {
        @Override
        public void onError(IOException e, HttpURLConnection uc) throws IOException {
            throw (IOException) new IOException("Abuse limit reached").initCause(e);
        }
    };
}
