/* Copyright (c) 2013-2014 Jesper Öqvist <jesper@llbit.se>
 *
 * This file is part of Chunky.
 *
 * Chunky is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Chunky is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with Chunky.  If not, see <http://www.gnu.org/licenses/>.
 */
package se.llbit.chunky.launcher;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import se.llbit.json.JsonParser;
import se.llbit.json.JsonParser.SyntaxError;

/**
 * Check for update and run update dialog (or just update in headless mode).
 *
 * @author Jesper Öqvist <jesper@llbit.se>
 */
public class UpdateChecker extends Thread {
  private final LauncherSettings settings;
  private final UpdateListener listener;

  public UpdateChecker(LauncherSettings settings, UpdateListener listener) {
    this.settings = settings;
    this.listener = listener;
  }

  @Override public void run() {
    try {
      if (!tryUpdate()) {
        listener.noUpdateAvailable();
      }
    } catch (MalformedURLException e1) {
      System.err.println("Malformed version info url");
      listener.updateError("Failed to fetch latest version info online.");
    } catch (IOException e1) {
      System.err.println("Failed to fetch version info " + e1.getMessage());
      listener.updateError(
          "Failed to fetch latest version info online. The server may be down right now.");
    } catch (SyntaxError e1) {
      System.err.println("Version info JSON error " + e1.getMessage());
      listener.updateError("The downloaded version info was corrupt. Can not update at this time.");
    } catch (Throwable e1) {
      System.err.println("Uncaught exception: " + e1.getMessage());
      listener.updateError("Can not update at this time.");
    }
  }

  private boolean tryUpdate() throws IOException, SyntaxError {
    List<VersionInfo> candidates = new LinkedList<>();

    candidates.add(getVersion("http://chunkyupdate.llbit.se/latest.json"));

    if (settings.downloadSnapshots) {
      candidates.add(getVersion("http://chunkyupdate.llbit.se/snapshot.json"));
    }

    // Filter out corrupt versions.
    Iterator<VersionInfo> iter = candidates.iterator();
    while (iter.hasNext()) {
      if (!iter.next().isValid()) {
        iter.remove();
      }
    }

    if (candidates.isEmpty()) {
      listener
          .updateError("The downloaded version info was corrupt. Can not update at this moment.");
      return false;
    } else {
      // Find latest candidate.
      VersionInfo latest = candidates.get(0);
      for (VersionInfo candidate : candidates) {
        if (candidate.compareTo(latest) < 0) {
          latest = candidate;
        }
      }

      // Check if more recent version than candidate is already installed.
      List<VersionInfo> versions = ChunkyDeployer.availableVersions();
      iter = versions.iterator();
      while (iter.hasNext()) {
        VersionInfo available = iter.next();
        if (available.compareTo(latest) <= 0 && ChunkyDeployer
            .checkVersionIntegrity(available.name)) {
          // More recent version already installed and not corrupt.
          return false;
        }
      }

      // Install the candidate!
      listener.updateAvailable(latest);
      return true;
    }
  }

  private VersionInfo getVersion(String url) throws IOException, SyntaxError {
    URL latestJson = new URL(url);
    InputStream in = latestJson.openStream();
    JsonParser parser = new JsonParser(in);
    VersionInfo version = new VersionInfo(parser.parse().object());
    in.close();
    return version;
  }
}