package be.nikiroo.fanfix;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;

import be.nikiroo.utils.Version;

/**
 * Version checker: can check the current version of the program against a
 * remote changelog, and list the missed updates and their description.
 * 
 * @author niki
 */
public class VersionCheck {
	private static final String base = "https://github.com/${PROJECT}/raw/master/changelog${LANG}.md";

	private Version current;
	private List<Version> newer;
	private Map<Version, List<String>> changes;

	/**
	 * Create a new {@link VersionCheck}.
	 * 
	 * @param current
	 *            the current version of the program
	 * @param newer
	 *            the list of available {@link Version}s newer the current one
	 * @param changes
	 *            the list of changes
	 */
	private VersionCheck(Version current, List<Version> newer,
			Map<Version, List<String>> changes) {
		this.current = current;
		this.newer = newer;
		this.changes = changes;
	}

	/**
	 * Check if there are more recent {@link Version}s of this program
	 * available.
	 * 
	 * @return TRUE if there is at least one
	 */
	public boolean isNewVersionAvailable() {
		return !newer.isEmpty();
	}

	/**
	 * The current {@link Version} of the program.
	 * 
	 * @return the current {@link Version}
	 */
	public Version getCurrentVersion() {
		return current;
	}

	/**
	 * The list of available {@link Version}s newer than the current one.
	 * 
	 * @return the newer {@link Version}s
	 */
	public List<Version> getNewer() {
		return newer;
	}

	/**
	 * The list of changes for each available {@link Version} newer than the
	 * current one.
	 * 
	 * @return the list of changes
	 */
	public Map<Version, List<String>> getChanges() {
		return changes;
	}

	/**
	 * Ignore the check result.
	 */
	public void ignore() {

	}

	/**
	 * Accept the information, and do not check again until the minimum wait
	 * time has elapsed.
	 */
	public void ok() {
		Instance.getInstance().setVersionChecked();
	}

	/**
	 * Check if there are available {@link Version}s of this program more recent
	 * than the current one.
	 * 
	 * @param githubProject
	 *            the GitHub project to check on, for instance "nikiroo/fanfix"
	 * 
	 * @return a {@link VersionCheck}
	 */
	public static VersionCheck check(String githubProject) {
		Version current = Version.getCurrentVersion();
		List<Version> newer = new ArrayList<Version>();
		Map<Version, List<String>> changes = new HashMap<Version, List<String>>();

		if (Instance.getInstance().isVersionCheckNeeded()) {
			try {
				// Use the right project:
				String base = VersionCheck.base.replace("${PROJECT}",
						githubProject);
				
				// Prepare the URLs according to the user's language:
				Locale lang = Instance.getInstance().getTrans().getLocale();
				String fr = lang.getLanguage();
				String BE = lang.getCountry().replace(".UTF8", "");
				String urlFrBE = base.replace("${LANG}", "-" + fr + "_" + BE);
				String urlFr = base.replace("${LANG}", "-" + fr);
				String urlDefault = base.replace("${LANG}", "");

				InputStream in = null;
				for (String url : new String[] { urlFrBE, urlFr, urlDefault }) {
					try {
						in = Instance.getInstance().getCache().openNoCache(
								new URL(url), null, null, null, null);
						break;
					} catch (IOException e) {
					}
				}

				if (in == null) {
					throw new IOException("No changelog found");
				}

				BufferedReader reader = new BufferedReader(
						new InputStreamReader(in, "UTF-8"));
				try {
					Version version = new Version();
					for (String line = reader.readLine(); line != null; line = reader
							.readLine()) {
						if (line.startsWith("## Version ")) {
							version = new Version(line.substring("## Version "
									.length()));
							if (version.isNewerThan(current)) {
								newer.add(version);
								changes.put(version, new ArrayList<String>());
							} else {
								version = new Version();
							}
						} else if (!version.isEmpty() && !newer.isEmpty()
								&& !line.isEmpty()) {
							List<String> ch = changes.get(newer.get(newer
									.size() - 1));
							if (!ch.isEmpty() && !line.startsWith("- ")) {
								int i = ch.size() - 1;
								ch.set(i, ch.get(i) + " " + line.trim());
							} else {
								ch.add(line.substring("- ".length()).trim());
							}
						}
					}
				} finally {
					reader.close();
				}
			} catch (IOException e) {
				Instance.getInstance().getTraceHandler()
						.error(new IOException("Cannot download latest changelist on github.com", e));
			}
		}

		return new VersionCheck(current, newer, changes);
	}
}