// BlacklistCleaner_p.java
// -----------------------
// part of YaCy
// (C) by Michael Peter Christen; mc@yacy.net
// first published on http://www.anomic.de
// Frankfurt, Germany, 2004
//
// This File is contributed by Franz Brausze
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// This program 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 2 of the License, or
// (at your option) any later version.
//
// This program 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 this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

// You must compile this file with
// javac -classpath .:../classes BlacklistCleaner_p.java
// if the shell's current path is HTROOT

import java.io.File;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import net.yacy.cora.document.id.Punycode.PunycodeException;
import net.yacy.cora.protocol.RequestHeader;
import net.yacy.cora.util.ConcurrentLog;
import net.yacy.data.ListManager;
import net.yacy.kelondro.util.FileUtils;
import net.yacy.repository.Blacklist;
import net.yacy.repository.BlacklistHostAndPath;
import net.yacy.repository.Blacklist.BlacklistError;
import net.yacy.repository.Blacklist.BlacklistType;
import net.yacy.search.Switchboard;
import net.yacy.search.query.SearchEventCache;
import net.yacy.server.serverObjects;
import net.yacy.server.serverSwitch;

public class BlacklistCleaner_p {

    /** Used for logging. */
    private static final String APP_NAME = "BLACKLIST-CLEANER";

    private static final String RESULTS = "results_";
    private static final String DISABLED = "disabled_";
    private static final String BLACKLISTS = "blacklists_";
    private static final String ENTRIES = "entries_";

    public static final Class<?>[] supportedBLEngines = { Blacklist.class };

    public static serverObjects respond(
                    @SuppressWarnings("unused") final RequestHeader header,
                    final serverObjects post,
                    @SuppressWarnings("unused") final serverSwitch env) {
        final serverObjects prop = new serverObjects();

        String blacklistToUse = null;

        prop.put(DISABLED + "checked", "1");

        if (post != null) {

            final boolean allowRegex = post.get("allowRegex", "off")
                            .equalsIgnoreCase("on") ? true : false;
            prop.put(DISABLED + "checked", (allowRegex) ? "1" : "0");

            if (post.containsKey("listNames")) {
                blacklistToUse = post.get("listNames");
                if (blacklistToUse.isEmpty()
                                || !ListManager.listSetContains(
                                                "listManager.listsPath",
                                                blacklistToUse)) {
                    prop.put("results", "2");

                }
            }

            putBlacklists(prop, FileUtils.getDirListing(ListManager.listsPath,
                            Blacklist.BLACKLIST_FILENAME_FILTER),
                            blacklistToUse);

            if (blacklistToUse != null) {
                prop.put("results", "1");

                if (post.containsKey("delete")) {
                    prop.put(RESULTS + "modified", "1");
                    prop.put(RESULTS + "modified_delCount",
                                    removeEntries(blacklistToUse,
                                                    BlacklistType.values(),
                                                    getKeysByPrefix(post,
                                                                    "select",
                                                                    true)));
                } else if (post.containsKey("alter")) {
                    prop.put(RESULTS + "modified", "2");
                    prop.put(RESULTS + "modified_alterCount",
                                    alterEntries(blacklistToUse,
                                                    BlacklistType.values(),
                                                    getKeysByPrefix(post,
                                                                    "select",
                                                                    false),
                                                    getValuesByPrefix(post,
                                                                    "entry",
                                                                    false)));
                }

                // list illegal entries
                final Map<String, BlacklistError> illegalEntries = getIllegalEntries(
                                blacklistToUse, Switchboard.urlBlacklist,
                                allowRegex);
                prop.put(RESULTS + "blList", blacklistToUse);
                prop.put(RESULTS + "entries", illegalEntries.size());
                prop.putHTML(RESULTS + "blEngine", Blacklist.getEngineInfo());
                prop.put(RESULTS + "disabled", (illegalEntries.isEmpty()) ? "1"
                                : "0");
                if (!illegalEntries.isEmpty()) {
                    prop.put(RESULTS + DISABLED + "entries",
                                    illegalEntries.size());
                    int i = 0;
                    String key;
                    for (final Entry<String, BlacklistError> entry : illegalEntries
                                    .entrySet()) {
                        key = entry.getKey();
                        prop.put(RESULTS + DISABLED + ENTRIES + i + "_error",
                                        entry.getValue().getLong());
                        prop.putHTML(RESULTS + DISABLED + ENTRIES + i
                                        + "_entry", key);
                        i++;
                    }
                }
            }
        } else {
            prop.put("results", "0");
            putBlacklists(prop, FileUtils.getDirListing(ListManager.listsPath,
                            Blacklist.BLACKLIST_FILENAME_FILTER),
                            blacklistToUse);
        }

        return prop;
    }

    /**
     * Adds a list of blacklist to the server objects properties which are used
     * to display the blacklist in the HTML page belonging to this servlet.
     * 
     * @param prop
     *            Server objects properties object.
     * @param lists
     *            List of blacklists.
     * @param selected
     *            Element in list of blacklists which will be preselected in
     *            HTML.
     */
    private static void putBlacklists(final serverObjects prop,
                    final List<String> lists, final String selected) {
        boolean supported = false;
        for (int i = 0; i < supportedBLEngines.length && !supported; i++) {
            supported |= (Switchboard.urlBlacklist.getClass() == supportedBLEngines[i]);
        }

        if (supported) {
            if (!lists.isEmpty()) {
                prop.put("disabled", "0");
                prop.put(DISABLED + "blacklists", lists.size());
                int count = 0;
                for (final String list : lists) {
                    prop.putHTML(DISABLED + BLACKLISTS + count + "_name", list);
                    prop.put(DISABLED + BLACKLISTS + count + "_selected",
                                    (list.equals(selected)) ? "1" : "0");
                    count++;
                }
            } else {
                prop.put("disabled", "2");
            }
        } else {
            prop.put("disabled", "1");
            for (int i = 0; i < supportedBLEngines.length; i++) {
                prop.putHTML(DISABLED + "engines_" + i + "_name",
                                supportedBLEngines[i].getName());
            }
            prop.put(DISABLED + "engines", supportedBLEngines.length);
        }
    }

    /**
     * Retrieves all keys with a certain prefix from the data which has been
     * sent and returns them as an array. This method is only a wrapper for
     * {@link getByPrefix(de.anomic.server.serverObjects, java.lang.String,
     * boolean, boolean)} which has been created to make it easier to understand
     * the code.
     * 
     * @param post
     *            All POST values.
     * @param prefix
     *            Prefix by which the input is filtered.
     * @param filterDoubles
     *            Set true if only unique results shall be returned, else false.
     * @return Keys which have been posted.
     */
    private static String[] getKeysByPrefix(final serverObjects post,
                    final String prefix, final boolean filterDoubles) {
        return getByPrefix(post, prefix, true, filterDoubles);
    }

    /**
     * Retrieves all values with a certain prefix from the data which has been
     * sent and returns them as an array. This method is only a wrapper for
     * {@link getByPrefix(de.anomic.server.serverObjects, java.lang.String,
     * boolean, boolean)}.
     * 
     * @param post
     *            All POST values.
     * @param prefix
     *            Prefix by which the input is filtered.
     * @param filterDoubles
     *            Set true if only unique results shall be returned, else false.
     * @return Values which have been posted.
     */
    private static String[] getValuesByPrefix(final serverObjects post,
                    final String prefix, final boolean filterDoubles) {
        return getByPrefix(post, prefix, false, filterDoubles);
    }

    /**
     * Method which does all the work for {@link
     * getKeysByPrefix(de.anomic.server.serverObjects, java.lang.String prefix,
     * boolean)} and {@link getValuesByPrefix(de.anomic.server.serverObjects,
     * java.lang.String prefix, boolean)} which have been crested to make it
     * easier to understand the code.
     * 
     * @param post
     * @param prefix
     * @param useKeys
     * @param useHashSet
     * @return
     */
    private static String[] getByPrefix(final serverObjects post,
                    final String prefix, final boolean useKeys,
                    final boolean useHashSet) {
        Collection<String> r;
        if (useHashSet) {
            r = new HashSet<String>();
        } else {
            r = new ArrayList<String>();
        }

        if (useKeys) {
            for (final String entry : post.keySet()) {
                if (entry.indexOf(prefix) == 0) {
                    r.add(entry.substring(prefix.length()));
                }
            }
        } else {
            for (final Map.Entry<String, String> entry : post.entrySet()) {
                if (entry.getKey().indexOf(prefix) == 0) {
                    r.add(entry.getValue());
                }
            }
        }

        return r.toArray(new String[r.size()]);
    }

    /**
     * Finds illegal entries in black list.
     * 
     * @param blacklistToUse
     *            The blacklist to be checked.
     * @param blEngine
     *            The blacklist engine which is used to check
     * @param allowRegex
     *            Set to true to allow regular expressions in host part of
     *            blacklist entry.
     * @return A map which contains all entries whoch have been identified as
     *         being illegal by the blacklistEngine with the entry as key and an
     *         error code as value.
     */
    private static Map<String, BlacklistError> getIllegalEntries(
                    final String blacklistToUse, final Blacklist blEngine,
                    final boolean allowRegex) {
        final Map<String, BlacklistError> illegalEntries = new HashMap<String, BlacklistError>();
        final Set<String> legalEntries = new HashSet<String>();

        final List<String> list = FileUtils.getListArray(new File(
                        ListManager.listsPath, blacklistToUse));
        final Map<String, String> properties = new HashMap<String, String>();
        properties.put("allowRegex", String.valueOf(allowRegex));

        BlacklistError err = BlacklistError.NO_ERROR;

        for (String element : list) {
            element = element.trim();

            // check for double-occurance
            if (legalEntries.contains(element)) {
                illegalEntries.put(element, BlacklistError.DOUBLE_OCCURANCE);
                continue;
            }
            legalEntries.add(element);

            err = Blacklist.checkError(element, properties);

            if (err.getInt() > 0) {
                illegalEntries.put(element, err);
            }
        }

        return illegalEntries;
    }

    /**
     * Removes existing entries from a blacklist.
     * 
     * @param blacklistToUse
     *            The blacklist which contains the
     * @param supportedBlacklistTypes
     *            Types of blacklists which the entry is to changed in.
     * @param entries
     *            Array of entries to be deleted.
     * @return Length of the list of entries to be removed.
     */
    private static int removeEntries(final String blacklistToUse,
                    final BlacklistType[] supportedBlacklistTypes,
                    final String[] entries) {
        for (final String entry : entries) {
            String s = entry;

            // get rid of escape characters which make it impossible to
            // properly use contains()
            if (s.contains("\\\\")) {
                s = s.replaceAll(Pattern.quote("\\\\"),
                                Matcher.quoteReplacement("\\"));
            }

            // remove the entry from the running blacklist engine
            for (final BlacklistType supportedBlacklistType : supportedBlacklistTypes) {
                if (ListManager.listSetContains(supportedBlacklistType
                                + ".BlackLists", blacklistToUse)) {
                    final String host = (s.indexOf('/', 0) == -1) ? s : s
                                    .substring(0, s.indexOf('/', 0));
                    final String path = (s.indexOf('/', 0) == -1) ? ".*" : s
                                    .substring(s.indexOf('/', 0) + 1);
                    try {
                        Switchboard.urlBlacklist.remove(supportedBlacklistType,
                                        blacklistToUse, host, path);
                    } catch (final RuntimeException e) {
                        ConcurrentLog.severe(APP_NAME, e.getMessage() + ": "
                                        + host + "/" + path);
                    }
                }
            }
            SearchEventCache.cleanupEvents(true);
        }
        return entries.length;
    }

    /**
     * Changes existing entry in a blacklist.
     * 
     * @param blacklistToUse
     *            The blacklist which contains the entry.
     * @param supportedBlacklistTypes
     *            Types of blacklists which the entry is to changed in.
     * @param oldEntry
     *            Entry to be changed.
     * @param newEntry
     *            Changed entry.
     * @return The length of the new entry.
     */
    private static int alterEntries(final String blacklistToUse,
                    final BlacklistType[] supportedBlacklistTypes,
                    final String[] oldEntry, final String[] newEntry) {
        removeEntries(blacklistToUse, supportedBlacklistTypes, oldEntry);
        String host, path;
        /* Prepare the new blacklist items list to add then them in one operation for better performance */
        final Collection<BlacklistHostAndPath> newEntries = new ArrayList<>();
        for (final String n : newEntry) {
            final int pos = n.indexOf('/', 0);
            if (pos < 0) {
                host = n;
                path = ".*";
            } else {
                host = n.substring(0, pos);
                path = n.substring(pos + 1);
            }
            newEntries.add(new BlacklistHostAndPath(host, path));
        }
        for (final BlacklistType s : supportedBlacklistTypes) {
            if (ListManager.listSetContains(s + ".BlackLists",
                            blacklistToUse)) {
                try {
                    Switchboard.urlBlacklist.add(s, blacklistToUse, newEntries);
                } catch (PunycodeException e) {
                    ConcurrentLog.warn(APP_NAME,
                                    "Unable to add blacklist entry to blacklist "
                                                    + s, e);
                }
            }
        }
        SearchEventCache.cleanupEvents(true);
        return newEntry.length;
    }
}