//
// Copyright 2017 Filippo "Fil" Bergamo <fil.bergamo@riseup.net>
// 
// This file is part of RepWifiApp.
//
// RepWifiApp 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.
// 
// RepWifiApp 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 RepWifiApp.  If not, see <http://www.gnu.org/licenses/>.
// 
// ********************************************************************

package fil.libre.repwifiapp.helpers;

import java.io.File;
import java.util.ArrayList;

public class NetworkManager {

    private static final String F_SEP = "\t";
    private static final int NET_MAX_AGE = 365; // Expressed in days

    private String _knownNetworksFile = null;

    public NetworkManager(String networksFilePath) {
        this._knownNetworksFile = networksFilePath;
    }

    private AccessPointInfo searchInFile(AccessPointInfo i) {

        if (i == null) {
            return null;
        }

        String bssid = i.getBssid();
        String ssid = i.getSsid();

        if (bssid == null || ssid == null || bssid.trim().equals("") || ssid.trim().equals("")) {
            return null;
        }

        AccessPointInfo ret = null;
        AccessPointInfo[] list = getKnownNetworks();

        if (list == null) {
            return null;
        }

        for (AccessPointInfo toTest : list) {

            // try to match both bssid and ssid.
            // if bssid doesn't match, but ssid does,
            // then the network is a candidate.
            // if no bssid equality is found,
            // then return the best match (only ssid), if any
            if (toTest.getSsid().equals(ssid)) {

                if (toTest.getBssid().equals(bssid)) {
                    i.setPassword(toTest.getPassword());
                    return i;

                } else {
                    i.setPassword(toTest.getPassword());
                    ret = i;
                }

            }

        }

        return ret;

    }

    private boolean saveOrRemove(AccessPointInfo info, boolean save) {

        String iText = InfoToString(info);
        if (iText == null) {
            return false;
        }

        AccessPointInfo[] existingNets = getKnownNetworks();

        ArrayList<AccessPointInfo> newlist = new ArrayList<AccessPointInfo>();

        if (existingNets == null || existingNets.length == 0) {
            // no existing storage yet, create it

            if (save) {
                // set timestamp
                info.setLastTimeUsed(System.currentTimeMillis());
                newlist.add(info);
                AccessPointInfo[] newContents = new AccessPointInfo[newlist.size()];
                newContents = newlist.toArray(newContents);

                return saveList(newContents);

            } else {
                // nothing to do, return
                return true;
            }

        }

        if (save) {
            // add the updated info to the storage
            info.setLastTimeUsed(System.currentTimeMillis());
            newlist.add(info);
        }

        for (AccessPointInfo old : existingNets) {

            if (old == null) {
                // error while loading from file. skip.
                continue;
            }

            // keep network only if it's not older than the max age for a
            // network
            else if (old.isOlderThan(NET_MAX_AGE)) {
                // skip it
                continue;
            }

            else if (old.getBssid().equals(info.getBssid()) && old.getSsid().equals(info.getSsid())) {
                // found previously saved entry for the same network we are
                // managing
                // skip it
                continue;
            }

            else {
                // old network info that can be kept in the storage
                newlist.add(old);
            }

        }

        AccessPointInfo[] newContents = new AccessPointInfo[newlist.size()];
        newContents = newlist.toArray(newContents);

        return saveList(newContents);

    }

    private AccessPointInfo getFromString(String savedString) {

        if (savedString == null || savedString.trim().equals("")) {
            return null;
        }

        String[] fields = savedString.split(F_SEP);

        if (fields.length < 4) {
            return null;
        }

        String bssid = fields[0];
        String ssid = fields[1];
        String pass = fields[2];
        String lastUsed = fields[3];
        String auth = null;

        if (fields.length > 4) {
            auth = fields[4];
        }

        long lastusedmillis = 0;
        try {
            lastusedmillis = Long.parseLong(lastUsed);
        } catch (NumberFormatException e) {
            // invalid format
            Utils.logError("Invalid time format in network manager \"" + lastUsed
                            + "\". Network BSSID: " + bssid, e);
        }

        if (bssid.trim().equals("") || ssid.trim().equals("") || pass.trim().equals("")) {
            return null;
        }

        AccessPointInfo i = new AccessPointInfo(ssid, bssid, auth, null, null);
        i.setPassword(pass);
        i.setLastTimeUsed(lastusedmillis);

        return i;

    }

    private String InfoToString(AccessPointInfo info) {

        if (info == null) {
            return null;
        }

        String bssid = info.getBssid();
        String ssid = info.getSsid();
        String pass = info.getPassword();
        String tsLastUsed = "" + info.getLastTimeUsed();
        String auth = info.getAuthType();

        if (bssid == null || bssid.trim().equals("")) {
            return null;
        }

        if (ssid == null || ssid.trim().equals("")) {
            return null;
        }

        if (pass == null || pass.trim().equals("")) {
            return null;
        }

        if (auth == null) {
            auth = "";
        }

        String iText = info.getBssid() + F_SEP + info.getSsid() + F_SEP + info.getPassword()
                        + F_SEP + tsLastUsed + F_SEP + auth;
        return iText;

    }

    private boolean saveList(AccessPointInfo[] list) {

        if (list == null) {
            return false;
        }

        String[] lines = new String[list.length];

        for (int i = 0; i < list.length; i++) {

            String storeString = InfoToString(list[i]);
            if (storeString == null) {
                return false;
            }
            lines[i] = storeString;

        }

        return Utils.writeFileLines(this._knownNetworksFile, lines, true);

    }

    public AccessPointInfo[] getKnownNetworks() {

        ArrayList<AccessPointInfo> list = new ArrayList<AccessPointInfo>();

        File f = new File(this._knownNetworksFile);
        if (!f.exists()) {
            return null;
        }

        String[] lines = Utils.readFileLines(_knownNetworksFile);
        if (lines == null || lines.length == 0) {
            return null;
        }

        for (String l : lines) {

            AccessPointInfo info = getFromString(l);
            if (info != null) {
                list.add(info);
            }

        }

        AccessPointInfo[] ret = new AccessPointInfo[list.size()];
        ret = list.toArray(ret);

        return ret;

    }

    public boolean isKnown(AccessPointInfo info) {

        AccessPointInfo i = searchInFile(info);
        if (i == null) {
            return false;
        } else {
            return true;
        }

    }

    public boolean save(AccessPointInfo info) {
        return saveOrRemove(info, true);
    }

    public boolean remove(AccessPointInfo info) {
        return saveOrRemove(info, false);
    }

    public AccessPointInfo getSavedNetwork(AccessPointInfo i) {
        return searchInFile(i);
    }

}