/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.nfc.cardemulation;

import android.util.Log;
import android.util.SparseArray;

import com.android.nfc.NfcService;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

public class AidRoutingManager {

    static final String TAG = "AidRoutingManager";

    static final boolean DBG = false;

    static final int ROUTE_HOST = 0x00;

    // Every routing table entry is matched exact
    static final int AID_MATCHING_EXACT_ONLY = 0x00;
    // Every routing table entry can be matched either exact or prefix
    static final int AID_MATCHING_EXACT_OR_PREFIX = 0x01;
    // Every routing table entry is matched as a prefix
    static final int AID_MATCHING_PREFIX_ONLY = 0x02;
    // Every routing table entry can be matched either exact or prefix or subset only
    static final int AID_MATCHING_EXACT_OR_SUBSET_OR_PREFIX = 0x03;

    int mDefaultIsoDepRoute;
    //Let mDefaultRoute as default aid route
    int mDefaultRoute;

    int mMaxAidRoutingTableSize;

    final byte[] mOffHostRouteUicc;
    final byte[] mOffHostRouteEse;
    // Used for backward compatibility in case application doesn't specify the
    // SE
    final int mDefaultOffHostRoute;

    // How the NFC controller can match AIDs in the routing table;
    // see AID_MATCHING constants
    final int mAidMatchingSupport;

    final Object mLock = new Object();

    // mAidRoutingTable contains the current routing table. The index is the route ID.
    // The route can include routes to a eSE/UICC.
    SparseArray<Set<String>> mAidRoutingTable =
            new SparseArray<Set<String>>();

    // Easy look-up what the route is for a certain AID
    HashMap<String, Integer> mRouteForAid = new HashMap<String, Integer>();

    private native int doGetDefaultRouteDestination();
    private native int doGetDefaultOffHostRouteDestination();
    private native byte[] doGetOffHostUiccDestination();
    private native byte[] doGetOffHostEseDestination();
    private native int doGetAidMatchingMode();
    private native int doGetDefaultIsoDepRouteDestination();

    final class AidEntry {
        boolean isOnHost;
        String offHostSE;
        int route;
        int aidInfo;
    }

    public AidRoutingManager() {
        mDefaultRoute = doGetDefaultRouteDestination();
        if (DBG)
            Log.d(TAG, "mDefaultRoute=0x" + Integer.toHexString(mDefaultRoute));
        mDefaultOffHostRoute = doGetDefaultOffHostRouteDestination();
        if (DBG)
            Log.d(TAG, "mDefaultOffHostRoute=0x" + Integer.toHexString(mDefaultOffHostRoute));
        mOffHostRouteUicc = doGetOffHostUiccDestination();
        if (DBG)
            Log.d(TAG, "mOffHostRouteUicc=" + Arrays.toString(mOffHostRouteUicc));
        mOffHostRouteEse = doGetOffHostEseDestination();
        if (DBG)
          Log.d(TAG, "mOffHostRouteEse=" + Arrays.toString(mOffHostRouteEse));
        mAidMatchingSupport = doGetAidMatchingMode();
        if (DBG) Log.d(TAG, "mAidMatchingSupport=0x" + Integer.toHexString(mAidMatchingSupport));

        mDefaultIsoDepRoute = doGetDefaultIsoDepRouteDestination();
        if (DBG) Log.d(TAG, "mDefaultIsoDepRoute=0x" + Integer.toHexString(mDefaultIsoDepRoute));
    }

    public boolean supportsAidPrefixRouting() {
        return mAidMatchingSupport == AID_MATCHING_EXACT_OR_PREFIX ||
                mAidMatchingSupport == AID_MATCHING_PREFIX_ONLY ||
                 mAidMatchingSupport == AID_MATCHING_EXACT_OR_SUBSET_OR_PREFIX;
    }

    public boolean supportsAidSubsetRouting() {
        return mAidMatchingSupport == AID_MATCHING_EXACT_OR_SUBSET_OR_PREFIX;
    }

    public int calculateAidRouteSize(HashMap<String, AidEntry> routeCache) {
        // TAG + ROUTE + LENGTH_BYTE + POWER
        int AID_HDR_LENGTH = 0x04;
        int routeTableSize = 0x00;
        for(Map.Entry<String, AidEntry> aidEntry : routeCache.entrySet()) {
            String aid = aidEntry.getKey();
            // removing prefix length
            if(aid.endsWith("*")) {
                routeTableSize += ((aid.length() - 0x01) / 0x02) + AID_HDR_LENGTH;
            } else {
                routeTableSize += (aid.length() / 0x02)+ AID_HDR_LENGTH;
            }
        }
        if (DBG) Log.d(TAG, "calculateAidRouteSize: " + routeTableSize);
        return routeTableSize;
    }

    void clearNfcRoutingTableLocked() {
        for (Map.Entry<String, Integer> aidEntry : mRouteForAid.entrySet())  {
            String aid = aidEntry.getKey();
            if (aid.endsWith("*")) {
                if (mAidMatchingSupport == AID_MATCHING_EXACT_ONLY) {
                    Log.e(TAG, "Device does not support prefix AIDs but AID [" + aid
                            + "] is registered");
                } else if (mAidMatchingSupport == AID_MATCHING_PREFIX_ONLY) {
                    if (DBG) Log.d(TAG, "Unrouting prefix AID " + aid);
                    // Cut off '*' since controller anyway treats all AIDs as a prefix
                    aid = aid.substring(0, aid.length() - 1);
                } else if (mAidMatchingSupport == AID_MATCHING_EXACT_OR_PREFIX ||
                    mAidMatchingSupport == AID_MATCHING_EXACT_OR_SUBSET_OR_PREFIX) {
                    aid = aid.substring(0, aid.length() - 1);
                    if (DBG) Log.d(TAG, "Unrouting prefix AID " + aid);
                }
            }  else if (aid.endsWith("#")) {
                if (mAidMatchingSupport == AID_MATCHING_EXACT_ONLY) {
                    Log.e(TAG, "Device does not support subset AIDs but AID [" + aid
                            + "] is registered");
                } else if (mAidMatchingSupport == AID_MATCHING_PREFIX_ONLY ||
                    mAidMatchingSupport == AID_MATCHING_EXACT_OR_PREFIX) {
                    Log.e(TAG, "Device does not support subset AIDs but AID [" + aid
                            + "] is registered");
                } else if (mAidMatchingSupport == AID_MATCHING_EXACT_OR_SUBSET_OR_PREFIX) {
                    if (DBG) Log.d(TAG, "Unrouting subset AID " + aid);
                    aid = aid.substring(0, aid.length() - 1);
                }
            } else {
                if (DBG) Log.d(TAG, "Unrouting exact AID " + aid);
            }

            NfcService.getInstance().unrouteAids(aid);
        }
        if(NfcService.getInstance().getNciVersion() != NfcService.getInstance().NCI_VERSION_1_0) {
          // unRoute EmptyAid
          NfcService.getInstance().unrouteAids("");
        }
    }

    private int getRouteForSecureElement(String se) {
        if (se == null || se.length() <= 3) {
            return 0;
        }
        try {
            if (se.startsWith("eSE") && mOffHostRouteEse != null) {
                int index = Integer.parseInt(se.substring(3));
                if (mOffHostRouteEse.length >= index && index > 0) {
                    return mOffHostRouteEse[index - 1] & 0xFF;
                }
            } else if (se.startsWith("SIM") && mOffHostRouteUicc != null) {
                int index = Integer.parseInt(se.substring(3));
                if (mOffHostRouteUicc.length >= index && index > 0) {
                    return mOffHostRouteUicc[index - 1] & 0xFF;
                }
            }
        } catch (NumberFormatException e) { }
        return 0;
    }

    public boolean configureRouting(HashMap<String, AidEntry> aidMap) {
        boolean aidRouteResolved = false;
        HashMap<String, AidEntry> aidRoutingTableCache = new HashMap<String, AidEntry>(aidMap.size());
        ArrayList<Integer> seList = new ArrayList<Integer>();
        seList.add(ROUTE_HOST);

        SparseArray<Set<String>> aidRoutingTable = new SparseArray<Set<String>>(aidMap.size());
        HashMap<String, Integer> routeForAid = new HashMap<String, Integer>(aidMap.size());
        HashMap<String, Integer> infoForAid = new HashMap<String, Integer>(aidMap.size());
        // Then, populate internal data structures first
        for (Map.Entry<String, AidEntry> aidEntry : aidMap.entrySet())  {
            int route = ROUTE_HOST;
            if (!aidEntry.getValue().isOnHost) {
                String offHostSE = aidEntry.getValue().offHostSE;
                if (offHostSE == null) {
                    route = mDefaultOffHostRoute;
                } else {
                    route = getRouteForSecureElement(offHostSE);
                    if (route == 0) {
                        Log.e(TAG, "Invalid Off host Aid Entry " + offHostSE);
                        continue;
                    }
                }
            }
            if (!seList.contains(route))
                seList.add(route);
            aidEntry.getValue().route = route;
            int aidType = aidEntry.getValue().aidInfo;
            String aid = aidEntry.getKey();
            Set<String> entries =
                    aidRoutingTable.get(route, new HashSet<String>());
            entries.add(aid);
            aidRoutingTable.put(route, entries);
            routeForAid.put(aid, route);
            infoForAid.put(aid, aidType);
        }

        synchronized (mLock) {
            if (routeForAid.equals(mRouteForAid)) {
                if (DBG) Log.d(TAG, "Routing table unchanged, not updating");
                return false;
            }

            // Otherwise, update internal structures and commit new routing
            clearNfcRoutingTableLocked();
            mRouteForAid = routeForAid;
            mAidRoutingTable = aidRoutingTable;

            mMaxAidRoutingTableSize = NfcService.getInstance().getAidRoutingTableSize();
            if (DBG) Log.d(TAG, "mMaxAidRoutingTableSize: " + mMaxAidRoutingTableSize);

            //calculate AidRoutingTableSize for existing route destination
            for(int index = 0; index < seList.size(); index ++) {
              mDefaultRoute = seList.get(index);
              if(index != 0)
                if (DBG) Log.d(TAG, "AidRoutingTable is full, try to switch mDefaultRoute to 0x" + Integer.toHexString(mDefaultRoute));

              aidRoutingTableCache.clear();

              if (mAidMatchingSupport == AID_MATCHING_PREFIX_ONLY) {
                  /* If a non-default route registers an exact AID which is shorter
                   * than this exact AID, this will create a problem with controllers
                   * that treat every AID in the routing table as a prefix.
                   * For example, if App A registers F0000000041010 as an exact AID,
                   * and App B registers F000000004 as an exact AID, and App B is not
                   * the default route, the following would be added to the routing table:
                   * F000000004 -> non-default destination
                   * However, because in this mode, the controller treats every routing table
                   * entry as a prefix, it means F0000000041010 would suddenly go to the non-default
                   * destination too, whereas it should have gone to the default.
                   *
                   * The only way to prevent this is to add the longer AIDs of the
                   * default route at the top of the table, so they will be matched first.
                   */
                  Set<String> defaultRouteAids = mAidRoutingTable.get(mDefaultRoute);
                  if (defaultRouteAids != null) {
                      for (String defaultRouteAid : defaultRouteAids) {
                          // Check whether there are any shorted AIDs routed to non-default
                          // TODO this is O(N^2) run-time complexity...
                          for (Map.Entry<String, Integer> aidEntry : mRouteForAid.entrySet()) {
                              String aid = aidEntry.getKey();
                              int route = aidEntry.getValue();
                              if (defaultRouteAid.startsWith(aid) && route != mDefaultRoute) {
                                  if (DBG) Log.d(TAG, "Adding AID " + defaultRouteAid + " for default " +
                                          "route, because a conflicting shorter AID will be " +
                                          "added to the routing table");
                                    aidRoutingTableCache.put(defaultRouteAid, aidMap.get(defaultRouteAid));
                              }
                          }
                      }
                  }
              }

              // Add AID entries for all non-default routes
              for (int i = 0; i < mAidRoutingTable.size(); i++) {
                  int route = mAidRoutingTable.keyAt(i);
                  if (route != mDefaultRoute) {
                      Set<String> aidsForRoute = mAidRoutingTable.get(route);
                      for (String aid : aidsForRoute) {
                          if (aid.endsWith("*")) {
                              if (mAidMatchingSupport == AID_MATCHING_EXACT_ONLY) {
                                  Log.e(TAG, "This device does not support prefix AIDs.");
                              } else if (mAidMatchingSupport == AID_MATCHING_PREFIX_ONLY) {
                                  if (DBG) Log.d(TAG, "Routing prefix AID " + aid + " to route "
                                          + Integer.toString(route));
                                  // Cut off '*' since controller anyway treats all AIDs as a prefix
                                    aidRoutingTableCache.put(aid.substring(0,aid.length() - 1), aidMap.get(aid));
                              } else if (mAidMatchingSupport == AID_MATCHING_EXACT_OR_PREFIX ||
                                mAidMatchingSupport == AID_MATCHING_EXACT_OR_SUBSET_OR_PREFIX) {
                                  if (DBG) Log.d(TAG, "Routing prefix AID " + aid + " to route "
                                          + Integer.toString(route));
                                  aidRoutingTableCache.put(aid.substring(0,aid.length() - 1), aidMap.get(aid));
                              }
                          } else if (aid.endsWith("#")) {
                              if (mAidMatchingSupport == AID_MATCHING_EXACT_ONLY) {
                                  Log.e(TAG, "Device does not support subset AIDs but AID [" + aid
                                          + "] is registered");
                              } else if (mAidMatchingSupport == AID_MATCHING_PREFIX_ONLY ||
                                  mAidMatchingSupport == AID_MATCHING_EXACT_OR_PREFIX) {
                                  Log.e(TAG, "Device does not support subset AIDs but AID [" + aid
                                          + "] is registered");
                              } else if (mAidMatchingSupport == AID_MATCHING_EXACT_OR_SUBSET_OR_PREFIX) {
                                  if (DBG) Log.d(TAG, "Routing subset AID " + aid + " to route "
                                          + Integer.toString(route));
                                  aidRoutingTableCache.put(aid.substring(0,aid.length() - 1), aidMap.get(aid));
                              }
                         } else {
                              if (DBG) Log.d(TAG, "Routing exact AID " + aid + " to route "
                                      + Integer.toString(route));
                                aidRoutingTableCache.put(aid, aidMap.get(aid));
                          }
                        }
                 }
              }

              if(mDefaultRoute != mDefaultIsoDepRoute) {
                if(NfcService.getInstance().getNciVersion() != NfcService.getInstance().NCI_VERSION_1_0) {
                  String emptyAid = "";
                  AidEntry entry = new AidEntry();
                  entry.route = mDefaultRoute;
                  if(mDefaultRoute==ROUTE_HOST) {
                    entry.isOnHost = true;
                  } else{
                    entry.isOnHost = false;
                   }
                  entry.aidInfo = RegisteredAidCache.AID_ROUTE_QUAL_PREFIX;
                  aidRoutingTableCache.put(emptyAid, entry);
                  if (DBG) Log.d(TAG, "Add emptyAid into AidRoutingTable");
                }
              }

              if( calculateAidRouteSize(aidRoutingTableCache) <= mMaxAidRoutingTableSize) {
                aidRouteResolved = true;
                break;
              }
          }

          if(aidRouteResolved == true) {
              commit(aidRoutingTableCache);
          } else {
              Log.e(TAG, "RoutingTable unchanged because it's full, not updating");
          }
        }
        return true;
    }

    private void commit(HashMap<String, AidEntry> routeCache ) {

        if(routeCache != null) {

            for (Map.Entry<String, AidEntry> aidEntry : routeCache.entrySet())  {
                int route = aidEntry.getValue().route;
                int aidType = aidEntry.getValue().aidInfo;
                String aid = aidEntry.getKey();
                Log.d (TAG, "commit aid:"+aid+"route:"+route+"aidtype:"+aidType);

                NfcService.getInstance().routeAids(aid, route, aidType);
            }
        }

        // And finally commit the routing
        NfcService.getInstance().commitRouting();
    }

    /**
     * This notifies that the AID routing table in the controller
     * has been cleared (usually due to NFC being turned off).
     */
    public void onNfccRoutingTableCleared() {
        // The routing table in the controller was cleared
        // To stay in sync, clear our own tables.
        synchronized (mLock) {
            mAidRoutingTable.clear();
            mRouteForAid.clear();
        }
    }

    public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
        pw.println("Routing table:");
        pw.println("    Default route: " + ((mDefaultRoute == 0x00) ? "host" : "secure element"));
        synchronized (mLock) {
            for (int i = 0; i < mAidRoutingTable.size(); i++) {
                Set<String> aids = mAidRoutingTable.valueAt(i);
                pw.println("    Routed to 0x" + Integer.toHexString(mAidRoutingTable.keyAt(i)) + ":");
                for (String aid : aids) {
                    pw.println("        \"" + aid + "\"");
                }
            }
        }
    }
}