/**
 * Copyright (C) 2011 Whisper Systems
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */
package org.thoughtcrime.securesms.database;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.support.annotation.NonNull;
import android.telephony.PhoneNumberUtils;
import android.text.TextUtils;
import android.util.Log;

import com.google.i18n.phonenumbers.NumberParseException;
import com.google.i18n.phonenumbers.PhoneNumberUtil;
import com.google.i18n.phonenumbers.Phonenumber;
import com.google.i18n.phonenumbers.ShortNumberInfo;

import org.thoughtcrime.securesms.util.GroupUtil;
import org.thoughtcrime.securesms.util.TextSecurePreferences;
import org.thoughtcrime.securesms.util.VisibleForTesting;
import org.whispersystems.textsecure.api.util.InvalidNumberException;
import org.whispersystems.textsecure.api.util.PhoneNumberFormatter;

import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class CanonicalAddressDatabase {

  private static final String TAG = CanonicalAddressDatabase.class.getSimpleName();

  private static final int    DATABASE_VERSION = 1;
  private static final String DATABASE_NAME    = "canonical_address.db";
  private static final String TABLE            = "canonical_addresses";
  private static final String ID_COLUMN        = "_id";
  private static final String ADDRESS_COLUMN   = "address";

  private static final String DATABASE_CREATE  = "CREATE TABLE " + TABLE + " (" + ID_COLUMN + " integer PRIMARY KEY, " + ADDRESS_COLUMN + " TEXT NOT NULL);";
  private static final String SELECTION_NUMBER = "PHONE_NUMBERS_EQUAL(" + ADDRESS_COLUMN + ", ?)";
  private static final String SELECTION_OTHER  = ADDRESS_COLUMN + " = ? COLLATE NOCASE";

  private static CanonicalAddressDatabase instance;
  private        DatabaseHelper           databaseHelper;
  private final  Context                  context;

  private final Map<String, Long> addressCache = new ConcurrentHashMap<>();
  private final Map<Long, String> idCache      = new ConcurrentHashMap<>();

  public synchronized static CanonicalAddressDatabase getInstance(Context context) {
    if (instance == null)
      instance = new CanonicalAddressDatabase(context.getApplicationContext());

    return instance;
  }

  private CanonicalAddressDatabase(Context context) {
    this.context        = context;
    this.databaseHelper = new DatabaseHelper(context, DATABASE_NAME, null, DATABASE_VERSION);

    fillCache();
  }

  public void reset(Context context) {
    DatabaseHelper old  = this.databaseHelper;
    this.databaseHelper = new DatabaseHelper(context.getApplicationContext(), DATABASE_NAME, null, DATABASE_VERSION);
    old.close();
    fillCache();
  }

  private void fillCache() {
    Cursor cursor = null;

    try {
      SQLiteDatabase db = databaseHelper.getReadableDatabase();
      cursor            = db.query(TABLE, null, null, null, null, null, null);

      while (cursor != null && cursor.moveToNext()) {
        long   id      = cursor.getLong(cursor.getColumnIndexOrThrow(ID_COLUMN));
        String address = cursor.getString(cursor.getColumnIndexOrThrow(ADDRESS_COLUMN));

        if (address == null || address.trim().length() == 0)
          address = "Anonymous";

        idCache.put(id, address);
        addressCache.put(address, id);
      }
    } finally {
      if (cursor != null)
        cursor.close();
    }
  }

  public @NonNull String getAddressFromId(long id) {
    String cachedAddress = idCache.get(id);

    if (cachedAddress != null)
      return cachedAddress;

    Cursor cursor = null;

    try {
      Log.w(TAG, "Hitting DB on query [ID].");

      SQLiteDatabase db = databaseHelper.getReadableDatabase();
      cursor            = db.query(TABLE, null, ID_COLUMN + " = ?", new String[] {id+""}, null, null, null);

      if (!cursor.moveToFirst())
        return "Anonymous";

      String address = cursor.getString(cursor.getColumnIndexOrThrow(ADDRESS_COLUMN));

      if (address == null || address.trim().equals("")) {
        return "Anonymous";
      } else {
        idCache.put(id, address);
        return address;
      }
    } finally {
      if (cursor != null)
        cursor.close();
    }
  }

  public void close() {
    databaseHelper.close();
    instance = null;
  }

  public long getCanonicalAddressId(@NonNull String address) {
    try {
      long canonicalAddressId;

      if (isNumberAddress(address) && TextSecurePreferences.isPushRegistered(context)) {
        String localNumber = TextSecurePreferences.getLocalNumber(context);

        if (!isShortCode(localNumber, address)) {
          address = PhoneNumberFormatter.formatNumber(address, localNumber);
        }
      }

      if ((canonicalAddressId = getCanonicalAddressFromCache(address)) != -1) {
        return canonicalAddressId;
      }

      canonicalAddressId = getCanonicalAddressIdFromDatabase(address);

      idCache.put(canonicalAddressId, address);
      addressCache.put(address, canonicalAddressId);

      return canonicalAddressId;
    } catch (InvalidNumberException e) {
      throw new AssertionError(e);
    }
  }

  public @NonNull List<Long> getCanonicalAddressIds(@NonNull List<String> addresses) {
    List<Long> addressList = new LinkedList<>();

    for (String address : addresses) {
      addressList.add(getCanonicalAddressId(address));
    }

    return addressList;
  }

  private long getCanonicalAddressFromCache(String address) {
    Long cachedAddress = addressCache.get(address);
    return cachedAddress == null ? -1L : cachedAddress;
  }

  private long getCanonicalAddressIdFromDatabase(@NonNull String address) {
    Log.w(TAG, "Hitting DB on query [ADDRESS]");

    Cursor cursor = null;

    try {
      SQLiteDatabase db                 = databaseHelper.getWritableDatabase();
      String[]       selectionArguments = new String[]{address};
      boolean        isNumber           = isNumberAddress(address);

      cursor = db.query(TABLE, null, isNumber ? SELECTION_NUMBER : SELECTION_OTHER,
                        selectionArguments, null, null, null);

      if (cursor.getCount() == 0 || !cursor.moveToFirst()) {
        ContentValues contentValues = new ContentValues(1);
        contentValues.put(ADDRESS_COLUMN, address);
        return db.insert(TABLE, ADDRESS_COLUMN, contentValues);
      } else {
        long   canonicalId = cursor.getLong(cursor.getColumnIndexOrThrow(ID_COLUMN));
        String oldAddress  = cursor.getString(cursor.getColumnIndexOrThrow(ADDRESS_COLUMN));

        if (!address.equals(oldAddress)) {
          ContentValues contentValues = new ContentValues(1);
          contentValues.put(ADDRESS_COLUMN, address);
          db.update(TABLE, contentValues, ID_COLUMN + " = ?", new String[]{canonicalId+""});

          addressCache.remove(oldAddress);
        }

        return canonicalId;
      }
    } finally {
      if (cursor != null) {
        cursor.close();
      }
    }
  }

  @VisibleForTesting
  static boolean isNumberAddress(@NonNull String number) {
    if (number.contains("@"))             return false;
    if (GroupUtil.isEncodedGroup(number)) return false;

    final String networkNumber = PhoneNumberUtils.extractNetworkPortion(number);

    if (TextUtils.isEmpty(networkNumber)) return false;
    if (networkNumber.length() < 3)       return false;

    return PhoneNumberUtils.isWellFormedSmsAddress(number);
  }

  private boolean isShortCode(@NonNull String localNumber, @NonNull String number) {
    try {
      PhoneNumberUtil         util              = PhoneNumberUtil.getInstance();
      Phonenumber.PhoneNumber localNumberObject = util.parse(localNumber, null);
      String                  localCountryCode  = util.getRegionCodeForNumber(localNumberObject);
      Phonenumber.PhoneNumber shortCode         = util.parse(number, localCountryCode);

      return ShortNumberInfo.getInstance().isPossibleShortNumberForRegion(shortCode, localCountryCode);
    } catch (NumberParseException e) {
      Log.w(TAG, e);
      return false;
    }
  }

  private static class DatabaseHelper extends SQLiteOpenHelper {

    public DatabaseHelper(Context context, String name, CursorFactory factory, int version) {
      super(context, name, factory, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
      db.execSQL(DATABASE_CREATE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }

  }
}