Esempio n. 1
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 public Cursor rawQuery(String sql, String[] selectionArgs) {
   return contentResolver.query(
       TransactionProvider.contentUri("raw"), null, sql, selectionArgs, null);
 }
Esempio n. 2
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 protected void rename(String oldTableName, String newTableName) {
   Uri uri = TransactionProvider.contentUri("rename");
   uri = Uri.withAppendedPath(uri, oldTableName);
   uri = Uri.withAppendedPath(uri, newTableName);
   contentResolver.query(uri, null, null, null, null);
 }
Esempio n. 3
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 protected void create(String tableName) {
   Uri uri = TransactionProvider.contentUri("create");
   uri = Uri.withAppendedPath(uri, tableName);
   contentResolver.query(uri, null, null, null, null);
 }
Esempio n. 4
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 public void drop(String tableName) {
   Uri uri = TransactionProvider.contentUri("drop");
   uri = Uri.withAppendedPath(uri, tableName);
   contentResolver.query(uri, null, null, null, null);
 }
Esempio n. 5
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 protected void _clear() {
   contentResolver.query(TransactionProvider.contentUri("clear"), null, null, null, null);
 }
Esempio n. 6
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/**
 * A class containing transactions and evaluation tools for a cost sharing system
 *
 * @author lotharla
 */
public class Transactor implements java.io.Serializable {
  private static final long serialVersionUID = 1619400649251233944L;

  public Transactor(Context context, Object... params) {
    contentResolver = context.getContentResolver();

    if (!tableExists(kitty)) _clear();
  }

  public Transactor(Object... params) {
    this(null, params);
  }

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

  private double debtLimit = ShareUtil.minAmount;

  private boolean breaksDebtLimit(double amount) {
    double total = total();
    if (total - amount < -debtLimit) {
      Log.w(TAG, String.format("retrieval of %f is more than allowed : %f", amount, total));
      return true;
    } else return false;
  }

  /** @hide */
  public double getDebtLimit() {
    return debtLimit;
  }

  /** @hide */
  public void setDebtLimit(double debtLimit) {
    this.debtLimit = debtLimit;
  }

  private boolean isInternal(String name) {
    return kitty.equals(name);
  }

  private String notInternalCondition() {
    return "name != " + enclose("'", kitty);
  }

  private String whereClause(String... clause) {
    return nullOrEmpty(clause) || !notNullOrEmpty(clause[0]) ? "" : " where " + clause[0];
  }

  public int composeFlags(int transactionCode, boolean expenseFlag) {
    return transactionCode * 100 + (expenseFlag ? 1 : 0);
  }
  /**
   * The transaction registers the negated sum of the shares with the submitter. Additionally all
   * the shares in the map are registered with the same entry id. This transaction does not change
   * the total. It registers an allocation of a certain amount. If submitter is an empty <code>
   * String</code> it means there is an internal reallocation which is not an expense. Such an
   * internal reallocation is not allowed if the transaction causes a negative total.
   *
   * @param submitter the name of the participant who expended an amount matching the negated sum of
   *     the shares
   * @param comment a <code>String</code> to make the transaction recognizable
   * @param shares a <code>ShareMap</code> containing the shares of participants involved
   * @return the entry id of the transaction or -1 in case the transaction failed or -2 if the
   *     transaction violates the 'no negative total' rule
   */
  public int performExpense(String submitter, String comment, ShareMap shares) {
    double amount = -shares.sum();

    boolean internal = isInternal(submitter);
    if (internal) {
      if (breaksDebtLimit(-amount)) return -2;
    }

    int transactionCode = 3;
    int flags = composeFlags(transactionCode, !internal);

    int entryId = addEntry(submitter, amount, currency, comment, flags);
    if (entryId < 0) return -1;

    if (allocate(flags, entryId, shares.rawMap)) {
      String action = internal ? "reallocation of" : submitter + " expended";
      Log.i(
          TAG,
          String.format(
              "entry %d: %s %f %s for '%s' shared by %s",
              entryId, action, Math.abs(amount), currency, comment, shares.toString()));
    } else {
      removeEntry(entryId);
      entryId = -1;
    }

    return entryId;
  }
  /**
   * The transaction registers the negated sum of the shares as an expense by a group of
   * contributors. Additionally all the shares in the map are registered with the same entry id.
   * Those names in the deals map that are empty <code>String</code> trigger transfers of internal
   * amounts. Such an internal transfer is not allowed if the transaction causes a negative total.
   *
   * @param deals the names of the contributors and their contributions who expended an amount
   *     matching the negated sum of the deals
   * @param comment a <code>String</code> to make the transaction recognizable
   * @param shares a <code>ShareMap</code> containing the shares of participants involved
   * @return the entry id of the transaction or a negative value in case the transaction failed
   */
  public int performComplexExpense(ShareMap deals, String comment, ShareMap shares) {
    int entryId = -1;

    int transactionCode = 3;
    int flags = composeFlags(transactionCode, true);

    double amount = deals.sum();
    if (Math.abs(amount + shares.sum()) < ShareUtil.delta) {
      if (deals.option != null)
        switch (deals.option) {
          default:
            setDebtLimit(1000. * deals.option);
            break;
        }

      if (deals.rawMap.containsKey(kitty))
        entryId = performTransfer(kitty, -deals.rawMap.get(kitty), comment, kitty);
      else entryId = getNewEntryId();

      Collection<String> dealers = ShareUtil.filter(deals.rawMap.keySet(), true, ShareUtil.isKitty);

      for (String name : dealers) {
        long rowId =
            addRecord(
                entryId,
                name,
                deals.rawMap.get(name),
                currency,
                Helper.timestampNow(),
                comment,
                flags);
        if (rowId < 0) {
          entryId = -1;
          break;
        }
      }
    } else
      Log.w(
          TAG,
          String.format(
              "the sum of the deals (%f) for '%s' doesn't match the sum of the shares (%f)",
              amount, comment, shares.sum()));

    if (entryId > -1) {
      if (allocate(flags, entryId, shares.rawMap)) {
        Log.i(
            TAG,
            String.format(
                "entry %d: %s expended %f %s for '%s' shared by %s",
                entryId, deals.toString(), Math.abs(amount), currency, comment, shares.toString()));
      } else {
        removeEntry(entryId);
        entryId = -1;
      }
    }

    if (entryId < 0) removeEntry(entryId);

    return entryId;
  }
  /**
   * The transaction performs a transfer of the amount from a submitter to a recipient. This is the
   * same as performing a contribution of the submitter and then a payout to the recipient.
   *
   * @param sender the name of the participant who lost the amount
   * @param amount the amount of the transfer
   * @param comment a <code>String</code> to make the transaction recognizable
   * @param recipient the name of the participant who got the amount
   * @return the entry id of the transaction or -1 in case the transaction failed or -2 if the
   *     transaction violates the 'no negative total' rule
   */
  public int performTransfer(String sender, double amount, String comment, String recipient) {
    boolean internal = isInternal(sender);
    if (internal) {
      if (breaksDebtLimit(amount)) return -2;
    }

    int transactionCode = 2;
    int flags = composeFlags(transactionCode, false);

    int entryId = addEntry(sender, amount, currency, comment, flags);
    if (entryId < 0) return -1;

    flags = composeFlags(transactionCode, sender.equals(recipient));
    long rowId =
        addRecord(entryId, recipient, -amount, currency, Helper.timestampNow(), comment, flags);
    if (rowId < 0) {
      removeEntry(entryId);
      return -1;
    }

    Log.i(
        TAG,
        String.format(
            "entry %d: %s transfer %f %s for '%s' to %s",
            entryId, sender, amount, currency, comment, recipient));

    return entryId;
  }
  /**
   * The transaction registers the amount as a contribution (positive) or a retrieval (negative). A
   * retrieval is not allowed if it surmounts the current total.
   *
   * @param submitter the name of the participant who did the submission
   * @param amount the amount of the submission
   * @param comment a <code>String</code> to make the transaction recognizable
   * @return the entry id of the transaction or -1 in case the transaction failed or -2 if the
   *     transaction violates the 'no negative total' rule
   */
  public int performSubmission(String submitter, double amount, String comment) {
    int transactionCode = 1;
    int flags = composeFlags(transactionCode, false);

    int entryId = addEntry(submitter, amount, currency, comment, flags);

    if (entryId > -1) {
      if (breaksDebtLimit(-amount)) {
        removeEntry(entryId);
        return -2;
      }

      String action = amount > 0 ? "contributed" : "retrieved";
      Log.i(
          TAG,
          String.format(
              "entry %d: %s %s %f %s as '%s'",
              entryId, submitter, action, Math.abs(amount), currency, comment));
    }

    return entryId;
  }
  /**
   * The transaction registers multiple submissions. This transaction as a whole is not allowed if
   * it causes a negative total.
   *
   * @param deals a <code>ShareMap</code> containing the deals of participants involved
   * @param comment a <code>String</code> to make the transactions recognizable
   * @return the entry id of the transaction or -1 in case the transaction failed or -2 if the
   *     transactions in the sum violate the 'no negative total' rule
   */
  public int performMultiple(ShareMap deals, String comment) {
    if (breaksDebtLimit(-deals.sum())) return -2;

    int transactionCode = 4;
    int flags = composeFlags(transactionCode, false);

    int entryId = getNewEntryId();

    if (entryId > -1) {
      for (Map.Entry<String, Double> share : deals.rawMap.entrySet())
        if (addRecord(
                entryId,
                share.getKey(),
                share.getValue(),
                currency,
                Helper.timestampNow(),
                comment,
                flags)
            < 0) {
          removeEntry(entryId);
          return -1;
        }

      Log.i(
          TAG,
          String.format("entry %d: '%s' submissions : %s", entryId, comment, deals.toString()));
    }

    return entryId;
  }
  /**
   * The transaction discards any record with that entry id.
   *
   * @param entryId the entry to be discarded
   * @return the number of affected records
   */
  public int performDiscard(int entryId) {
    int affected = removeEntry(entryId);
    Log.i(TAG, String.format("entry %d: discarded, %d records deleted", entryId, affected));
    return affected;
  }
  /**
   * summarizes the cash flows caused by the participants
   *
   * @return a sorted map containing the names as key and the cash flow of that participant as value
   */
  public ShareMap cashFlow() {
    return rawQuery(
        "select name, sum(amount) as balance from "
            + kitty
            + whereClause(notInternalCondition())
            + " and timestamp not null group by name order by name",
        null,
        new QueryEvaluator<ShareMap>() {
          public ShareMap evaluate(Cursor cursor, ShareMap defaultResult, Object... params) {
            ShareMap sm = new ShareMap();

            if (cursor.moveToFirst())
              do {
                sm.rawMap.put(cursor.getString(0), cursor.getDouble(1));
              } while (cursor.moveToNext());

            Log.i(TAG, String.format("cash flow : %s", sm.toString()));
            return sm;
          }
        },
        null);
  }
  /**
   * calculates the balances of all participants identified by their names
   *
   * @return a sorted map containing the names as keys and the balances as values
   */
  public ShareMap balances() {
    return rawQuery(
        "select name, sum(amount) as balance from "
            + kitty
            + whereClause(notInternalCondition())
            + " group by name order by name",
        null,
        new QueryEvaluator<ShareMap>() {
          public ShareMap evaluate(Cursor cursor, ShareMap defaultResult, Object... params) {
            ShareMap sm = new ShareMap();

            if (cursor.moveToFirst())
              do {
                sm.rawMap.put(cursor.getString(0), cursor.getDouble(1));
              } while (cursor.moveToNext());

            Log.i(TAG, String.format("balances : %s", sm.toString()));
            return sm;
          }
        },
        null);
  }
  /**
   * calculates the current over-all amount
   *
   * @return the sum over the amounts of all records in the table
   */
  public double total() {
    return getSum();
  }
  /**
   * calculates the accumulated costs
   *
   * @return the sum over all entries marked as 'expense'
   */
  public double expenses() {
    return getSum("flags % 10 > 0 and timestamp not null");
  }

  private static String sharingPolicy = ""; // 	uniform sharing among all participants
  /**
   * A sharing policy depicts the way the volume of all the cash flows is to be shared among the
   * participants when it comes to calculating compensations (x:y:z ...). The given integers are
   * proportional weights for those participants who are involved in the compensation procedure.
   * They are assigned according to the sorted list of names.
   *
   * @return an array containing integer values or empty meaning the default sharing policy (uniform
   *     sharing among all participants)
   */
  public static String getSharingPolicy() {
    return Transactor.sharingPolicy;
  }
  /**
   * sets the sharing policy. Note that a call of <code>clear</code> or <code>clearAll</code> resets
   * the sharing policy to its default (uniform sharing among all participants).
   *
   * @param sharingPolicy
   */
  public static void setSharingPolicy(String sharingPolicy) {
    Transactor.sharingPolicy = sharingPolicy;
  }
  /**
   * calculates a compensation for each participant from the balance and the all-over cash flow at
   * this point. The sharing policy is taken into account for this calculation. An example: A
   * sharing policy 1:2:3 splits the volume of all the cash flows minus the current total which is
   * the remaining amount among the first, second and third participants out of the sorted list of
   * names. The first portion is 1/6, the second 2/6 and the third is 3/6 of the volume.
   *
   * @return a sorted map containing the names as keys and the compensations as values
   */
  public ShareMap compensations(String sharingPolicy) {
    String[] sortedNames = sortedNames();
    ShareMap cashFlow = cashFlow();
    double volume = cashFlow.sum() - total();

    ShareMap differences = new ShareMap(sortedNames, volume);
    ShareMap sharedCosts = new ShareMap(sortedNames, volume, sharingPolicy);
    differences.minus(sharedCosts.rawMap.values());

    ShareMap compensations = balances().negated();
    compensations.minus(differences.negated().rawMap.values());
    return compensations;
  }
  /** @return a sorted array of all names of the participants */
  public String[] sortedNames() {
    return rawQuery(
        "select distinct name from " + kitty + whereClause(notInternalCondition()),
        null,
        new QueryEvaluator<String[]>() {
          public String[] evaluate(Cursor cursor, String[] defaultResult, Object... params) {
            TreeSet<String> names = new TreeSet<String>();
            if (cursor.moveToFirst())
              do {
                names.add(cursor.getString(0));
              } while (cursor.moveToNext());
            return names.toArray(defaultResult);
          }
        },
        new String[0]);
  }
  /** @return a sorted array of distinct comments */
  public String[] sortedComments() {
    return rawQuery(
        "select distinct comment from " + kitty + whereClause("length(comment) > 0"),
        null,
        new QueryEvaluator<String[]>() {
          public String[] evaluate(Cursor cursor, String[] defaultResult, Object... params) {
            TreeSet<String> comments = new TreeSet<String>();
            if (cursor.moveToFirst())
              do {
                comments.add(cursor.getString(0));
              } while (cursor.moveToNext());
            return comments.toArray(defaultResult);
          }
        },
        new String[0]);
  }
  /**
   * @param clause the condition constraining the query through a where clause
   * @return a sorted array of entries identified by their id
   */
  public Integer[] getEntryIds(String... clause) {
    return rawQuery(
        "select entry from " + kitty + whereClause(clause),
        null,
        new QueryEvaluator<Integer[]>() {
          public Integer[] evaluate(Cursor cursor, Integer[] defaultResult, Object... params) {
            TreeSet<Integer> ids = new TreeSet<Integer>();
            if (cursor.moveToFirst())
              do {
                ids.add(cursor.getInt(0));
              } while (cursor.moveToNext());
            return ids.toArray(defaultResult);
          }
        },
        new Integer[0]);
  }
  /**
   * @param clause the condition constraining the query through a where clause
   * @return the textual representations of all the entries to the active database table
   */
  public String[] getEntryStrings(String clause, final String tableName) {
    return rawQuery(
        "select distinct entry from " + tableName + whereClause(clause),
        null,
        new QueryEvaluator<String[]>() {
          public String[] evaluate(Cursor cursor, String[] defaultResult, Object... params) {
            ArrayList<String> strings = new ArrayList<String>();
            if (cursor.moveToFirst())
              do {
                strings.add(getEntryString(cursor.getInt(0), tableName));
              } while (cursor.moveToNext());
            return strings.toArray(defaultResult);
          }
        },
        new String[0]);
  }
  /**
   * @param entryId the integer value identifying the entry in question
   * @return textual representation of the entry to the active database table
   */
  public String getEntryString(int entryId, String tableName) {
    return rawQuery(
        "select * from " + tableName + whereClause("entry=" + entryId),
        null,
        new QueryEvaluator<String>() {
          public String evaluate(Cursor cursor, String defaultResult, Object... params) {
            String s = "";
            if (cursor.moveToFirst()) {
              s +=
                  String.format(
                      "Entry %d on %s comment '%s'",
                      cursor.getInt(0), cursor.getString(4), cursor.getString(5));
              do {
                String assoc =
                    ShareMap.association(
                        cursor.getString(1), Helper.formatAmount(cursor.getDouble(2)));
                s += " : " + assoc;
              } while (cursor.moveToNext());
            }
            return s;
          }
        },
        "");
  }
  /**
   * @param clause a condition constraining the query through a where clause
   * @return a sorted array of records identified by their row id
   */
  public Long[] getRowIds(String... clause) {
    return rawQuery(
        "select rowid from " + kitty + whereClause(clause),
        null,
        new QueryEvaluator<Long[]>() {
          public Long[] evaluate(Cursor cursor, Long[] defaultResult, Object... params) {
            TreeSet<Long> ids = new TreeSet<Long>();
            if (cursor.moveToFirst())
              do {
                ids.add(cursor.getLong(0));
              } while (cursor.moveToNext());
            return ids.toArray(defaultResult);
          }
        },
        new Long[0]);
  }
  /**
   * @param clause a condition constraining the query through a where clause
   * @return a aggregated sum of the amount values in the queried records
   */
  public Double getSum(String... clause) {
    return rawQuery(
        "select sum(amount) from " + kitty + whereClause(clause),
        null,
        new QueryEvaluator<Double>() {
          public Double evaluate(Cursor cursor, Double defaultResult, Object... params) {
            if (cursor.moveToFirst()) return cursor.getDouble(0);
            else return defaultResult;
          }
        },
        null);
  }
  /**
   * @param params an array of parameters : the first is the name of the table to count the records
   *     in (default is the main table) and the second is a condition constraining the query in a
   *     where clause
   * @return the count of the queried records
   */
  public Integer getCount(Object... params) {
    String tableName = param(kitty, 0, params);
    String clause = param(null, 1, params);
    return rawQuery(
        "select count(*) from " + tableName + whereClause(clause),
        null,
        new QueryEvaluator<Integer>() {
          public Integer evaluate(Cursor cursor, Integer defaultResult, Object... params) {
            if (cursor.moveToFirst()) return cursor.getInt(0);
            else return defaultResult;
          }
        },
        null);
  }
  /**
   * determines whether the table with the name exists in the database
   *
   * @param name name of the table
   * @return the table does not exist if false
   */
  public Boolean tableExists(String name) {
    return rawQuery(
        "select name from sqlite_master where type = 'table'",
        null,
        new QueryEvaluator<Boolean>() {
          public Boolean evaluate(Cursor cursor, Boolean defaultResult, Object... params) {
            Boolean result = defaultResult;
            String name = param("", 0, params);

            if (cursor.moveToFirst())
              do {
                if (name.compareToIgnoreCase(cursor.getString(0)) == 0) {
                  result = true;
                  break;
                }
              } while (cursor.moveToNext());

            return result;
          }
        },
        false,
        name);
  }
  /**
   * retrieves the names of tables that exist under a given name or - if no name is given - are
   * current
   *
   * @param suffix the name of a saved table if given
   * @return the <code>Set</code> of table names
   */
  public Set<String> tableSet(Object... suffix) {
    return rawQuery(
        "select name from sqlite_master where type = 'table'",
        null,
        new QueryEvaluator<Set<String>>() {
          public Set<String> evaluate(Cursor cursor, Set<String> defaultResult, Object... params) {
            TreeSet<String> set = new TreeSet<String>();
            String suffix = param(null, 0, params);

            if (cursor.moveToFirst())
              do {
                String name = cursor.getString(0);
                if (suffix == null) {
                  if (tableList.contains(name)) set.add(name);
                } else if (name.endsWith("_" + suffix)) set.add(name);
              } while (cursor.moveToNext());

            return set;
          }
        },
        null,
        suffix);
  }
  /**
   * retrieves the names of tables that had been 'saved' in the past
   *
   * @return the <code>Set</code> of saved table names
   */
  public Set<String> savedTables() {
    return rawQuery(
        "select name from sqlite_master where type = 'table'",
        null,
        new QueryEvaluator<Set<String>>() {
          public Set<String> evaluate(Cursor cursor, Set<String> defaultResult, Object... params) {
            TreeSet<String> names = new TreeSet<String>();
            String prefix = ShareUtil.tableName("");

            if (cursor.moveToFirst())
              do {
                String name = cursor.getString(0);
                if (name.startsWith(prefix)) names.add(name);
              } while (cursor.moveToNext());

            Log.i(TAG, String.format("saved tables : %s", names.toString()));
            return names;
          }
        },
        null);
  }
  /**
   * changes the name of the table that has been worked on (current table). Thus this table is
   * 'saved' in the same database. Note that the current table is non-existing after this operation.
   * In order to continue the current table has to be restored (loadFrom) or recreated (clear).
   *
   * @param suffix the <code>String</code> to append to the name of the current table in order to
   *     form the new table name
   * @return success if true
   */
  public boolean saveAs(String suffix) {
    if (!notNullOrEmpty(suffix)) return false;

    String newTableName = ShareUtil.tableName(suffix);
    if (savedTables().contains(newTableName)) return false;

    for (int index : savedTableIndices()) {
      String oldTableName = tableList.get(index);
      if (tableExists(oldTableName) && getCount(oldTableName) > 0) {
        newTableName = ShareUtil.tableName(oldTableName, suffix);
        rename(oldTableName, newTableName);
      } else drop(oldTableName);
    }

    Log.i(TAG, String.format("table saved as '%s'", newTableName));
    return true;
  }

  protected int[] savedTableIndices() {
    return new int[] {0, 1};
  }

  /**
   * restores one of the saved tables as the current table. Note that the table that was current up
   * to this point will be dropped. Also there will be one less 'saved' table after this operation.
   *
   * @param suffix the <code>String</code> to append to the name of the current table in order to
   *     form the old table name
   * @return success if true
   */
  public boolean loadFrom(String suffix) {
    if (!notNullOrEmpty(suffix)) return false;

    String oldTableName = ShareUtil.tableName(suffix);
    if (!savedTables().contains(oldTableName)) return false;

    for (int index : savedTableIndices()) {
      String newTableName = tableList.get(index);
      oldTableName = ShareUtil.tableName(newTableName, suffix);
      if (tableExists(oldTableName)) rename(oldTableName, newTableName);
      else create(newTableName);
    }

    Log.i(TAG, String.format("table loaded from '%s'", oldTableName));
    return true;
  }
  /** deletes all records from the current table and recreates it */
  public void clear() {
    Integer count = tableExists(kitty) ? getCount() : 0;
    _clear();
    Log.i(TAG, String.format("table '%s' cleared, %d records deleted", kitty, count));
    setSharingPolicy(null);
  }
  /** clears the current table and drops all saved tables */
  public void clearAll() {
    for (String table : savedTables()) drop(table);

    _clear();
    Log.i(TAG, String.format("table '%s' cleared, all saved tables dropped", kitty));
    setSharingPolicy(null);
  }

  private String currency = "";

  public String getCurrency() {
    return currency;
  }

  public void setCurrency(String currency) {
    this.currency = currency;
  }

  /** @hide */
  public int columnIndex(String key) {
    return Arrays.asList(getFieldNames()).indexOf(key);
  }

  /** @hide */
  public boolean isExpense(long rowId) {
    return rawQuery(
        "select flags from " + kitty + " where ROWID=" + rowId,
        null,
        new QueryEvaluator<Boolean>() {
          public Boolean evaluate(Cursor cursor, Boolean defaultResult, Object... params) {
            return cursor.moveToFirst() && cursor.getInt(0) % 10 > 0;
          }
        },
        false);
  }

  /** @hide */
  public int getNewEntryId() {
    return 1
        + rawQuery(
            "select max(entry) from " + kitty,
            null,
            new QueryEvaluator<Integer>() {
              public Integer evaluate(Cursor cursor, Integer defaultResult, Object... params) {
                if (cursor.moveToFirst()) return cursor.getInt(0);
                else return defaultResult;
              }
            },
            -1);
  }

  /** @hide */
  public int addEntry(String name, double amount, String currency, String comment, int flags) {
    int entryId = getNewEntryId();

    long rowId = addRecord(entryId, name, amount, currency, Helper.timestampNow(), comment, flags);
    if (rowId < 0) {
      removeEntry(entryId);
      entryId = -1;
    }

    return entryId;
  }

  /** @hide */
  public String fetchField(int entryId, final String name) {
    return fetchEntry(
        entryId,
        new QueryEvaluator<String>() {
          public String evaluate(Cursor cursor, String defaultResult, Object... params) {
            int timestampIndex = columnIndex("timestamp");
            if (cursor.moveToFirst())
              do {
                if (cursor.getString(timestampIndex) != null)
                  return cursor.getString(columnIndex(name));
              } while (cursor.moveToNext());
            return defaultResult;
          }
        },
        null);
  }

  /** @hide */
  public boolean allocate(int flags, int entryId, Map<String, Double> portions) {
    for (String name : portions.keySet()) {
      double portion = portions.get(name);

      if (addRecord(entryId, name, portion, null, null, null, flags) < 0) return false;
    }

    return portions.size() > 0;
  }

  /** @hide */
  public interface QueryEvaluator<T> {
    public T evaluate(Cursor cursor, T defaultResult, Object... params);
  }

  /** @hide */
  public <T> T rawQuery(
      String sql, String[] selectionArgs, QueryEvaluator<T> qe, T defaultResult, Object... params) {
    Cursor cursor = null;

    try {
      cursor = rawQuery(sql, selectionArgs);
      if (cursor != null) return qe.evaluate(cursor, defaultResult, params);
    } catch (SQLiteException ex) {
    } finally {
      if (cursor != null) cursor.close();
    }

    return defaultResult;
  }

  /** @hide */
  public <T> T fetchEntry(int entryId, QueryEvaluator<T> qe, T defaultResult, Object... params) {
    Cursor cursor = null;

    try {
      cursor = query(getFieldNames(), "entry=" + entryId);
      if (cursor != null) return qe.evaluate(cursor, defaultResult, params);
    } catch (SQLiteException ex) {
    } finally {
      if (cursor != null) cursor.close();
    }

    return defaultResult;
  }

  /** @hide */
  public int removeEntry(int entryId) {
    return delete("entry=" + entryId);
  }

  protected ContentValues putValues(
      Integer entry,
      String name,
      Double amount,
      String currency,
      String timestamp,
      String comment,
      Integer flags) {
    ContentValues values = new ContentValues();

    String[] fields = getFieldNames();
    if (entry != null) values.put(fields[0], entry);
    if (name != null) values.put(fields[1], name);
    if (amount != null) values.put(fields[2], amount);
    if (currency != null) values.put(fields[3], currency);
    if (timestamp != null) values.put(fields[4], timestamp);
    if (comment != null) values.put(fields[5], comment);
    if (flags != null) values.put(fields[6], flags);

    return values;
  }

  protected long addRecord(
      int entryId,
      String name,
      double amount,
      String currency,
      String timestamp,
      String comment,
      int flags) {
    ContentValues values = putValues(entryId, name, amount, currency, timestamp, comment, flags);
    long rowId = insert(values);
    if (rowId < 0) Log.e(TAG, String.format(".addRecord failed with : %s", values.toString()));
    return rowId;
  }

  protected int updateExpenseFlag(long rowId, int flags) {
    return update(rowId, putValues(null, null, null, null, null, null, flags));
  }

  protected String[] getFieldNames() {
    return new String[] {
      "entry", "name", "amount", "currency", "timestamp", "comment", "flags", "ROWID"
    };
  }

  private static List<String> tableList = new ArrayList<String>(Transaction.tableDefs.keySet());

  private ContentResolver contentResolver;

  protected void _clear() {
    contentResolver.query(TransactionProvider.contentUri("clear"), null, null, null, null);
  }

  public void drop(String tableName) {
    Uri uri = TransactionProvider.contentUri("drop");
    uri = Uri.withAppendedPath(uri, tableName);
    contentResolver.query(uri, null, null, null, null);
  }

  protected void create(String tableName) {
    Uri uri = TransactionProvider.contentUri("create");
    uri = Uri.withAppendedPath(uri, tableName);
    contentResolver.query(uri, null, null, null, null);
  }

  protected void rename(String oldTableName, String newTableName) {
    Uri uri = TransactionProvider.contentUri("rename");
    uri = Uri.withAppendedPath(uri, oldTableName);
    uri = Uri.withAppendedPath(uri, newTableName);
    contentResolver.query(uri, null, null, null, null);
  }

  private Uri KITTY_URI = TransactionProvider.contentUri(0);

  protected long insert(ContentValues values) {
    Uri uri = contentResolver.insert(KITTY_URI, values);
    return toLong(-1L, uri.getPathSegments().get(1));
  }

  protected int update(long rowId, ContentValues values) {
    return contentResolver.update(ContentUris.withAppendedId(KITTY_URI, rowId), values, "", null);
  }

  protected int delete(String clause) {
    return contentResolver.delete(KITTY_URI, clause, null);
  }

  protected Cursor query(String[] columns, String clause) {
    return contentResolver.query(KITTY_URI, columns, clause, null, null);
  }

  public Cursor rawQuery(String sql, String[] selectionArgs) {
    return contentResolver.query(
        TransactionProvider.contentUri("raw"), null, sql, selectionArgs, null);
  }
}