OwningIterator.java

package com.nicewuerfel.blockown.database;

import com.google.common.base.Optional;

import com.nicewuerfel.blockown.Ownable;
import com.nicewuerfel.blockown.OwnedBlock;
import com.nicewuerfel.blockown.OwnedEntity;
import com.nicewuerfel.blockown.OwningState;
import com.nicewuerfel.blockown.User;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Iterator;
import java.util.UUID;

class OwningIterator implements Iterator<OwningState> {

  private final java.sql.Statement stmnt;
  private ResultSet rs;
  private int state = 0;

  OwningIterator(java.sql.Statement stmnt) {
    this.stmnt = stmnt;
    rs = getBlockOwnings();
    if (rs == null) {
      rs = getEntityOwnings();
    }
  }

  private synchronized ResultSet getBlockOwnings() {
    try {
      String query = "SELECT * \nFROM " + Database.BLOCK_TABLE + ";";
      ResultSet rs = stmnt.executeQuery(query);
      return rs;
    } catch (SQLException e) {
      return null;
    }
  }

  private synchronized ResultSet getEntityOwnings() {
    try {
      String query = "SELECT * \nFROM " + Database.ENTITY_TABLE + ";";
      ResultSet rs = stmnt.executeQuery(query);
      return rs;
    } catch (SQLException e) {
      return null;
    }
  }

  @Override
  protected void finalize() throws Throwable {
    if (stmnt != null) {
      stmnt.close();
    }
  }

  @Override
  public synchronized boolean hasNext() {
    try {
      return state == 0 || (state == 1 && !rs.isLast());
    } catch (SQLException e) {
      return false;
    }
  }

  @Override
  public synchronized OwningState next() {
    if (state == 2) {
      return null;
    }

    if (state == 0) {
      if (rs == null) {
        rs = getEntityOwnings();
        state++;
        if (rs == null) {
          state++;
          return null;
        }
      }
    }

    try {
      if (state == 0) {
        if (rs.next()) {
          String worldName = rs.getString(Database.WORLD_COLUMN);
          int x = rs.getInt(Database.X_COLUMN);
          int y = rs.getInt(Database.Y_COLUMN);
          int z = rs.getInt(Database.Z_COLUMN);
          UUID id = UUID.fromString(rs.getString(Database.PLAYER_ID_COLUMN));

          Ownable ownable = OwnedBlock.newInstance(worldName, x, y, z);
          User user = User.getInstance(id);
          return new OwningState(ownable, Optional.of(user));
        } else {
          rs = getEntityOwnings();
          state++;
          if (rs == null) {
            state++;
            stmnt.close();
            return null;
          }
        }
      }

      if (state == 1) {
        if (rs.next()) {
          String worldName = rs.getString(Database.WORLD_COLUMN);
          UUID entityId = UUID.fromString(rs.getString(Database.ENTITY_ID_COLUMN));
          UUID playerId = UUID.fromString(rs.getString(Database.PLAYER_ID_COLUMN));

          Ownable ownable = OwnedEntity.newInstance(entityId, worldName);
          User user = User.getInstance(playerId);
          return new OwningState(ownable, Optional.of(user));
        } else {
          state++;
          stmnt.close();
          return null;
        }
      }
      stmnt.close();
      return null;
    } catch (SQLException e) {
      return null;
    }
  }

  @Override
  public void remove() {
    throw new IllegalStateException("Can't remove elements through read-only iterator");
  }

}