/*
 *    Copyright 2009-2011 The MyBatis Team
 *
 *    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 org.apache.ibatis.session.defaults;

import org.apache.ibatis.binding.BindingException;
import org.apache.ibatis.exceptions.ExceptionFactory;
import org.apache.ibatis.exceptions.TooManyResultsException;
import org.apache.ibatis.executor.BatchResult;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.executor.result.DefaultMapResultHandler;
import org.apache.ibatis.executor.result.DefaultResultContext;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.session.*;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class DefaultSqlSession implements SqlSession {

  private Configuration configuration;
  private Executor executor;

  private boolean dirty;

  @Deprecated
  public DefaultSqlSession(Configuration configuration, Executor executor, boolean autoCommit) {
    this(configuration, executor);
  }

  public DefaultSqlSession(Configuration configuration, Executor executor) {
    this.configuration = configuration;
    this.executor = executor;
    this.dirty = false;
  }

  public <T> T selectOne(String statement) {
    return this.<T>selectOne(statement, null);
  }

  public <T> T selectOne(String statement, Object parameter) {
    // Popular vote was to return null on 0 results and throw exception on too many.
    List<T> list = this.<T>selectList(statement, parameter);
    if (list.size() == 1) {
      return list.get(0);
    } else if (list.size() > 1) {
      throw new TooManyResultsException("Expected one result (or null) to be returned by selectOne(), but found: " + list.size());
    } else {
      return null;
    }
  }

  public <K, V> Map<K, V> selectMap(String statement, String mapKey) {
    return this.<K, V>selectMap(statement, null, mapKey, RowBounds.DEFAULT);
  }

  public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey) {
    return this.<K, V>selectMap(statement, parameter, mapKey, RowBounds.DEFAULT);
  }

  public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey, RowBounds rowBounds) {
    final List<?> list = selectList(statement, parameter, rowBounds);
    final DefaultMapResultHandler<K, V> mapResultHandler = new DefaultMapResultHandler<K, V>(mapKey,
        configuration.getObjectFactory());
    final DefaultResultContext context = new DefaultResultContext();
    for (Object o : list) {
      context.nextResultObject(o);
      mapResultHandler.handleResult(context);
    }
    Map<K, V> selectedMap = mapResultHandler.getMappedResults();
    return selectedMap;
  }

  public <E> List<E> selectList(String statement) {
    return this.<E>selectList(statement, null);
  }

  public <E> List<E> selectList(String statement, Object parameter) {
    return this.<E>selectList(statement, parameter, RowBounds.DEFAULT);
  }

  public <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds) {
    try {
      MappedStatement ms = configuration.getMappedStatement(statement);
      List<E> result = executor.<E>query(ms, wrapCollection(parameter), rowBounds, Executor.NO_RESULT_HANDLER);
      return result;
    } catch (Exception e) {
      throw ExceptionFactory.wrapException("Error querying database.  Cause: " + e, e);
    } finally {
      ErrorContext.instance().reset();
    }
  }

  public void select(String statement, Object parameter, ResultHandler handler) {
    select(statement, parameter, RowBounds.DEFAULT, handler);
  }

  public void select(String statement, ResultHandler handler) {
    select(statement, null, RowBounds.DEFAULT, handler);
  }

  public void select(String statement, Object parameter, RowBounds rowBounds, ResultHandler handler) {
    try {
      MappedStatement ms = configuration.getMappedStatement(statement);
      executor.query(ms, wrapCollection(parameter), rowBounds, handler);
    } catch (Exception e) {
      throw ExceptionFactory.wrapException("Error querying database.  Cause: " + e, e);
    } finally {
      ErrorContext.instance().reset();
    }
  }

  public int insert(String statement) {
    return insert(statement, null);
  }

  public int insert(String statement, Object parameter) {
    return update(statement, parameter);
  }

  public int update(String statement) {
    return update(statement, null);
  }

  public int update(String statement, Object parameter) {
    try {
      dirty = true;
      MappedStatement ms = configuration.getMappedStatement(statement);
      return executor.update(ms, wrapCollection(parameter));
    } catch (Exception e) {
      throw ExceptionFactory.wrapException("Error updating database.  Cause: " + e, e);
    } finally {
      ErrorContext.instance().reset();
    }
  }

  public int delete(String statement) {
    return update(statement, null);
  }

  public int delete(String statement, Object parameter) {
    return update(statement, parameter);
  }

  public void commit() {
    commit(false);
  }

  public void commit(boolean force) {
    try {
      executor.commit(isCommitOrRollbackRequired(force));
      dirty = false;
    } catch (Exception e) {
      throw ExceptionFactory.wrapException("Error committing transaction.  Cause: " + e, e);
    } finally {
      ErrorContext.instance().reset();
    }
  }

  public void rollback() {
    rollback(false);
  }

  public void rollback(boolean force) {
    try {
      executor.rollback(isCommitOrRollbackRequired(force));
      dirty = false;
    } catch (Exception e) {
      throw ExceptionFactory.wrapException("Error rolling back transaction.  Cause: " + e, e);
    } finally {
      ErrorContext.instance().reset();
    }
  }

  public List<BatchResult> flushStatements() {
    try {
      return executor.flushStatements();
    } catch (Exception e) {
      throw ExceptionFactory.wrapException("Error flushing statements.  Cause: " + e, e);
    } finally {
      ErrorContext.instance().reset();
    }
  }

  public void close() {
    try {
      executor.close(isCommitOrRollbackRequired(false));
      dirty = false;
    } finally {
      ErrorContext.instance().reset();
    }
  }

  public Configuration getConfiguration() {
    return configuration;
  }

  public <T> T getMapper(Class<T> type) {
    return configuration.<T>getMapper(type, this);
  }

  public Connection getConnection() {
    try {
      return executor.getTransaction().getConnection();
    } catch (SQLException e) {
      throw ExceptionFactory.wrapException("Error getting a new connection.  Cause: " + e, e);
    }
  }

  public void clearCache() {
    executor.clearLocalCache();
  }

  private boolean isCommitOrRollbackRequired(boolean force) {
    return dirty || force;
  }

  private Object wrapCollection(final Object object) {
    if (object instanceof List) {
      StrictMap<Object> map = new StrictMap<Object>();
      map.put("list", object);
      return map;
    } else if (object != null && object.getClass().isArray()) {
      StrictMap<Object> map = new StrictMap<Object>();
      map.put("array", object);
      return map;
    }
    return object;
  }

  public static class StrictMap<V> extends HashMap<String, V> {

    private static final long serialVersionUID = -5741767162221585340L;

    @Override
    public V get(Object key) {
      if (!super.containsKey(key)) {
        throw new BindingException("Parameter '" + key + "' not found. Available parameters are " + this.keySet());
      }
      return super.get(key);
    }

  }

}
