/*
    * Copyright 2006-2013 the original author or authors.
    *
    * 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.springframework.batch.core.repository.dao;
  
  import java.io.UnsupportedEncodingException;
  import java.math.BigInteger;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.sql.Timestamp;
  import java.sql.Types;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  
  import org.springframework.batch.core.JobExecution;
  import org.springframework.batch.core.JobInstance;
  import org.springframework.batch.core.JobParameter;
  import org.springframework.batch.core.JobParameter.ParameterType;
  import org.springframework.batch.core.JobParameters;
  import org.springframework.beans.factory.InitializingBean;
  import org.springframework.dao.DataAccessException;
  import org.springframework.dao.EmptyResultDataAccessException;
  import org.springframework.jdbc.core.ResultSetExtractor;
  import org.springframework.jdbc.core.RowCallbackHandler;
  import org.springframework.jdbc.core.simple.ParameterizedRowMapper;
  import org.springframework.jdbc.support.incrementer.DataFieldMaxValueIncrementer;
  import org.springframework.util.Assert;
  import org.springframework.util.StringUtils;
  
  /**
   * JDBC implementation of {@link JobInstanceDao}. Uses sequences (via Spring's
   * {@link DataFieldMaxValueIncrementer} abstraction) to create all primary keys
   * before inserting a new row. Objects are checked to ensure all mandatory
   * fields to be stored are not null. If any are found to be null, an
   * IllegalArgumentException will be thrown. This could be left to JdbcTemplate,
   * however, the exception will be fairly vague, and fails to highlight which
   * field caused the exception.
   *
   * @author Lucas Ward
   * @author Dave Syer
   * @author Robert Kasanicky
   */
  public class JdbcJobInstanceDao extends AbstractJdbcBatchMetadataDao implements
  JobInstanceDao, InitializingBean {
  
  	private static final String CREATE_JOB_INSTANCE = "INSERT into %PREFIX%JOB_INSTANCE(JOB_INSTANCE_ID, JOB_NAME, JOB_KEY, VERSION)"
  			+ " values (?, ?, ?, ?)";
  
  	private static final String CREATE_JOB_PARAMETERS = "INSERT into %PREFIX%JOB_PARAMS(JOB_INSTANCE_ID, KEY_NAME, TYPE_CD, "
  			+ "STRING_VAL, DATE_VAL, LONG_VAL, DOUBLE_VAL) values (?, ?, ?, ?, ?, ?, ?)";
  
  	private static final String FIND_JOBS_WITH_NAME = "SELECT JOB_INSTANCE_ID, JOB_NAME from %PREFIX%JOB_INSTANCE where JOB_NAME = ?";
  
  	private static final String FIND_JOBS_WITH_KEY = FIND_JOBS_WITH_NAME
  			+ " and JOB_KEY = ?";
  
  	private static final String FIND_JOBS_WITH_EMPTY_KEY = "SELECT JOB_INSTANCE_ID, JOB_NAME from %PREFIX%JOB_INSTANCE where JOB_NAME = ? and (JOB_KEY = ? OR JOB_KEY is NULL)";
  
  	private static final String GET_JOB_FROM_ID = "SELECT JOB_INSTANCE_ID, JOB_NAME, JOB_KEY, VERSION from %PREFIX%JOB_INSTANCE where JOB_INSTANCE_ID = ?";
  
  	private static final String GET_JOB_FROM_EXECUTION_ID = "SELECT ji.JOB_INSTANCE_ID, JOB_NAME, JOB_KEY, ji.VERSION from %PREFIX%JOB_INSTANCE ji, "
  			+ "%PREFIX%JOB_EXECUTION je where JOB_EXECUTION_ID = ? and ji.JOB_INSTANCE_ID = je.JOB_INSTANCE_ID";
  
  	private static final String FIND_PARAMS_FROM_ID = "SELECT JOB_INSTANCE_ID, KEY_NAME, TYPE_CD, "
  			+ "STRING_VAL, DATE_VAL, LONG_VAL, DOUBLE_VAL from %PREFIX%JOB_PARAMS where JOB_INSTANCE_ID = ?";
  
  	private static final String FIND_JOB_NAMES = "SELECT distinct JOB_NAME from %PREFIX%JOB_INSTANCE order by JOB_NAME";
  
  	private static final String FIND_LAST_JOBS_BY_NAME = "SELECT JOB_INSTANCE_ID, JOB_NAME from %PREFIX%JOB_INSTANCE where JOB_NAME = ? order by JOB_INSTANCE_ID desc";
  
  	private DataFieldMaxValueIncrementer jobIncrementer;
  
  	/**
  	 * In this jdbc implementation a job id is obtained by asking the
  	 * jobIncrementer (which is likely a sequence) for the next long value, and
  	 * then passing the Id and parameter values into an INSERT statement.
  	 *
  	 * @see JobInstanceDao#createJobInstance(String, JobParameters)
  	 * @throws IllegalArgumentException
  	 *             if any {@link JobParameters} fields are null.
 	 */
 	@Override
 	public JobInstance createJobInstance(String jobName,
 			JobParameters jobParameters) {
 
 		Assert.notNull(jobName, "Job name must not be null.");
 		Assert.notNull(jobParameters, "JobParameters must not be null.");
 
 		Assert.state(getJobInstance(jobName, jobParameters) == null,
 				"JobInstance must not already exist");
 
 		Long jobId = jobIncrementer.nextLongValue();
 
 		JobInstance jobInstance = new JobInstance(jobId, jobParameters, jobName);
 		jobInstance.incrementVersion();
 
 		Object[] parameters = new Object[] { jobId, jobName,
 				createJobKey(jobParameters), jobInstance.getVersion() };
 		getJdbcTemplate().update(
 				getQuery(CREATE_JOB_INSTANCE),
 				parameters,
 				new int[] { Types.BIGINT, Types.VARCHAR, Types.VARCHAR,
 					Types.INTEGER });
 
 		insertJobParameters(jobId, jobParameters);
 
 		return jobInstance;
 	}
 
 	protected String createJobKey(JobParameters jobParameters) {
 
 		Map<String, JobParameter> props = jobParameters.getParameters();
 		StringBuffer stringBuffer = new StringBuffer();
 		List<String> keys = new ArrayList<String>(props.keySet());
 		Collections.sort(keys);
 		for (String key : keys) {
 			JobParameter jobParameter = props.get(key);
 			String value = jobParameter.getValue()==null ? "" : jobParameter.toString();
 			stringBuffer.append(key + "=" + value + ";");
 		}
 
 		MessageDigest digest;
 		try {
 			digest = MessageDigest.getInstance("MD5");
 		} catch (NoSuchAlgorithmException e) {
 			throw new IllegalStateException(
 					"MD5 algorithm not available.  Fatal (should be in the JDK).");
 		}
 
 		try {
 			byte[] bytes = digest.digest(stringBuffer.toString().getBytes(
 					"UTF-8"));
 			return String.format("%032x", new BigInteger(1, bytes));
 		} catch (UnsupportedEncodingException e) {
 			throw new IllegalStateException(
 					"UTF-8 encoding not available.  Fatal (should be in the JDK).");
 		}
 	}
 
 	/**
 	 * Convenience method that inserts all parameters from the provided
 	 * JobParameters.
 	 *
 	 */
 	private void insertJobParameters(Long jobId, JobParameters jobParameters) {
 
 		for (Entry<String, JobParameter> entry : jobParameters.getParameters()
 				.entrySet()) {
 			JobParameter jobParameter = entry.getValue();
 			insertParameter(jobId, jobParameter.getType(), entry.getKey(),
 					jobParameter.getValue());
 		}
 	}
 
 	/**
 	 * Convenience method that inserts an individual records into the
 	 * JobParameters table.
 	 */
 	private void insertParameter(Long jobId, ParameterType type, String key,
 			Object value) {
 
 		Object[] args = new Object[0];
 		int[] argTypes = new int[] { Types.BIGINT, Types.VARCHAR,
 				Types.VARCHAR, Types.VARCHAR, Types.TIMESTAMP, Types.BIGINT,
 				Types.DOUBLE };
 
 		if (type == ParameterType.STRING) {
 			args = new Object[] { jobId, key, type, value, new Timestamp(0L),
 					0L, 0D };
 		} else if (type == ParameterType.LONG) {
 			args = new Object[] { jobId, key, type, "", new Timestamp(0L),
 					value, new Double(0) };
 		} else if (type == ParameterType.DOUBLE) {
 			args = new Object[] { jobId, key, type, "", new Timestamp(0L), 0L,
 					value };
 		} else if (type == ParameterType.DATE) {
 			args = new Object[] { jobId, key, type, "", value, 0L, 0D };
 		}
 
 		getJdbcTemplate().update(getQuery(CREATE_JOB_PARAMETERS), args, argTypes);
 	}
 
 	/**
 	 * The job table is queried for <strong>any</strong> jobs that match the
 	 * given identifier, adding them to a list via the RowMapper callback.
 	 *
 	 * @see JobInstanceDao#getJobInstance(String, JobParameters)
 	 * @throws IllegalArgumentException
 	 *             if any {@link JobParameters} fields are null.
 	 */
 	@Override
 	public JobInstance getJobInstance(final String jobName,
 			final JobParameters jobParameters) {
 
 		Assert.notNull(jobName, "Job name must not be null.");
 		Assert.notNull(jobParameters, "JobParameters must not be null.");
 
 		String jobKey = createJobKey(jobParameters);
 
 		ParameterizedRowMapper<JobInstance> rowMapper = new JobInstanceRowMapper(
 				jobParameters);
 
 		List<JobInstance> instances;
 		if (StringUtils.hasLength(jobKey)) {
 			instances = getJdbcTemplate().query(getQuery(FIND_JOBS_WITH_KEY),
 					rowMapper, jobName, jobKey);
 		} else {
 			instances = getJdbcTemplate().query(
 					getQuery(FIND_JOBS_WITH_EMPTY_KEY), rowMapper, jobName,
 					jobKey);
 		}
 
 		if (instances.isEmpty()) {
 			return null;
 		} else {
 			Assert.state(instances.size() == 1);
 			return instances.get(0);
 		}
 	}
 
 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see
 	 * org.springframework.batch.core.repository.dao.JobInstanceDao#getJobInstance
 	 * (java.lang.Long)
 	 */
 	@Override
 	public JobInstance getJobInstance(Long instanceId) {
 
 		try {
 			return getJdbcTemplate().queryForObject(getQuery(GET_JOB_FROM_ID),
 					new JobInstanceRowMapper(), instanceId);
 		} catch (EmptyResultDataAccessException e) {
 			return null;
 		}
 
 	}
 
 	/**
 	 * @param instanceId
 	 * @return
 	 */
 	private JobParameters getJobParameters(Long instanceId) {
 		final Map<String, JobParameter> map = new HashMap<String, JobParameter>();
 		RowCallbackHandler handler = new RowCallbackHandler() {
 			@Override
 			public void processRow(ResultSet rs) throws SQLException {
 				ParameterType type = ParameterType.valueOf(rs.getString(3));
 				JobParameter value = null;
 				if (type == ParameterType.STRING) {
 					value = new JobParameter(rs.getString(4));
 				} else if (type == ParameterType.LONG) {
 					value = new JobParameter(rs.getLong(6));
 				} else if (type == ParameterType.DOUBLE) {
 					value = new JobParameter(rs.getDouble(7));
 				} else if (type == ParameterType.DATE) {
 					value = new JobParameter(rs.getTimestamp(5));
 				}
 				// No need to assert that value is not null because it's an enum
 				map.put(rs.getString(2), value);
 			}
 		};
 		getJdbcTemplate().query(getQuery(FIND_PARAMS_FROM_ID), new Object[] { instanceId }, handler);
 		return new JobParameters(map);
 	}
 
 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see
 	 * org.springframework.batch.core.repository.dao.JobInstanceDao#getJobNames
 	 * ()
 	 */
 	@Override
 	public List<String> getJobNames() {
 		return getJdbcTemplate().query(getQuery(FIND_JOB_NAMES),
 				new ParameterizedRowMapper<String>() {
 			@Override
 			public String mapRow(ResultSet rs, int rowNum)
 					throws SQLException {
 				return rs.getString(1);
 			}
 		});
 	}
 
 	/*
 	 * (non-Javadoc)
 	 *
 	 * @seeorg.springframework.batch.core.repository.dao.JobInstanceDao#
 	 * getLastJobInstances(java.lang.String, int)
 	 */
 	@Override
 	@SuppressWarnings("rawtypes")
 	public List<JobInstance> getJobInstances(String jobName, final int start,
 			final int count) {
 
 		ResultSetExtractor extractor = new ResultSetExtractor() {
 
 			private List<JobInstance> list = new ArrayList<JobInstance>();
 
 			@Override
 			public Object extractData(ResultSet rs) throws SQLException,
 			DataAccessException {
 				int rowNum = 0;
 				while (rowNum < start && rs.next()) {
 					rowNum++;
 				}
 				while (rowNum < start + count && rs.next()) {
 					ParameterizedRowMapper<JobInstance> rowMapper = new JobInstanceRowMapper();
 					list.add(rowMapper.mapRow(rs, rowNum));
 					rowNum++;
 				}
 				return list;
 			}
 
 		};
 
 		@SuppressWarnings("unchecked")
 		List<JobInstance> result = (List<JobInstance>) getJdbcTemplate().query(getQuery(FIND_LAST_JOBS_BY_NAME),
 				new Object[] { jobName }, extractor);
 
 		return result;
 	}
 
 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see
 	 * org.springframework.batch.core.repository.dao.JobInstanceDao#getJobInstance
 	 * (org.springframework.batch.core.JobExecution)
 	 */
 	@Override
 	public JobInstance getJobInstance(JobExecution jobExecution) {
 
 		try {
 			return getJdbcTemplate().queryForObject(
 					getQuery(GET_JOB_FROM_EXECUTION_ID),
 					new JobInstanceRowMapper(), jobExecution.getId());
 		} catch (EmptyResultDataAccessException e) {
 			return null;
 		}
 	}
 
 	/**
 	 * Setter for {@link DataFieldMaxValueIncrementer} to be used when
 	 * generating primary keys for {@link JobInstance} instances.
 	 *
 	 * @param jobIncrementer
 	 *            the {@link DataFieldMaxValueIncrementer}
 	 */
 	public void setJobIncrementer(DataFieldMaxValueIncrementer jobIncrementer) {
 		this.jobIncrementer = jobIncrementer;
 	}
 
 	@Override
 	public void afterPropertiesSet() throws Exception {
 		super.afterPropertiesSet();
 		Assert.notNull(jobIncrementer);
 	}
 
 	/**
 	 * @author Dave Syer
 	 *
 	 */
 	private final class JobInstanceRowMapper implements
 	ParameterizedRowMapper<JobInstance> {
 
 		private JobParameters jobParameters;
 
 		public JobInstanceRowMapper() {
 		}
 
 		public JobInstanceRowMapper(JobParameters jobParameters) {
 			this.jobParameters = jobParameters;
 		}
 
 		@Override
 		public JobInstance mapRow(ResultSet rs, int rowNum) throws SQLException {
 			Long id = rs.getLong(1);
 			if (jobParameters == null) {
 				jobParameters = getJobParameters(id);
 			}
 			JobInstance jobInstance = new JobInstance(rs.getLong(1),
 					jobParameters, rs.getString(2));
 			// should always be at version=0 because they never get updated
 			jobInstance.incrementVersion();
 			return jobInstance;
 		}
 	}
 }