/*
 * Slightly modified version of the com.ibatis.common.jdbc.ScriptRunner class
 * from the iBATIS Apache project. Only removed dependency on Resource class
 * and a constructor
 *
 *
 *
 *  Copyright 2004 Clinton Begin
 *
 *  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.ambari.server.orm.helpers;

import java.io.IOException;
import java.io.LineNumberReader;
import java.io.PrintWriter;
import java.io.Reader;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Tool to run database scripts
 * TODO replace logging, deal with licence properly or rewrite completely
 */
public class ScriptRunner {
  private static final Logger LOG = LoggerFactory.getLogger(ScriptRunner.class);

  private static final String DEFAULT_DELIMITER = ";";

  private Connection connection;

  private boolean stopOnError;
  private boolean autoCommit;

  private PrintWriter logWriter = new PrintWriter(System.out);
  private PrintWriter errorLogWriter = new PrintWriter(System.err);

  private String delimiter = DEFAULT_DELIMITER;
  private boolean fullLineDelimiter = false;

  /**
   * Default constructor
   */
  public ScriptRunner(Connection connection, boolean autoCommit,
                      boolean stopOnError) {
    this.connection = connection;
    this.autoCommit = autoCommit;
    this.stopOnError = stopOnError;
  }

  public void setDelimiter(String delimiter, boolean fullLineDelimiter) {
    this.delimiter = delimiter;
    this.fullLineDelimiter = fullLineDelimiter;
  }

  /**
   * Setter for logWriter property
   *
   * @param logWriter
   *            - the new value of the logWriter property
   */
  public void setLogWriter(PrintWriter logWriter) {
    this.logWriter = logWriter;
  }

  /**
   * Setter for errorLogWriter property
   *
   * @param errorLogWriter
   *            - the new value of the errorLogWriter property
   */
  public void setErrorLogWriter(PrintWriter errorLogWriter) {
    this.errorLogWriter = errorLogWriter;
  }

  /**
   * Runs an SQL script (read in using the Reader parameter)
   *
   * @param reader
   *            - the source of the script
   */
  public void runScript(Reader reader) throws IOException, SQLException {
    try {
      boolean originalAutoCommit = connection.getAutoCommit();
      try {
        if (originalAutoCommit != this.autoCommit) {
          connection.setAutoCommit(this.autoCommit);
        }
        runScript(connection, reader);
      } finally {
        connection.setAutoCommit(originalAutoCommit);
      }
    } catch (IOException | SQLException e) {
      throw e;
    } catch (Exception e) {
      throw new RuntimeException("Error running script.  Cause: " + e, e);
    }
  }

  /**
   * Runs an SQL script (read in using the Reader parameter) using the
   * connection passed in
   *
   * @param conn
   *            - the connection to use for the script
   * @param reader
   *            - the source of the script
   * @throws SQLException
   *             if any SQL errors occur
   * @throws IOException
   *             if there is an error reading from the Reader
   */
  private void runScript(Connection conn, Reader reader) throws IOException,
    SQLException {
    StringBuffer command = null;
    Statement statement = null;
    try {
      LineNumberReader lineReader = new LineNumberReader(reader);
      String line = null;
      statement = conn.createStatement();
      while ((line = lineReader.readLine()) != null) {
        if (command == null) {
          command = new StringBuffer();
        }
        String trimmedLine = line.trim();
        if (trimmedLine.startsWith("--")) {
          println(trimmedLine);
        } else if (trimmedLine.length() < 1
          || trimmedLine.startsWith("//")
          || trimmedLine.startsWith("--")) {
          // Do nothing
        } else if (!fullLineDelimiter
          && trimmedLine.endsWith(getDelimiter())
          || fullLineDelimiter
          && trimmedLine.equals(getDelimiter())) {
          command.append(line.substring(0, line
            .lastIndexOf(getDelimiter())));
          command.append(" ");

          println(command);

          boolean hasResults = false;
          if (stopOnError) {
            hasResults = statement.execute(command.toString());
          } else {
            try {
              statement.execute(command.toString());
            } catch (SQLException e) {
              printlnError("Error executing: " + command);
              printlnError(e);
            }
          }

          if (autoCommit && !conn.getAutoCommit()) {
            conn.commit();
          }

          ResultSet rs = statement.getResultSet();
          if (hasResults && rs != null) {
            ResultSetMetaData md = rs.getMetaData();
            int cols = md.getColumnCount();
            for (int i = 0; i < cols; i++) {
              String name = md.getColumnLabel(i);
              print(name + "\t");
            }
            println("");
            while (rs.next()) {
              for (int i = 0; i < cols; i++) {
                String value = rs.getString(i);
                print(value + "\t");
              }
              println("");
            }
          }

          command = null;
          Thread.yield();
        } else {
          command.append(line);
          command.append(" ");
        }
      }
      if (!autoCommit) {
        conn.commit();
      }
    } catch (SQLException | IOException e) {
      printlnError("Error executing: " + command);
      printlnError(e);
      throw e;
    } finally {
      if (!autoCommit) {
        conn.rollback();
      }
      if (statement != null) {
        statement.close();
      }
      flush();
    }
  }

  private String getDelimiter() {
    return delimiter;
  }

  private void print(Object o) {
    if (logWriter != null) {
      System.out.print(o);
    }
  }

  private void println(Object o) {
    if (logWriter != null) {
      logWriter.println(o);
    }
  }

  private void printlnError(Object o) {
    if (errorLogWriter != null) {
      errorLogWriter.println(o);
    }
  }

  private void flush() {
    if (logWriter != null) {
      logWriter.flush();
    }
    if (errorLogWriter != null) {
      errorLogWriter.flush();
    }
  }
}