/*
 Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights
 reserved.
 
 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; version 2 of
 the License.
 
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 02110-1301  USA
*/

/*global unified_debug, exports */

"use strict";

/* Requires version 2.0 of Felix Geisendoerfer's MySQL client */

var stats = {
  "created"             : 0,
  "list_tables"         : 0,
  "get_table_metadata"  : 0,
  "connections"         : { "successful" : 0, "failed" : 0 }	
};

var path = require("path");
var mysql = require("mysql");
var mysqlConnection = require("./MySQLConnection.js");
var mysqlDictionary = require("./MySQLDictionary.js");
var udebug = unified_debug.getLogger("MySQLConnectionPool.js");
var util = require('util');
var stats_module = require(mynode.api.stats);
var MySQLTime = require("../common/MySQLTime.js");
var DBTableHandler = require("../common/DBTableHandler.js").DBTableHandler;
var meta = require("../../api/TableMapping.js").meta;

stats_module.register(stats, "spi","mysql","DBConnectionPool");

/* Translate our properties to the driver's */
function getDriverProperties(props) {
  var driver = {};

  if(props.mysql_socket) {
    driver.SocketPath = props.mysql_socket;
  }
  else {
    driver.host = props.mysql_host;
    driver.port = props.mysql_port;
  }

  if(props.mysql_user) {
    driver.user = props.mysql_user;
  }
  if(props.mysql_password) {
    driver.password = props.mysql_password;
  }
  driver.database = props.database;
  driver.debug = props.mysql_debug;
  driver.trace = props.mysql_trace;

  if (props.mysql_charset) {
    driver.charset = props.mysql_charset;
  } else {
    // by default, use utf-8 multibyte for character encoding
    driver.charset = 'UTF8MB4';
  }

  if (typeof props.mysql_sql_mode !== 'undefined') {
    driver.sql_mode = props.mysql_sql_mode;
  } else {
    // default to STRICT_ALL_TABLES
    driver.sql_mode = 'STRICT_ALL_TABLES';
  }

  // connection pool maximum size
  if (typeof props.mysql_pool_size !== 'undefined') {
    driver.connectionLimit = props.mysql_pool_size;
    if (props.mysql_pool_queue_size !== 'undefined') {
      driver.queueLimit = props.mysql_pool_queue_size;
    }
  }
  
  // allow multiple statements in one query (used to set character set)
  driver.multipleStatements = true;
  return driver;
}

/** Default domain type converter for timestamp and datetime objects. The domain type is Date
 * and the intermediate type is MySQLTime. MySQLTime provides a lossless conversion from
 * database DATETIME and TIMESTAMP with fractional microseconds. The default domain type converter
 * to javascript Date is lossy: javascript Date does not support microseconds. Users might supply
 * their own domain type with a converter that supports microseconds.
 */
var DomainTypeConverterDateTime = function() {
  // just a bit of documentation for debugging
  this.converter = 'DomainTypeConverterDateTime';
};

DomainTypeConverterDateTime.prototype.toDB = function toDB(userDate) {
  if (userDate === null || userDate === undefined) {
    return userDate;
  }
  // convert to the string form of the mySQLTime object
  var mysqlTime = new MySQLTime();
  mysqlTime.fsp = 6;
  mysqlTime.initializeFromJsDateLocal(userDate);
  return mysqlTime;
};
  
DomainTypeConverterDateTime.prototype.fromDB =  function fromDB(mysqlTime) {
  if (mysqlTime === null || mysqlTime === undefined) {
    return mysqlTime;
  }
  var jsDate = mysqlTime.toJsDateLocal();
  return jsDate;
};

/** Default database type converter for timestamp and datetime objects. The database type is string
 * and the intermediate type is MySQLTime. MySQLTime provides a lossless conversion from
 * database DATETIME and TIMESTAMP with fractional microseconds.
 */
var DatabaseTypeConverterDateTime = function() {
  // just a bit of documentation for debugging
  this.converter = 'DatabaseTypeConverterDateTime';
};

DatabaseTypeConverterDateTime.prototype.toDB = function toDB(mysqlTime) {
  if (mysqlTime === null || mysqlTime === undefined) {
    return mysqlTime;
  }
  // convert to the string form of the mySQLTime object
  var dbDateTime = mysqlTime.toDateTimeString();
  return dbDateTime;
};
  
DatabaseTypeConverterDateTime.prototype.fromDB =  function fromDB(dbDateTime) {
  if (dbDateTime === null || dbDateTime === undefined) {
    return dbDateTime;
  }
  var mysqlTime = new MySQLTime();
  mysqlTime.initializeFromDateTimeString(dbDateTime);
  return mysqlTime;
};



/* Constructor saves properties but doesn't actually do anything with them until connect is called.
*/
exports.DBConnectionPool = function(props) {
  this.props = props;
  this.driverproperties = getDriverProperties(props);
  udebug.log('MySQLConnectionPool constructor with driverproperties: ' + util.inspect(this.driverproperties));
  // connections that are being used (wrapped by DBSession)
  this.openConnections = [];
  this.is_connected = false;
  // create database type converter map
  this.databaseTypeConverterMap = {};
  this.databaseTypeConverterMap.TIMESTAMP = new DatabaseTypeConverterDateTime();
  this.databaseTypeConverterMap.DATETIME = new DatabaseTypeConverterDateTime();
  // create domain type converter map
  this.domainTypeConverterMap = {};
  this.domainTypeConverterMap.TIMESTAMP = new DomainTypeConverterDateTime();
  this.domainTypeConverterMap.DATETIME = new DomainTypeConverterDateTime();
  this.pooling = props.mysql_pool_size ? true:false ;
  stats.created++;
};

/** Register a user-specified domain type converter for this connection pool.
 * Called by SessionFactory.registerTypeConverter.
 */
exports.DBConnectionPool.prototype.registerTypeConverter = function(typeName, converterObject) {
  if (converterObject) {
    this.domainTypeConverterMap[typeName] = converterObject;
  } else {
    this.domainTypeConverterMap[typeName] = undefined;
  }
};

/** Get the database type converter for the parameter type name.
 * Called when creating the DBTableHandler for a constructor.
 */
exports.DBConnectionPool.prototype.getDatabaseTypeConverter = function(typeName) {
  return this.databaseTypeConverterMap[typeName];
};

/** Get the domain type converter for the parameter type name.
 * Called when creating the DBTableHandler for a constructor.
 */
exports.DBConnectionPool.prototype.getDomainTypeConverter = function(typeName) {
  return this.domainTypeConverterMap[typeName];
};

/** Get a connection. If pooling via felix, get a connection from the pool.
 * If not, create a connection. This api does not manage the list of open connections.
 * 
 * @param callback (err, connection)
 */
exports.DBConnectionPool.prototype.getConnection = function(callback) {
  var connectionPool = this;
  var connection, error, pool;

  function getConnectionOnConnection(err, c) {
    udebug.log('getConnectionOnConnection');
    if (err) {
      stats.connections.failed++;
      // create a new Error with a message and this stack
      error = new Error('Connection failed.');
      // add cause to the error
      error.cause = err;
      // add sqlstate to error
      error.sqlstate = '08000';
      callback(error);      
    } else {
      stats.connections.successful++;
      if (connectionPool.pooling) {
        // some older versions of node-mysql do not have release()
        if(typeof c.release !== 'function') { c.release = c.end; }
        callback(null, c);
      } else {
        callback(null, connection);
      }
    }
  }

  // getConnection starts here
  if (connectionPool.pooling) {
    // get a connection from the felix pool
    udebug.log('getConnection using connection pooling: true');
    connectionPool.pool.getConnection(getConnectionOnConnection);
  } else if (connectionPool.is_connected || connectionPool.is_connecting) {
    // create a new connection
    udebug.log('getConnection using connection pooling: false');
    connection = mysql.createConnection(connectionPool.driverproperties);
    connection.connect(getConnectionOnConnection);
  } else {
    // error
    callback(new Error('getConnection called before connect.'));
  }
};

/** Release a connection (synchronous). If pooling via felix, return the connection to the pool.
 * If not, end the connection. No errors are reported to the user.
 */
exports.DBConnectionPool.prototype.releaseConnection = function(connection) {
  var connectionPool = this;
  if (connectionPool.pooling) {
    udebug.log('releaseConnection using connection pooling: true');
    connection.release();
  } else {
    udebug.log('releaseConnection using connection pooling: false');
    connection.end();
  }
};

/** Connect to the database. Verify connection properties.
 * @param user_callback (err, connectionPool)
 */
exports.DBConnectionPool.prototype.connect = function(callback) {
  var connectionPool = this;
  var error;

  function connectOnConnection(err, connection) {
    connectionPool.is_connecting = false;
    if (err) {
      stats.connections.failed++;
      // create a new Error with a message and this stack
      error = new Error('Connection failed.');
      // add cause to the error
      error.cause = err;
      // add sqlstate to error
      error.sqlstate = '08000';
      callback(error);
    } else {
      stats.connections.successful++;
      connectionPool.is_connected = true;
      connectionPool.releaseConnection(connection);
      callback(null, connectionPool);
    }
  }

  // connect begins here
  if (connectionPool.is_connected) {
    udebug.log('MySQLConnectionPool.connect is already connected');
    callback(null, connectionPool);
  } else {
    connectionPool.is_connecting = true;
    if (connectionPool.pooling) {
      connectionPool.pool = mysql.createPool(connectionPool.driverproperties);
    }
    // verify that the connection properties work by getting a connection
    connectionPool.getConnection(connectOnConnection);
  }
};

exports.DBConnectionPool.prototype.close = function(user_callback) {
  var connectionPool = this;
  udebug.log('close');
  var i;
  for (i = 0; i < this.openConnections.length; ++i) {
    var openConnection = this.openConnections[i];
    udebug.log('close ending open connection', i);
    if (openConnection && openConnection._connectCalled) {
      connectionPool.releaseConnection(openConnection);
    }
  }
  this.openConnections = [];
  this.is_connected = false;

  user_callback();
};

exports.DBConnectionPool.prototype.destroy = function() { 
};

exports.DBConnectionPool.prototype.isConnected = function() {
  return this.is_connected;
};

var countOpenConnections = function(connectionPool) {
  var i, count = 0;
  for (i = 0; i < connectionPool.openConnections.length; ++i) {
    if (connectionPool.openConnections[i] !== null) {
      count++;
    }
  }
  return count;
};

exports.DBConnectionPool.prototype.getDBSession = function(index, callback) {
  var connectionPool = this;
  var newDBSession = null;
  var charset = connectionPool.driverproperties.charset;
  var charsetQuery = 
       'SET character_set_client=\'' + charset +
    '\';SET character_set_connection=\'' + charset +
    '\';SET character_set_results=\'' + charset + 
    '\';';
  var sqlModeQuery = '';
  // set SQL_MODE if specified in driverproperties
  if (typeof connectionPool.driverproperties.sql_mode !== 'undefined') {
    sqlModeQuery = 'SET SQL_MODE = \'' + connectionPool.driverproperties.sql_mode + '\';';
  }
  udebug.log(sqlModeQuery);
  function charsetComplete(err) {
    callback(err, newDBSession);
  }
    var connected_callback = function(err, pooledConnection) {
      if (err) {
        callback(err);
        return;
      }
      newDBSession = new mysqlConnection.DBSession(pooledConnection, connectionPool, index);
      connectionPool.openConnections[index] = pooledConnection;
      udebug.log_detail('MySQLConnectionPool.getDBSession created a new pooledConnection for index ' + index + ' ; ', 
          ' openConnections: ', countOpenConnections(connectionPool));
      // set character set server variables      
      pooledConnection.query(charsetQuery + sqlModeQuery, charsetComplete);
    };
    // create a new connection
    connectionPool.getConnection(connected_callback);
};

/** Close the connection being used by the dbSession.
 * @param dbSession contains index the index into the openConnections array
 *                           pooledConnection the connection being used
 * @param callback when the connection is closed call the user
 */
exports.DBConnectionPool.prototype.closeConnection = function(dbSession, callback) {
  var connectionPool = this;
  if (dbSession.pooledConnection) {
    connectionPool.releaseConnection(dbSession.pooledConnection);
    dbSession.pooledConnection = null;
  }
  connectionPool.openConnections[dbSession.index] = null;
  if (typeof(callback) === 'function') {
    callback(null);
  }
};

exports.DBConnectionPool.prototype.getTableMetadata = function(databaseName, tableName, dbSession, user_callback) {
  var connectionPool = this;
  var connection, dictionary;
  stats.get_table_metadata++;

  function getTableMetadataOnMetadata(err, metadata) {
    if (!dbSession) {
      connectionPool.releaseConnection(connection);
    }
    user_callback(err, metadata);
  }

  function getTableMetadataOnConnection(err, c) {
    if (err) {
      user_callback(err);
    } else {
      connection = c;
      dictionary = new mysqlDictionary.DataDictionary(connection, connectionPool);
      udebug.log_detail('MySQLConnectionPool.getTableMetadata calling dictionary.getTableMetadata for',
          databaseName, tableName);
      dictionary.getTableMetadata(databaseName, tableName, getTableMetadataOnMetadata);
    }
  }

  // getTableMetadata starts here

  if (dbSession) {
    // dbSession exists; use the connection in the db session
    getTableMetadataOnConnection(null, dbSession.pooledConnection);
  } else {
    // dbSession does not exist; get a connection for the call
    connectionPool.getConnection(getTableMetadataOnConnection);
  }

};

exports.DBConnectionPool.prototype.listTables = function(databaseName, dbSession, user_callback) {

  var connectionPool = this;
  var connection, dictionary;
  stats.list_tables++;

  function listTablesOnTableList(err, list) {
    if (!dbSession) {
      // return the connection we got just for this call
      connectionPool.releaseConnection(connection);
    }
    // return the list to the user
    user_callback(err, list);
  }

  function listTablesOnConnection(err, c) {
    if (err) {
      user_callback(err);
    } else {
      connection = c;
      dictionary = new mysqlDictionary.DataDictionary(connection);
      dictionary.listTables(databaseName, listTablesOnTableList);
    }
  }

  // listTables starts here
  
  if (dbSession) {
    listTablesOnConnection(null, dbSession.pooledConnection);
  } else {
    // dbSession does not exist; get a connection for the call
    connectionPool.getConnection(listTablesOnConnection);
  }
};

function defaultFieldMeta(fieldMapping) {
  if (fieldMapping.fieldName == 'id') {
    return 'id INT PRIMARY KEY';
  } 
  return fieldMapping.fieldName + ' VARCHAR(32) ';
}

function pn(nullable) {return nullable? '': ' NOT NULL ';}
function pu(unsigned) {return unsigned? ' UNSIGNED' : '';}

var translateMeta = {};

translateMeta.binary = function(length, nullable) {return 'BINARY(' + length + ')' +  pn(nullable);};
translateMeta.char = function(length, nullable) {return 'CHAR(' + length + ')' +  pn(nullable);};
translateMeta.date = function(nullable) {return 'DATE' +  pn(nullable);};
translateMeta.datetime = function(fsp, nullable) {return 'DATETIME(' +  fsp + ')' + pn(nullable);};
translateMeta.decimal = function(precision, scale, nullable) {return 'DECIMAL(' + precision + ', ' + scale + ')' +  pn(nullable);};
translateMeta.double = function(nullable) {return 'DOUBLE' +  pn(nullable);};
translateMeta.float = function(nullable) {return 'FLOAT' +  pn(nullable);};
translateMeta.integer = function(bits, unsigned, nullable) {
  var u = pu(unsigned);
  var n = pn(nullable);
  if (bits < 8) return 'BIT' + u + n;
  if (bits == 8) return 'TINYINT' + u + n;
  if (bits <= 16) return 'SMALLINT' + u + n;
  if (bits <= 24) return 'MEDIUMINT' + u + n;
  if (bits <= 32) return 'INT' + u + n;
  return 'BIGINT' + u + n;
};
translateMeta.interval = function(fsp, nullable) {return 'TIME' + pn(nullable);};
translateMeta.time = function(fsp, nullable) {return 'TIME' + pn(nullable);};
translateMeta.timestamp = function(fsp, nullable) {return 'TIMESTAMP' + pn(nullable);};
translateMeta.varbinary = function(length, lob, nullable) {
  if (lob) {
    return 'BLOB(' + length + ')' + pn(nullable);
  }
  return 'VARBINARY(' + length + ')' + pn(nullable);
};
translateMeta.varchar = function(length, lob, nullable) {
  if (lob) {
    return 'TEXT(' + length + ')' + pn(nullable);
  }
  return 'VARCHAR(' + length + ')' + pn(nullable);
};
translateMeta.year = function(nullable) {return 'YEAR' + pn(nullable);};

function sqlForTableCreation(tableMapping, defaultDatabaseName, engine) {
  udebug.log('sqlForTableCreation tableMapping', tableMapping, engine);
  var i, field, delimiter = '';
  var tableMeta;
  var sql = 'CREATE TABLE ';
  var columnMeta;
  sql += tableMapping.database || defaultDatabaseName;
  sql += '.';
  sql += tableMapping.table;
  sql += '(';
  for (i = 0; i < tableMapping.fields.length; ++i) {
    sql += delimiter;
    delimiter = ', ';
    field = tableMapping.fields[i];
    sql += field.columnName;
    sql += ' ';
    meta = field.meta;
    if (meta) {
      columnMeta = meta.doit(translateMeta);
      sql += columnMeta;
      sql += meta.isPrimaryKey? ' PRIMARY KEY ' : '';
      sql += meta.isUniqueKey? ' UNIQUE KEY ': '';
      udebug.log('sqlForTableCreation field:', field.fieldName, 'column:', field.columnName, 'meta:', meta, 'columnMeta:', columnMeta);
    } else {
      sql += defaultFieldMeta(field);
    }
  }
  // process meta for the table
  // need to support PRIMARY and HASH
  for (i = 0; i < tableMapping.meta.length; ++i) {
    tableMeta = tableMapping.meta[i];
    if (tableMeta.index) {
      sql += delimiter;
      // index name calculation
      sql += tableMeta.unique?' UNIQUE': '';
      sql += ' INDEX ' + tableMeta.columns + ' ( ' + tableMeta.columns + ') ';
    }
  }
  sql += ') ENGINE=' + engine;
  udebug.log('sqlForTableMapping sql: ', sql);
  return sql;
}

/** Create the table in the database for the mapping.
 * @param tableMapping the mapping for this table
 * @param session the session to use for database operations
 * @param sessionFactory the session factory to use for database operations
 * @param user_callback the user callback(err)
 * @return err if any errors
 */
exports.DBConnectionPool.prototype.createTable = function(tableMapping, session, sessionFactory, user_callback) {
  var connectionPool = this;
  var createTableSQL, connection, dictionary, databaseName, tableName, qualifiedTableName, tableHandler;
  tableName = tableMapping.table;
  databaseName = tableMapping.database || connectionPool.driverproperties.database;
  qualifiedTableName = databaseName + '.' + tableName;
  function createTableOnTableMetadata(err, tableMetadata) {
    udebug.log('createTableOnTableMetadata with err:', err, '\n', util.inspect(tableMetadata));
    // remember the table metadata in the session factory
    sessionFactory.tableMetadatas[qualifiedTableName] = tableMapping;
    // create the table handler
    tableHandler = new DBTableHandler(tableMetadata, tableMapping, null);
    // remember the table handler in the session factory
    sessionFactory.tableHandlers[qualifiedTableName] = tableHandler;
    if (!session || !session.dbSession) {
      // return the connection we got just for this call
      connectionPool.releaseConnection(connection);
    }    
    user_callback(err);
  }
  function createTableOnTableCreation(err) {
    if (err) {
      user_callback(err);
    } else {
      // create the table metadata and table handler for the new table
      dictionary = new mysqlDictionary.DataDictionary(connection, connectionPool);
      dictionary.getTableMetadata(databaseName, tableName, createTableOnTableMetadata);
    }
  }
  function createTableOnConnection(err, c) {
    if (err) {
      user_callback(err);
    } else {
      connection = c;
      createTableSQL = sqlForTableCreation(tableMapping, databaseName, connectionPool.props.engine);
    connection.query(createTableSQL, createTableOnTableCreation);
    }
  }

  // createTable starts here
  
  udebug.log('createTable for tableMapping:', util.inspect(tableMapping));
  if (session && session.dbSession) {
    // dbSession exists; use the connection in the db session
    createTableOnConnection(null, session.dbSession.pooledConnection);
  } else {
    // dbSession does not exist; get a connection for the call
    connectionPool.getConnection(createTableOnConnection);
  }
};