module ActiveRecord::ConnectionHandling

def clear_cache! # :nodoc:
  connection.schema_cache.clear!
end

def connected?
  connection_handler.connected?(self)
end

def connection
  retrieve_connection
end

def connection_config
  connection_pool.spec.config
end

def connection_id
  ActiveRecord::RuntimeRegistry.connection_id
end

def connection_id=(connection_id)
  ActiveRecord::RuntimeRegistry.connection_id = connection_id
end

def connection_pool
  connection_handler.retrieve_connection_pool(self) or raise ConnectionNotEstablished
end

def establish_connection(spec = nil)
  spec     ||= DEFAULT_ENV.call.to_sym
  resolver =   ConnectionAdapters::ConnectionSpecification::Resolver.new configurations
  spec     =   resolver.spec(spec)
  unless respond_to?(spec.adapter_method)
    raise AdapterNotFound, "database configuration specifies nonexistent #{spec.config[:adapter]} adapter"
  end
  remove_connection
  connection_handler.establish_connection self, spec
end

def mysql2_connection(config)
  config = config.symbolize_keys
  config[:username] = 'root' if config[:username].nil?
  if Mysql2::Client.const_defined? :FOUND_ROWS
    config[:flags] = Mysql2::Client::FOUND_ROWS
  end
  client = Mysql2::Client.new(config)
  options = [config[:host], config[:username], config[:password], config[:database], config[:port], config[:socket], 0]
  ConnectionAdapters::Mysql2Adapter.new(client, logger, options, config)
rescue Mysql2::Error => error
  if error.message.include?("Unknown database")
    raise ActiveRecord::NoDatabaseError.new(error.message, error)
  else
    raise
  end
end

def mysql_connection(config)
  config = config.symbolize_keys
  host     = config[:host]
  port     = config[:port]
  socket   = config[:socket]
  username = config[:username] ? config[:username].to_s : 'root'
  password = config[:password].to_s
  database = config[:database]
  mysql = Mysql.init
  mysql.ssl_set(config[:sslkey], config[:sslcert], config[:sslca], config[:sslcapath], config[:sslcipher]) if config[:sslca] || config[:sslkey]
  default_flags = Mysql.const_defined?(:CLIENT_MULTI_RESULTS) ? Mysql::CLIENT_MULTI_RESULTS : 0
  default_flags |= Mysql::CLIENT_FOUND_ROWS if Mysql.const_defined?(:CLIENT_FOUND_ROWS)
  options = [host, username, password, database, port, socket, default_flags]
  ConnectionAdapters::MysqlAdapter.new(mysql, logger, options, config)
rescue Mysql::Error => error
  if error.message.include?("Unknown database")
    raise ActiveRecord::NoDatabaseError.new(error.message, error)
  else
    raise
  end
end

def postgresql_connection(config)
  conn_params = config.symbolize_keys
  conn_params.delete_if { |_, v| v.nil? }
  # Map ActiveRecords param names to PGs.
  conn_params[:user] = conn_params.delete(:username) if conn_params[:username]
  conn_params[:dbname] = conn_params.delete(:database) if conn_params[:database]
  # Forward only valid config params to PGconn.connect.
  conn_params.keep_if { |k, _| VALID_CONN_PARAMS.include?(k) }
  # The postgres drivers don't allow the creation of an unconnected PGconn object,
  # so just pass a nil connection object for the time being.
  ConnectionAdapters::PostgreSQLAdapter.new(nil, logger, conn_params, config)
end

def remove_connection(klass = self)
  connection_handler.remove_connection(klass)
end

def retrieve_connection
  connection_handler.retrieve_connection(self)
end

def sqlite3_connection(config)
  # Require database.
  unless config[:database]
    raise ArgumentError, "No database file specified. Missing argument: database"
  end
  # Allow database path relative to Rails.root, but only if the database
  # path is not the special path that tells sqlite to build a database only
  # in memory.
  if ':memory:' != config[:database]
    config[:database] = File.expand_path(config[:database], Rails.root) if defined?(Rails.root)
    dirname = File.dirname(config[:database])
    Dir.mkdir(dirname) unless File.directory?(dirname)
  end
  db = SQLite3::Database.new(
    config[:database].to_s,
    :results_as_hash => true
  )
  db.busy_timeout(ConnectionAdapters::SQLite3Adapter.type_cast_config_to_integer(config[:timeout])) if config[:timeout]
  ConnectionAdapters::SQLite3Adapter.new(db, logger, nil, config)
rescue Errno::ENOENT => error
  if error.message.include?("No such file or directory")
    raise ActiveRecord::NoDatabaseError.new(error.message, error)
  else
    raise
  end
end