module AdapterExtensions::SQLServerAdapter
  
  def support_select_into_table?
    true
  end
  
  # Inserts an INTO table_name clause to the sql_query.
  def add_select_into_table(new_table_name, sql_query)
    sql_query.sub(/FROM/i, "INTO #{new_table_name} FROM")
  end
  
  # Copy the specified table.
  def copy_table(old_table_name, new_table_name)
    execute add_select_into_table(new_table_name, "SELECT * FROM #{old_table_name}")
  end
      
protected
  # Call +bulk_load+, as that method wraps this method.
  # 
  # Bulk load the data in the specified file. This implementation relies
  # on freebcp being in your PATH.
  #
  # Currently supported options:
  # * <tt>:bin</tt> -- alternate path to freebcp
  # * <tt>:max_errors</tt> -- maximum number of errors (freebcp -m parameter)
  # * <tt>:env</tt> -- override ActiveRecord environment to be used
  # * <tt>:fields</tt> -- Hash of options for fields:
  # * <tt>:delimited_by</tt> -- The field delimiter
  # :columns is currently unsupported and will raise an exception
  def do_bulk_load(filename, table_name, options={})
    env_name = options[:env] || Rails.env
    config = ActiveRecord::Base.configurations[env_name]

    raise NotImplementedError.new(":columns option is not currently supported") if options[:columns]

    # work in progress.
    # - http://linux.die.net/man/1/freebcp
    # - http://stackoverflow.com/a/924943/20302
    # - http://msdn.microsoft.com/en-us/library/ms162802.aspx
    # - http://www.dbforums.com/microsoft-sql-server/1624618-how-bring-out-column-names-bcp.html
    
    command = []
    command << (options[:bin] || 'freebcp')
    command << "\"#{config['database']}.dbo.#{table_name}\""
    command << "in \"#{filename}\""
    command << "-S \"#{config['host']}\""
    command << "-U \"#{config['username']}\""
    command << "-P \"#{config['password']}\""
    command << "-c" # character mode
    command << "-t \"#{options[:fields][:delimited_by]}\"" if options[:fields] && options[:fields][:delimited_by]
    command << "-b 10000" # bulk size

    command << "-m #{options[:max_errors]}" if options[:max_errors]
    command << "-e \"#{filename}.in.errors\""
    command = command.join(' ')

    # left-overs from legacy bcp call - must see if they must remain or not
    # -a8192 -q -E 

    # TODO - raise a better exception here
    raise "bulk load failed!" unless Kernel.system(command)
  end
end