# encoding: utf-8
module Freeberry
  module MysqlUtils
    def self.included(base)
      base.extend(ClassMethods)
    end
    
    module ClassMethods
      
      def values(column = 'id')
        query = scoped.select(column)
        connection.select_values(query.to_sql).map(&:to_i).uniq
      end
      
      # Check if database exists
		  def database_exists?
			  _options = configurations[Rails.env].dup
			  _options.symbolize_keys!

		    begin
		      connection
		      return true
		    rescue Exception => e
		      return false
		    end
		  end
		
		  # Deletes all rows in table very fast, but without calling +destroy+ method
      # nor any hooks.
		  def truncate_table
			  transaction { connection.execute("TRUNCATE TABLE #{quoted_table_name};") }
		  end
		
      # Disables key updates for model table
      def disable_keys
        connection.execute("ALTER TABLE #{quoted_table_name} DISABLE KEYS")
      end
      
      # Enables key updates for model table
      def enable_keys
        connection.execute("ALTER TABLE #{quoted_table_name} ENABLE KEYS")
      end

      # Disables keys, yields block, enables keys.
      def with_keys_disabled
        disable_keys
        yield
        enable_keys
      end
      
      # Loads data from file(s) using MySQL native LOAD DATA INFILE query, disabling
      # key updates for even faster import speed
      #
      # ==== Parameters
      # * +files+ file(s) to import
      # * +options+ (see <tt>load_data_infile</tt>)
      def fast_import(files, options = {})
        files = [files] unless files.is_a? Array
        with_keys_disabled do
          load_data_infile_multiple(files, options)
        end
      end

      # Loads data from multiple files using MySQL native LOAD DATA INFILE query
      def load_data_infile_multiple(files, options = {})
        files.each do |file|
          load_data_infile(file, options)
        end
      end

      # Loads data from file using MySQL native LOAD DATA INFILE query
      #
      # ==== Parameters
      # * +file+ the file to import
      # * +options+
      def load_data_infile(file, options = {})
        sql = "LOAD DATA LOCAL INFILE '#{file}' "
        sql << "#{options[:insert_method]} " if options[:insert_method]
        sql << "INTO TABLE #{quoted_table_name} "
        sql << "CHARACTER SET #{options[:charset_name]} " if options[:charset_name]
        
        fields = ""
        fields << "TERMINATED BY '#{options[:fields_terminated_by]}' " if options[:fields_terminated_by]
        fields << "OPTIONALLY ENCLOSED BY '#{options[:fields_optionally_enclosed_by]}' " if options[:fields_optionally_enclosed_by]
        fields << "ESCAPED BY '#{options[:fields_escaped_by]}' " if options[:fields_escaped_by]

        sql << "FIELDS #{fields} " unless fields.empty?
        sql << "LINES TERMINATED BY '#{options[:lines_terminated_by]}' " if options[:lines_terminated_by]
        sql << "IGNORE #{options[:ignore_lines]} LINES " if options[:ignore_lines]
        sql << "(" + options[:columns].join(', ') + ") " if options[:columns]
        if options[:mapping]
          mappings = []
          options[:mapping].each_pair do |column, mapping|
            mappings << "#{column} = #{mapping}"
          end
          sql << "SET #{mappings.join(', ')} " if mappings.size > 0
        end
        sql << ";"
        connection.execute(sql)
      end
    end
  end
end