module Workarea
  module MagentoMigrator
    class MagentoBase
      class << self
        attr_writer :client, :table_name
        STORE_ID = 0

        def client
          @@client ||= Workarea::MagentoMigrator::SqlConnection.new.client
        end

        def entity_type_id
          rows = client.query("SELECT entity_type_id FROM eav_entity_type WHERE entity_type_code = '#{table_name}'")
          rows.to_a.map{|ent| ent['entity_type_id']}.first
        end

        def column_types()
          rows = client.query("SELECT distinct(backend_type) FROM eav_attribute WHERE entity_type_id = #{entity_type_id}")
          rows.to_a.map{|r| r["backend_type"]}
        end

        def attribute_id_query(col)
          rows = client.query("SELECT attribute_id FROM eav_attribute WHERE attribute_code = '#{col}' AND entity_type_id = #{entity_type_id}")
          rows.to_a.map{|r| r["attribute_id"]}.first
        end

        def field_names_query
          "SELECT attribute_code, backend_type FROM eav_attribute WHERE entity_type_id = ? and backend_type = ?"
        end

        def select_query
          select_query = "SELECT #{select_columns} FROM #{table_name}_entity e #{join_clause} "
          select_query += "\nwhere e.entity_id in (#{ids_to_include})"
        end

        def all
          client.query(select_query).to_a
        end

        def columns_to_consider
          YAML.load_file("#{Gem.loaded_specs['workarea-magento_migrator'].full_gem_path}/config/data/#{table_name}.yml")["columns"]["eav"]
        end

        def allowed_field_names
          field_names.values.flatten.map{|fn| fn if columns_to_consider.include?(fn)}
        end

        def select_columns
          select_cluses = own_field_names.map{|tc| "\ne.#{tc}"}
          index = 1

          field_names.each do |column_type, column_names|
            column_names.each do |column_name|
              if columns_to_consider.include?(column_name)
                select_cluses << " \nv#{index}.value AS '#{column_name}'"
                index += 1
              end
            end
          end

          select_cluses.join(', ')
        end

        def join_clause
          join_clauses = []
          index = 1

          field_names.each do |column_type, column_names|
            column_names.each do |column_name|
              if columns_to_consider.include?(column_name)
                attribute_id = attribute_id_query(column_name)
                join_clauses << "\nLEFT JOIN #{table_name}_entity_#{column_type} v#{index} ON e.entity_id = v#{index}.entity_id AND v#{index}.store_id = #{STORE_ID} AND v#{index}.attribute_id = (#{attribute_id}) "
                index += 1
              end
            end
          end

          join_clauses.join
        end

        def execute_query(query)
          if client
            rows = client.query(query)
            rows.to_a
          else
            Rails.logger.error(Mysql2::ConnectionError)
          end
        end

        def own_field_names
          client.query("describe #{table_name}_entity").to_a.map{|tc| tc["Field"]}
        end

        def all_field_names
          own_field_names + field_names.values.flatten
        end

        def field_names
          statement = client.prepare(field_names_query)
          field_names = {}
          column_types.each do |col|
            rows = statement.execute(entity_type_id, col)
            field_names[col.to_s.to_sym] = rows.to_a.map{|r| r["attribute_code"]}.sort
          end
          field_names
        end
      end # class self declaration

    end # class end
  end
end