#require 'pry'
#require 'pry-nav'

  module Embulk
    module Filter

      class Unpivot < FilterPlugin
        Plugin.register_filter("unpivot", self)

        def self.transaction(config, in_schema, &control)

          task = {
            "outer_key"  => config.param("outer_key", :string),
            "inner_key"  => config.param("inner_key", :string),
            "columns"    => config.param("columns", :array, default: []),
            "additional" => config.param("additional", :array, default: []),
          }

          out_columns = [
            Column.new(nil, task["outer_key"], :string),
            Column.new(nil, task["inner_key"], :string),
          ]

          task["additional"].each do |name|
            col = in_schema.find { |sch| sch.name == name }
            col.index = nil
            out_columns.push(col)
          end

          yield(task, out_columns)
        end

        def init
          # initialization code:
          @idx_outer = get_index(task["outer_key"], in_schema)
          @idx_inner = get_index(task["inner_key"], in_schema)
          @indexes = {}
          task["additional"].each do |name|
            @indexes[name] = get_index(name, in_schema)
          end
          task["columns"].each do |target|
            @indexes[target["name"]] = get_index(target["name"], in_schema)
          end
        end

        def close
        end

        def add(page)
          page.each do |record|
            new_record = []
            new_record.push(record[@idx_outer])
            new_record.push(record[@idx_inner])

            task["additional"].each do |name|
              new_record.push(record[@indexes[name]])
            end

            task["columns"].each do |target|
              index = @indexes[target["name"]]
              next if record[index] == 0 or record[index] == ''
              new_record[1] = target["id"]
              page_builder.add(new_record)
            end
          end
        end

        def finish
          page_builder.finish
        end

        private

        def get_index(name, schema)
          col = schema.select{|c| c.name == name }
          col[0].index
        end

      end

    end
  end