18F/C2

module TabularData
  class Container
    attr_reader :columns, :frozen_sort, :filter, :query
    attr_accessor :es_response

    def initialize(name, config)
      @name = name
      @frozen_sort = config.fetch(:frozen_sort, false)
      @filter = config.fetch(:filter, false)
      @query = init_query(config[:engine].constantize, config.fetch(:joins, []))
      @columns = init_columns(config.fetch(:column_configs, {}), config.fetch(:columns, {}))
      self.sort = config[:sort]
    end

    def alter_query
      @query = yield(@query)
      self
    end

    def apply_limit(limit)
      alter_query { |rel| rel.limit(limit) }
    end

    def apply_offset(offset)
      alter_query { |rel| rel.offset(offset) }
    end

    def rows
      results = @query

      if @sort && !@frozen_sort
        results = results.order(@sort)
      end

      apply_filter(results)
    end

    def total
      rows.offset(0).limit(nil).count
    end

    def size
      (@initial_params[:size] || @initial_params[:limit] || Proposal::MAX_SEARCH_RESULTS).to_i
    end

    def from
      if @initial_params[:page]
        (@initial_params[:page].to_i - 1) * size.to_i
      else
        (@initial_params[:from] || @initial_params[:offset] || 0).to_i
      end
    end

    def limit_value
      size
    end

    def page
      @initial_params[:page]
    end

    def current_page
      from / size + 1
    end

    def total_pages
      (total / size).ceil
    end

    def apply_filter(results)
      if @filter
        @filter.call(results)
      else
        results
      end
    end

    def state_from_params=(params)
      @initial_params = params
      relevant = params.permit(tables: { @name => [:sort] })
      config = relevant.fetch(:tables, {}).fetch(@name, {}) || {}

      if config.key?(:sort)
        self.sort = config[:sort]
      end

      self
    end

    def sort_params(original_params, col)
      if col.sort_dir == :asc   # flip to descending
        original_params.deep_merge(tables: { @name => { sort: "-" + col.name } })
      else
        original_params.deep_merge(tables: { @name => { sort: col.name } })
      end
    end

    private

    def sort=(field)
      sort_field = field || ""
      direction = sort_field.start_with?("-") ? :desc : :asc
      field_name = sort_field.gsub(/\A-/, "")

      @columns.each do |column|
        if column.name == field_name && !@frozen_sort
          @sort = column.sort(direction)
        else
          column.sort(nil)
        end
      end
    end

    def init_query(klass, joins)
      query = klass.all

      joins.each do |table_name, config|
        if config == true
          query = join_table(query, klass, table_name)
        else
          query = query.joins(config)
        end
      end

      query
    end

    def join_table(query, klass, table_name)
      join_tables = klass.joins(table_name).join_sources
      join_tables[-1].left.table_alias = table_name
      query.joins(join_tables).includes(table_name)
    end

    def init_columns(config, order)
      column_hash = {}
      config.map do |name, col_config|
        if col_config == true   # short hand for "no configuration"
          col_config = {}
        end
        qualified_name = "#{@query.table_name}.#{name}"
        column_hash[name] = Column.new(name, qualified_name, col_config)
      end

      order.map { |name| column_hash[name.to_sym] }
    end
  end
end