class Pagy::Countless

def finalize(fetched)
  fetched == 0 && @page > 1 and raise(OverflowError.new(self), "page #{@page} got no items")
  @pages = @last = (fetched > @items ? @page + 1 : @page)         # set the @pages and @last
  @items = fetched if fetched < @items && fetched > 0             # adjust items for last non-empty page
  @from  = fetched == 0 ? 0 : @offset+1 - @outset                 # page begins from item
  @to    = fetched == 0 ? 0 : @offset + @items - @outset          # page ends to item
  @prev  = (@page-1 unless @page == 1)                            # nil if no prev page
  @next  = @page == @last ? (1 if @vars[:cycle]) : @page+1        # nil if no next page, 1 if :cycle
  self
end

def finalize_with_overflow(items)
  @overflow = false
  finalize_without_overflow(items)
rescue OverflowError
  @overflow = true                            # add the overflow flag
  case @vars[:overflow]
  when :exception
    raise                                     # same as without the extra
  when :empty_page
    @offset = @items = @from = @to = 0        # vars relative to the actual page
    @vars[:size] = []                         # no page in the series
    self
  else
    raise ArgumentError, "expected :overflow variable in [:empty_page, :exception]; got #{@vars[:overflow].inspect}"
  end
end

def initialize(vars={})
  @vars = VARS.merge(vars.delete_if{|_,v| v.nil? || v == '' })      # default vars + cleaned vars (can be overridden)
  { items:1, outset:0, page:1 }.each do |k,min|                     # validate instance variables
    (@vars[k] && instance_variable_set(:"@#{k}", @vars[k].to_i) >= min) \
     or raise(ArgumentError, "expected :#{k} >= #{min}; got #{@vars[k].inspect}")
  end
  @offset = @items * (@page - 1) + @outset                          # pagination offset + outset (initial offset)
end