class Pagy::Calendar

Base class for time units subclasses (Year, Quarter, Month, Week, Day)
:nodoc:

def active_period

Period of the active page (used internally for nested units) 
def active_period
  [[@starting, @from].max, [@to - 1, @ending].min] # -1 sec: include only last unit day
end

def create(unit, vars)

Create a subclass instance by unit name (internal use) 
def create(unit, vars)
  raise InternalError, "unit must be in #{UNITS.inspect}; got #{unit}" unless UNITS.include?(unit)
  name    = unit.to_s
  name[0] = name[0].capitalize
  Object.const_get("Pagy::Calendar::#{name}").new(vars)
end

def initialize(vars) # rubocop:disable Lint/MissingSuper

rubocop:disable Lint/MissingSuper
Merge and validate the options, do some simple arithmetic and set a few instance variables 
def initialize(vars) # rubocop:disable Lint/MissingSuper
  raise InternalError, 'Pagy::Calendar is a base class; use one of its subclasses' if instance_of?(Pagy::Calendar)
  vars = self.class::DEFAULT.merge(vars)  # subclass specific default
  normalize_vars(vars)                    # general default
  setup_vars(page: 1)
  setup_unit_vars
  setup_params_var
  raise OverflowError.new(self, :page, "in 1..#{@last}", @page) if @page > @last
  @prev = (@page - 1 unless @page == 1)
  @next = @page == @last ? (1 if @vars[:cycle]) : @page + 1
end

def label(opts = {})

The label for the current page (it can pass along the I18n gem opts when it's used with the i18n extra) 
def label(opts = {})
  label_for(@page, opts)
end

def label_for(page, opts = {})

The label for any page (it can pass along the I18n gem opts when it's used with the i18n extra) 
def label_for(page, opts = {})
  opts[:format] ||= @vars[:format]
  localize(starting_time_for(page.to_i), opts)  # page could be a string
end

def localize(time, opts)

Apply the strftime format to the time (overridden by the i18n extra when localization is required) 
def localize(time, opts)
  time.strftime(opts[:format])
end

def offset_units_for(page)

Used in starting_time_for(page) with a logic equivalent to: @initial + (offset_units_for(page) * unit_time_length)
Number of units to offset from the @initial time, in order to get the ordered starting time for the page. 
def offset_units_for(page)
  @order == :asc ? page - 1 : @pages - page
end

def setup_unit_vars

Base class method for the setup of the unit variables (subclasses must implement it and call super) 
def setup_unit_vars
  raise VariableError.new(self, :format, 'to be a strftime format', @vars[:format]) unless @vars[:format].is_a?(String)
  raise VariableError.new(self, :order, 'to be in [:asc, :desc]', @order) \
        unless %i[asc desc].include?(@order = @vars[:order])
  @starting, @ending = @vars[:period]
  raise VariableError.new(self, :period, 'to be a an Array of min and max local Time instances', @vars[:period]) \
        unless @starting.is_a?(Time) && @ending.is_a?(Time) && !@starting.utc? && !@ending.utc? && @starting <= @ending
  @with_zone = @starting.is_a?(ActiveSupport::TimeWithZone) # remove in 6.0 and reu]place Time in the line above
end