Module Hoodoo::ActiveRecord::Dated::ClassMethods

# File lib/hoodoo/active/active_record/dated.rb, line 223
def dated( context, unquoted_column_names: nil )
  date_time = context.request.dated_at || Time.now
  return self.dated_at( date_time, unquoted_column_names: unquoted_column_names )
end

# File lib/hoodoo/active/active_record/dated.rb, line 249
def dated_at( date_time = Time.now, unquoted_column_names: nil )

  dating_table_name = dated_with_table_name()
  return all() if dating_table_name.nil? # "Model.all" -> returns anonymous scope

  # Rationalise and convert the date time to UTC.

  date_time      = Hoodoo::Utilities.rationalise_datetime( date_time ).utc
  safe_date_time = self.connection.quoted_date( date_time )

  # Create strings that specify the required attributes escaped and
  # joined by commas for use in a SQL query, for both main and history
  # tables.

  safe_name_string = self.quoted_column_name_string(
    unquoted_column_names: unquoted_column_names
  )

  safe_history_name_string = self.quoted_column_name_string_for_history(
    unquoted_column_names: unquoted_column_names
  )

  # A query that combines historical and current records which are
  # effective at the specified date time.

  nested_query = %{
    (
      SELECT #{ safe_name_string } FROM (
        SELECT #{ safe_name_string },"updated_at" AS "effective_start",NULL AS "effective_end"
        FROM #{ self.table_name }
        UNION ALL
        SELECT #{ safe_history_name_string },"effective_start","effective_end"
        FROM #{ dating_table_name }
      ) AS u
      WHERE "effective_start" <= '#{ safe_date_time }' AND ("effective_end" > '#{ safe_date_time }' OR "effective_end" IS NULL)
    ) AS #{ self.table_name }
  }

  # Form a query which uses ActiveRecord to list a dated or current
  # record.

  return from( nested_query )
end

# File lib/hoodoo/active/active_record/dated.rb, line 310
def dated_historical_and_current( unquoted_column_names: nil )

  dating_table_name = dated_with_table_name()
  return all() if dating_table_name.nil? # "Model.all" -> returns anonymous scope

  # Create strings that specify the required attributes escaped and
  # joined by commas for use in a SQL query, for both main and history
  # tables.

  safe_name_string = self.quoted_column_name_string(
    unquoted_column_names: unquoted_column_names
  )

  safe_history_name_string = self.quoted_column_name_string_for_history(
    unquoted_column_names: unquoted_column_names
  )

  # A query that combines historical and current records.

  nested_query = %{
    (
      SELECT #{ safe_name_string }
      FROM #{ self.table_name }
      UNION ALL
      SELECT #{ safe_history_name_string }
      FROM #{ dating_table_name }
    ) AS #{ self.table_name }
  }

  # Form a query which uses ActiveRecord to list current and dated
  # records.

  return from( nested_query )
end

# File lib/hoodoo/active/active_record/dated.rb, line 349
def dated_with
  return self.nz_co_loyalty_hoodoo_dated_with
end

# File lib/hoodoo/active/active_record/dated.rb, line 361
def dated_with_table_name
  instance = self.dated_with()
  instance.nil? ? nil : instance.table_name
end

# File lib/hoodoo/active/active_record/dated.rb, line 166
def dating_enabled( history_table_name: self.table_name + '_history_entries' )

  # Define an anonymous model for the history entries.

  history_klass = Class.new( ::ActiveRecord::Base ) do
    self.primary_key = :id
    self.table_name  = history_table_name
  end

  # Record the anonymous model class in a namespaced class attribute
  # for reference in the rest of the dating code via #dated_with().

  self.nz_co_loyalty_hoodoo_dated_with = history_klass

  # Enable the monkey patch to the Finder module's '#acquire_in' class
  # method, if need be.

  if self.include?( Hoodoo::ActiveRecord::Finder )
    Hoodoo::Monkey.register(
      target_unit:      self,
      extension_module: Hoodoo::Monkey::Patch::ActiveRecordDatedFinderAdditions
    )

    Hoodoo::Monkey.enable( extension_module: Hoodoo::Monkey::Patch::ActiveRecordDatedFinderAdditions )
  end
end

# File lib/hoodoo/active/active_record/dated.rb, line 196
def dating_enabled?
  return self.dated_with().present?
end

# File lib/hoodoo/active/active_record/dated.rb, line 390
def quoted_column_name_string( unquoted_column_names: nil )
  unquoted_column_names ||= self.attribute_names()
  unquoted_column_names   = unquoted_column_names + [ 'id' ] unless unquoted_column_names.include?( 'id' )

  return self.quoted_column_names( unquoted_column_names ).join( ',' )
end

# File lib/hoodoo/active/active_record/dated.rb, line 408
def quoted_column_name_string_for_history( unquoted_column_names: nil )
  unquoted_column_names ||= self.attribute_names
  primary_key_index       = unquoted_column_names.index( 'id' )

  if primary_key_index.nil?
    unquoted_column_names = unquoted_column_names + [ 'id' ]
    primary_key_index     = unquoted_column_names.count - 1
  end

  quoted_column_names     = self.quoted_column_names( unquoted_column_names )
  quoted_primary_key_name = quoted_column_names[ primary_key_index ]
  history_primary_key     = '"uuid" AS ' << quoted_primary_key_name

  quoted_column_names[ primary_key_index ] = history_primary_key

  return quoted_column_names.join( ',' )
end

# File lib/hoodoo/active/active_record/dated.rb, line 374
def quoted_column_names( unquoted_column_names )
  return unquoted_column_names.map do | c |
    ActiveRecord::Base.connection.quote_column_name( c )
  end
end