module Krikri::Enrichments
  ##
  # Splits edm:TimeSpan labels and populates `#begin` and `#end`. Any values
  # generated from string values are left as strings to be normalized by
  # another enrichment.
  #
  # Ignores values that are neither a String or an edm:TimeSpan
  #
  # Converts string values to a timespan with the value as providedLabel
  # and enriches as below.
  #
  # Populates the `#providedLabel`, `#begin`, and `#end` properties of TimeSpan
  # objects, and:
  #   - If a `#providedLabel` is present, but begin and end are missing:
  #     - Attempts to parse `#providedLabel` as an EDTF interval and populates
  #       begin and end with their respective values.
  #     - Splits dates
  #   - If no
  #   - Returns the TimeSpan unaltered if all three fields are present.
  class TimespanSplit
    include Krikri::FieldEnrichment

    def enrich_value(value)
      value = timespan_from_string(value) if value.is_a? String
      return value unless value.is_a? DPLA::MAP::TimeSpan
      populate_timespan(value)
    end

    def timespan_from_string(value)
      timespan = DPLA::MAP::TimeSpan.new
      timespan.providedLabel = value
      timespan
    end

    def populate_timespan(timespan)
      return timespan unless timespan.providedLabel.empty? ||
        timespan.begin.empty? || timespan.end.empty?
      parse_label(timespan.providedLabel)

      return timespan
    end

    ##
    # e.g. 1970-08-01/02 or 1970-12/10
    def partial_edtf(str)
      /^(\d{4}(-\d{2})*)-(\d{2})\/(\d{2})$/.match(str) do |m|
        Date.edtf("#{m[1]}-#{m[3]}/#{m[1]}-#{m[4]}")
      end
    end

    ##
    # e.g. 01-2045
    def month_year(str)
      /\d{2}-(\d{4})/.match(str) do |m|
        Date.edtf("#{m[2]}-#{m[1]}")
      end
    end

    ##
    # e.g. 1990-92
    def hyphenated_partial_range(str)
      /^(\d{2})(\d{2})-(\d{2})$/.match(str) do |m|
        Date.edtf("#{m[1]}#{m[2]}/#{m[1]}#{m[3]}")
      end
    end

    ##
    # e.g. 1990s
    def decade_s(str)
      /^(\d{3})0s)$/.match(str) do |m|
        Date.edtf("#{m}x")
      end
    end

    ##
    # e.g. 199-
    def decade_hyphen
      /^(\d{3})-)$/.match(str) do |m|
        Date.edtf("#{m}x")
      end
    end
  end
end