date_parser.rb

module SugarCube
  module DateParser
    # Parse a date string: E.g.:
    #
    # SugarCube::DateParser.parse_date "There is a date in here tomorrow at 9:00 AM"
    #
    # => 2013-02-20 09:00:00 -0800
    def self.parse_date(date_string)
      detect(date_string).first.date
    end

    # Parse time zone from date
    #
    # SugarCube::DateParser.parse_date "There is a date in here tomorrow at 9:00 AM EDT"
    def self.parse_time_zone(date_string)
      detect(date_string).first.timeZone
    end

    # Parse a date string: E.g.:
    #
    # SugarCube::DateParser.parse_date "You have a meeting from 9:00 AM to 3:00 PM"
    #
    # => 21600.0
    #
    # Divide by 3600.0 to get number of hours duration.
    def self.parse_duration(date_string)
      detect(date_string).first.duration
    end

    # Parse a date into a raw match array for further processing
    def self.match(date_string)
      detect(date_string)
    end

    private
    def self.detect(date_string)
      error = Pointer.new(:object)
      detector = NSDataDetector.dataDetectorWithTypes(NSTextCheckingTypeDate, error:error)
      matches = detector.matchesInString(date_string, options:0, range:NSMakeRange(0, date_string.length))
    end
  end
end