module Csvlint
  module Csvw
    class DateFormat
      attr_reader :pattern

      def initialize(pattern, datatype = nil)
        @pattern = pattern

        if @pattern.nil?
          @regexp = DEFAULT_REGEXP[datatype]
          @type = datatype
        else
          test_pattern = pattern.clone
          test_pattern.gsub!(/S+/, "")
          FIELDS.keys.sort_by { |f| -f.length }.each do |field|
            test_pattern.gsub!(field, "")
          end
          raise Csvw::DateFormatError, "unrecognised date field symbols in date format" if /[GyYuUrQqMLlwWdDFgEecahHKkjJmsSAzZOvVXx]/.match?(test_pattern)

          @regexp = DATE_PATTERN_REGEXP[@pattern]
          @type = @regexp.nil? ? "http://www.w3.org/2001/XMLSchema#time" : "http://www.w3.org/2001/XMLSchema#date"
          @regexp ||= TIME_PATTERN_REGEXP[@pattern]
          @type = @regexp.nil? ? "http://www.w3.org/2001/XMLSchema#dateTime" : @type
          @regexp ||= DATE_TIME_PATTERN_REGEXP[@pattern]

          if @regexp.nil?
            regexp = @pattern

            @type = "http://www.w3.org/2001/XMLSchema#date" if !(regexp =~ /HH/) && regexp =~ /yyyy/
            @type = "http://www.w3.org/2001/XMLSchema#time" if regexp =~ /HH/ && !(regexp =~ /yyyy/)
            @type = "http://www.w3.org/2001/XMLSchema#dateTime" if regexp =~ /HH/ && regexp =~ /yyyy/

            regexp = regexp.sub("HH", FIELDS["HH"].to_s)
            regexp = regexp.sub("mm", FIELDS["mm"].to_s)
            if /ss\.S+/.match?(@pattern)
              max_fractional_seconds = @pattern.split(".")[-1].length
              regexp = regexp.sub(/ss\.S+$/, "(?<second>#{FIELDS["ss"]}(.[0-9]{1,#{max_fractional_seconds}})?)")
            else
              regexp = regexp.sub("ss", "(?<second>#{FIELDS["ss"]})")
            end

            if /yyyy/.match?(regexp)
              regexp = regexp.sub("yyyy", FIELDS["yyyy"].to_s)
              regexp = regexp.sub("MM", FIELDS["MM"].to_s)
              regexp = regexp.sub("M", FIELDS["M"].to_s)
              regexp = regexp.sub("dd", FIELDS["dd"].to_s)
              regexp = regexp.sub(/d(?=[-T \/.])/, FIELDS["d"].to_s)
            end

            regexp = regexp.sub("XXX", FIELDS["XXX"].to_s)
            regexp = regexp.sub("XX", FIELDS["XX"].to_s)
            regexp = regexp.sub("X", FIELDS["X"].to_s)
            regexp = regexp.sub("xxx", FIELDS["xxx"].to_s)
            regexp = regexp.sub("xx", FIELDS["xx"].to_s)
            regexp = regexp.sub(/x(?!:)/, FIELDS["x"].to_s)

            @regexp = Regexp.new("^#{regexp}$")
          end
        end
      end

      def match(value)
        value&.match?(@regexp) ? true : false
      end

      def parse(value)
        match = @regexp.match(value)
        return nil if match.nil?
        # STDERR.puts(@regexp)
        # STDERR.puts(value)
        # STDERR.puts(match.inspect)
        value = {}
        match.names.each do |field|
          unless match[field].nil?
            case field
            when "timezone"
              tz = match["timezone"]
              tz = "+00:00" if tz == "Z"
              tz += ":00" if tz.length == 3
              tz = "#{tz[0..2]}:#{tz[3..4]}" unless /:/.match?(tz)
              value[:timezone] = tz
            when "second"
              value[:second] = match["second"].to_f
            else
              value[field.to_sym] = match[field].to_i
            end
          end
        end
        case @type
        when "http://www.w3.org/2001/XMLSchema#date"
          begin
            value[:dateTime] = Date.new(match["year"].to_i, match["month"].to_i, match["day"].to_i)
          rescue ArgumentError
            return nil
          end
        when "http://www.w3.org/2001/XMLSchema#dateTime"
          begin
            value[:dateTime] = DateTime.new(match["year"].to_i, match["month"].to_i, match["day"].to_i, match["hour"].to_i, match["minute"].to_i, (match.names.include?("second") ? match["second"].to_f : 0), (match.names.include?("timezone") && match["timezone"]) ? match["timezone"] : "")
          rescue ArgumentError
            return nil
          end
        else
          value[:dateTime] = DateTime.new(value[:year] || 0, value[:month] || 1, value[:day] || 1, value[:hour] || 0, value[:minute] || 0, value[:second] || 0, value[:timezone] || "+00:00")
        end
        value[:string] = if value[:year]
          if value[:month]
            if value[:day]
              if value[:hour]
                # dateTime
                "#{format("%04d", value[:year])}-#{format("%02d", value[:month])}-#{format("%02d", value[:day])}T#{format("%02d", value[:hour])}:#{format("%02d", value[:minute] || 0)}:#{format("%02g", value[:second] || 0)}#{value[:timezone] ? value[:timezone].sub("+00:00", "Z") : ""}"
              else
                # date
                "#{format("%04d", value[:year])}-#{format("%02d", value[:month])}-#{format("%02d", value[:day])}#{value[:timezone] ? value[:timezone].sub("+00:00", "Z") : ""}"
              end
            else
              # gYearMonth
              "#{format("%04d", value[:year])}-#{format("%02d", value[:month])}#{value[:timezone] ? value[:timezone].sub("+00:00", "Z") : ""}"
            end
          else
            # gYear
            "#{format("%04d", value[:year])}#{value[:timezone] ? value[:timezone].sub("+00:00", "Z") : ""}"
          end
        elsif value[:month]
          if value[:day]
            # gMonthDay
            "--#{format("%02d", value[:month])}-#{format("%02d", value[:day])}#{value[:timezone] ? value[:timezone].sub("+00:00", "Z") : ""}"
          else
            # gMonth
            "--#{format("%02d", value[:month])}#{value[:timezone] ? value[:timezone].sub("+00:00", "Z") : ""}"
          end
        elsif value[:day]
          # gDay
          "---#{format("%02d", value[:day])}#{value[:timezone] ? value[:timezone].sub("+00:00", "Z") : ""}"
        else
          "#{format("%02d", value[:hour])}:#{format("%02d", value[:minute])}:#{format("%02g", value[:second] || 0)}#{value[:timezone] ? value[:timezone].sub("+00:00", "Z") : ""}"
        end
        value
      end

      private

      FIELDS = {
        "yyyy" => /(?<year>-?([1-9][0-9]{3,}|0[0-9]{3}))/,
        "MM" => /(?<month>0[1-9]|1[0-2])/,
        "M" => /(?<month>[1-9]|1[0-2])/,
        "dd" => /(?<day>0[1-9]|[12][0-9]|3[01])/,
        "d" => /(?<day>[1-9]|[12][0-9]|3[01])/,
        "HH" => /(?<hour>[01][0-9]|2[0-3])/,
        "mm" => /(?<minute>[0-5][0-9])/,
        "ss" => /([0-6][0-9])/,
        "X" => /(?<timezone>Z|[-+]((0[0-9]|1[0-3])([0-5][0-9])?|14(00)?))/,
        "XX" => /(?<timezone>Z|[-+]((0[0-9]|1[0-3])[0-5][0-9]|1400))/,
        "XXX" => /(?<timezone>Z|[-+]((0[0-9]|1[0-3]):[0-5][0-9]|14:00))/,
        "x" => /(?<timezone>[-+]((0[0-9]|1[0-3])([0-5][0-9])?|14(00)?))/,
        "xx" => /(?<timezone>[-+]((0[0-9]|1[0-3])[0-5][0-9]|1400))/,
        "xxx" => /(?<timezone>[-+]((0[0-9]|1[0-3]):[0-5][0-9]|14:00))/
      }

      DATE_PATTERN_REGEXP = {
        "yyyy-MM-dd" => Regexp.new("^#{FIELDS["yyyy"]}-#{FIELDS["MM"]}-#{FIELDS["dd"]}$"),
        "yyyyMMdd" => Regexp.new("^#{FIELDS["yyyy"]}#{FIELDS["MM"]}#{FIELDS["dd"]}$"),
        "dd-MM-yyyy" => Regexp.new("^#{FIELDS["dd"]}-#{FIELDS["MM"]}-#{FIELDS["yyyy"]}$"),
        "d-M-yyyy" => Regexp.new("^#{FIELDS["d"]}-#{FIELDS["M"]}-#{FIELDS["yyyy"]}$"),
        "MM-dd-yyyy" => Regexp.new("^#{FIELDS["MM"]}-#{FIELDS["dd"]}-#{FIELDS["yyyy"]}$"),
        "M-d-yyyy" => Regexp.new("^#{FIELDS["M"]}-#{FIELDS["d"]}-#{FIELDS["yyyy"]}$"),
        "dd/MM/yyyy" => Regexp.new("^#{FIELDS["dd"]}/#{FIELDS["MM"]}/#{FIELDS["yyyy"]}$"),
        "d/M/yyyy" => Regexp.new("^#{FIELDS["d"]}/#{FIELDS["M"]}/#{FIELDS["yyyy"]}$"),
        "MM/dd/yyyy" => Regexp.new("^#{FIELDS["MM"]}/#{FIELDS["dd"]}/#{FIELDS["yyyy"]}$"),
        "M/d/yyyy" => Regexp.new("^#{FIELDS["M"]}/#{FIELDS["d"]}/#{FIELDS["yyyy"]}$"),
        "dd.MM.yyyy" => Regexp.new("^#{FIELDS["dd"]}.#{FIELDS["MM"]}.#{FIELDS["yyyy"]}$"),
        "d.M.yyyy" => Regexp.new("^#{FIELDS["d"]}.#{FIELDS["M"]}.#{FIELDS["yyyy"]}$"),
        "MM.dd.yyyy" => Regexp.new("^#{FIELDS["MM"]}.#{FIELDS["dd"]}.#{FIELDS["yyyy"]}$"),
        "M.d.yyyy" => Regexp.new("^#{FIELDS["M"]}.#{FIELDS["d"]}.#{FIELDS["yyyy"]}$")
      }

      TIME_PATTERN_REGEXP = {
        "HH:mm:ss" => Regexp.new("^#{FIELDS["HH"]}:#{FIELDS["mm"]}:(?<second>#{FIELDS["ss"]})$"),
        "HHmmss" => Regexp.new("^#{FIELDS["HH"]}#{FIELDS["mm"]}(?<second>#{FIELDS["ss"]})$"),
        "HH:mm" => Regexp.new("^#{FIELDS["HH"]}:#{FIELDS["mm"]}$"),
        "HHmm" => Regexp.new("^#{FIELDS["HH"]}#{FIELDS["mm"]}$")
      }

      DATE_TIME_PATTERN_REGEXP = {
        "yyyy-MM-ddTHH:mm:ss" => Regexp.new("^#{FIELDS["yyyy"]}-#{FIELDS["MM"]}-#{FIELDS["dd"]}T#{FIELDS["HH"]}:#{FIELDS["mm"]}:(?<second>#{FIELDS["ss"]})$"),
        "yyyy-MM-ddTHH:mm" => Regexp.new("^#{FIELDS["yyyy"]}-#{FIELDS["MM"]}-#{FIELDS["dd"]}T#{FIELDS["HH"]}:#{FIELDS["mm"]}$")
      }

      DEFAULT_REGEXP = {
        "http://www.w3.org/2001/XMLSchema#date" =>
          Regexp.new("^#{FIELDS["yyyy"]}-#{FIELDS["MM"]}-#{FIELDS["dd"]}#{FIELDS["XXX"]}?$"),
        "http://www.w3.org/2001/XMLSchema#dateTime" =>
          Regexp.new("^#{FIELDS["yyyy"]}-#{FIELDS["MM"]}-#{FIELDS["dd"]}T#{FIELDS["HH"]}:#{FIELDS["mm"]}:(?<second>#{FIELDS["ss"]}(.[0-9]+)?)#{FIELDS["XXX"]}?$"),
        "http://www.w3.org/2001/XMLSchema#dateTimeStamp" =>
          Regexp.new("^#{FIELDS["yyyy"]}-#{FIELDS["MM"]}-#{FIELDS["dd"]}T#{FIELDS["HH"]}:#{FIELDS["mm"]}:(?<second>#{FIELDS["ss"]}(.[0-9]+)?)#{FIELDS["XXX"]}$"),
        "http://www.w3.org/2001/XMLSchema#gDay" =>
          Regexp.new("^---#{FIELDS["dd"]}#{FIELDS["XXX"]}?$"),
        "http://www.w3.org/2001/XMLSchema#gMonth" =>
          Regexp.new("^--#{FIELDS["MM"]}#{FIELDS["XXX"]}?$"),
        "http://www.w3.org/2001/XMLSchema#gMonthDay" =>
          Regexp.new("^--#{FIELDS["MM"]}-#{FIELDS["dd"]}#{FIELDS["XXX"]}?$"),
        "http://www.w3.org/2001/XMLSchema#gYear" =>
          Regexp.new("^#{FIELDS["yyyy"]}#{FIELDS["XXX"]}?$"),
        "http://www.w3.org/2001/XMLSchema#gYearMonth" =>
          Regexp.new("^#{FIELDS["yyyy"]}-#{FIELDS["MM"]}#{FIELDS["XXX"]}?$"),
        "http://www.w3.org/2001/XMLSchema#time" =>
          Regexp.new("^#{FIELDS["HH"]}:#{FIELDS["mm"]}:(?<second>#{FIELDS["ss"]}(.[0-9]+)?)#{FIELDS["XXX"]}?$")
      }
    end

    class DateFormatError < StandardError
    end
  end
end