testmycode/tmc-server

# frozen_string_literal: true

require 'date_and_time_utils'

# Parses and abstracts specification in the "deadline" field of a `metadata.yml` file.
class DeadlineSpec # (the name of this class is unfortunate as it confuses IDEs when jumping to tests)
  class InvalidSyntaxError < StandardError; end

  def initialize(exercise, specs)
    @exercise = exercise
    @specs = []
    for i in 0...specs.size
      begin
        spec = specs[i].to_s.strip
        parse_spec(spec) if spec.present?
      rescue InvalidSyntaxError
        raise InvalidSyntaxError, "Invalid syntax in deadline spec #{i + 1} (#{specs[i]})"
      rescue StandardError
        raise "Problem with unlock spec #{i + 1} (#{specs[i]}): #{$!.message}"
      end
    end
  end

  def universal_description
    if @specs.empty?
      nil
    elsif @specs.size == 1
      @specs.first.universal_description
    else
      @specs.map(&:universal_description).join(' or ') + ', whichever comes first'
    end
  end

  def description_for(user)
    min_spec(user)&.personal_describer&.call(user) || 'none'
  end

  def deadline_for(user)
    @specs.map { |s| s.timefun.call(user) }.reject(&:nil?).min
  end

  def depends_on_unlock_time?
    !!@depends_on_unlock_time
  end

  def static_deadline_spec
    @specs.select { |n| !n.nil? && DateAndTimeUtils.looks_like_date_or_time(n.raw_spec) }.map(&:raw_spec).first
  end

  def unlock_deadline_spec
    @specs.select { |n| !n.nil? && !DateAndTimeUtils.looks_like_date_or_time(n.raw_spec) }.map(&:raw_spec).first
  end

  private
    def min_spec(user)
      @specs.map { |s| [s.timefun.call(user), s] }.reject { |p| p.first.nil? }.min_by(&:first)&.map(&:second)
    end

    class SingleSpec
      def initialize(spec, timefun, universal_description, personal_describer)
        @raw_spec = spec
        @timefun = timefun
        @universal_description = universal_description
        @personal_describer = personal_describer
      end
      attr_accessor :raw_spec, :timefun, :universal_description, :personal_describer
    end

    def parse_spec(spec)
      # A spec is a proc that takes a user and returns a Time object or nil
      if DateAndTimeUtils.looks_like_date_or_time(spec)
        time = DateAndTimeUtils.to_time(spec, prefer_end_of_day: true)
        timefun = ->(_user) { time }
        universal = time.to_s
        personal = ->(_u) { universal }
        @specs << SingleSpec.new(spec, timefun, universal, personal)
      elsif spec =~ /^unlock\s*[+]\s*(\d+)\s+(minutes?|hours?|days?|weeks?|months?|years?)$/
        time_scalar = Regexp.last_match(1)
        time_unit = Regexp.last_match(2)
        time_delta = time_scalar.to_i.send(time_unit)
        @depends_on_unlock_time = true
        timefun = lambda do |user|
          unlock_time = @exercise.time_unlocked_for(user)
          unlock_time + time_delta if unlock_time
        end
        universal = "#{time_scalar} #{time_unit} after unlock"
        personal = lambda do |_user|
          "#{time_scalar} #{time_unit} after unlock"
        end
        @specs << SingleSpec.new(spec, timefun, universal, personal)
      else
        raise InvalidSyntaxError, 'Invalid syntax'
      end
    end
end