module PrxAuth
  class ScopeList < Array
    SCOPE_SEPARATOR = " "
    NAMESPACE_SEPARATOR = ":"
    NO_NAMESPACE = :_

    Entry = Struct.new(:namespace, :scope, :string)

    class Entry
      def ==(other)
        namespace == other.namespace && scope == other.scope
      end

      def to_s
        string
      end

      def namespaced?
        !(namespace.nil? || namespace == NO_NAMESPACE)
      end

      def unnamespaced
        if namespaced?
          Entry.new(NO_NAMESPACE, scope, string.split(":").last)
        else
          self
        end
      end

      def inspect
        "#<ScopeList::Entry \"#{self}\">"
      end
    end

    def self.new(list)
      case list
      when PrxAuth::ScopeList then list
      when Array then super(list.join(" "))
      else super(list)
      end
    end

    def initialize(list)
      @string = list
      @string.split(SCOPE_SEPARATOR).uniq.each do |value|
        next if value.length < 1

        parts = value.split(NAMESPACE_SEPARATOR, 2)
        if parts.length == 2
          push Entry.new(symbolize(parts[0]), symbolize(parts[1]), value)
        else
          push Entry.new(NO_NAMESPACE, symbolize(parts[0]), value)
        end
      end
    end

    def contains?(namespace, scope = nil)
      entries = if scope.nil?
        scope, namespace = namespace, NO_NAMESPACE
        [Entry.new(namespace, symbolize(scope), nil)]
      else
        scope = symbolize(scope)
        namespace = symbolize(namespace)
        [Entry.new(namespace, scope, nil), Entry.new(NO_NAMESPACE, scope, nil)]
      end

      entries.any? do |possible_match|
        include?(possible_match)
      end
    end

    def to_s
      entries.join(SCOPE_SEPARATOR)
    end

    def condense
      tripped = false
      result = []

      each do |entry|
        if entry.namespaced? && include?(entry.unnamespaced)
          tripped = true
        else
          result << entry
        end
      end

      if tripped
        ScopeList.new(result.join(SCOPE_SEPARATOR))
      else
        self
      end
    end

    def as_json(opts = ()) # standard:disable Lint/EmptyExpression
      to_s.as_json(opts)
    end

    def -(other)
      return self if other.nil?

      tripped = false
      result = []

      each do |entry|
        if other.include?(entry) || other.include?(entry.unnamespaced)
          tripped = true
        else
          result << entry
        end
      end

      if tripped
        ScopeList.new(result.join(SCOPE_SEPARATOR))
      else
        self
      end
    end

    def +(other)
      return self if other.nil?

      ScopeList.new([to_s, other.to_s].join(SCOPE_SEPARATOR)).condense
    end

    def &(other)
      return ScopeList.new("") if other.nil?

      self - (self - other) + (other - (other - self))
    end

    def ==(other)
      condense.sort_by(&:to_s) == other.condense.sort_by(&:to_s)
    end

    private

    def symbolize(value)
      case value
      when Symbol then value
      when String then value.downcase.tr("-", "_").intern
      else symbolize value.to_s
      end
    end
  end
end