module Opener
  class OpinionDetectorBasic
    class Opinion
      attr_reader :term
      attr_accessor :left_candidates, :right_candidates, :target_ids, :holders
      
      def initialize(term)
        @term = term
        @left_candidates = []
        @right_candidates = []
        @holders = []
        @target_ids = []
      end
      
      ##
      # Returns the term ids of the opinion expression.
      #
      # @return [Array]
      #
      def ids
        @ids ||= term.list_ids.sort
      end
      
      ##
      # Returns the sentence id of the opinion.
      #
      # @return [String]
      #
      def sentence
        @sentence ||= term.sentence
      end
      
      ##
      # Returns the strength of the opinion.
      #
      # @return [Integer]
      #
      def strength
        @strength ||= term.accumulated_strength
      end
      
      ##
      # Returns the polarity of the opinion.
      #
      # @return [String]
      #
      def polarity
        @polarity ||= if strength > 0
          "positive"
        elsif strength < 0
          "negative"
        else
          "neutral"
        end
      end
      
      ##
      # Obtain the opinion holders from the terms that belong to the same
      # sentence.
      #
      def obtain_holders(sentences, language)
        sentence_terms = sentences[sentence]
        sentence_terms.each do |term|
          if opinion_holders[language].include?(term.lemma)
            @holders << term.id
            break
          end
        end
      end
      
      ##
      # Get the potential right and left candidates of the sentence and
      # decide which ones are the actual targets of the opinion
      #
      def obtain_targets(sentences)
        sentence_terms = sentences[sentence]
        max_distance = 3
        terms_count = sentence_terms.count
        
        index = -1
        sentence_terms.each_with_index do |term, i|
          if ids.include?(term.id)
            index = i
          end
        end
        
        unless index+1 >= terms_count
          min = index+1
          max = [index+1+max_distance,terms_count].min
          @right_candidates = filter_candidates(sentence_terms[min..max])
        end
        
        index = 0
        sentence_terms.each_with_index do |term, i|
          if ids.include?(term.id)
            index = i
            break # needed for left_candidates
          end
        end
        
        unless index == 0
          min = [0, index-1-max_distance].max
          max = index
          @left_candidates = filter_candidates(sentence_terms[min..max])
        end

        unless right_candidates.empty?
          candidate = right_candidates.first
          @target_ids << candidate.id
        end
        
        if target_ids.empty?
          list = mix_lists(right_candidates, left_candidates)
          list.each do |l|
            @target_ids << l.id
            break
          end
        end
      end
      
      protected
      
      ##
      # If there are no opinion targets, right and left candidates
      # are mixed into one list and the first one is picked as the target.
      #
      # @return [Array]
      #
      def mix_lists(lista, listb)
        list = []
        min = [lista.count, listb.count].min
        (0..min).each do |i|
          list << lista[i]
          list << listb[i]
          if lista.count > listb.count
            list << lista[min]
          elsif listb.count > lista.count
            list << listb[min]
          end
        end
        return list.compact
      end
      
      ##
      # Filters candidate terms depending on their part of speech and if
      # they are already part of the expression.
      #
      # @return [Hash]
      #
      def filter_candidates(sentence_terms)
        sentence_terms.select{|t| (t.pos == "N" || t.pos == "R") && !ids.include?(t.id)}
      end
      
      ##
      # Opinion holders for each language code.
      #
      # @return [Hash]
      #
      def opinion_holders
        {
          'nl' => ['ik','we','wij','ze','zij','jullie','u','hij','het','jij','je','mij','me','hem','haar','ons','hen','hun'],
          'en' => ['i','we','he','she','they','it','you'],
          'es' => ['yo','tu','nosotros','vosotros','ellos','ellas','nosotras','vosotras'],
          'it' => ['io','tu','noi','voi','loro','lei','lui'],
          'de' => ['ich','du','wir','ihr','sie','er'],
          'fr' => ['je','tu','lui','elle','nous','vous','ils','elles']
        }
      end
    end # Opinion
  end # OpinionDetectorBasic
end # Opener