module PlainSearch

# File lib/plain_search/concern.rb, line 43
def auto_update_search_terms?
  !!auto_update_search_terms
end

# File lib/plain_search/concern.rb, line 11
def changed_searchable_attributes
  self.class.searchable_attributes.select do |attribute_name|
    if has_attribute? attribute_name
      attribute_changed? attribute_name
    else
      true # not all attributes map to DB columns and support *_changed?
    end
  end
end

# File lib/plain_search/concern.rb, line 7
def clear_search_terms_for(attributes)
  search_terms.where(source: attributes).delete_all
end

# File lib/plain_search/concern.rb, line 28
def create_search_terms_for(attributes)
  self.class.transaction do
    Array.wrap(attributes).each do |attr_name|
      attr_value = send(attr_name)
      self.class.tokenize_search_terms(attr_value).each do |term|
        SearchTerm.create!(findable: self, term: term, source: attr_name)
      end
    end
  end
end

# File lib/plain_search/concern.rb, line 144
    def perform_scored_search(terms)
      conditions = search_conditions_for_terms(terms)

      score_statement = searchable_attributes.collect do |attr_name|
        "WHEN search_terms.source = '#{attr_name}' then #{searchable_attribute_scores[attr_name]}"
      end.join("\n           ")

      find_by_sql <<-SQL
        SELECT SUM(e1.match_score) AS score, e1.*
        FROM (
          SELECT
           CASE
           #{score_statement}
           ELSE 0
           END AS match_score,
           #{table_name}.*
          FROM #{table_name}
          JOIN #{SearchTerm.table_name}
            ON #{SearchTerm.table_name}.findable_id = #{table_name}.id
            AND #{SearchTerm.table_name}.findable_type = '#{self.name}'
          WHERE #{conditions.join(' OR ')}
          ) AS e1
        GROUP BY e1.id
        ORDER BY score DESC
      SQL
    end

# File lib/plain_search/concern.rb, line 171
    def perform_unscored_search(terms)
      conditions = search_conditions_for_terms(terms)
      find_by_sql <<-SQL
        SELECT #{table_name}.*, COUNT(#{SearchTerm.table_name}.id) as hits
        FROM #{table_name}
        JOIN #{SearchTerm.table_name}
          ON #{SearchTerm.table_name}.findable_id = #{table_name}.id
          AND #{SearchTerm.table_name}.findable_type = '#{self.name}'
        WHERE #{conditions.join(' OR ')}
        GROUP BY #{table_name}.id
        ORDER BY hits DESC
      SQL
    end

# File lib/plain_search/concern.rb, line 21
def rebuild_search_terms
  self.class.transaction do
    clear_search_terms_for(self.class.searchable_attributes)
    create_search_terms_for(self.class.searchable_attributes)
  end
end

# File lib/plain_search/concern.rb, line 105
def rebuild_search_terms_for_all
  self.transaction do
    SearchTerm.where("findable_type = '#{self.name}'").delete_all
    all.each do |record|
      record.create_search_terms_for(self.searchable_attributes)
    end
  end
end

# File lib/plain_search/concern.rb, line 129
def score_search?
  not searchable_attribute_scores.nil?
end

# File lib/plain_search/concern.rb, line 114
def search(query)

  return none if searchable_attributes.empty?

  terms = tokenize_search_terms(query)
  return none if terms.empty?

  if score_search?
    perform_scored_search(terms)
  else
    perform_unscored_search(terms)
  end

end

# File lib/plain_search/concern.rb, line 135
def search_conditions_for_terms(terms)
  quoted_terms = terms.collect do |t|
    ActiveRecord::Base.connection.quote("#{t}%")
  end
  quoted_terms.collect do |quoted_term|
    "#{SearchTerm.table_name}.term LIKE #{quoted_term}"
  end
end

# File lib/plain_search/concern.rb, line 47
def searchable?
  searchable_attributes.present? and searchable_attributes.any?
end

# File lib/plain_search/concern.rb, line 61
def searchable_by(*attributes)

  has_many :search_terms, as: :findable

  cattr_accessor :searchable_attributes
  cattr_accessor :searchable_attribute_scores

  cattr_accessor :auto_update_search_terms
  self.auto_update_search_terms = true

  cattr_accessor :search_terms_delimiter

  # Add latin-1 umlauts to word characters.
  # Add more if you must.
  self.search_terms_delimiter = /[^\w\u00C0-\u00ff]/

  delegate :searchable?, to: :class
  delegate :auto_update_search_terms, to: :class
  delegate :auto_update_search_terms?, to: :class

  if attributes.size == 1 and attributes[0].is_a? Hash
    # searchable_by attr1: 5, attr2: 1, ...
    self.searchable_attribute_scores = attributes[0]
    self.searchable_attributes = attributes[0].keys
  else
    # searchable_by :attr1, :attr2, ...
    self.searchable_attribute_scores = nil
    self.searchable_attributes = attributes
  end

  after_save do
    if searchable? and auto_update_search_terms?
      attribs = changed_searchable_attributes
      clear_search_terms_for(attribs)
      create_search_terms_for(attribs)
    end
  end

end

# File lib/plain_search/concern.rb, line 101
def tokenize_search_terms(value)
  value.to_s.gsub(search_terms_delimiter, ' ').gsub(/\s+/, ' ').split(' ')
end

# File lib/plain_search/concern.rb, line 51
def without_search_term_updates
  orig_value = self.auto_update_search_terms
  begin
    self.auto_update_search_terms = false
    yield if block_given?
  ensure
    self.auto_update_search_terms = orig_value
  end
end