class PgSearch::Features::TSearch

def conditions
  ["(#{tsdocument}) @@ (#{tsquery})", interpolations]
end

def dictionary
  @options[:dictionary] || :simple
end

def document
  @columns.map { |column| column.to_sql }.join(" || ' ' || ")
end

def initialize(query, options, columns, model, normalizer)
  @query = query
  @options = options || {}
  @model = model
  @columns = columns
  @normalizer = normalizer
  if @options[:prefix] && @model.connection.send(:postgresql_version) < 80400
    raise PgSearch::NotSupportedForPostgresqlVersion.new(<<-MESSAGE.gsub /^\s*/, '')
      Sorry, {:using => {:tsearch => {:prefix => true}}} only works in PostgreSQL 8.4 and above.")
    MESSAGE
  end
end

def interpolations
  {:query => @query.to_s, :dictionary => dictionary.to_s}
end

def normalization
  @options[:normalization] || 0
end

def rank
  tsearch_rank
end

def tsdocument
  if @options[:tsvector_column]
    @options[:tsvector_column].to_s
  else
    @columns.map do |search_column|
      tsvector = "to_tsvector(:dictionary, #{@normalizer.add_normalization(search_column.to_sql)})"
      search_column.weight.nil? ? tsvector : "setweight(#{tsvector}, #{connection.quote(search_column.weight)})"
    end.join(" || ")
  end
end

def tsearch_rank
  ["ts_rank((#{tsdocument}), (#{tsquery}), #{normalization})", interpolations]
end

def tsquery
  return "''" if @query.blank?
  @query.split(" ").compact.map { |term| tsquery_for_term(term) }.join(@options[:any_word] ? ' || ' : ' && ')
end

def tsquery_for_term(term)
  sanitized_term = term.gsub(DISALLOWED_TSQUERY_CHARACTERS, " ")
  term_sql = @normalizer.add_normalization(connection.quote(sanitized_term))
  # After this, the SQL expression evaluates to a string containing the term surrounded by single-quotes.
  # If :prefix is true, then the term will also have :* appended to the end.
  tsquery_sql = [
      connection.quote("' "),
      term_sql,
      connection.quote(" '"),
      (connection.quote(':*') if @options[:prefix])
  ].compact.join(" || ")
  "to_tsquery(:dictionary, #{tsquery_sql})"
end