# frozen_string_literal: true

# transforms "english like" text queries into a tsquery operation
# https://www.postgresql.org/docs/9.5/textsearch-controls.html#TEXTSEARCH-PARSING-QUERIES
class TextToTsquery
  attr_reader :text

  def initialize(text, wildcard: true)
    @text = text.to_s.strip
    @wildcard = wildcard
    @exact_matches = []
    validate!
  end

  EXACT_WORD_CHAR = '§'.freeze

  def tsquery
    @tsquery = @text
    strip_exact_words
    remove_duplicated_spaces
    transform_or_into_operator
    transform_and_into_operator
    strip_spaces_from_parenthesis
    transform_remaining_spaces_into_and_operator
    transform_keywords
    join_operators_with_and
    remove_partial_match_from_not_keywords
    add_exact_words
    @tsquery
  end

  def validate!
    parenthesis_error unless self.class.valid_search_parenthesis?(@text)
  end

  def self.valid_search_parenthesis?(text)
    text.split('').reduce(0) do |acc, char|
      return false if acc < 0

      if char == '('
        acc + 1
      elsif char == ')'
        acc - 1
      else
        acc
      end
    end.zero?
  end

  def parenthesis_error
    raise ArgumentError, "incorrect number/order of parenthesis in search query: '#{@text}'"
  end

  def strip_exact_words
    @exact_matches << Regexp.last_match(1) while @tsquery.sub!(/"(.*?)"/, EXACT_WORD_CHAR)
  end

  def remove_duplicated_spaces
    @tsquery = @tsquery.gsub(/\s+/, ' ')
  end

  # transforms or/OR/|/|| into | operator
  def transform_or_into_operator
    @tsquery = @tsquery.gsub(/ ((or|\|+) )+/i, '|').gsub(/ *\|+ */, '|')
  end

  # transforms and/AND/&/&& into & operator
  def transform_and_into_operator
    @tsquery = @tsquery.gsub(/ ((and|\&+) )+/i, '&')
  end

  def strip_spaces_from_parenthesis
    @tsquery = @tsquery.gsub(/ *([()]) */, '\1')
  end

  def transform_remaining_spaces_into_and_operator
    @tsquery = @tsquery.tr(' ', '&')
  end

  # adds :* for partial match of words
  def transform_keywords
    keyword = @wildcard ? '\1:*' : '\1:'
    @tsquery = @tsquery.gsub(/([^#{EXACT_WORD_CHAR}|&!())]+)/, keyword)
  end

  # adds & between operations
  def join_operators_with_and
    @tsquery = @tsquery.gsub(/:(\**)\!/, ':\1&!').gsub(/:(\**)\(/, ':\1&(').gsub(/\&+/, '&')
  end

  # removes partial match from NOT operations
  def remove_partial_match_from_not_keywords
    @tsquery = @tsquery.gsub(/\!([^|&!())]+):\**/, '!\1')
  end

  def add_exact_words
    @exact_matches.each { |phrase| @tsquery = @tsquery.sub(EXACT_WORD_CHAR, "'#{phrase}'") }
  end
end