# frozen_string_literal: true

require 'math-to-itex/parser'
require 'math-to-itex/version'

module MathToItex
  class Math
    def initialize(string)
      @string = string
    end

    def convert(&block)
      @string.gsub(MathToItex::Parser::REGEX) do |maths|
        if /\A\$(?!\$)/.match?(maths)
          just_maths = maths[1..-2]
          type = :inline
        elsif /^\\\((?!\\\()/.match?(maths)
          just_maths = maths[2..-3]
          type = :inline
        elsif /\A\$\$/.match?(maths)
          just_maths = maths[2..-3]
          type = :display
        elsif /\A\\\[(?!\\\[)/.match?(maths)
          just_maths = maths[2..-3]
          type = :display
        elsif /\A\\begin{equation}(?!\\begin{equation})/.match?(maths)
          just_maths = maths[16..-15]
          type = :display
        elsif /\A\\begin{math}(?!\\begin{math})/.match?(maths)
          just_maths = maths[12..-11]
          type = :inline
        elsif /\A\\begin{displaymath}(?!\\begin{displaymath})/.match?(maths)
          just_maths = maths[19..-18]
          type = :display
        elsif /\A\\begin{#{MathToItex::Parser::JOINED_ENVIRONMENTS}}(?!\\begin{#{MathToItex::Parser::JOINED_ENVIRONMENTS}})/.match?(maths)
          just_maths = maths
          type = :display
        end

        # this is the format itex2MML expects
        all_maths = if type == :inline
                      "$#{just_maths}$"
                    else
                      "$$#{just_maths}$$"
                    end

        next(all_maths) if block.nil?

        yield all_maths, type, just_maths
      end
    end
  end
end

def MathToItex(string)
  MathToItex::Math.new(string)
end