Convert mysql to rails migration file

convertion.rb

require 'date'

class Converter
  def initialize(file_name)
    @file_name = file_name
    @tables    = {}
    @current_table = {}
  end

  def to_ruby(rails_v)
    @tables.each do |t_name, table|
      file_name = "#{DateTime.now().strftime('%Y%m%d%H%M')}_create_#{t_name}.rb"

      File.open("db/migrate/#{file_name}", 'wb') do |f|
        if rails_v < 5.0
          f << "class Create#{t_name.capitalize} < ActiveRecord::Migration\n"
        else
          f << "class Create#{t_name.capitalize} < ActiveRecord::Migration[#{rails_v}]\n"
        end

        f << "  def change\n"
        f << "    create_table :#{t_name} do |t|\n"

        table[:columns].each do |name, column|
          str_options = column[:options].inject('') { |options, (k, v)| options + ", #{k}: #{v}" } if column[:options].length > 0

          next if name == 'id'
          f << "      t.#{column[:type]} :#{column[:name]}#{str_options}\n"
        end

        f << "    end\n"
        f << "  end\n"
        f << "end\n"
      end
    end
  end

  def read
    in_table = false

    File.open(@file_name, 'r') do |f|
      f.each_line do |line|
        line = line.strip

        if in_table
          if /\);/.match? line
            @tables[@current_table[:name]] = @current_table
            in_table = false
            next
          end


          column = /^`(.*)`/.match(line)[1] if /^`(.*)`/.match? line
          type = sql_to_rails(/INT|varchar|bool/.match(line)[0]) if /INT|varchar/.match? line
          options = options_to_hash(line)

          @current_table[:columns][column] = { name: column, type: type, options: options } if (column && type)
        end

        create_table_regex = /^CREATE TABLE `(.*)` \(/
        alter_table_regex = /^ALTER TABLE `.*` ADD CONSTRAINT `.*` FOREIGN KEY \(`.*`\) REFERENCES `.*`\(`.*`\)/
        table_name_regex  = /^ALTER TABLE `(.*)` ADD CONSTRAINT `.*` FOREIGN KEY \(`.*`\) REFERENCES `.*`\(`.*`\)/
        column_regex      = /^ALTER TABLE `.*` ADD CONSTRAINT `.*` FOREIGN KEY \(`(.*)`\) REFERENCES `.*`\(`.*`\)/

        if create_table_regex.match? line
          table_name = create_table_regex.match(line)[1]
          @current_table = { name: table_name, columns: {} }
          in_table = true
        elsif alter_table_regex.match? line
          table_name = table_name_regex.match(line)[1]
          column = column_regex.match(line)[1]

          @tables[table_name][:columns][column][:name] = column
          @tables[table_name][:columns][column][:type] = 'references'
        end
      end

      self
    end
  end

  private
  def sql_to_rails(type_in_sql)
    case type_in_sql
    when 'INT'
      'integer'
    when 'varchar'
      'string'
    when 'bool'
      'boolean'
    end
  end

  def options_to_hash(line)
    options = {}

    options['null'] = false if /NOT NULL/.match? line
    options['uniqueness'] = true if /UNIQUE/.match? line
    options['default'] = /DEFAULT (.*)/.match(line)[1] if /DEFAULT (.*)/.match? line

    options
  end
end


converter = Converter.new('./mysqls/Kakaxi_mysql_create.sql').read
converter.to_ruby(5.1)