module GemBootstrap
  class MiscUtils
    class << self
      # Receives a string and convert it to snake case.
      # SnakeCase returns snake_case.
      #
      # @param [String] str the input string
      def snake_case(str)
        # for testing only
        return str.downcase if str =~ /^[A-Z_]+$/
        str.gsub(/\B[A-Z]/, '_\&').squeeze('_') =~ /_*(.*)/
        $+.downcase
      end

      # Receives a string and convert it to camel case.
      # camel_case returns CamelCase.
      #
      # @param [String] str the input string
      def camel_case(str)
        return str if str !~ /_/ && str =~ /[A-Z]+.*/
        str.split('_').map { |i| i.capitalize }.join
      end

      # List files base on simple criteria
      #
      # @param [Hash<Symbol, Object>] args keys and values of argument
      def files(args = {})
        opts = {
          base_dir:  Dir.pwd,
          recursive: false,
          exts:      [],
          non_exts:  []
        }.merge(args)

        base_dir = opts[:base_dir]
        fail Errors::CustomError, "The directory #{base_dir} is not valid or or not readable!" unless File.exist?(base_dir)

        wildcard = opts[:recursive] ? '**' : ''
        exts     = opts[:exts]
        non_exts = opts[:non_exts]

        file_with_extension    = Dir.glob(File.join(base_dir, wildcard, "*.{#{exts.join(',')}}"))
        file_with_no_extension = no_extension_files(base_dir, wildcard, non_exts)

        (file_with_extension + file_with_no_extension).sort
      end

      # List files that do not have any extension
      #
      # @param [String] base_dir the starting directory
      # @param [String] wildcard the wildcard string e.g. '**' or '' (empty string)
      # @param [Array<String>] non_exts list of file without extension
      # @return [Array<String> list of matching files that do not have any extension
      def no_extension_files(base_dir, wildcard, non_exts = [])
        list = []
        unless non_exts.empty?
          list = Dir.glob(File.join(base_dir, wildcard, "{#{non_exts.join(',')}}"))
        end
        list
      end

      # Wrapper function to call the 'popen3' and return the result
      #
      # @param [Array<String>] commands list of command
      # @return [String] result of the command as the string
      def shell(commands = [])
        raise "commands list must be valid and not empty" unless commands.present?
        # Join the list of commands to a single string
        command = commands.join(' ')
        stdin, _stderr, _status = Open3.capture3(command)
        stdin
      rescue => e
        raise "Problem processing `#{command}`, #{e.message}"
      end
    end
  end
end