Fight with changelog conflicts

# Class to handle changelog
class ChangelogManagerService
  EXCLUDE_VARS = %w[. ..].freeze
  RELEASE_TITLE  = './changelog/release_name.md'.freeze

  def initialize
    @changelog_to_add = ''

    if File.exist?(RELEASE_TITLE)
      @release_name = File.read(RELEASE_TITLE)
    else
      now = Time.zone.now.strftime("%Y.%m.%d-%H:%M")
      @release_name = "## [stowaway-changes.#{now}]\n"
    end
  end

  def create_new_content
    # Function to create the text that will be added to the changelog
    create_unreleased_changelog
    add_changelog_subtitle
    file = File.read('./CHANGELOG.md')
    "#{@changelog_to_add}#{file}"
  end

  def write_new_changelog
    # Function that will get the content, write it in the changelog file and will delete individual changelog files
    new_content = create_new_content
    File.open('./CHANGELOG.md', 'w') { |line| line.puts new_content }
    clear_unreleased_files
  end

  private

  def add_changelog_subtitle
    # Function that will concatenate the release name and the content of all individual changelog
    return if @changelog_to_add.empty?

    @changelog_to_add = "#{@wagon_name}#{@changelog_to_add}\n"
  end

  def clear_unreleased_files
     # Function that will loop on each folders inside `changelog` folder and call the delete function and will delete the file `changelog/release_name.md`
    folders = Dir.entries('./changelog/').reject { |entry| (EXCLUDE_VARS.include? entry) }
    folders.each do |folder|
      delete_files(path: "./changelog/#{folder}")
    end
    File.delete(WAGON_TITLE) if File.exist?(RELEASE_TITLE)
  end

  def concatenate_files(list_of_files:)
    # Loop on a list of files and will concatenate the content to create the text that will appear in the final changelog
    list_of_files.each do |file|
      File.readlines(file).each do |line|
        @changelog_to_add << line.to_s
      end
      @changelog_to_add << "\n" unless File.read(file)[/\n$/]
    end
  end

  def subpart_unreleased_changelog(path:, title:)
    # Get the list of files in a folder and call the concatenate_files function only if there is file in this folder
    files = Dir.glob("#{path}/**/*").select { |e| File.file? e }.reject { |i| i == "#{path}/README.md" }
    if files.length.positive?
      @changelog_to_add << "\n#{title}\n\n"
      concatenate_files(list_of_files: files)
    end
  end

  def create_unreleased_changelog
    # Loop on all folders og changelog and call subpart_unreleased_changelog to do the job
    folders = Dir.entries('./changelog/').reject { |entry| (EXCLUDE_VARS.include? entry) }
    folders.each do |folder|
      subpart_unreleased_changelog(path: "./changelog/#{folder}", title: "### #{folder.capitalize}")
    end
  end

  def delete_files(path:)
    # Function that will delete all the files present in a folder except the one called READMDE.md 
    files = Dir.glob("#{path}/**/*").select { |e| File.file? e }.reject { |i| i == "#{path}/README.md" }
    files.each do |file|
      File.delete(file)
    end
  end
end