class EcoRake
  module Shell
    module Files
      include Rake::DSL
      DAY_SECONDS = (60 * 60 * 24)

      # It creates directory `path` constructively.
      # @note if any parent directory does not exist, it creates it as well.
      def upsert_local_dir(path)
        return if path.to_s.strip.empty?
        return if File.directory?(path)
        require 'fileutils'
        puts "Creating directory '#{path}'"
        FileUtils.mkdir_p(path)
      end

      # TODO: check delete status
      def delete_file(*files, message: 'Deleting files:')
        files = files.select {|file| File.exist?(file)}
        return if files.empty?
        puts message if message
        files.each do |file|
          File.delete(file)
          puts " • #{file}" if message
        end
      end

      def move_file(*files, folder:, message: 'Moving files:')
        puts message if message
        files.each do |file|
          new_name = File.join(folder, File.basename(file))
          File.name(file, new_name)
          puts "  • #{File.basename(file)}" if message
        end
      end

      # It identifies files in a folder by using different criteria.
      # @return [Array<String>] files that match the criteria **sorted** by name ascendant (i.e. abc)
      def folder_files(folder = ".", pattern = "*", regexp: nil, older_than: nil)
        target = File.join(File.expand_path(folder), pattern)
        Dir[target].tap do |dir_files|
          dir_files.select! {|f| File.file?(f)}
          dir_files.select! {|f| file_older_than?(f, days: older_than)} if older_than
          dir_files.select! {|f| File.basename(f).match(regexp)}        if regexp.is_a?(Regexp)
        end.sort
      end

      # @see #folder_files . Same but fixed to `*.csv` **pattern**
      def csv_files(folder = ".", regexp: nil, older_than: nil)
        folder_files(folder, "*.csv", regexp: regexp, older_than: older_than)
      end

      # @see #folder_files . Same but fixed to `*.csv.gpg` **pattern**
      def gpg_files(folder = ".", regexp: nil, older_than: nil)
        gpg = folder_files(folder, "*.gpg", regexp: regexp, older_than: older_than)
        pgp = folder_files(folder, "*.pgp", regexp: regexp, older_than: older_than)
        gpg.concat(pgp)
      end

      # Preserves the folder and the base name of `gpg_file` name
      # and changes its extension to `csv`.
      # @return [String]
      def gpg_to_csv_filename(gpg_file)
        return nil unless gpg_file
        ext    = gpg_file.split('.')[1..-1].join('.')
        base   = File.basename(gpg_file, ".#{ext}")
        folder = File.dirname(gpg_file)
        File.join(folder, "#{base}.csv")
      end

      private

      def file_older_than?(file, days:)
        File.mtime(file) < Time.now - days_to_seconds(days)
      end

      def days_to_seconds(days)
        return nil unless days
        days * DAY_SECONDS
      end
    end
  end
end