# frozen_string_literal: true

require "English"
require "English"
require "tempfile"
require "open3"
require "date"

module Bup
  class Tar
    def initialize(config)
      @config = config
    end

    def expand_string(str)
      while str =~ /\${?([a-zA-Z0-9]+)}?/
        all = $LAST_MATCH_INFO[0]
        nm = $LAST_MATCH_INFO[1]
        str = str.sub(all, ENV[nm] || "")
      end

      str
    end

    def build_exclude_file(patterns)
      tf = Tempfile.new("bup")
      patterns.each do |p|
        p = expand_string(p)
        tf.write(p)
        tf.write("\n")
      end
      tf.close
      tf
    end

    # Prepare the destination directory.
    def prepare_destination(profile_name)
      destination = expand_string(@config.profile(profile_name)["destination"] || ".")
      suffix = ".tar.xz"
      type = @config.runtime["type"] || "full"

      FileUtils.mkdir_p(destination) unless File.exist?(destination)

      filename_base = "#{profile_name}-#{type}"
      filename = File.join(destination,
                           "#{filename_base}-#{DateTime.now.new_offset(0).strftime("%Y%m%d%H%M%S")}#{suffix}")

      history = @config.profile(profile_name)["history"] || 0

      if type == "full" && history.positive?

        oldest_kept_file = nil

        # Keep some full backups and remove the others.
        # We capture the oldest full backup and get rid of preceeding incrementals.
        Dir["#{destination}/#{filename_base}*"].sort.reverse.each_with_index do |fullbackup, idx|
          if idx < history
            oldest_kept_file = fullbackup
          else
            File.delete(fullbackup)
          end
        end

        # Remove all incremental files that are older than the oldest kept full backup.
        remove_before = File.stat(oldest_kept_file).ctime
        Dir["#{destination}/#{profile_name}*"].each do |backupfile|
          File.delete(backupfile) if File.stat(backupfile).ctime < remove_before
        end
      end

      filename
    end

    def call(profile_name = nil)
      profile_name ||= @config.runtime["profile"]
      profile = @config.config["profiles"][profile_name]

      raise "Missing profile #{profile_name}." unless profile

      args = @config.profile(profile_name)["tarcmd"].dup || ["tar"]

      args << "cJvf"

      filename = prepare_destination(profile_name)
      args << filename

      if @config.runtime["type"] == "incremental"
        lastrun = @config.lastrun(profile_name)
        args += ["--newer", lastrun.strftime("%Y-%m-%d %H:%M:%S %z")] if lastrun
      end

      @config.update_lastrun(profile_name)

      tf = build_exclude_file(profile["exclude"] || [])

      args += ["--exclude-from", tf.path]
      args += (@config.profile(profile_name)["include"] || ["."]).map do |str|
        expand_string(str)
      end

      begin
        Open3.popen3(*args) do |stdin, stdout, stderr, wait_thr|
          stdin.close

          while wait_thr.status
            r, w, e = IO.select([stdout, stderr])
            r.each do |stream|
              print stream.read
            end
          end

          wait_thr.join
          print stdout.read
          print stderr.read
        end
      ensure
        tf.unlink
      end
    end
  end
end