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# Copyright (C) 2013-2020 all contributors <dtas-all@nongnu.org>
# License: GPL-3.0+ <https://www.gnu.org/licenses/gpl-3.0.txt>
# frozen_string_literal: true
require_relative '../dtas'
require_relative 'nonblock'
begin
  module DTAS::Watchable # :nodoc:
    module InotifyCommon # :nodoc:
      FLAGS = 8 | 128 # IN_CLOSE_WRITE | IN_MOVED_TO

      def readable_iter
        or_call = false
        while event = take(true) # drain the buffer
          w = @watches[event.wd] or next
          if (event.mask & FLAGS) != 0 && w[event.name]
            or_call = true
          end
        end
        if or_call
          @on_readable.call
          :delete
        else
          :wait_readable
        end
      end

      # we must watch the directory, since
      def watch_files(paths, blk)
        @watches = {} # wd -> { basename -> true }
        @on_readable = blk
        @dir2wd = {}
        Array(paths).each do |path|
          watchdir, watchbase = File.split(File.expand_path(path))
          begin
            wd = @dir2wd[watchdir] ||= add_watch(watchdir, FLAGS)
            m = @watches[wd] ||= {}
            m[watchbase] = true
          rescue SystemCallError => e
            warn "#{watchdir.dump}: #{e.message} (#{e.class})"
          end
        end
      end
    end # module InotifyCommon

    begin
      require_relative 'watchable/inotify'
    rescue LoadError
      # TODO: support kevent
      require_relative 'watchable/fiddle_ino'
    end

    def watch_begin(blk)
      @ino = DTAS::Watchable::InotifyReadableIter.new
      @ino.watch_files(@watch_extra << @infile, blk)
      @ino
    end

    def watch_extra(paths)
      @ino.watch_extra(paths)
    end

    # Closing the inotify descriptor (instead of using inotify_rm_watch)
    # is cleaner because it avoids EINVAL on race conditions in case
    # a directory is deleted: https://lkml.org/lkml/2007/7/9/3
    def watch_end(srv)
      srv.wait_ctl(@ino, :delete)
      @ino = @ino.close
    end
  end # module DTAS::Watchable
rescue LoadError, StandardError => e
  warn "#{e.message} (#{e.class})"
end # begin