#
# history for irb
#
# Copyright (c) 2001 akira yamada <akira@ruby-lang.org>
# You can redistribute it and/or modify it under the same term as Ruby.
#
# Version 0.0.0.0.1.
#
# Special Thanks:
#   * Satoru Takabayashi <satoru@namazu.org>
#     An idea and some comments.
#

begin
  require 'readline'
  class HisReadlineInputMethod < IRB::ReadlineInputMethod
    HISTORY_FILE = '~/.irb_history'
    MAX_HISTORY_LINES = 50000

    def HisReadlineInputMethod.finilizer(path, history)
      proc {
	skip_history = 0
	if history.length > MAX_HISTORY_LINES
	  skip_history = history.length - MAX_HISTORY_LINES
	end
        open(path, 'w') {|io|
	  io.flock(File::LOCK_EX)
    	  history.each {|x|
	    if skip_history > 0
	      skip_history -= 1
	      next
	    end
    	    io.puts x
    	  }
    	  io.truncate(io.pos)
     	}
      }
    end

    include Readline
    def initialize
      super
      begin
        @history_file = File.expand_path(HISTORY_FILE) 
        open(@history_file) {|io|
	  io.flock(File::LOCK_EX)
	  io.each {|line|
	    @line << line
	    HISTORY << line.chomp
	  }
        }
	@line_no = @line.size
      rescue Errno::ENOENT
      ensure
	ObjectSpace.define_finalizer(self, HisReadlineInputMethod.finilizer(@history_file, HISTORY))
      end
    end
  end
  IRB.conf[:SCRIPT] = HisReadlineInputMethod.new

rescue LoadError
end