#/usr/bin/ruby
require 'fileutils'

=begin
  Use cache like this

  c = ::Dms::Cache.new
  c.set_dir "directory"
  c.set_section "main"
  data = c.command(req){
    puts "got data by request: "+req.to_s
  }
=end


module Dms
  class Cache

    def initialize
      @datadir = Dir.pwd+'/cache/'
      @section = false
    end

    def set_dir dir
      @datadir = dir
    end

    def set_section name
      s = (name.gsub(/[^-.a-z0-9\/]/,'_').sub(/^\//, '') rescue '')
      s = false if s==''
      @section = s
    end

    def dirname
      @datadir+(@section ? @section+'/' : '')
    end

    def is_in? fn
      File.file?(self.dirname+fn)
    end

    def get fn
      return false unless self.is_in?(fn)
      return File.read(self.dirname+fn)
    end

    def put file, data
      fn = self.dirname+file
      reg = fn.match /^(.*)\/.*?$/
      FileUtils.mkdir_p(reg[1]) unless File.directory?(reg[1])
      File.write(fn, data)
    end

    def filename name
      (name.gsub(/[^-.a-z0-9]/,'_').sub(/^_/, '') rescue '').sub(/^$/,'__root_dir')
    end

    def command name
      raise 'Missing block' unless block_given?
      file = filename name

      return self.get(file) if self.is_in?(file)
      data = yield
      self.put file, data
      data
    end
  end
end