require 'singleton'

module Capistrano
  module RightScale
    class Cache
      include Singleton

      attr_accessor :lifetime
      attr_reader :array, :array_instances, :deployment
      def initialize
        @lifetime = 86400
      end

      def load_server_cache(role, prefix=nil)
         server_cache = self.instance_variable_get("@#{role}_cache")

         begin
           cache_files = Dir.glob("#{Dir.tmpdir}/cap-rightscale-#{ENV['USER']}-*/#{prefix}*#{role}.cache")

           if cache_files.size > 0 && !server_cache
             c = Marshal.load(open(cache_files.first) {|f| f.read})
             self.instance_variable_set("@#{role}_cache", c)
           end
           server_cache = self.instance_variable_get("@#{role}_cache")
           return [] unless server_cache # No cache entry

           # get servers
           if Time.now - server_cache[role][:cache] > lifetime
             STDERR.puts("The cache of server list has expired.")
             server_list = []
           elsif server_cache[role][:servers]
             server_list = server_cache[role][:servers]
           else
             server_list = []
           end
         rescue => e
           return [] unless server_cache
         end

         server_list
      end

      def dump_server_cache(role, servers, prefix=nil)
        h = {role => {:servers => servers, :cache => Time.now}}
        obj_dump = Marshal.dump(h)

        # Get cache directory
        cache_dir = Dir.glob("#{Dir.tmpdir}/cap-rightscale-#{ENV['USER']}-*").first
        if cache_dir.nil?
          RSUtils.mk_rs_cache_dir
          cache_dir = Dir.glob("#{Dir.tmpdir}/cap-rightscale-#{ENV['USER']}-*").first
          exit if cache_dir.nil?
        end
        cache_file = File.join(cache_dir, "#{prefix}-#{role}.cache")

        begin
          open(cache_file, "w") {|f| f.write(obj_dump)}
        rescue => e
          STDERR.puts("#{e.class}: #{e.pretty_inspect}")
          warn("Backtrace:\n#{e.backtrace.pretty_inspect}")
        end
      end
    end
  end
end