#
#  Copyright (c) 2009 Caelum - www.caelum.com.br/opensource
#  All rights reserved.
# 
#  Licensed under the Apache License, Version 2.0 (the "License"); 
#  you may not use this file except in compliance with the License. 
#  You may obtain a copy of the License at 
#  
#   http://www.apache.org/licenses/LICENSE-2.0 
#  
#  Unless required by applicable law or agreed to in writing, software 
#  distributed under the License is distributed on an "AS IS" BASIS, 
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
#  See the License for the specific language governing permissions and 
#  limitations under the License. 
#

# Basic cache implementation for restfulie.
#
# It uses the request headers and uri to store it in memory.
# This cache might not be optimal for long running clients, which should use a memcached based one.
# Use Restfulie.cache_provider to change the provider
class Restfulie::BasicCache
  
  def put(url, req, response)
    if Restfulie::Cache::Restrictions.may_cache?(req, response)
      Restfulie.logger.debug "caching #{url} #{req} #{response}"
      cache[key_for(url, req)] = response
    end
    response
  end
  
  def get(url, req)
    
    response = cache[key_for(url, req)]
    return nil if response.nil?
    
    if response.has_expired_cache?
      remove(key_for(url, req))
    else
      Restfulie.logger.debug "RETURNING cache #{url} #{req}"
      response
    end
    
  end

  # removes all elements from the cache
  def clear
    cache.clear
  end
  
  private
  
  def remove(what)
    @cache.delete(what)
    nil
  end
  
  def cache
    @cache ||= {}
  end
  
  def key_for(url, req)
    [url, req.class]
  end
  
end

# Fake cache that does not cache anything
# Use Restfulie.cache_provider = Restfulie::FakeCache.new
class Restfulie::FakeCache
  
  def put(url, req, response)
    response
  end
  
  def get(url, req)
  end
  
  def clear
  end
  
end

module Restfulie::Cache
  module Restrictions
    
    class << self
    
      # checks whether this request verb and its cache headers allow caching
      def may_cache?(request,response)
        may_cache_method?(request) && response.may_cache?
      end
      
      # only Post and Get requests are cacheable so far
      def may_cache_method?(verb)
        verb.kind_of?(Net::HTTP::Post) || verb.kind_of?(Net::HTTP::Get)
      end

    end
    
  end
end