#
#--
# Copyright (c) 2006-2008, Nicolas Modryzk and John Mettraux, OpenWFE.org
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# . Redistributions of source code must retain the above copyright notice, this
#   list of conditions and the following disclaimer.
#
# . Redistributions in binary form must reproduce the above copyright notice,
#   this list of conditions and the following disclaimer in the documentation
#   and/or other materials provided with the distribution.
#
# . Neither the name of the "OpenWFE" nor the names of its contributors may be
#   used to endorse or promote products derived from this software without
#   specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#++
#

#
# "made in Japan"
#
# Nicolas Modrzyk at openwfe.org
# John Mettraux at openwfe.org
#

require 'find'
require 'yaml'
require 'monitor'
require 'fileutils'

require 'openwfe/utils'
require 'openwfe/service'

require 'openwfe/expressions/flowexpression'
  #--
  # making sure classes in those files are loaded
  # before their yaml persistence is tuned
  # (else the reopening of the class is interpreted as
  # a definition of the class...)
  #++

module OpenWFE

  #
  # Stores OpenWFEru related objects into yaml encoded files.
  # This storage is meant to look and feel like a Hash.
  #
  class YamlFileStorage
    include ServiceMixin
    #include MonitorMixin

    #
    # The root path for this file persistence mecha.
    #
    attr_accessor :basepath

    def initialize (service_name, application_context, path)

      super()

      service_init(service_name, application_context)

      @basepath = get_work_directory + path
      @basepath += "/" unless @basepath[-1, 1] == "/"

      FileUtils.makedirs @basepath
    end

    #
    # Stores an object with its FlowExpressionId instance as its key.
    #
    def []= (fei, object)
      #synchronize do

      #linfo { "[]= #{fei}" }

      fei_path = compute_file_path fei

      fei_parent_path = File.dirname fei_path

      FileUtils.makedirs(fei_parent_path) \
        unless File.exist?(fei_parent_path)

      File.open(fei_path, "w") do |file|
        YAML.dump object, file
      end
      #end
    end

    #
    # Deletes the whole storage directory... beware...
    #
    def purge
      #synchronize do

      FileUtils.remove_dir @basepath
      #end
    end

    #
    # Checks whether there is an object (expression, workitem) stored
    # for the given FlowExpressionId instance.
    #
    def has_key? (fei)

      File.exist?(compute_file_path(fei))
    end

    #
    # Removes the object (file) stored for the given FlowExpressionId
    # instance.
    #
    def delete (fei)
      #synchronize do

      fei_path = compute_file_path fei

      ldebug { "delete()\n  for #{fei.to_debug_s}\n  at #{fei_path}" }

      File.delete fei_path
      #end
    end

    #
    # Actually loads and returns the object for the given
    # FlowExpressionId instance.
    #
    def [] (fei)

      fei_path = compute_file_path(fei)

      if not File.exist?(fei_path)

        ldebug { "[] didn't find file at #{fei_path}" }
        #puts  "[] didn't find file at #{fei_path}"

        return nil
      end

      load_object(fei_path)
    end

    #
    # Returns the count of objects currently stored in this instance.
    #
    def length

      count_objects()
    end

    alias :size :length

    protected

      def load_object (path)

        object = YAML.load_file(path)

        object.application_context = @application_context \
          if object.respond_to? :application_context=

        object
      end

      #
      # Returns the number of 'objects' currently in this storage.
      #
      def count_objects

        count = 0

        Find.find(@basepath) do |path|

          next unless File.exist? path
          next if File.stat(path).directory?

          count += 1 if OpenWFE::ends_with(path, ".yaml")
        end

        count
      end

      #
      # Passes each object path to the given block
      #
      def each_object_path (path=@basepath, &block)
        #synchronize do

        Find.find(path) do |p|

          next unless File.exist?(p)
          next if File.stat(p).directory?
          next unless OpenWFE::ends_with(p, ".yaml")

          ldebug { "each_object_path() considering #{p}" }
          block.call p
        end
        #end
      end

      #
      # Passes each object to the given block
      #
      def each_object (&block)

        each_object_path do |path|
          block.call load_object(path)
        end
      end

      #
      # each_value() is a method from Hash, by providing it here
      # it's easier to disguise a YamlFileStorage as a hash.
      #
      alias :each_value :each_object

      protected

        #
        # Each object is meant to have a unique file path,
        # this method wraps the determination of that path. It has to
        # be provided by extending classes.
        #
        def compute_file_path (object)
          raise NotImplementedError.new
        end

    end

  end