module Dor
  module Releaseable
    extend ActiveSupport::Concern
    include Itemizable
    
    
    #Generate XML structure for inclusion to Purl 
    #
    #@return [String] The XML release node as a string, with ReleaseDigest as the root document
    def generate_release_xml
      builder = Nokogiri::XML::Builder.new do |xml|
        xml.ReleaseDigest {
          self.released_for.each do |project,released_value|
            xml.release(released_value["release"],:to=>project)
          end  
          }        
        end
      return builder.to_xml
    end
    
    #Determine which projects an item is released for
    #
    #@return [Hash] all namespaces in the form of {"Project" => Boolean}
    def released_for
      released_hash = {}
      
      #Get release tags on the item itself 
      release_tags_on_this_item = self.release_tags
      
      #Get any self tags on this item
      self_release_tags = self.get_self_release_tags(release_tags_on_this_item)
      
      #Get the most recent self tag for all targets and save their result since most recent self always trumps any other non self tags
      latest_self_tags = self.get_newest_release_tag(self_release_tags)
      latest_self_tags.keys.each do |target|
        released_hash[target] =  self.clean_release_tag_for_purl(latest_self_tags[target])
      end
      
      #With Self Tags Resolved We Now need to deal with tags on all sets this object is part of 
      
      potential_applicable_release_tags = {}  #This will be where we store all tags that apply, regardless of their timestamp
       
      #Get all release tags on the item and strip out the what = self ones, we've already processed all the self tags on this item 
      potential_applicable_release_tags = get_tags_for_what_value(self.get_release_tags_for_item_and_all_governing_sets, 'collection')
      
      administrative_tags = self.tags  #Get them once here and pass them down
      
      #We now have the keys for all potential releases, we need to check the tags and the most recent time stamp with an explicit true or false wins, in a nil case, the lack of an explicit false tag we do nothing
      (potential_applicable_release_tags.keys-released_hash.keys).each do |key|  #don't bother checking the ones already added to the release hash, they were added due to a self tag and that has won
        latest_applicable_tag_for_key = latest_applicable_release_tag_in_array(potential_applicable_release_tags[key], administrative_tags)
        if latest_applicable_tag_for_key != nil #We have a valid tag, record it
          released_hash[key] = self.clean_release_tag_for_purl(latest_applicable_tag_for_key) 
        end
        
      end
        
      return released_hash
    end
    
    #Take a hash of tags as obtained via Dor::Item.release_tags and returns all self tags
    #
    #@param tags [Hash] a hash of tags obtained via Dor::Item.release_tags or matching format
    #
    #@return [Hash] a hash of self tags for each to value
    def get_self_release_tags(tags)
      return get_tags_for_what_value(tags, 'self')
    end
    
    #Take an item and get all of its release tags and all tags on collections it is a member of it
    #
    #
    #@return [Hash] a hash of all tags
    def get_release_tags_for_item_and_all_governing_sets
      return_tags = self.release_tags || {}
      self.collections.each do |collection|
        return_tags = combine_two_release_tag_hashes(return_tags, Dor::Item.find(collection.id).get_release_tags_for_item_and_all_governing_sets) #this will function recurvisely so parents of parents are found
      end
      return return_tags  
    end
    
    #Take two hashes of tags and combine them, will not overwrite but will enforce uniqueness of the tags
    #
    #@param hash_one [Hash] a hash of tags obtained via Dor::Item.release_tags or matching format
    #@param hash_two [Hash] a hash of tags obtained via Dor::Item.release_tags or matching format
    #
    #@return [Hash] the combined hash with uniquiness enforced 
    def combine_two_release_tag_hashes(hash_one, hash_two)
      hash_two.keys.each do |key|
        hash_one[key] = hash_two[key] if hash_one[key] == nil
        hash_one[key] = (hash_one[key] + hash_two[key]).uniq if hash_one[key] != nil
      end
      return hash_one
    end
    
    #Take a hash of tags and return all tags with the matching what target
    #
    #@param tags [Hash] a hash of tags obtained via Dor::Item.release_tags or matching format
    #@param what_target [String] the target for the 'what' key, self or collection
    #
    #@return [Hash] a hash of self tags for each to value
    def get_tags_for_what_value(tags, what_target)
      return_hash = {}
      tags.keys.each do |key|
        self_tags =  tags[key].select{|tag| tag['what'] == what_target.downcase}
        return_hash[key] = self_tags if self_tags.size > 0
      end
      return return_hash
    end
    
    #Take a hash of tags as obtained via Dor::Item.release_tags and returns the newest tag for each namespace
    #
    #@params tags [Hash] a hash of tags obtained via Dor::Item.release_tags or matching format
    #
    #@return [Hash] a hash of latest tags for each to value
    def get_newest_release_tag(tags)
      return_hash = {}
      tags.keys.each do |key|
        latest_for_key = newest_release_tag_in_an_array(tags[key])
        return_hash[key] = latest_for_key         
      end
      return return_hash
    end
    
    #Take a tag and return only the attributes  we want to put into purl
    #
    #@param tag [Hash] a tag
    #
    #@return [Hash] a hash of the attributes we want for purl
    def clean_release_tag_for_purl(tag)
      for_purl = ['release']
      return_hash = {}
      for_purl.each do |attr|
        return_hash[attr] = tag[attr]
      end
      return return_hash
    end
    
    #Takes an array of release tags and returns the most recent one
    #
    #@params tags [Array] an array of hashes, with the hashes being release tags
    #
    #@return [Hash] the most recent tag
    def newest_release_tag_in_an_array(array_of_tags)
      latest_tag_in_array = array_of_tags[0] || {}
      array_of_tags.each do |tag|
        latest_tag_in_array = tag if tag['when'] > latest_tag_in_array['when']
      end
      return latest_tag_in_array
    end
    
    
    #Takes a tag and returns true or false if it applies to the specific item
    #
    #@param release_tag [Hash] the tag in a hashed form
    #@param Optional admin_tags [Array] the administrative tags on an item, if not supplied it will attempt to retrieve them
    #
    #@return [Boolean] true or false if it applies (not true or false if it is released, that is the release_tag data)
    def does_release_tag_apply(release_tag, admin_tags=false)
      #Is the tag global or restricted 
      return true if release_tag['tag'] == nil  #there is no specific tag specificied, so that means this tag is global to all members of the collection, it applies, return true
        
      admin_tags = self.tags if not admin_tags #We use false instead of [], since an item can have no admin_tags that which point we'd be passing down this variable as [] and would not an attempt to retrieve it
      return admin_tags.include?(release_tag['tag'])
    end
    
    #Takes an array of release tags and returns the most recent one that applies to this item
    #
    #@param release_tags [Array] an array of release tags in hashed form
    #param admin_tags [Array] the administrative tags on an on item
    #
    #@return [Hash] the tag
    def latest_applicable_release_tag_in_array(release_tags, admin_tags)
      newest_tag = newest_release_tag_in_an_array(release_tags)
      return newest_tag if does_release_tag_apply(newest_tag, admin_tags) #Return true if we have it
      
      #The latest tag wasn't applicable, slice it off and try again
      #This could be optimized by reordering on the timestamp and just running down it instead of constantly resorting, at least if we end up getting numerous release tags on an item
      release_tags.slice!(release_tags.index(newest_tag))
      
      return latest_applicable_release_tag_in_array(release_tags, admin_tags) if release_tags.size > 0 #Try again after dropping the one that wasn't applicable 
      
      return nil #We're out of tags, no applicable ones
    end

  end
end