class Tag < ApplicationModel
  belongs_to :tag_object,       :class_name => 'Tag::Object'
  belongs_to :tag_item,         :class_name => 'Tag::Item'

  @@cache_item = {}
  @@cache_object = {}

  def self.tag_add(data) 

    # lookups
    if data[:object]
      tag_object_id = self.tag_object_lookup( data[:object] )
    end
    if data[:item]
      tag_item_id = self.tag_item_lookup( data[:item] )
    end

    # create history
    Tag.create(
      :tag_object_id      => tag_object_id,
      :tag_item_id        => tag_item_id,
      :o_id               => data[:o_id],
      :created_by_id      => data[:created_by_id]
    )
    return true
  end

  def self.tag_remove(data) 

    # lookups
    if data[:object]
      tag_object_id = self.tag_object_lookup( data[:object] )
    end
    if data[:item]
      tag_item_id = self.tag_item_lookup( data[:item] )
    end

    # create history
    result = Tag.where(
      :tag_object_id      => tag_object_id,
      :tag_item_id        => tag_item_id,
      :o_id               => data[:o_id],
    )
    result.each { |item|
      item.destroy
    }
    return true
  end

  def self.tag_list( data )
    tag_object_id_requested = self.tag_object_lookup( data[:object] )
    tag_search = Tag.where(
        :tag_object_id => tag_object_id_requested,
        :o_id          => data[:o_id],
    )
    tags = []
    tag_search.each {|tag|
      tags.push self.tag_item_lookup_id( tag.tag_item_id ) 
    }
    return tags
  end

  private

    def self.tag_item_lookup_id( id )

      # use cache
      return @@cache_item[ id ] if @@cache_item[ id ]

      # lookup
      tag_item = Tag::Item.find(id)
      @@cache_item[ id ] = tag_item.name
      return tag_item.name
    end

    def self.tag_item_lookup( name )

      # use cache
      return @@cache_item[ name ] if @@cache_item[ name ]

      # lookup
      tag_item = Tag::Item.where( :name => name ).first
      if tag_item
        @@cache_item[ name ] = tag_item.id
        return tag_item.id
      end

      # create
      tag_item = Tag::Item.create(
        :name => name
      )
      @@cache_item[ name ] = tag_item.id
      return tag_item.id
    end

    def self.tag_object_lookup_id( id ) 

      # use cache
      return @@cache_object[ id ] if @@cache_object[ id ]

      # lookup
      tag_object = Tag::Object.find(id)
      @@cache_object[ id ] = tag_object.name
      return tag_object.name
    end

    def self.tag_object_lookup( name ) 

      # use cache
      return @@cache_object[ name ] if @@cache_object[ name ]

      # lookup
      tag_object = Tag::Object.where( :name => name ).first
      if tag_object
        @@cache_object[ name ] = tag_object.id
        return tag_object.id
      end

      # create
      tag_object = Tag::Object.create(
        :name => name
      )
      @@cache_object[ name ] = tag_object.id
      return tag_object.id
    end

  class Object < ActiveRecord::Base
  end

  class Item < ActiveRecord::Base
  end

end