class Segment < ActiveRecord::Base
  require 'xml/libxml'
  set_table_name 'current_segments'

  validates_numericality_of :node_a
  validates_numericality_of :node_b

  has_many :old_segments, :foreign_key => :id
  belongs_to :user

  # using belongs_to :foreign_key = 'node_*', since if use has_one :foreign_key = 'id', segment preconditions? fails checking for segment id in node table
  belongs_to :from_node, :class_name => 'Node', :foreign_key => 'node_a'
  belongs_to :to_node, :class_name => 'Node', :foreign_key => 'node_b'

  def self.from_xml(xml, create=false)
    p = XML::Parser.new
    p.string = xml
    doc = p.parse

    segment = Segment.new

    doc.find('//osm/segment').each do |pt|

      segment.node_a = pt['from'].to_i
      segment.node_b = pt['to'].to_i

      if pt['id'] != '0'
        segment.id = pt['id'].to_i
      end

      segment.visible = true

      if create
        segment.timestamp = Time.now
      else
        if pt['timestamp']
          segment.timestamp = Time.parse(pt['timestamp'])
        end
      end

      tags = []

      pt.find('tag').each do |tag|
        tags << [tag['k'],tag['v']]
      end

      tags = tags.collect { |k,v| "#{k}=#{v}" }.join(';')
      tags = '' if tags.nil?

      segment.tags = tags

    end
    return segment
  end

  def save_with_history
    begin
      Segment.transaction do
        self.timestamp = Time.now
        self.save
        old_segment = OldSegment.from_segment(self)
        old_segment.save
      end
      return true
    rescue Exception => ex
      return nil
    end
  end

  def to_xml
    doc = OSM::API.new.get_xml_doc
    doc.root << to_xml_node()
    return doc
  end

  def to_xml_node(user_display_name_cache  = nil)
    el1 = XML::Node.new 'segment'
    el1['id'] = self.id.to_s
    el1['from'] = self.node_a.to_s
    el1['to'] = self.node_b.to_s

    user_display_name_cache = {} if user_display_name_cache.nil?
    if user_display_name_cache and user_display_name_cache[self.user_id]
      # use the cache if available
    else
      user_display_name_cache[self.user_id] = self.user.display_name
    end
    
    #el1['user'] = self.user.display_name if self.user.data_public?
    el1['user'] = user_display_name_cache[self.user_id]

    Segment.split_tags(el1, self.tags)
    el1['visible'] = self.visible.to_s
    el1['timestamp'] = self.timestamp.xmlschema
    return el1
  end

  def self.split_tags(el, tags)
    tags.split(';').each do |tag|
      parts = tag.split('=')
      key = ''
      val = ''
      key = parts[0].strip unless parts[0].nil?
      val = parts[1].strip unless parts[1].nil?
      if key != '' && val != ''
        el2 = XML::Node.new('tag')
        el2['k'] = key.to_s
        el2['v'] = val.to_s
        el << el2
      end
    end
  end

  def preconditions_ok?
    from_node and from_node.visible and to_node and to_node.visible
  end

end