class RelationController < ApplicationController
  require "xml/libxml"

  skip_before_action :verify_authenticity_token
  before_action :authorize, :only => [:create, :update, :delete]
  before_action :require_allow_write_api, :only => [:create, :update, :delete]
  before_action :require_public_data, :only => [:create, :update, :delete]
  before_action :check_api_writable, :only => [:create, :update, :delete]
  before_action :check_api_readable, :except => [:create, :update, :delete]
  around_action :api_call_handle_error, :api_call_timeout

  def create
    assert_method :put

    relation = Relation.from_xml(request.raw_post, true)

    # Assume that Relation.from_xml has thrown an exception if there is an error parsing the xml
    relation.create_with_history current_user
    render :plain => relation.id.to_s
  end

  def read
    relation = Relation.find(params[:id])
    response.last_modified = relation.timestamp
    if relation.visible
      render :xml => relation.to_xml.to_s
    else
      head :gone
    end
  end

  def update
    logger.debug request.raw_post

    relation = Relation.find(params[:id])
    new_relation = Relation.from_xml(request.raw_post)

    raise OSM::APIBadUserInput, "The id in the url (#{relation.id}) is not the same as provided in the xml (#{new_relation.id})" unless new_relation && new_relation.id == relation.id

    relation.update_from new_relation, current_user
    render :plain => relation.version.to_s
  end

  def delete
    relation = Relation.find(params[:id])
    new_relation = Relation.from_xml(request.raw_post)
    if new_relation && new_relation.id == relation.id
      relation.delete_with_history!(new_relation, current_user)
      render :plain => relation.version.to_s
    else
      head :bad_request
    end
  end

  # -----------------------------------------------------------------
  # full
  #
  # input parameters: id
  #
  # returns XML representation of one relation object plus all its
  # members, plus all nodes part of member ways
  # -----------------------------------------------------------------
  def full
    relation = Relation.find(params[:id])

    if relation.visible

      # first find the ids of nodes, ways and relations referenced by this
      # relation - note that we exclude this relation just in case.

      node_ids = relation.members.select { |m| m[0] == "Node" }.map { |m| m[1] }
      way_ids = relation.members.select { |m| m[0] == "Way" }.map { |m| m[1] }
      relation_ids = relation.members.select { |m| m[0] == "Relation" && m[1] != relation.id }.map { |m| m[1] }

      # next load the relations and the ways.

      relations = Relation.where(:id => relation_ids).includes(:relation_tags)
      ways = Way.where(:id => way_ids).includes(:way_nodes, :way_tags)

      # now additionally collect nodes referenced by ways. Note how we
      # recursively evaluate ways but NOT relations.

      way_node_ids = ways.collect do |way|
        way.way_nodes.collect(&:node_id)
      end
      node_ids += way_node_ids.flatten
      nodes = Node.where(:id => node_ids.uniq).includes(:node_tags)

      # create XML.
      doc = OSM::API.new.get_xml_doc
      visible_nodes = {}
      changeset_cache = {}
      user_display_name_cache = {}

      nodes.each do |node|
        next unless node.visible? # should be unnecessary if data is consistent.

        doc.root << node.to_xml_node(changeset_cache, user_display_name_cache)
        visible_nodes[node.id] = node
      end

      ways.each do |way|
        next unless way.visible? # should be unnecessary if data is consistent.

        doc.root << way.to_xml_node(visible_nodes, changeset_cache, user_display_name_cache)
      end

      relations.each do |rel|
        next unless rel.visible? # should be unnecessary if data is consistent.

        doc.root << rel.to_xml_node(changeset_cache, user_display_name_cache)
      end

      # finally add self and output
      doc.root << relation.to_xml_node(changeset_cache, user_display_name_cache)
      render :xml => doc.to_s

    else
      head :gone
    end
  end

  def relations
    raise OSM::APIBadUserInput, "The parameter relations is required, and must be of the form relations=id[,id[,id...]]" unless params["relations"]

    ids = params["relations"].split(",").collect(&:to_i)

    raise OSM::APIBadUserInput, "No relations were given to search for" if ids.empty?

    doc = OSM::API.new.get_xml_doc

    Relation.find(ids).each do |relation|
      doc.root << relation.to_xml_node
    end

    render :xml => doc.to_s
  end

  def relations_for_way
    relations_for_object("Way")
  end

  def relations_for_node
    relations_for_object("Node")
  end

  def relations_for_relation
    relations_for_object("Relation")
  end

  def relations_for_object(objtype)
    relationids = RelationMember.where(:member_type => objtype, :member_id => params[:id]).collect(&:relation_id).uniq

    doc = OSM::API.new.get_xml_doc

    Relation.find(relationids).each do |relation|
      doc.root << relation.to_xml_node if relation.visible
    end

    render :xml => doc.to_s
  end
end