# The ChangesetController is the RESTful interface to Changeset objects

class ChangesetController < ApplicationController
  require 'xml/libxml'

  before_filter :authorize, :only => [:create, :update, :delete, :upload]
  before_filter :check_write_availability, :only => [:create, :update, :delete, :upload]
  before_filter :check_read_availability, :except => [:create, :update, :delete, :upload]
  after_filter :compress_output

  # Create a changeset from XML.
  def create
    if request.put?
      cs = Changeset.from_xml(request.raw_post, true)

      if cs
        cs.user_id = @user.id
        cs.save_with_tags!
        render :text => cs.id.to_s, :content_type => "text/plain"
      else
        render :nothing => true, :status => :bad_request
      end
    else
      render :nothing => true, :status => :method_not_allowed
    end
  end

  def create_prim(ids, prim, nd)
    prim.version = 0
    prim.user_id = @user.id
    prim.visible = true
    prim.save_with_history!

    ids[nd['id'].to_i] = prim.id
  end

  def fix_way(w, node_ids)
    w.nds = w.instance_eval { @nds }.
      map { |nd| node_ids[nd] || nd }
    return w
  end

  def fix_rel(r, ids)
    r.members = r.instance_eval { @members }.
      map { |memb| [memb[0], ids[memb[0]][memb[1].to_i] || memb[1], memb[2]] }
    return r
  end
  
  def read
    begin
      changeset = Changeset.find(params[:id])
      render :text => changeset.to_xml.to_s, :content_type => "text/xml"
    rescue ActiveRecord::RecordNotFound
      render :nothing => true, :status => :not_found
    end
  end
  
  def close 
    begin
      unless request.put?
        render :nothing => true, :status => :method_not_allowed
        return
      end
      changeset = Changeset.find(params[:id])
      changeset.open = false
      changeset.save!
      render :nothing => true
    rescue ActiveRecord::RecordNotFound
      render :nothing => true, :status => :not_found
    end
  end

  def upload
    unless request.put?
      render :nothing => true, :status => :method_not_allowed
      return
    end

    p = XML::Reader.new request.raw_post

    node_ids, way_ids, rel_ids = {}, {}, {}
    ids = {"node"=>node_ids, "way"=>way_ids, "relation"=>rel_ids}

    models = {"node"=>Node, "way"=>Way, "relation"=>Relation}

    # FIXME shouldn't this be done through the 
    # res = OSM::API.new.get_xml_doc
    # as everything else is?
    res = XML::Document.new
    res.encoding = 'UTF-8'
    root = XML::Node.new 'osm'
    root['version'] = API_VERSION
    root['creator'] = 'OpenStreetMap.org'
    res.root = root

    root << XML::Node.new_comment(" Warning: this is a 0.6 result document, " +
      "not a normal OSM file. ")

    Changeset.transaction do
      while p.read == 1
        break if p.node_type == 15 # end element
        next unless p.node_type == 1 # element

        case p.name
        when 'create':
            while p.read == 1
            break if p.node_type == 15 # end element
            next unless p.node_type == 1 # element

            model = models[p.name]
            next if model.nil?

            elem = XML::Node.new p.name
            nd = p.expand; p.next
            osm = model.from_xml_node(nd, true)
            elem['old_id'] = nd['id']

            case nd.name
            when 'way':
                fix_way(osm, node_ids)
              raise OSM::APIPreconditionFailedError.new if !osm.preconditions_ok?
            when 'relation':
                fix_rel(osm, ids)
              raise OSM::APIPreconditionFailedError.new if !osm.preconditions_ok?
            end

            create_prim ids[nd.name], osm, nd
            elem['new_id'] = osm.id.to_s
            elem['new_version'] = osm.version.to_s
            root << elem
          end
        when 'modify':
            while p.read == 1
            break if p.node_type == 15 # end element
            next unless p.node_type == 1 # element

            model = models[p.name]
            next if model.nil?

            elem = XML::Node.new p.name
            new_osm = model.from_xml_node(p.expand); p.next
            osm = model.find(new_osm.id)
            osm.update_from new_osm, @user
            elem['old_id'] = elem['new_id'] = osm.id.to_s
            elem['new_version'] = osm.version.to_s
            root << elem
          end
        when 'delete':
            while p.read == 1
            break if p.node_type == 15 # end element
            next unless p.node_type == 1 # element

            model = models[p.name]
            next if model.nil?

            elem = XML::Node.new p.name
            osm = model.find(p.expand['id']); p.next
            osm.delete_with_history(@user)
            elem['old_id'] = elem['new_id'] = osm.id.to_s
            elem['new_version'] = osm.version.to_s
            root << elem
          end
        end
      end
    end

    render :text => res.to_s, :content_type => "text/xml"

  rescue OSM::APIError => ex
    render ex.render_opts
  end
end