Add CyclOSM layer

[rails.git] / app / controllers / api / amf_controller.rb

# amf_controller is a semi-standalone API for Flash clients, particularly
# Potlatch. All interaction between Potlatch (as a .SWF application) and the
# OSM database takes place using this controller. Messages are
# encoded in the Actionscript Message Format (AMF).
#
# Helper functions are in /lib/potlatch.rb
#
# Author::  editions Systeme D / Richard Fairhurst 2004-2008
# Licence:: public domain.
#
# == General structure
#
# Apart from the amf_read and amf_write methods (which distribute the requests
# from the AMF message), each method generally takes arguments in the order
# they were sent by the Potlatch SWF. Do not assume typing has been preserved.
# Methods all return an array to the SWF.
#
# == API 0.6
#
# Note that this requires a patched version of composite_primary_keys 1.1.0
# (see http://groups.google.com/group/compositekeys/t/a00e7562b677e193)
# if you are to run with POTLATCH_USE_SQL=false .
#
# == Debugging
#
# Any method that returns a status code (0 for ok) can also send:
# return(-1,"message")        <-- just puts up a dialogue
# return(-2,"message")        <-- also asks the user to e-mail me
# return(-3,["type",v],id)    <-- version conflict
# return(-4,"type",id)        <-- object not found
# -5 indicates the method wasn't called (due to a previous error)
#
# To write to the Rails log, use logger.info("message").

# Remaining issues:
# * version conflict when POIs and ways are reverted

module Api
  class AmfController < ApiController
    include Potlatch

    before_action :check_api_writable

    # AMF Controller implements its own authentication and authorization checks
    # completely independently of the rest of the codebase, so best just to let
    # it keep doing its own thing.
    skip_authorization_check

    # Main AMF handlers: process the raw AMF string (using AMF library) and
    # calls each action (private method) accordingly.

    def amf_read
      self.status = :ok
      self.content_type = Mime[:amf]
      self.response_body = Dispatcher.new(request.raw_post) do |message, *args|
        logger.info("Executing AMF #{message}(#{args.join(',')})")

        case message
        when "getpresets" then        result = getpresets(*args)
        when "whichways" then         result = whichways(*args)
        when "whichways_deleted" then result = whichways_deleted(*args)
        when "getway" then            result = getway(args[0].to_i)
        when "getrelation" then       result = getrelation(args[0].to_i)
        when "getway_old" then        result = getway_old(args[0].to_i, args[1])
        when "getway_history" then    result = getway_history(args[0].to_i)
        when "getnode_history" then   result = getnode_history(args[0].to_i)
        when "findgpx" then           result = findgpx(*args)
        when "findrelations" then     result = findrelations(*args)
        when "getpoi" then            result = getpoi(*args)
        end

        result
      end
    end

    def amf_write
      renumberednodes = {}              # Shared across repeated putways
      renumberedways = {}               # Shared across repeated putways
      err = false                       # Abort batch on error

      self.status = :ok
      self.content_type = Mime[:amf]
      self.response_body = Dispatcher.new(request.raw_post) do |message, *args|
        logger.info("Executing AMF #{message}")

        if err
          result = [-5, nil]
        else
          case message
          when "putway"
            orn = renumberednodes.dup
            result = putway(renumberednodes, *args)
            result[4] = renumberednodes.reject { |k, _v| orn.key?(k) }
            renumberedways[result[2]] = result[3] if result[0].zero? && result[2] != result[3]
          when "putrelation"
            result = putrelation(renumberednodes, renumberedways, *args)
          when "deleteway"
            result = deleteway(*args)
          when "putpoi"
            result = putpoi(*args)
            renumberednodes[result[2]] = result[3] if result[0].zero? && result[2] != result[3]
          when "startchangeset"
            result = startchangeset(*args)
          end

          err = true if result[0] == -3 # If a conflict is detected, don't execute any more writes
        end

        result
      end
    end

    private

    def amf_handle_error(call, rootobj, rootid)
      yield
    rescue OSM::APIAlreadyDeletedError => e
      [-4, e.object, e.object_id]
    rescue OSM::APIVersionMismatchError => e
      [-3, [rootobj, rootid], [e.type.downcase, e.id, e.latest]]
    rescue OSM::APIUserChangesetMismatchError => e
      [-2, e.to_s]
    rescue OSM::APIBadBoundingBox => e
      [-2, "Sorry - I can't get the map for that area. The server said: #{e}"]
    rescue OSM::APIError => e
      [-1, e.to_s]
    rescue StandardError => e
      [-2, "An unusual error happened (in #{call}). The server said: #{e}"]
    end

    def amf_handle_error_with_timeout(call, rootobj, rootid, &block)
      amf_handle_error(call, rootobj, rootid) do
        OSM::Timer.timeout(Settings.api_timeout, OSM::APITimeoutError, &block)
      end
    end

    # Start new changeset
    # Returns success_code,success_message,changeset id

    def startchangeset(usertoken, cstags, closeid, closecomment, opennew)
      amf_handle_error("'startchangeset'", nil, nil) do
        user = getuser(usertoken)
        return -1, "You are not logged in, so Potlatch can't write any changes to the database." unless user
        return -1, t("application.setup_user_auth.blocked") if user.blocks.active.exists?
        return -1, "You must accept the contributor terms before you can edit." if user.terms_agreed.nil?

        if cstags
          return -1, "One of the tags is invalid. Linux users may need to upgrade to Flash Player 10.1." unless tags_ok(cstags)

          cstags = strip_non_xml_chars cstags
        end

        # close previous changeset and add comment
        if closeid
          cs = Changeset.find(closeid.to_i)
          cs.set_closed_time_now
          if cs.user_id != user.id
            raise OSM::APIUserChangesetMismatchError
          elsif closecomment.empty?
            cs.save!
          else
            cs.tags["comment"] = closecomment
            # in case closecomment has chars not allowed in xml
            cs.tags = strip_non_xml_chars cs.tags
            cs.save_with_tags!
          end
        end

        # open a new changeset
        if opennew.nonzero?
          cs = Changeset.new
          cs.tags = cstags
          cs.user_id = user.id
          unless closecomment.empty?
            cs.tags["comment"] = closecomment
            # in case closecomment has chars not allowed in xml
            cs.tags = strip_non_xml_chars cs.tags
          end
          # smsm1 doesn't like the next two lines and thinks they need to be abstracted to the model more/better
          cs.created_at = Time.now.getutc
          cs.closed_at = cs.created_at + Changeset::IDLE_TIMEOUT
          cs.save_with_tags!
          return [0, "", cs.id]
        else
          return [0, "", nil]
        end
      end
    end

    # Return presets (default tags, localisation etc.):
    # uses POTLATCH_PRESETS global, set up in OSM::Potlatch.

    def getpresets(usertoken, _lang)
      user = getuser(usertoken)

      langs = if user && !user.languages.empty?
                Locale.list(user.languages)
              else
                Locale.list(http_accept_language.user_preferred_languages)
              end

      lang = getlocales.preferred(langs)
      (real_lang, localised) = getlocalized(lang.to_s)

      # Tell Potlatch what language it's using
      localised["__potlatch_locale"] = real_lang

      # Get help from i18n but delete it so we won't pass it around
      # twice for nothing
      help = localised["help_html"]
      localised.delete("help_html")

      # Populate icon names
      POTLATCH_PRESETS[10].each do |id|
        POTLATCH_PRESETS[11][id] = localised["preset_icon_#{id}"]
        localised.delete("preset_icon_#{id}")
      end

      POTLATCH_PRESETS + [localised, help]
    end

    def getlocalized(lang)
      # What we end up actually using. Reported in Potlatch's created_by=* string
      loaded_lang = "en"

      # Load English defaults
      en = YAML.safe_load(File.open(Rails.root.join("config/potlatch/locales/en.yml")))["en"]

      if lang == "en"
        [loaded_lang, en]
      else
        # Use English as a fallback
        begin
          other = YAML.safe_load(File.open(Rails.root.join("config/potlatch/locales/#{lang}.yml")))[lang]
          loaded_lang = lang
        rescue StandardError
          other = en
        end

        # We have to return a flat list and some of the keys won't be
        # translated (probably)
        [loaded_lang, en.merge(other)]
      end
    end

    ##
    # Find all the ways, POI nodes (i.e. not part of ways), and relations
    # in a given bounding box. Nodes are returned in full; ways and relations
    # are IDs only.
    #
    # return is of the form:
    # [success_code, success_message,
    #  [[way_id, way_version], ...],
    #  [[node_id, lat, lon, [tags, ...], node_version], ...],
    #  [[rel_id, rel_version], ...]]
    # where the ways are any visible ways which refer to any visible
    # nodes in the bbox, nodes are any visible nodes in the bbox but not
    # used in any way, rel is any relation which refers to either a way
    # or node that we're returning.
    def whichways(xmin, ymin, xmax, ymax)
      amf_handle_error_with_timeout("'whichways'", nil, nil) do
        enlarge = [(xmax - xmin) / 8, 0.01].min
        xmin -= enlarge
        ymin -= enlarge
        xmax += enlarge
        ymax += enlarge

        # check boundary is sane and area within defined
        # see /config/application.yml
        bbox = BoundingBox.new(xmin, ymin, xmax, ymax)
        bbox.check_boundaries
        bbox.check_size

        if POTLATCH_USE_SQL
          ways = sql_find_ways_in_area(bbox)
          points = sql_find_pois_in_area(bbox)
          relations = sql_find_relations_in_area_and_ways(bbox, ways.collect { |x| x[0] })
        else
          # find the way ids in an area
          nodes_in_area = Node.bbox(bbox).visible.includes(:ways)
          ways = nodes_in_area.inject([]) do |sum, node|
            visible_ways = node.ways.select(&:visible?)
            sum + visible_ways.collect { |w| [w.id, w.version] }
          end.uniq
          ways.delete([])

          # find the node ids in an area that aren't part of ways
          nodes_not_used_in_area = nodes_in_area.select { |node| node.ways.empty? }
          points = nodes_not_used_in_area.collect { |n| [n.id, n.lon, n.lat, n.tags, n.version] }.uniq

          # find the relations used by those nodes and ways
          relations = Relation.nodes(nodes_in_area.collect(&:id)).visible +
                      Relation.ways(ways.collect { |w| w[0] }).visible
          relations = relations.collect { |relation| [relation.id, relation.version] }.uniq
        end

        [0, "", ways, points, relations]
      end
    end

    # Find deleted ways in current bounding box (similar to whichways, but ways
    # with a deleted node only - not POIs or relations).

    def whichways_deleted(xmin, ymin, xmax, ymax)
      amf_handle_error_with_timeout("'whichways_deleted'", nil, nil) do
        enlarge = [(xmax - xmin) / 8, 0.01].min
        xmin -= enlarge
        ymin -= enlarge
        xmax += enlarge
        ymax += enlarge

        # check boundary is sane and area within defined
        # see /config/application.yml
        bbox = BoundingBox.new(xmin, ymin, xmax, ymax)
        bbox.check_boundaries
        bbox.check_size

        nodes_in_area = Node.bbox(bbox).joins(:ways_via_history).where(:current_ways => { :visible => false })
        way_ids = nodes_in_area.collect { |node| node.ways_via_history.invisible.collect(&:id) }.flatten.uniq

        [0, "", way_ids]
      end
    end

    # Get a way including nodes and tags.
    # Returns the way id, a Potlatch-style array of points, a hash of tags, the version number, and the user ID.

    def getway(wayid)
      amf_handle_error_with_timeout("'getway' #{wayid}", "way", wayid) do
        if POTLATCH_USE_SQL
          points = sql_get_nodes_in_way(wayid)
          tags = sql_get_tags_in_way(wayid)
          version = sql_get_way_version(wayid)
          uid = sql_get_way_user(wayid)
        else
          # Ideally we would do ":include => :nodes" here but if we do that
          # then rails only seems to return the first copy of a node when a
          # way includes a node more than once
          way = Way.where(:id => wayid).first

          # check case where way has been deleted or doesn't exist
          return [-4, "way", wayid] if way.nil? || !way.visible

          points = way.nodes.preload(:node_tags).collect do |node|
            nodetags = node.tags
            nodetags.delete("created_by")
            [node.lon, node.lat, node.id, nodetags, node.version]
          end
          tags = way.tags
          version = way.version
          uid = way.changeset.user.id
        end

        [0, "", wayid, points, tags, version, uid]
      end
    end

    # Get an old version of a way, and all constituent nodes.
    #
    # For undelete (version<0), always uses the most recent version of each node,
    # even if it's moved.  For revert (version >= 0), uses the node in existence
    # at the time, generating a new id if it's still visible and has been moved/
    # retagged.
    #
    # Returns:
    # 0. success code,
    # 1. id,
    # 2. array of points,
    # 3. hash of tags,
    # 4. version,
    # 5. is this the current, visible version? (boolean)

    def getway_old(id, timestamp)
      amf_handle_error_with_timeout("'getway_old' #{id}, #{timestamp}", "way", id) do
        if timestamp == ""
          # undelete
          old_way = OldWay.where(:visible => true, :way_id => id).unredacted.order("version DESC").first
          points = old_way.get_nodes_undelete unless old_way.nil?
        else
          begin
            # revert
            timestamp = Time.zone.strptime(timestamp.to_s, "%d %b %Y, %H:%M:%S")
            old_way = OldWay.where("way_id = ? AND timestamp <= ?", id, timestamp).unredacted.order("timestamp DESC").first
            unless old_way.nil?
              if old_way.visible
                points = old_way.get_nodes_revert(timestamp)
              else
                return [-1, "Sorry, the way was deleted at that time - please revert to a previous version.", id]
              end
            end
          rescue ArgumentError
            # thrown by date parsing method. leave old_way as nil for
            # the error handler below.
            old_way = nil
          end
        end

        if old_way.nil?
          return [-1, "Sorry, the server could not find a way at that time.", id]
        else
          curway = Way.find(id)
          old_way.tags["history"] = "Retrieved from v#{old_way.version}"
          return [0, "", id, points, old_way.tags, curway.version, (curway.version == old_way.version && curway.visible)]
        end
      end
    end

    # Find history of a way.
    # Returns 'way', id, and an array of previous versions:
    # - formerly [old_way.version, old_way.timestamp.strftime("%d %b %Y, %H:%M"), old_way.visible ? 1 : 0, user, uid]
    # - now [timestamp,user,uid]
    #
    # Heuristic: Find all nodes that have ever been part of the way;
    # get a list of their revision dates; add revision dates of the way;
    # sort and collapse list (to within 2 seconds); trim all dates before the
    # start date of the way.

    def getway_history(wayid)
      revdates = []
      revusers = {}
      Way.find(wayid).old_ways.unredacted.collect do |a|
        revdates.push(a.timestamp)
        revusers[a.timestamp.to_i] = change_user(a) unless revusers.key?(a.timestamp.to_i)
        a.nds.each do |n|
          Node.find(n).old_nodes.unredacted.collect do |o|
            revdates.push(o.timestamp)
            revusers[o.timestamp.to_i] = change_user(o) unless revusers.key?(o.timestamp.to_i)
          end
        end
      end
      waycreated = revdates[0]
      revdates.uniq!
      revdates.sort!
      revdates.reverse!

      # Remove any dates (from nodes) before first revision date of way
      revdates.delete_if { |d| d < waycreated }
      # Remove any elements where 2 seconds doesn't elapse before next one
      revdates.delete_if { |d| revdates.include?(d + 1) || revdates.include?(d + 2) }
      # Collect all in one nested array
      revdates.collect! { |d| [(d + 1).strftime("%d %b %Y, %H:%M:%S")] + revusers[d.to_i] }
      revdates.uniq!

      ["way", wayid, revdates]
    rescue ActiveRecord::RecordNotFound
      ["way", wayid, []]
    end

    # Find history of a node. Returns 'node', id, and an array of previous versions as above.

    def getnode_history(nodeid)
      history = Node.find(nodeid).old_nodes.unredacted.reverse.collect do |old_node|
        [(old_node.timestamp + 1).strftime("%d %b %Y, %H:%M:%S")] + change_user(old_node)
      end
      ["node", nodeid, history]
    rescue ActiveRecord::RecordNotFound
      ["node", nodeid, []]
    end

    def change_user(obj)
      user_object = obj.changeset.user
      user = user_object.data_public? ? user_object.display_name : "anonymous"
      uid  = user_object.data_public? ? user_object.id : 0
      [user, uid]
    end

    # Find GPS traces with specified name/id.
    # Returns array listing GPXs, each one comprising id, name and description.

    def findgpx(searchterm, usertoken)
      amf_handle_error_with_timeout("'findgpx'", nil, nil) do
        user = getuser(usertoken)

        return -1, "You must be logged in to search for GPX traces." unless user
        return -1, t("application.setup_user_auth.blocked") if user.blocks.active.exists?

        query = Trace.visible_to(user)
        query = if searchterm.to_i.positive?
                  query.where(:id => searchterm.to_i)
                else
                  query.where("MATCH(name) AGAINST (?)", searchterm).limit(21)
                end
        gpxs = query.collect do |gpx|
          [gpx.id, gpx.name, gpx.description]
        end
        [0, "", gpxs]
      end
    end

    # Get a relation with all tags and members.
    # Returns:
    # 0. success code?
    # 1. object type?
    # 2. relation id,
    # 3. hash of tags,
    # 4. list of members,
    # 5. version.

    def getrelation(relid)
      amf_handle_error("'getrelation' #{relid}", "relation", relid) do
        rel = Relation.where(:id => relid).first

        return [-4, "relation", relid] if rel.nil? || !rel.visible

        [0, "", relid, rel.tags, rel.members, rel.version]
      end
    end

    # Find relations with specified name/id.
    # Returns array of relations, each in same form as getrelation.

    def findrelations(searchterm)
      rels = []
      if searchterm.to_i.positive?
        rel = Relation.where(:id => searchterm.to_i).first
        rels.push([rel.id, rel.tags, rel.members, rel.version]) if rel&.visible
      else
        RelationTag.where("v like ?", "%#{searchterm}%").limit(11).each do |t|
          rels.push([t.relation.id, t.relation.tags, t.relation.members, t.relation.version]) if t.relation.visible
        end
      end
      rels
    end

    # Save a relation.
    # Returns
    # 0. 0 (success),
    # 1. original relation id (unchanged),
    # 2. new relation id,
    # 3. version.

    def putrelation(renumberednodes, renumberedways, usertoken, changeset_id, version, relid, tags, members, visible)
      amf_handle_error("'putrelation' #{relid}", "relation", relid) do
        user = getuser(usertoken)

        return -1, "You are not logged in, so the relation could not be saved." unless user
        return -1, t("application.setup_user_auth.blocked") if user.blocks.active.exists?
        return -1, "You must accept the contributor terms before you can edit." if user.terms_agreed.nil?

        return -1, "One of the tags is invalid. Linux users may need to upgrade to Flash Player 10.1." unless tags_ok(tags)

        tags = strip_non_xml_chars tags

        relid = relid.to_i
        visible = visible.to_i.nonzero?

        new_relation = nil
        relation = nil
        Relation.transaction do
          # create a new relation, or find the existing one
          relation = Relation.find(relid) if relid.positive?
          # We always need a new node, based on the data that has been sent to us
          new_relation = Relation.new

          # check the members are all positive, and correctly type
          typedmembers = []
          members.each do |m|
            mid = m[1].to_i
            if mid.negative?
              mid = renumberednodes[mid] if m[0] == "Node"
              mid = renumberedways[mid] if m[0] == "Way"
            end
            typedmembers << [m[0], mid, m[2].delete("\000-\037\ufffe\uffff", "^\011\012\015")] if mid
          end

          # assign new contents
          new_relation.members = typedmembers
          new_relation.tags = tags
          new_relation.visible = visible
          new_relation.changeset_id = changeset_id.to_i
          new_relation.version = version

          if relid <= 0
            # We're creating the relation
            new_relation.create_with_history(user)
          elsif visible
            # We're updating the relation
            new_relation.id = relid
            relation.update_from(new_relation, user)
          else
            # We're deleting the relation
            new_relation.id = relid
            relation.delete_with_history!(new_relation, user)
          end
        end

        if relid <= 0
          return [0, "", relid, new_relation.id, new_relation.version]
        else
          return [0, "", relid, relid, relation.version]
        end
      end
    end

    # Save a way to the database, including all nodes. Any nodes in the previous
    # version and no longer used are deleted.
    #
    # Parameters:
    # 0. hash of renumbered nodes (added by amf_controller)
    # 1. current user token (for authentication)
    # 2. current changeset
    # 3. new way version
    # 4. way ID
    # 5. list of nodes in way
    # 6. hash of way tags
    # 7. array of nodes to change (each one is [lon,lat,id,version,tags]),
    # 8. hash of nodes to delete (id->version).
    #
    # Returns:
    # 0. '0' (code for success),
    # 1. message,
    # 2. original way id (unchanged),
    # 3. new way id,
    # 4. hash of renumbered nodes (old id=>new id),
    # 5. way version,
    # 6. hash of changed node versions (node=>version)
    # 7. hash of deleted node versions (node=>version)

    def putway(renumberednodes, usertoken, changeset_id, wayversion, originalway, pointlist, attributes, nodes, deletednodes)
      amf_handle_error("'putway' #{originalway}", "way", originalway) do
        # -- Initialise

        user = getuser(usertoken)
        return -1, "You are not logged in, so the way could not be saved." unless user
        return -1, t("application.setup_user_auth.blocked") if user.blocks.active.exists?
        return -1, "You must accept the contributor terms before you can edit." if user.terms_agreed.nil?

        return -2, "Server error - way is only #{pointlist.length} points long." if pointlist.length < 2

        return -1, "One of the tags is invalid. Linux users may need to upgrade to Flash Player 10.1." unless tags_ok(attributes)

        attributes = strip_non_xml_chars attributes

        originalway = originalway.to_i
        pointlist.collect!(&:to_i)

        way = nil # this is returned, so scope it outside the transaction
        nodeversions = {}
        Way.transaction do
          # -- Update each changed node

          nodes.each do |a|
            lon = a[0].to_f
            lat = a[1].to_f
            id = a[2].to_i
            version = a[3].to_i

            return -2, "Server error - node with id 0 found in way #{originalway}." if id.zero?
            return -2, "Server error - node with latitude -90 found in way #{originalway}." if lat == 90

            id = renumberednodes[id] if renumberednodes[id]

            node = Node.new
            node.changeset_id = changeset_id.to_i
            node.lat = lat
            node.lon = lon
            node.tags = a[4]

            # fixup node tags in a way as well
            return -1, "One of the tags is invalid. Linux users may need to upgrade to Flash Player 10.1." unless tags_ok(node.tags)

            node.tags = strip_non_xml_chars node.tags

            node.tags.delete("created_by")
            node.version = version
            if id <= 0
              # We're creating the node
              node.create_with_history(user)
              renumberednodes[id] = node.id
              nodeversions[node.id] = node.version
            else
              # We're updating an existing node
              previous = Node.find(id)
              node.id = id
              previous.update_from(node, user)
              nodeversions[previous.id] = previous.version
            end
          end

          # -- Save revised way

          pointlist.collect! do |a|
            renumberednodes[a] || a
          end
          new_way = Way.new
          new_way.tags = attributes
          new_way.nds = pointlist
          new_way.changeset_id = changeset_id.to_i
          new_way.version = wayversion
          if originalway <= 0
            new_way.create_with_history(user)
            way = new_way # so we can get way.id and way.version
          else
            way = Way.find(originalway)
            if way.tags != attributes || way.nds != pointlist || !way.visible?
              new_way.id = originalway
              way.update_from(new_way, user)
            end
          end

          # -- Delete unwanted nodes

          deletednodes.each do |id, v|
            node = Node.find(id.to_i)
            new_node = Node.new
            new_node.changeset_id = changeset_id.to_i
            new_node.version = v.to_i
            new_node.id = id.to_i
            begin
              node.delete_with_history!(new_node, user)
            rescue OSM::APIPreconditionFailedError
              # We don't do anything here as the node is being used elsewhere
              # and we don't want to delete it
            end
          end
        end

        [0, "", originalway, way.id, renumberednodes, way.version, nodeversions, deletednodes]
      end
    end

    # Save POI to the database.
    # Refuses save if the node has since become part of a way.
    # Returns array with:
    # 0. 0 (success),
    # 1. success message,
    # 2. original node id (unchanged),
    # 3. new node id,
    # 4. version.

    def putpoi(usertoken, changeset_id, version, id, lon, lat, tags, visible)
      amf_handle_error("'putpoi' #{id}", "node", id) do
        user = getuser(usertoken)
        return -1, "You are not logged in, so the point could not be saved." unless user
        return -1, t("application.setup_user_auth.blocked") if user.blocks.active.exists?
        return -1, "You must accept the contributor terms before you can edit." if user.terms_agreed.nil?

        return -1, "One of the tags is invalid. Linux users may need to upgrade to Flash Player 10.1." unless tags_ok(tags)

        tags = strip_non_xml_chars tags

        id = id.to_i
        visible = (visible.to_i == 1)
        node = nil
        new_node = nil
        Node.transaction do
          if id.positive?
            begin
              node = Node.find(id)
            rescue ActiveRecord::RecordNotFound
              return [-4, "node", id]
            end

            return -1, "Point #{id} has since become part of a way, so you cannot save it as a POI.", id, id, version unless visible || node.ways.empty?
          end
          # We always need a new node, based on the data that has been sent to us
          new_node = Node.new

          new_node.changeset_id = changeset_id.to_i
          new_node.version = version
          new_node.lat = lat
          new_node.lon = lon
          new_node.tags = tags
          if id <= 0
            # We're creating the node
            new_node.create_with_history(user)
          elsif visible
            # We're updating the node
            new_node.id = id
            node.update_from(new_node, user)
          else
            # We're deleting the node
            new_node.id = id
            node.delete_with_history!(new_node, user)
          end
        end

        if id <= 0
          return [0, "", id, new_node.id, new_node.version]
        else
          return [0, "", id, node.id, node.version]
        end
      end
    end

    # Read POI from database
    # (only called on revert: POIs are usually read by whichways).
    #
    # Returns array of id, long, lat, hash of tags, (current) version.

    def getpoi(id, timestamp)
      amf_handle_error("'getpoi' #{id}", "node", id) do
        id = id.to_i
        n = Node.where(:id => id).first
        if n
          v = n.version
          n = OldNode.where("node_id = ? AND timestamp <= ?", id, timestamp).unredacted.order("timestamp DESC").first unless timestamp == ""
        end

        if n
          return [0, "", id, n.lon, n.lat, n.tags, v]
        else
          return [-4, "node", id]
        end
      end
    end

    # Delete way and all constituent nodes.
    # Params:
    # * The user token
    # * the changeset id
    # * the id of the way to change
    # * the version of the way that was downloaded
    # * a hash of the id and versions of all the nodes that are in the way, if any
    # of the nodes have been changed by someone else then, there is a problem!
    # Returns 0 (success), unchanged way id, new way version, new node versions.

    def deleteway(usertoken, changeset_id, way_id, way_version, deletednodes)
      amf_handle_error("'deleteway' #{way_id}", "way", way_id) do
        user = getuser(usertoken)
        return -1, "You are not logged in, so the way could not be deleted." unless user
        return -1, t("application.setup_user_auth.blocked") if user.blocks.active.exists?
        return -1, "You must accept the contributor terms before you can edit." if user.terms_agreed.nil?

        way_id = way_id.to_i
        nodeversions = {}
        old_way = nil # returned, so scope it outside the transaction
        # Need a transaction so that if one item fails to delete, the whole delete fails.
        Way.transaction do
          # -- Delete the way

          old_way = Way.find(way_id)
          delete_way = Way.new
          delete_way.version = way_version
          delete_way.changeset_id = changeset_id.to_i
          delete_way.id = way_id
          old_way.delete_with_history!(delete_way, user)

          # -- Delete unwanted nodes

          deletednodes.each do |id, v|
            node = Node.find(id.to_i)
            new_node = Node.new
            new_node.changeset_id = changeset_id.to_i
            new_node.version = v.to_i
            new_node.id = id.to_i
            begin
              node.delete_with_history!(new_node, user)
              nodeversions[node.id] = node.version
            rescue OSM::APIPreconditionFailedError
              # We don't do anything with the exception as the node is in use
              # elsewhere and we don't want to delete it
            end
          end
        end
        [0, "", way_id, old_way.version, nodeversions]
      end
    end

    # ====================================================================
    # Support functions

    # Authenticate token
    # (can also be of form user:pass)
    # When we are writing to the api, we need the actual user model,
    # not just the id, hence this abstraction

    def getuser(token)
      if token =~ /^(.+):(.+)$/
        User.authenticate(:username => Regexp.last_match(1), :password => Regexp.last_match(2))
      else
        User.authenticate(:token => token)
      end
    end

    def getlocales
      @getlocales ||= Locale.list(Dir.glob(Rails.root.join("config/potlatch/locales/*")).collect { |f| File.basename(f, ".yml") })
    end

    ##
    # check that all key-value pairs are valid UTF-8.
    def tags_ok(tags)
      tags.each do |k, v|
        return false unless UTF8.valid? k
        return false unless UTF8.valid? v
      end
      true
    end

    ##
    # strip characters which are invalid in XML documents from the strings
    # in the +tags+ hash.
    def strip_non_xml_chars(tags)
      new_tags = {}
      tags&.each do |k, v|
        new_k = k.delete "\000-\037\ufffe\uffff", "^\011\012\015"
        new_v = v.delete "\000-\037\ufffe\uffff", "^\011\012\015"
        new_tags[new_k] = new_v
      end
      new_tags
    end

    # ====================================================================
    # Alternative SQL queries for getway/whichways

    def sql_find_ways_in_area(bbox)
      sql = <<~SQL.squish
        SELECT DISTINCT current_ways.id AS wayid,current_ways.version AS version
          FROM current_way_nodes
        INNER JOIN current_nodes ON current_nodes.id=current_way_nodes.node_id
        INNER JOIN current_ways  ON current_ways.id =current_way_nodes.id
           WHERE current_nodes.visible=TRUE
           AND current_ways.visible=TRUE
           AND #{OSM.sql_for_area(bbox, 'current_nodes.')}
      SQL
      ActiveRecord::Base.connection.select_all(sql).collect { |a| [a["wayid"].to_i, a["version"].to_i] }
    end

    def sql_find_pois_in_area(bbox)
      pois = []
      sql = <<~SQL.squish
        SELECT current_nodes.id,current_nodes.latitude*0.0000001 AS lat,current_nodes.longitude*0.0000001 AS lon,current_nodes.version
        FROM current_nodes
         LEFT OUTER JOIN current_way_nodes cwn ON cwn.node_id=current_nodes.id
         WHERE current_nodes.visible=TRUE
         AND cwn.id IS NULL
         AND #{OSM.sql_for_area(bbox, 'current_nodes.')}
      SQL
      ActiveRecord::Base.connection.select_all(sql).each do |row|
        poitags = {}
        ActiveRecord::Base.connection.select_all("SELECT k,v FROM current_node_tags WHERE id=#{row['id']}").each do |n|
          poitags[n["k"]] = n["v"]
        end
        pois << [row["id"].to_i, row["lon"].to_f, row["lat"].to_f, poitags, row["version"].to_i]
      end
      pois
    end

    def sql_find_relations_in_area_and_ways(bbox, way_ids)
      # ** It would be more Potlatchy to get relations for nodes within ways
      #    during 'getway', not here
      sql = <<~SQL.squish
        SELECT DISTINCT cr.id AS relid,cr.version AS version
        FROM current_relations cr
        INNER JOIN current_relation_members crm ON crm.id=cr.id
        INNER JOIN current_nodes cn ON crm.member_id=cn.id AND crm.member_type='Node'
         WHERE #{OSM.sql_for_area(bbox, 'cn.')}
      SQL
      unless way_ids.empty?
        sql += <<~SQL.squish
          UNION
           SELECT DISTINCT cr.id AS relid,cr.version AS version
           FROM current_relations cr
           INNER JOIN current_relation_members crm ON crm.id=cr.id
            WHERE crm.member_type='Way'
            AND crm.member_id IN (#{way_ids.join(',')})
        SQL
      end
      ActiveRecord::Base.connection.select_all(sql).collect { |a| [a["relid"].to_i, a["version"].to_i] }
    end

    def sql_get_nodes_in_way(wayid)
      points = []
      sql = <<~SQL.squish
        SELECT latitude*0.0000001 AS lat,longitude*0.0000001 AS lon,current_nodes.id,current_nodes.version
        FROM current_way_nodes,current_nodes
         WHERE current_way_nodes.id=#{wayid.to_i}
         AND current_way_nodes.node_id=current_nodes.id
         AND current_nodes.visible=TRUE
        ORDER BY sequence_id
      SQL
      ActiveRecord::Base.connection.select_all(sql).each do |row|
        nodetags = {}
        ActiveRecord::Base.connection.select_all("SELECT k,v FROM current_node_tags WHERE id=#{row['id']}").each do |n|
          nodetags[n["k"]] = n["v"]
        end
        nodetags.delete("created_by")
        points << [row["lon"].to_f, row["lat"].to_f, row["id"].to_i, nodetags, row["version"].to_i]
      end
      points
    end

    def sql_get_tags_in_way(wayid)
      tags = {}
      ActiveRecord::Base.connection.select_all("SELECT k,v FROM current_way_tags WHERE id=#{wayid.to_i}").each do |row|
        tags[row["k"]] = row["v"]
      end
      tags
    end

    def sql_get_way_version(wayid)
      ActiveRecord::Base.connection.select_one("SELECT version FROM current_ways WHERE id=#{wayid.to_i}")["version"]
    end

    def sql_get_way_user(wayid)
      ActiveRecord::Base.connection.select_one("SELECT user FROM current_ways,changesets WHERE current_ways.id=#{wayid.to_i} AND current_ways.changeset=changesets.id")["user"]
    end
  end
end