modules/actions/connect.js

import { utilArrayUniq } from '@id-sdk/util';

import { actionDeleteNode } from './delete_node';
import { actionDeleteWay } from './delete_way';


// Connect the ways at the given nodes.
//
// First choose a node to be the survivor, with preference given
// to an existing (not new) node.
//
// Tags and relation memberships of of non-surviving nodes are merged
// to the survivor.
//
// This is the inverse of `iD.actionDisconnect`.
//
// Reference:
//   https://github.com/openstreetmap/potlatch2/blob/master/net/systemeD/halcyon/connection/actions/MergeNodesAction.as
//   https://github.com/openstreetmap/josm/blob/mirror/src/org/openstreetmap/josm/actions/MergeNodesAction.java
//
export function actionConnect(nodeIDs) {
    var action = function(graph) {
        var survivor;
        var node;
        var parents;
        var i, j;

        // Choose a survivor node, prefer an existing (not new) node - #4974
        for (i = 0; i < nodeIDs.length; i++) {
            survivor = graph.entity(nodeIDs[i]);
            if (survivor.version) break;  // found one
        }

        // Replace all non-surviving nodes with the survivor and merge tags.
        for (i = 0; i < nodeIDs.length; i++) {
            node = graph.entity(nodeIDs[i]);
            if (node.id === survivor.id) continue;

            parents = graph.parentWays(node);
            for (j = 0; j < parents.length; j++) {
                graph = graph.replace(parents[j].replaceNode(node.id, survivor.id));
            }

            parents = graph.parentRelations(node);
            for (j = 0; j < parents.length; j++) {
                graph = graph.replace(parents[j].replaceMember(node, survivor));
            }

            survivor = survivor.mergeTags(node.tags);
            graph = actionDeleteNode(node.id)(graph);
        }

        graph = graph.replace(survivor);

        // find and delete any degenerate ways created by connecting adjacent vertices
        parents = graph.parentWays(survivor);
        for (i = 0; i < parents.length; i++) {
            if (parents[i].isDegenerate()) {
                graph = actionDeleteWay(parents[i].id)(graph);
            }
        }

        return graph;
    };


    action.disabled = function(graph) {
        var seen = {};
        var restrictionIDs = [];
        var survivor;
        var node, way;
        var relations, relation, role;
        var i, j, k;

        // Choose a survivor node, prefer an existing (not new) node - #4974
        for (i = 0; i < nodeIDs.length; i++) {
            survivor = graph.entity(nodeIDs[i]);
            if (survivor.version) break;  // found one
        }

        // 1. disable if the nodes being connected have conflicting relation roles
        for (i = 0; i < nodeIDs.length; i++) {
            node = graph.entity(nodeIDs[i]);
            relations = graph.parentRelations(node);

            for (j = 0; j < relations.length; j++) {
                relation = relations[j];
                role = relation.memberById(node.id).role || '';

                // if this node is a via node in a restriction, remember for later
                if (relation.hasFromViaTo()) {
                    restrictionIDs.push(relation.id);
                }

                if (seen[relation.id] !== undefined && seen[relation.id] !== role) {
                    return 'relation';
                } else {
                    seen[relation.id] = role;
                }
            }
        }

        // gather restrictions for parent ways
        for (i = 0; i < nodeIDs.length; i++) {
            node = graph.entity(nodeIDs[i]);

            var parents = graph.parentWays(node);
            for (j = 0; j < parents.length; j++) {
                var parent = parents[j];
                relations = graph.parentRelations(parent);

                for (k = 0; k < relations.length; k++) {
                    relation = relations[k];
                    if (relation.hasFromViaTo()) {
                        restrictionIDs.push(relation.id);
                    }
                }
            }
        }


        // test restrictions
        restrictionIDs = utilArrayUniq(restrictionIDs);
        for (i = 0; i < restrictionIDs.length; i++) {
            relation = graph.entity(restrictionIDs[i]);
            if (!relation.isComplete(graph)) continue;

            var memberWays = relation.members
                .filter(function(m) { return m.type === 'way'; })
                .map(function(m) { return graph.entity(m.id); });

            memberWays = utilArrayUniq(memberWays);
            var f = relation.memberByRole('from');
            var t = relation.memberByRole('to');
            var isUturn = (f.id === t.id);

            // 2a. disable if connection would damage a restriction
            // (a key node is a node at the junction of ways)
            var nodes = { from: [], via: [], to: [], keyfrom: [], keyto: [] };
            for (j = 0; j < relation.members.length; j++) {
                collectNodes(relation.members[j], nodes);
            }

            nodes.keyfrom = utilArrayUniq(nodes.keyfrom.filter(hasDuplicates));
            nodes.keyto = utilArrayUniq(nodes.keyto.filter(hasDuplicates));

            var filter = keyNodeFilter(nodes.keyfrom, nodes.keyto);
            nodes.from = nodes.from.filter(filter);
            nodes.via = nodes.via.filter(filter);
            nodes.to = nodes.to.filter(filter);

            var connectFrom = false;
            var connectVia = false;
            var connectTo = false;
            var connectKeyFrom = false;
            var connectKeyTo = false;

            for (j = 0; j < nodeIDs.length; j++) {
                var n = nodeIDs[j];
                if (nodes.from.indexOf(n) !== -1)    { connectFrom = true; }
                if (nodes.via.indexOf(n) !== -1)     { connectVia = true; }
                if (nodes.to.indexOf(n) !== -1)      { connectTo = true; }
                if (nodes.keyfrom.indexOf(n) !== -1) { connectKeyFrom = true; }
                if (nodes.keyto.indexOf(n) !== -1)   { connectKeyTo = true; }
            }
            if (connectFrom && connectTo && !isUturn) { return 'restriction'; }
            if (connectFrom && connectVia) { return 'restriction'; }
            if (connectTo   && connectVia) { return 'restriction'; }

            // connecting to a key node -
            // if both nodes are on a member way (i.e. part of the turn restriction),
            // the connecting node must be adjacent to the key node.
            if (connectKeyFrom || connectKeyTo) {
                if (nodeIDs.length !== 2) { return 'restriction'; }

                var n0 = null;
                var n1 = null;
                for (j = 0; j < memberWays.length; j++) {
                    way = memberWays[j];
                    if (way.contains(nodeIDs[0])) { n0 = nodeIDs[0]; }
                    if (way.contains(nodeIDs[1])) { n1 = nodeIDs[1]; }
                }

                if (n0 && n1) {    // both nodes are part of the restriction
                    var ok = false;
                    for (j = 0; j < memberWays.length; j++) {
                        way = memberWays[j];
                        if (way.areAdjacent(n0, n1)) {
                            ok = true;
                            break;
                        }
                    }
                    if (!ok) {
                        return 'restriction';
                    }
                }
            }

            // 2b. disable if nodes being connected will destroy a member way in a restriction
            // (to test, make a copy and try actually connecting the nodes)
            for (j = 0; j < memberWays.length; j++) {
                way = memberWays[j].update({});   // make copy
                for (k = 0; k < nodeIDs.length; k++) {
                    if (nodeIDs[k] === survivor.id) continue;

                    if (way.areAdjacent(nodeIDs[k], survivor.id)) {
                        way = way.removeNode(nodeIDs[k]);
                    } else {
                        way = way.replaceNode(nodeIDs[k], survivor.id);
                    }
                }
                if (way.isDegenerate()) {
                    return 'restriction';
                }
            }
        }

        return false;


        // if a key node appears multiple times (indexOf !== lastIndexOf) it's a FROM-VIA or TO-VIA junction
        function hasDuplicates(n, i, arr) {
            return arr.indexOf(n) !== arr.lastIndexOf(n);
        }

        function keyNodeFilter(froms, tos) {
            return function(n) {
                return froms.indexOf(n) === -1 && tos.indexOf(n) === -1;
            };
        }

        function collectNodes(member, collection) {
            var entity = graph.hasEntity(member.id);
            if (!entity) return;

            var role = member.role || '';
            if (!collection[role]) {
                collection[role] = [];
            }

            if (member.type === 'node') {
                collection[role].push(member.id);
                if (role === 'via') {
                    collection.keyfrom.push(member.id);
                    collection.keyto.push(member.id);
                }

            } else if (member.type === 'way') {
                collection[role].push.apply(collection[role], entity.nodes);
                if (role === 'from' || role === 'via') {
                    collection.keyfrom.push(entity.first());
                    collection.keyfrom.push(entity.last());
                }
                if (role === 'to' || role === 'via') {
                    collection.keyto.push(entity.first());
                    collection.keyto.push(entity.last());
                }
            }
        }
    };


    return action;
}