function processClick()

in modules/behavior/select.js [274:365]
64 lines of code
28 McCabe index (conditional complexity)

    function processClick(datum, isMultiselect, point, alsoSelectId) {
        var mode = context.mode();
        var showMenu = _showMenu;
        var interactionType = _lastInteractionType;

        var entity = datum && datum.properties && datum.properties.entity;
        if (entity) datum = entity;

        if (datum && datum.type === 'midpoint') {
            // treat targeting midpoints as if targeting the parent way
            datum = datum.parents[0];
        }

        var newMode;
        if (datum && datum.__fbid__) {    // clicked a RapiD feature ..
            context
                .selectedNoteID(null)
                .selectedErrorID(null)
                .enter(modeRapidSelectFeatures(context, datum));

        } else if (datum instanceof osmEntity) {    // clicked an entity..
            var selectedIDs = context.selectedIDs();
            context.selectedNoteID(null);
            context.selectedErrorID(null);

            if (!isMultiselect) {
                // don't change the selection if we're toggling the menu atop a multiselection
                if (!showMenu ||
                    selectedIDs.length <= 1 ||
                    selectedIDs.indexOf(datum.id) === -1) {

                    if (alsoSelectId === datum.id) alsoSelectId = null;

                    selectedIDs = (alsoSelectId ? [alsoSelectId] : []).concat([datum.id]);
                    // always enter modeSelect even if the entity is already
                    // selected since listeners may expect `context.enter` events,
                    // e.g. in the walkthrough
                    newMode = mode.id === 'select' ? mode.selectedIDs(selectedIDs) : modeSelect(context, selectedIDs).selectBehavior(behavior);
                    context.enter(newMode);
                }

            } else {
                if (selectedIDs.indexOf(datum.id) !== -1) {
                    // clicked entity is already in the selectedIDs list..
                    if (!showMenu) {
                        // deselect clicked entity, then reenter select mode or return to browse mode..
                        selectedIDs = selectedIDs.filter(function(id) { return id !== datum.id; });
                        newMode = selectedIDs.length ? mode.selectedIDs(selectedIDs) : modeBrowse(context).selectBehavior(behavior);
                        context.enter(newMode);
                    }
                } else {
                    // clicked entity is not in the selected list, add it..
                    selectedIDs = selectedIDs.concat([datum.id]);
                    newMode = mode.selectedIDs(selectedIDs);
                    context.enter(newMode);
                }
            }

        } else if (datum && datum.__featurehash__ && !isMultiselect) {
            // targeting custom data
            context
                .selectedNoteID(null)
                .enter(modeSelectData(context, datum));

        } else if (datum instanceof osmNote && !isMultiselect) {
            // targeting a note
            context
                .selectedNoteID(datum.id)
                .enter(modeSelectNote(context, datum.id));

        } else if (datum instanceof QAItem & !isMultiselect) {
            // targeting an external QA issue
            context
                .selectedErrorID(datum.id)
                .enter(modeSelectError(context, datum.id, datum.service));

        } else {
            // targeting nothing
            context.selectedNoteID(null);
            context.selectedErrorID(null);
            if (!isMultiselect && mode.id !== 'browse') {
                context.enter(modeBrowse(context));
            }
        }

        context.ui().closeEditMenu();

        // always request to show the edit menu in case the mode needs it
        if (showMenu) context.ui().showEditMenu(point, interactionType);

        resetProperties();
    }