/*
 * Copyright 2016-present Open Networking Laboratory
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 ONOS GUI -- Topology Select Module.
 */

(function () {
    'use strict';

    var t2rs, t2zs;

    // internal state
    var consumeClick,
        zoomer,
        previousNearestLink;    // previous link to mouse position

    function init(svg) {
        zoomer = t2zs.getZoomer();
        svg.on('mousemove', mouseMoveHandler);
        svg.on('click', mouseClickHandler);
    }

    function selectObject(obj) {}

    function clickConsumed(x) {
        var cc = consumeClick;
        consumeClick = Boolean(x);
        return cc;
    }

    function mouseClickHandler() {

        if (!d3.event.shiftKey) {
            t2rs.deselectLink();
        }

        if (!clickConsumed()) {
            if (previousNearestLink) {
                previousNearestLink.select();
            }
        }

    }

    // Select Links
    function mouseMoveHandler() {
        var mp = getLogicalMousePosition(this),
            link = computeNearestLink(mp);

        if (link) {
            if (previousNearestLink && previousNearestLink !== link) {
                previousNearestLink.unenhance();
            }
            link.enhance();
        } else if (previousNearestLink) {
            previousNearestLink.unenhance();
        }

        previousNearestLink = link;
    }

    function getLogicalMousePosition(container) {
        var m = d3.mouse(container),
            sc = zoomer.scale(),
            tr = zoomer.translate(),
            mx = (m[0] - tr[0]) / sc,
            my = (m[1] - tr[1]) / sc;
        return { x: mx, y: my };
    }

    function sq(x) {
        return x * x;
    }

    function mdist(p, m) {
        return Math.sqrt(sq(p.x - m.x) + sq(p.y - m.y));
    }

    function prox(dist) {
        return dist / zoomer.scale();
    }

    function computeNearestLink(mouse) {
        var proximity = prox(30),
            nearest = null,
            minDist;

        function pdrop(line, mouse) {
            var x1 = line.x1,
                y1 = line.y1,
                x2 = line.x2,
                y2 = line.y2,
                x3 = mouse.x,
                y3 = mouse.y,
                k = ((y2 - y1) * (x3 - x1) - (x2 - x1) * (y3 - y1)) /
                    (sq(y2 - y1) + sq(x2 - x1)),
                x4 = x3 - k * (y2 - y1),
                y4 = y3 + k * (x2 - x1);
            return { x: x4, y: y4 };
        }

        function lineHit(line, p, m) {
            if (p.x < line.x1 && p.x < line.x2) return false;
            if (p.x > line.x1 && p.x > line.x2) return false;
            if (p.y < line.y1 && p.y < line.y2) return false;
            if (p.y > line.y1 && p.y > line.y2) return false;
            // line intersects, but are we close enough?
            return mdist(p, m) <= proximity;
        }

        var links = [];

        if (t2rs.model.get('links')) {
            links = (t2rs.backgroundRendered) ? t2rs.regionLinks() : [];
        }

        if (links.length) {
            minDist = proximity * 2;

            links.forEach(function (d) {
                var line = d.get('position'),
                    point,
                    hit,
                    dist;

                // TODO: Reinstate when showHost() is implemented
                // if (!api.showHosts() && d.type() === 'hostLink') {
                //     return; // skip hidden host links
                // }

                if (line) {
                    point = pdrop(line, mouse);
                    hit = lineHit(line, point, mouse);
                    if (hit) {
                        dist = mdist(point, mouse);
                        if (dist < minDist) {
                            minDist = dist;
                            nearest = d;
                        }
                    }
                }
            });
        }

        return nearest;
    }

    angular.module('ovTopo2')
    .factory('Topo2SelectService', [
        'Topo2RegionService', 'Topo2ZoomService',
        function (_t2rs_, _t2zs_) {

            t2rs = _t2rs_;
            t2zs = _t2zs_;

            return {
                init: init,
                selectObject: selectObject,
                clickConsumed: clickConsumed
            };
        }
    ]);

})();