/**
 * quadtree-js
 * @version 1.2.2
 * @license MIT
 * @author Timo Hausmann
 */

/* https://github.com/timohausmann/quadtree-js.git v1.2.2 */

/*
Copyright © 2012-2020 Timo Hausmann
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/



/**
 * Quadtree Constructor
 * @param Object bounds            bounds of the node { x, y, width, height }
 * @param Integer max_objects      (optional) max objects a node can hold before splitting into 4 subnodes (default: 10)
 * @param Integer max_levels       (optional) total max levels inside root Quadtree (default: 4) 
 * @param Integer level            (optional) deepth level, required for subnodes (default: 0)
 */
function Quadtree(bounds, max_objects, max_levels, level) {

    this.max_objects = max_objects || 10;
    this.max_levels = max_levels || 4;

    this.level = level || 0;
    this.bounds = bounds;

    this.objects = [];
    this.nodes = [];
};


/**
 * Split the node into 4 subnodes
 */
Quadtree.prototype.split = function() {

    var nextLevel = this.level + 1,
        subWidth = this.bounds.width / 2,
        subHeight = this.bounds.height / 2,
        x = this.bounds.x,
        y = this.bounds.y;

    //top right node
    this.nodes[0] = new Quadtree({
        x: x + subWidth,
        y: y,
        width: subWidth,
        height: subHeight
    }, this.max_objects, this.max_levels, nextLevel);

    //top left node
    this.nodes[1] = new Quadtree({
        x: x,
        y: y,
        width: subWidth,
        height: subHeight
    }, this.max_objects, this.max_levels, nextLevel);

    //bottom left node
    this.nodes[2] = new Quadtree({
        x: x,
        y: y + subHeight,
        width: subWidth,
        height: subHeight
    }, this.max_objects, this.max_levels, nextLevel);

    //bottom right node
    this.nodes[3] = new Quadtree({
        x: x + subWidth,
        y: y + subHeight,
        width: subWidth,
        height: subHeight
    }, this.max_objects, this.max_levels, nextLevel);
};


/**
 * Determine which node the object belongs to
 * @param Object pRect      bounds of the area to be checked, with x, y, width, height
 * @return Array            an array of indexes of the intersecting subnodes 
 *                          (0-3 = top-right, top-left, bottom-left, bottom-right / ne, nw, sw, se)
 */
Quadtree.prototype.getIndex = function(pRect) {

    var indexes = [],
        verticalMidpoint = this.bounds.x + (this.bounds.width / 2),
        horizontalMidpoint = this.bounds.y + (this.bounds.height / 2);

    var startIsNorth = pRect.y < horizontalMidpoint,
        startIsWest = pRect.x < verticalMidpoint,
        endIsEast = pRect.x + pRect.width > verticalMidpoint,
        endIsSouth = pRect.y + pRect.height > horizontalMidpoint;

    //top-right quad
    if (startIsNorth && endIsEast) {
        indexes.push(0);
    }

    //top-left quad
    if (startIsWest && startIsNorth) {
        indexes.push(1);
    }

    //bottom-left quad
    if (startIsWest && endIsSouth) {
        indexes.push(2);
    }

    //bottom-right quad
    if (endIsEast && endIsSouth) {
        indexes.push(3);
    }

    return indexes;
};


/**
 * Insert the object into the node. If the node
 * exceeds the capacity, it will split and add all
 * objects to their corresponding subnodes.
 * @param Object pRect        bounds of the object to be added { x, y, width, height }
 */
Quadtree.prototype.insert = function(pRect) {

    var i = 0,
        indexes;

    //if we have subnodes, call insert on matching subnodes
    if (this.nodes.length) {
        indexes = this.getIndex(pRect);

        for (i = 0; i < indexes.length; i++) {
            this.nodes[indexes[i]].insert(pRect);
        }
        return;
    }

    //otherwise, store object here
    this.objects.push(pRect);

    //max_objects reached
    if (this.objects.length > this.max_objects && this.level < this.max_levels) {

        //split if we don't already have subnodes
        if (!this.nodes.length) {
            this.split();
        }

        //add all objects to their corresponding subnode
        for (i = 0; i < this.objects.length; i++) {
            indexes = this.getIndex(this.objects[i]);
            for (var k = 0; k < indexes.length; k++) {
                this.nodes[indexes[k]].insert(this.objects[i]);
            }
        }

        //clean up this node
        this.objects = [];
    }
};


/**
 * Return all objects that could collide with the given object
 * @param Object pRect      bounds of the object to be checked { x, y, width, height }
 * @Return Array            array with all detected objects
 */
Quadtree.prototype.retrieve = function(pRect) {

    var indexes = this.getIndex(pRect),
        returnObjects = this.objects;

    //if we have subnodes, retrieve their objects
    if (this.nodes.length) {
        for (var i = 0; i < indexes.length; i++) {
            returnObjects = returnObjects.concat(this.nodes[indexes[i]].retrieve(pRect));
        }
    }

    //remove duplicates
    returnObjects = returnObjects.filter(function(item, index) {
        return returnObjects.indexOf(item) >= index;
    });

    return returnObjects;
};


/**
 * Clear the quadtree
 */
Quadtree.prototype.clear = function() {

    this.objects = [];

    for (var i = 0; i < this.nodes.length; i++) {
        if (this.nodes.length) {
            this.nodes[i].clear();
        }
    }

    this.nodes = [];
};



// 判断矩形是否在象限范围内
function isInner(rect, bounds) {
    return rect.x >= bounds.x &&
        rect.x + width <= bounds.x + bounds.width &&
        rect.y >= bounds.y &&
        rect.y + rect.height <= bounds.y + bounds.height;
}

/*
  动态更新：
    从根节点深入四叉树，检查四叉树各个节点存储的物体是否依旧属于该节点（象限）的范围之内，如果不属于，则重新插入该物体。
*/
Quadtree.prototype.refresh = function(root) {
    var objs = this.objects,
        rect, index, i, len;

    root = root || this;

    for (i = objs.length - 1; i >= 0; i--) {
        rect = objs[i];
        index = this.getIndex(rect);

        // 如果矩形不属于该象限，则将该矩形重新插入
        if (!isInner(rect, this.bounds)) {
            if (this !== root) {
                root.insert(objs.splice(i, 1)[0]);
            }

        // 如果矩形属于该象限 且 该象限具有子象限，则
        // 将该矩形安插到子象限中
        } else if (this.nodes.length) {
            this.nodes[index].insert(objs.splice(i, 1)[0]);
        }
    }

    // 递归刷新子象限
    for (i = 0, len = this.nodes.length; i < len; i++) {
        this.nodes[i].refresh(root);
    }
};

module.exports = Quadtree;