<?php

namespace App\Handlers;
class CheckAreaHandler
{
    // 一个表示区域的三维数组
    protected $config = null;

    // 包含每个区域的四边形
    protected $rectangles = null;

    // 每个区域（多边形）的所有边
    protected $lines = null;

    // 要判断的点的x, y坐标
    protected $_x = null;
    protected $_y = null;

    public function __construct($config)
    {
        $this->config = $config;
        $this->initRectangles();
        $this->initLines();
    }

    /*
        获取包含每个配送区域的四边形
    */
    private function initRectangles()
    {
        foreach ($this->config as $k => $v) {
            $this->rectangles[$k]['minX'] = $this->getMinXInEachConfig($k);
            $this->rectangles[$k]['minY'] = $this->getMinYInEachConfig($k);
            $this->rectangles[$k]['maxX'] = $this->getMaxXInEachConfig($k);
            $this->rectangles[$k]['maxY'] = $this->getMaxYInEachConfig($k);
        }
    }

    /*
        初始化每个区域（多边形）的边（线段：直线的一部分【限制x或者y坐标范围】）
        n 个顶点构成的多边形，有 n-1 条边
    */
    private function initLines()
    {
        foreach ($this->config as $k => $v) {
            $pointNum = count($v);        // 区域的顶点个数
            $lineNum = $pointNum - 1;    // 区域的边条数
            for ($i = 0; $i < $lineNum; $i++) {
                // y=kx+b : k
                if ($this->config[$k][$i]['longitude'] - $this->config[$k][$i + 1]['longitude'] == 0) $this->lines[$k][$i]['k'] = 0;
                else $this->lines[$k][$i]['k'] =
                    ($this->config[$k][$i]['latitude'] - $this->config[$k][$i + 1]['latitude']) / ($this->config[$k][$i]['longitude'] - $this->config[$k][$i + 1]['longitude']);
                // y=kx+b : b
                $this->lines[$k][$i]['b'] = $this->config[$k][$i + 1]['latitude'] - $this->lines[$k][$i]['k'] * $this->config[$k][$i + 1]['longitude'];
                $this->lines[$k][$i]['lx'] = min($this->config[$k][$i]['longitude'], $this->config[$k][$i + 1]['longitude']);
                $this->lines[$k][$i]['rx'] = max($this->config[$k][$i]['longitude'], $this->config[$k][$i + 1]['longitude']);
            }
            $pointNum -= 1;
            if ($this->config[$k][$pointNum]['longitude'] - $this->config[$k][0]['longitude'] == 0) $this->lines[$k][$pointNum]['k'] = 0;
            else $this->lines[$k][$pointNum]['k'] =
                ($this->config[$k][$pointNum]['latitude'] - $this->config[$k][0]['latitude']) / ($this->config[$k][$pointNum]['longitude'] - $this->config[$k][0]['longitude']);
            // y=kx+b : b
            $this->lines[$k][$pointNum]['b'] = $this->config[$k][0]['latitude'] - $this->lines[$k][$pointNum]['k'] * $this->config[$k][0]['longitude'];
            $this->lines[$k][$pointNum]['lx'] = min($this->config[$k][$pointNum]['longitude'], $this->config[$k][0]['longitude']);
            $this->lines[$k][$pointNum]['rx'] = max($this->config[$k][$pointNum]['longitude'], $this->config[$k][0]['longitude']);
        }
    }

    /*
        获取一组坐标中，x坐标最小值
    */
    private function getMinXInEachConfig($index)
    {
        $minX = 200;
        foreach ($this->config[$index] as $k => $v) {
            if ($v['longitude'] < $minX) {
                $minX = $v['longitude'];
            }
        }
        return $minX;
    }

    /*
        获取一组坐标中，y坐标最小值
    */
    private function getMinYInEachConfig($index)
    {
        $minY = 200;
        foreach ($this->config[$index] as $k => $v) {
            if ($v['latitude'] < $minY) {
                $minY = $v['latitude'];
            }
        }
        return $minY;
    }

    /*
        获取一组坐标中，x坐标最大值
    */
    public function getMaxXInEachConfig($index)
    {
        $maxX = 0;
        foreach ($this->config[$index] as $k => $v) {
            if ($v['longitude'] > $maxX) {
                $maxX = $v['longitude'];
            }
        }
        return $maxX;
    }

    /*
        获取一组坐标中，y坐标最大值
    */
    public function getMaxYInEachConfig($index)
    {
        $maxY = 0;
        foreach ($this->config[$index] as $k => $v) {
            if ($v['latitude'] > $maxY) {
                $maxY = $v['latitude'];
            }
        }
        return $maxY;
    }

    /*
        获取 y=y0 与特定区域的所有边的交点，并去除和顶点重复的，再将交点分为左和右两部分
    */
    private function getCrossPointInCertainConfig($index)
    {
        $crossPoint = ['left' => [], 'right' => []];
        foreach ($this->lines[$index] as $k => $v) {
            if ($v['k'] == 0) return true;
            $x0 = ($this->_y - $v['b']) / $v['k'];    // 交点x坐标
            if ($x0 == $this->_x) return true;        // 点在边上
            if ($x0 > $v['lx'] && $x0 < $v['rx']) {
                if ($x0 < $this->_x) $crossPoint['left'][] = $x0;
                if ($x0 > $this->_x) $crossPoint['right'][] = $x0;
            }
        }
        return $crossPoint;
    }

    /*
        检测一个点，是否在区域内
        返回结果：
            return === false : 点不在区域内
            return 0, 1, 2, 3 ... 点所在的区域编号（配置文件中的区域编号。）
    */
    public function checkPoint($lng, $lat)
    {
        $this->_x = $lng;
        $this->_y = $lat;
        $contain = null;
        foreach ($this->rectangles as $k => $v) {
            if ($lng > $v['maxX'] || $lng < $v['minX'] || $lat > $v['maxY'] || $lat < $v['minY']) {
                continue;
            } else {
                $contain = $k;
                break;
            }
        }
        if ($contain === null) return false;
        $crossPoint = $this->getCrossPointInCertainConfig($contain);
        if ($crossPoint === true) return $contain;
        if (count($crossPoint['left']) % 2 == 1 && count($crossPoint['right']) % 2 == 1) return $contain;
        return false;
    }

}