function random(a = 1, b = 100, num = 1) {
    if (num === 1) {
        return randomOne();
    } else {
        let arr = [];
        for (let i = 0; i < num; i++) {
            arr.push(randomOne());
        }
        return arr;
    }

    function randomOne() {
        let rand = Math.random();
        return Math.ceil((a + ((b - a) * rand)));
    }
}

module.exports = function (req, res) {
    const data = "{\
        backgroundColor: new echarts.graphic.RadialGradient("+ `${Math.random()},${Math.random()},${Math.random()}` + ", [{\
            offset: 0,\
            color: '#f7f8fa'\
        }, {\
            offset: 1,\
            color: '#cdd0d5'\
        }]),\
        title: {\
            text: '1990 与 2015 年各国家人均寿命与 GDP'\
        },\
        legend: {\
            right: 10,\
            data: ['1990', '2015']\
        },\
        xAxis: {\
            splitLine: {\
                lineStyle: {\
                    type: 'dashed'\
                }\
            }\
        },\
        yAxis: {\
            splitLine: {\
                lineStyle: {\
                    type: 'dashed'\
                }\
            },\
            scale: true\
        },\
        series: [{\
            name: '1990',\
            data: [[28604,77,17096869,'Australia',1990],[31163,77.4,27662440,'Canada',1990],[1516,68,1154605773,'China',1990],[13670,74.7,10582082,'Cuba',1990],[28599,75,4986705,'Finland',1990],[29476,77.1,56943299,'France',1990],[31476,75.4,78958237,'Germany',1990],[28666,78.1,254830,'Iceland',1990],[1777,57.7,870601776,'India',1990],[29550,79.1,122249285,'Japan',1990],[2076,67.9,20194354,'North Korea',1990],[12087,72,42972254,'South Korea',1990],[24021,75.4,3397534,'New Zealand',1990],[43296,76.8,4240375,'Norway',1990],[10088,70.8,38195258,'Poland',1990],[19349,69.6,147568552,'Russia',1990],[10670,67.3,53994605,'Turkey',1990],[26424,75.7,57110117,'United Kingdom',1990],[37062,75.4,252847810,'United States',1990]],\
            type: 'scatter',\
            symbolSize: function (data) {\
                return Math.sqrt(data[2]) / 5e2;\
            },\
            label: {\
                emphasis: {\
                    show: true,\
                    formatter: function (param) {\
                        return param.data[3];\
                    },\
                    position: 'top'\
                }\
            },\
            itemStyle: {\
                normal: {\
                    shadowBlur: 10,\
                    shadowColor: 'rgba(120, 36, 50, 0.5)',\
                    shadowOffsetY: 5,\
                    color: new echarts.graphic.RadialGradient(0.4, 0.3, 1, [{\
                        offset: 0,\
                        color: 'rgb(251, 118, 123)'\
                    }, {\
                        offset: 1,\
                        color: 'rgb(204, 46, 72)'\
                    }])\
                }\
            }\
        }, {\
            name: '2015',\
            data: [[44056,81.8,23968973,'Australia',2015],[43294,81.7,35939927,'Canada',2015],[13334,76.9,1376048943,'China',2015],[21291,78.5,11389562,'Cuba',2015],[38923,80.8,5503457,'Finland',2015],[37599,81.9,64395345,'France',2015],[44053,81.1,80688545,'Germany',2015],[42182,82.8,329425,'Iceland',2015],[5903,66.8,1311050527,'India',2015],[36162,83.5,126573481,'Japan',2015],[1390,71.4,25155317,'North Korea',2015],[34644,80.7,50293439,'South Korea',2015],[34186,80.6,4528526,'New Zealand',2015],[64304,81.6,5210967,'Norway',2015],[24787,77.3,38611794,'Poland',2015],[23038,73.13,143456918,'Russia',2015],[19360,76.5,78665830,'Turkey',2015],[38225,81.4,64715810,'United Kingdom',2015],[53354,79.1,321773631,'United States',2015]],\
            type: 'scatter',\
            symbolSize: function (data) {\
                return Math.sqrt(data[2]) / 5e2;\
            },\
            label: {\
                emphasis: {\
                    show: true,\
                    formatter: function (param) {\
                        return param.data[3];\
                    },\
                    position: 'top'\
                }\
            },\
            itemStyle: {\
                normal: {\
                    shadowBlur: 10,\
                    shadowColor: 'rgba(25, 100, 150, 0.5)',\
                    shadowOffsetY: 5,\
                    color: new echarts.graphic.RadialGradient(0.4, 0.3, 1, [{\
                        offset: 0,\
                        color: 'rgb(129, 227, 238)'\
                    }, {\
                        offset: 1,\
                        color: 'rgb(25, 183, 207)'\
                    }])\
                }\
            }\
        }]\
      }";

    res.json({
        status: 0,
        msg: 'ok',
        data
    });
}