//获取当前的地理位置
function getLocation(callback) {
    wx.getLocation({
        success: function(res) {
        	callback(true, res.latitude, res.longitude);
        },
        fail: function() {
        	callback(false);
        }
    })
}

//根据darksky.net接口获取天气信息
function getWeatherByLocation(latitude, longitude, callback) {
    var apiKey = "cb4b12e15af2771d497f762476d754f5";
    var apiURL = "https://api.darksky.net/forecast/" + apiKey + "/" + latitude + "," + longitude + "?lang=zh&units=ca";
    
    wx.request({
        url: apiURL,
        success: function(res){
 
            var weatherData = parseWeatherData(res.data);
       
            getCityName(latitude, longitude, function(city){
                weatherData.city = city;
                callback(weatherData);
            });
        }
    });
}

//Reverse Geocoding 根据经纬度获取城市名称
function getCityName(latitude, longitude, callback) {
    var apiURL = "http://api.map.baidu.com/geocoder?output=json&location="+ latitude + "," + longitude + "&key=37492c0ee6f924cb5e934fa08c6b1676";
    wx.request({
        url: apiURL,
        success: function(res) {
            callback(res.data["result"]["addressComponent"]["city"]);
        }
    });
}

//取得我们需要的数据并重组成新的结果
function parseWeatherData(data) {
    var weather = {};
    weather["current"] = data.currently;
    weather["daily"] = data.daily;
    return weather;
}

//加载天气数据
function requestWeatherData(cb) {
    getLocation(function(success, latitude, longitude){
      //如果 GPS 信息获取不成功， 设置一个默认坐标
      if(success == false) {
          latitude = 0;
          longitude = 0;
      }
      //请求天气数据 API
      getWeatherByLocation(latitude, longitude, function(weatherData){
            cb(weatherData);
      });
    });
}
//将时间戳格式化为日期
function formatDate(timestamp) {
    var date = new Date(timestamp * 1000);
    return date.getMonth()+1 + "月" + date.getDate() + "日 " + formatWeekday(timestamp);
}
//将时间戳格式化为时间
function formatTime(timestamp) {
    var date = new Date(timestamp * 1000);
    return date.getHours() + ":" + date.getMinutes();
}
//中文形式的每周日期
function formatWeekday(timestamp) {
    var date = new Date(timestamp * 1000);
    var weekday = ["周日", "周一", "周二", "周三", "周四", "周五", "周六"];
    var index = date.getDay();
    return weekday[index];
}
function loadWeatherData(callback) {
    requestWeatherData(function(data){
      
      //对原始数据做一些修整， 然后输出给前端
      var weatherData = {};
      weatherData = data;      
      weatherData.current.formattedDate = formatDate(data.current.time);
      weatherData.current.formattedTime = formatTime(data.current.time);
      weatherData.current.temperature = parseInt(weatherData.current.temperature);
      var wantedDaily = [];
      for(var i = 1;i < weatherData.daily.data.length;i++) {
        
        var wantedDailyItem = weatherData.daily.data[i];
        var time = weatherData.daily.data[i].time;
        wantedDailyItem["weekday"] = formatWeekday(time);
        wantedDailyItem["temperatureMin"] = parseInt(weatherData.daily.data[i]["temperatureMin"])
        wantedDailyItem["temperatureMax"] = parseInt(weatherData.daily.data[i]["temperatureMax"])
        
        wantedDaily.push(wantedDailyItem);
      }      
      weatherData.daily.data = wantedDaily;
      callback(weatherData);
    });
}

module.exports = {
    loadWeatherData: loadWeatherData
}