/**
 * 语义化时间转换  
 * @param {number} [timestamp] - 当前的时间，可传格式化的字符串或时间戳  
 */
function convertDate(timestamp=Date.now()){
    // pass in `yyyy-mm-dd hh:ii:ss`
    // convert to `yyyy-mm-ddThh:ii:ss.000+08:00`
    const targetTimestamp = Number(timestamp) ? timestamp : Date.parse(`${timestamp.split(' ').join('T')}.000+08:00`);
    const diff = new Date().getTime() - targetTimestamp;
    let time = '';
    //小于5分钟->刚刚
    if(diff < 5*60*1000){
        time = '刚刚';
    }
    //小于1小时->xx分钟前
    else if(diff < 1*60*60*1000){
        time = parseInt(diff/1000/60) + '分钟前';
    }
    //小于24小时->xx小时前
    else if(diff < 24*60*60*1000){
        time = parseInt(diff/1000/60/60) + '小时前';
    }
    //小于30天->xx天前
    else if(diff < 30*24*60*60*1000){
        time = parseInt(diff/1000/60/60/24) < 2 ? '昨天' : (parseInt(diff/1000/60/60/24) + '天前');
    }
    //小于1年->xx个月前
    else if(diff < 365*24*60*60*1000){
        time = parseInt(diff/1000/60/60/24/30) + '个月前';
    }
    //x年x月前
    else{
        let days = parseInt(diff/1000/60/60/24);
        time = parseInt(days/365) + '年' + (parseInt(days%365/30) ? (parseInt(days%365/30) + '个月前') : '前');
    }
    return time;
};

/**
 * 时间戳转化为日期
 * @param {string} [formateString] 要转化的格式，默认 'y-m-d h:i:s'
 * @param {number} [timestamp] 要转化的时间戳，默认 Date.now()
 * @returns {string} 格式化后的日期
 */
function timestampToDate(formateString='y-m-d h:i:s', timestamp=Date.now()){
    if(isNaN(+timestamp)){
        console.error('util.timeStampToDate: timestamp is invilid.');
        return null;
    }
    if(String(timestamp).length === 10){
        timestamp *= 1000;
    }
    const reg = /y|m|d|h|i|s/g;
    const date = new Date(+timestamp);
    const saithToDual = time => {
        if(time.toString().length < 2){
            time = '0' + time;
        }
        return time;
    };

    return formateString.replace(reg, function($1){
        switch($1){
            case 'y':
                return date.getFullYear();
            case 'm':
                return saithToDual(date.getMonth() + 1);
            case 'd':
                return saithToDual(date.getDate());
            case 'h':
                return saithToDual(date.getHours());
            case 'i':
                return saithToDual(date.getMinutes());
            case 's':
                return saithToDual(date.getSeconds());
        }
        return $1;
    });
};

module.exports = {
    convertDate,
    timestampToDate
};