//File System
var fs = require('fs');
//fd is the file descriptor used by the WriteStream.
var logFd;
//日志文件
var log = 'i_access.log';
//读取过程需要的
var buf,
	logSize,
	start = 0,
	length,
	offse = 0,
	logArr = '',
	LENGHT = 1024 * 1024;//每次读取的长度，1M
 
//读取文件信息，获取文件长度
fs.stat(log, function(err, stats){
	if(err) throw err;
//	console.log(JSON.stringify(stats));
	logSize = stats.size;
	//打开文件
	fs.open(log, 'r', 0666, function(err, fd){
		if(err) throw err;
		logFd = fd;
		length = LENGHT < (logSize - offse) ? LENGHT : (logSize - offse);
		buf = new Buffer(length);
		//日志读取
		readLog();
	});
});
//日志读取
function readLog(){
	//读取
	fs.read(logFd, buf, start, length, offse, function(err){
		if(err) throw err;
		//按行切分
		logArr = buf.toString('utf8').split('\n');
		var last = false;
		//判断是否是最后一次调用
		if(offse + length < logSize){
			//最后一行不完整，抛掉，下次在取
			last = logArr.pop();
		}
		//调用日志分析模块，对logArr做处理
		logAnalysis();
		//处理参数，准备下次调用
		if(last !== false){
			offse += length - last.length;
			length = LENGHT < (logSize - offse) ? LENGHT : (logSize - offse);
			buf = new Buffer(length);
			//递归读取
			if(!lastRead){
				readLog();
			}
		}
	});
}
//日志分析模块
function logAnalysis(){
	//TODO:日志分析与读取......
	console.log(logArr.length);
	console.log(logArr[0]);
	console.log(logArr[logArr.length - 1]);
	console.log('------');
}