Qquanwei/Koa video stream server

## Koa video stream server
"use strict"
let koa = require('koa');
let Router = require('koa-router');
let fs = require('fs');
let assert = require('http-assert');
let sscanf = require('scanf').sscanf;


let app = new koa();
let router = new Router();
let hash_streams = {} ;

//partial size
const SEED_SIZE = 5*1024*1024;


router.get('/file',function*(ctx,next){
  assert(this.query.filename,400,'Can\'t find the file');
  const self = this;
  const filename = this.query.filename;
  const range = sscanf(this.request.header.range,'bytes=%d-%d\r\n','begin','end');

  yield new Promise(function(resolve,done){
    fs.stat(filename,function(err,stat){
      assert(!err,404,'Nothing!');
      range.begin = range.begin || 0;
      range.end =Math.min( range.end || (range.begin + SEED_SIZE ),stat.size-1);
      assert(range.begin < range.end,403,`${range.begin} ${range.end}`);

      let stream = null;

      //if(!(filename in hash_streams))
      stream =   fs.createReadStream(filename,{start: range.begin,end: range.end,autoClose: true });

      self.set('Cache-Control','no-cache');
      self.set('Content-Range',`bytes ${range.begin}-${range.end}/${stat.size}`);
      self.set('Content-Length',range.end-range.begin+1);
      self.set('Date',Date());
      self.set('ETag',Date.now().toString());
      self.set('Expires',new Date(Date.now()+24*60*60*1000));
      self.set('Content-type','text/plain');
      self.body = stream;
      self.status = 206;
      resolve('done');
    });
  });
});

app.use(function*(next){
  try{
    yield next;
  }catch(e){
    this.status = 403;
    this.body = e.message;
  }
});
app.use(router.routes());

const start = function(cb){
  return app.listen(1333,'127.0.0.1',cb);
}


module.exports = {
  start
}
	"use strict"
	let koa = require('koa');
	let Router = require('koa-router');
	let fs = require('fs');
	let assert = require('http-assert');
	let sscanf = require('scanf').sscanf;


	let app = new koa();
	let router = new Router();
	let hash_streams = {} ;

	//partial size
	const SEED_SIZE = 510241024;


	router.get('/file',function*(ctx,next){
	assert(this.query.filename,400,'Can\'t find the file');
	const self = this;
	const filename = this.query.filename;
	const range = sscanf(this.request.header.range,'bytes=%d-%d\r\n','begin','end');

	yield new Promise(function(resolve,done){
	fs.stat(filename,function(err,stat){
	assert(!err,404,'Nothing!');
	range.begin = range.begin \|\| 0;
	range.end =Math.min( range.end \|\| (range.begin + SEED_SIZE ),stat.size-1);
	assert(range.begin < range.end,403,`${range.begin} ${range.end}`);

	let stream = null;

	//if(!(filename in hash_streams))
	stream = fs.createReadStream(filename,{start: range.begin,end: range.end,autoClose: true });

	self.set('Cache-Control','no-cache');
	self.set('Content-Range',`bytes ${range.begin}-${range.end}/${stat.size}`);
	self.set('Content-Length',range.end-range.begin+1);
	self.set('Date',Date());
	self.set('ETag',Date.now().toString());
	self.set('Expires',new Date(Date.now()+246060*1000));
	self.set('Content-type','text/plain');
	self.body = stream;
	self.status = 206;
	resolve('done');
	});
	});
	});

	app.use(function*(next){
	try{
	yield next;
	}catch(e){
	this.status = 403;
	this.body = e.message;
	}
	});
	app.use(router.routes());

	const start = function(cb){
	return app.listen(1333,'127.0.0.1',cb);
	}


	module.exports = {
	start
	}