app.js

var express = require('express')
  , multer = require('multer')
  , shortid = require('shortid')
  , level = require('level')
  , fs = require('fs')
  , hashFiles = require('hash-files')
  , RSVP = require('rsvp')
  , app = express()
  , db = level(__dirname + '/db/')

var getChecksum = function(fileName) {
  var promise = new RSVP.Promise(function(resolve) {
    hashFiles({files:[__dirname + '/uploads/' + fileName]}, function(err, hash) {
        if(!err) resolve(hash)
    });
  })
  
  return promise
}

var fileExists = function(fileHash) {
  var promise = new RSVP.Promise(function(resolve) {
    db.get(fileHash, function(err, value) {
        resolve(value)
    })
  })
  
  return promise
}

app.get('/', function (req, res) {
  res.send('sup')
})

app.get('/:file', function (req, res) {
  res.sendFile(req.params.file, {root:__dirname + '/uploads/'}, function(err) {
    if(err) res.status(404).send('sup')
  })
})

app.post('/api/upload',
  multer({
    dest: './uploads/',
    limits: {
      fileSize: 100000000
    },
    rename: function (fieldname, filename, req, res) {
      return shortid.generate()
    },
    onFileUploadComplete: function (file, req, res) {
      getChecksum(file.name)
        .then(function(fileHash) {
          return fileExists(fileHash)
        }).then(function(value) {
          if(value) {
            res.status(200).json({status:200,file:value})
            fs.unlinkSync(__dirname + '/uploads/' + file.name)
          } else {
            res.status(200).json({status:200,file:file.name})
            db.put(hashFiles.sync({files:[__dirname + '/uploads/' + file.name]}), file.name)
          }
        })
    }
  }), 
function (req, res) {
  res.status(400).json({status:400,err:'no file uploaded'})
})

app.get('*', function(req, res){
  res.status(404).send('sup')
});

app.listen(8081)