server.js

// Create an app
const fs = require("fs")
const server = require('diet')
const exec = require('child_process').exec
const { k2pdfoptPath } = require('./k2pdfopt.js')
const TempDir = '/tmp/rayk/'

app = server()

newFiles = []
spawnedProcesses = {}

function createTemp() {
  // Creates the temp directory
  exec("mkdir -p " + TempDir)
}

function deleteTemp() {
  // Deletes the temp directory
  exec("rm -rf " + TempDir)
}

app.post('/cancel', function($) {
  data = JSON.parse($.body)

  fileToDelete = data.fileToDelete
  console.log(data);
  // for (i = 0, p = spawnedProcesses[i]; p; i ++) {
  //   console.log(data)
  //   p.kill()
  // }
  i = null
  for (i in newFiles) {
     f = newFiles[i]
     if (f.path === fileToDelete.path) {
       spawnedProcesses[f.path].kill()
       break
     }
  }
  if (i) {
    newFiles.splice(i, 1)
  }
  $.end('Success')

})

app.post('/convert', function($) {
  data = JSON.parse($.body)
  console.log(data)

  newFiles = []
  for (i in data.files) {
    f = data.files[i]
    console.log('Converting ' + f.path)
    newPath = TempDir + f.name + '_converted.pdf'
    command = k2pdfoptPath + ' "' + f.path + '" -ui- -x -a- -o "' + newPath + '"'
    f.newPath = newPath
    spawnedProcess = exec(command)
    spawnedProcesses[f.path] = spawnedProcess
    console.log(spawnedProcess.pid)
    f.convertData = {
      bufferedOutput: '',
      bufferedError: '',
      status: null
    }
  f.sentToKindle = false

    spawnedProcess.stdout.on('data', function(tempObj) {
      return function(data) {
        // console.log('stdout: ' + tempObj.name + data)
        tempObj.convertData.bufferedOutput += '' + data;
      }
    }(f))

    spawnedProcess.stderr.on('data', function(tempObj) {
      return function(error) {
        console.log('stderr: ' + tempObj.name + JSON.stringify(data))
        tempObj.convertData.bufferedError += '' + JSON.stringify(data);
      }
    }(f))

    spawnedProcess.on('close', function(tempObj) {
      return function(code) {
        if (code !== 0) {
          tempObj.convertData.status = 'failed'
        } else {
          tempObj.convertData.status = 'done'
        }
      }
    }(f))

    newFiles.push(f)
  }
  $.end('Success')
})

app.get('/get_status', function($) {
  if (newFiles)
    $.end(JSON.stringify(newFiles))
})

app.get('/send_files', function($) {
	// Copies files to Kindle
  if (newFiles) {
    for (i in newFiles) {
      f = newFiles[i];
      if (f.convertData.status === "done" && !f.sentToKindle) {
		console.log(fs)
		fs.copyFile(f.newPath, "/Volumes/Kindle/documents/" + f.name, (err) => {
		  if (err) {
		    console.log(err);
		  }
          else {
		    f.sentToKindle = true
		  }
		});
      }
    }
  }
  $.end("Success")
})

app.get("/cleanup", function($) {
	// Refreshes state for new file conversion
	deleteTemp()
	createTemp()
	for (i in newFiles) {
		proc = spawnedProcess[newFiles[i].path]
		if (proc) proc.kill()
	}
	newFiles = []
	spawnedProcess = []
	$.end("Success")
})

// Set exit function
process.on('message', (msg) => {
  if (msg == 'exit') {
    process.exit()
  }
})

process.on('createTemp', createTemp)
process.on('deleteTemp', deleteTemp)

function startServer() {
  app.listen('http://localhost:8000')
}
startServer();