const Tasker = require('@dataparty/tasker')
  const Task = Tasker.Task
  const TaskRunner = Tasker.Runner
  
  function delayedResolve(value){
    return new Promise((resolve,reject)=>{
      setTimeout(()=>{resolve(value)}, Math.random()*9000)
    })
  }
  
  let taskA = new Task({
    name: 'a',
    depends: ['b', 'd'],
    exec: ()=>{return delayedResolve('aA') }
  })
  
  let taskB = new Task({
    name: 'b',
    exec: ()=>{ return delayedResolve('bB') }
  })
  
  let taskC = new Task({
    name: 'c',
    exec: ()=>{ return delayedResolve('cC') }
  })
  
  let taskD = new Task({
    name: 'd',
    depends: ['c'],
    exec: ()=>{ return delayedResolve('dD') }
  })
  
  let taskE = new Task({
    name: 'e',
    exec: ()=>{ return delayedResolve('eE') }
  })
  
  let runner = new TaskRunner()
  
  runner.addTask(taskA)
  runner.addTask(taskB)
  runner.addTask(taskC)
  runner.addTask(taskD)
  runner.addTask(taskE)
  
  
  let order = runner.runOrder
  
  console.log(order)
  
  let logDone = function(task){
    console.log('\t done task - ', task.name)
  }
  
  let logRunning = function(task){
    console.log('\t run task - ', task.name)
  }
  
  taskA.on('running', logRunning)
  taskB.on('running', logRunning)
  taskC.on('running', logRunning)
  taskD.on('running', logRunning)
  taskE.on('running', logRunning)
  
  taskA.on('done', logDone)
  taskB.on('done', logDone)
  taskC.on('done', logDone)
  taskD.on('done', logDone)
  taskE.on('done', logDone)
  
  runner.on('running', ()=>{ console.log('running TaskRunner - ',runner.taskOrder) })
  runner.on('idle', ()=>{ console.log('idle TaskRunner - ',runner.taskOrder) })
  
  runner.start().then(console.log).catch(console.log)