import { spawn } from 'child_process'
import interpreters from './interpreters'
import modules from './modules'
import kill from 'tree-kill'
import { remote } from './remote'
import { set_connected } from './rpc'
import uuidv1 from 'uuid/v1'

import * as q from './queue'

const idle_state = { status: 'IDLE', task: {} }

export const state = {
	current_cpu_task: idle_state,
	current_gpu_task: idle_state,
}

export function status() {
  return {
    cpu: serialize_task(state.current_cpu_task),
    gpu: serialize_task(state.current_gpu_task),
  }
}

export function get_current_cpu_task(){
	return state.current_cpu_task
}

export function get_current_gpu_task(){
	return state.current_gpu_task
}

export function get_current_task(processor) {
  if (processor === 'cpu') {
    return state.current_cpu_task
  } else {
    return state.current_gpu_task
  }
}

function serialize_task(t){
  if (!t || t.status === 'IDLE') {
    return {
      status: 'IDLE',
    }
  }
  if (!t.subprocess) {
    // TODO: figure out why there's no subprocess here
    return {
      status: 'IDLE',
    }
  }
  return {
    status: 'RUNNING',
    task: t.task,
    uuid: t.task.uuid,
    pid: t.subprocess.pid,
  }
}

function clear_task(is_gpu, task){
  if (is_gpu) {
    if (state.current_gpu_task.task && state.current_gpu_task.task.uuid === task.uuid) {
      state.current_gpu_task.processor = null
      state.current_gpu_task = idle_state
    }
  } else {
    if (state.current_cpu_task.task && state.current_cpu_task.task.uuid === task.uuid) {
      state.current_gpu_task.processor = null
      state.current_cpu_task = idle_state
    }
  }
}

export function build_params(module, activity, task) {
	const interpreter = interpreters[activity.type]
  let opt_params, activity_params;
	if (typeof activity.params === 'function') {
		opt_params = activity.params(task)
    if (opt_params === 'CANCEL') {
      return { cancelled: true };
    }
    activity_params = []
	}
	else {
		const opt = task.opt || {}
		opt_params = Object.keys(opt).map(key => {
			const flag = '--' + key.replace(/-/g, '_')
			const value = opt[key]
			if (value === 'true') {
				return [flag]
			}
			return [flag, value]
		}).reduce((acc, cur) => acc.concat(cur), [])
    activity_params = activity.params
	}
  const params = (interpreter.params || [])
    .concat([ activity.script ])
    .concat(activity_params)
    .concat(opt_params)
	return {
		activity,
    interpreter,
		params
	}
}

export function get_processor(task){
  if (! task) return null
  const module = modules[task.module]
  if (! module) return null
  const activity = module.activities[task.activity]
  if (! activity) return null
  const interpreter = interpreters[activity.type]
  return interpreter.gpu ? 'gpu' : 'cpu'
}

export function get_queue(task){
  const processor = get_processor(task)
  if (!processor) return null
  return (processor === 'cpu') ? q.cpu : q.gpu
}

export function run_task(task, preempt=false, watch=false){
  if (! task) return null
	const module = modules[task.module]
	if (! module) return { type: 'error', error: "No such module: " + task.module }
  const activity = task.activity_object || module.activities[task.activity]
  delete task.activity_object
  if (! activity) return { type: 'error', error: 'No such activity in module: ' + task.module + ' ' + task.activity }
  return run_task_with_activity(task, module, activity, preempt, watch)
}

export function run_task_with_activity(task, module, activity, preempt=false, watch=false) {
	const { interpreter, params, cancelled } = build_params(module, activity, task)
  if (cancelled) return finish({ type: 'task_error', task, err: "Task generator cancelled task", })
  if (! interpreter) return { type: 'error', error: "No such interpreter: " + activity.interpreter }

  if (interpreter.gpu && state.current_gpu_task.status !== 'IDLE') {
    if (preempt) {
      console.log('preempting currently running GPU task')
      terminate(state.current_gpu_task)
    } else {
      console.log('already running GPU task :(', state.current_gpu_task.pid)
      return { type: 'error', busy: true, preempt: false, error: 'task already running on gpu' }
    }
  } else if (!interpreter.gpu && state.current_cpu_task.status !== 'IDLE') {
    if (preempt) {
      console.log('preempting currently running CPU task')
      terminate(state.current_cpu_task)
    } else {
      console.log('already running CPU task :(')
      return { type: 'error', busy: true, preempt: false, error: 'task already running on cpu' }
    }
  }

	console.log('running task', task.activity)
  console.log(module.cwd)
	console.log(interpreter.cmd, params)

  task.uuid = task.uuid || uuidv1()
  task.started = new Date().toString()
  task.processing = true
	const subprocess = spawn(interpreter.cmd, params, {
    cwd: module.cwd,
    env: module.env || {},
  })
	if (interpreter.gpu) {
		state.current_gpu_task = {
      subprocess, task, status: 'RUNNING'
    }
	}
	else {
    state.current_cpu_task = {
      subprocess, task, status: 'RUNNING'
    }
	}
  
  const processor = task.processor = interpreter.gpu ? 'gpu' : 'cpu'
  remote.emit('task_res', { type: 'task_begin', task })
  
  watch && console.log("watching stdout..")

  let count = 0
  subprocess.stdout.on('data', buf => {
    const data = buf.toString('utf8')
    watch && remote.emit('task_res', { type: 'stdout', processor, data })
    if (activity.listen) {
      const res = activity.listen(task, data, count++)
      if (res) remote.emit('task_res', res)
    }
  })
  subprocess.stderr.on('data', buf => {
    const data = buf.toString('utf8')
    watch && remote.emit('task_res', { type: 'stderr', processor, data })
    if (activity.listen) {
      const res = activity.listen(task, data, count++)
      if (res) remote.emit('task_res', res)
    }
  })

  let finished = false
	
  subprocess.on('error', (err) => {
    if (finished) return console.log('already finished')
    finished = true
    task.processing = false
    task.completed = true
    task.success = false
		console.log('>>> task error', subprocess.exitCode, err)
    finish({
      type: 'task_error',
      task, err,
    })
	})

	subprocess.on('close', () => {
    if (finished) return console.log('already finished')
    finished = true
		console.log('>>> task ended', subprocess.exitCode || '')
    task.processing = false
    task.completed = true
    task.success = true
    finish({
      type: 'task_finish',
      task,
    })
	})

  function finish (task_res) {
    remote.emit('task_res', task_res)
    interpreter && clear_task(interpreter.gpu, task_res.task)
    set_connected(false)
    // remove task from queue..?
    // queue.remove_task(task)
    console.log('success?', task.success, activity)
    if (task.success && activity.after) {
      if (activity.after in modules[task.module].activities) {
        const after_activity = modules[task.module].activities[activity.after]
        const task_result = run_task_with_activity(task, module, after_activity, preempt, watch)
        if (task_result.busy) {
          task.activity_object = after_activity
          const interpreter = interpreters[activity.type]
          if (interpreter.gpu) {
            q.gpu.add_next_task(task)
          } else {
            q.cpu.add_next_task(task)
          }
        }
        return task_result
      } else {
        console.warn('no such after activity:', task.module, activity.after)
      }
    }
    return run_next_task()
  }

  return task
}

export function start_queue () {
  console.log('starting queue!')
  const res = run_next_task()
  console.log(res)
}

export function run_next_task () {
  const status = [q.cpu, q.gpu].map(queue => {
    const status = queue.processor === 'gpu' ? state.current_gpu_task.status : state.current_cpu_task.status
    console.log(queue.is_active(), status)
    if (queue.is_active() && status === 'IDLE') {
      console.log(queue.processor, "is free")
      const task = queue.get_next_task()
      return run_task(task, false, true)
    } else {
      console.log(queue.processor, "is busy")
      return { processor: queue.processor, status: 'busy' }
    }
  })
  return status
}

export function stop_task (task, sigkill) {
  if (!task) return { error: 'no such task' }
  if (task === 'cpu' || (task.uuid && state.current_cpu_task.task.uuid === task.uuid)) {
    console.log('stop cpu task')
    terminate(state.current_cpu_task, sigkill)
    return { status: 'ok' }
  } else if (task === 'gpu' || (task.uuid && state.current_gpu_task.task.uuid === task.uuid)) {
    console.log('stop gpu task')
    terminate(state.current_gpu_task, sigkill)
    return { status: 'ok' }
  }
  console.log('no task to kill')
  return { error: 'no such task' }
}

export function terminate (processor, sigkill=false) {
  if (!processor || !processor.subprocess) {
    console.log('nothing running on', processor)
    return
  }
  console.log('kill pid', processor.subprocess.pid)
  processor.task.cancelled = true
  if (sigkill) {
    kill(processor.subprocess.pid, 'SIGKILL', err => {
      if (err) {
        console.error(err)
      }
      else {
        console.log('process killed via SIGKILL -', processor.subprocess)
        processor.subprocess = null
      }
    })
  } else {
    kill(processor.subprocess.pid, 'SIGTERM', err => {
      if (err) {
        console.log(err)
      }
      else {
        console.log('process killed via SIGTERM -', processor.subprocess)
        processor.subprocess = null
      }
    })
  }
}