package foobar

import (
	"context"
	"errors"
)

// Controller is a base pattern controller
type Controller struct {
	ctx     context.Context
	workers sync.WaitGroup
	stopped chan struct{}
}

// New returns a initialized & started controller
func New(ctx context.Context) (c *Controller, err error) {
	if ctx == nil {
		err = errors.New("context can't be nill")
		return
	}
	// Init
	c = &Controller{
		ctx:     ctx,
		stopped: make(chan struct{}),
	}
	// Start workers
	c.workers.Add(1)
	go func() {
		c.workerA()
		c.workers.Done()
	}()
	c.workers.Add(1)
	go func() {
		c.workerB()
		c.workers.Done()
	}()
	// Create the auto-stopper (must be launch after the worker(s) in case ctx is cancelled while launching workers)
	go c.autostop()
	// Return the initialized & started controller
	return
}

func (c *Controller) autostop() {
	// Wait for signal
	<-c.ctx.Done()
	// Begin the stopping proceedure
	c.workers.Wait()
	// TODO: save some state ?
	// Close the stopped chan to indicate we are fully stopped
	close(c.stopped)
}

// WaitStopped will block until c is fully stopped.
// To be stopped, c needs to have its context cancelled.
// WaitStopped is safe to be called from multiples goroutines.
func (c *Controller) WaitStopped() {
	<-c.stopped
}