package main

import (
	"fmt"
	"time"
)

// worker simulates a task that sometimes needs to respond to urgent control signals.
func worker(dataCh <-chan string, controlCh <-chan string, done chan<- bool) {
	for {
		select {
		case msg := <-controlCh: // Priority 1: Always check control signals first
			fmt.Printf("Worker: !!! URGENT Control received: %s !!!
", msg)
			if msg == "stop" {
				fmt.Println("Worker: Stopping due to control signal.")
				done <- true
				return
			}
		case data := <-dataCh: // Priority 2: Process data if no control signal
			fmt.Printf("Worker: Processing data: %s
", data)
			time.Sleep(50 * time.Millisecond) // Simulate work
		case <-time.After(200 * time.Millisecond): // Priority 3: Do something if no messages for a while
			fmt.Println("Worker: Idle, performing routine check...")
		}
	}
}

func main() {
	dataChannel := make(chan string)
	controlChannel := make(chan string)
	doneChannel := make(chan bool)

	go worker(dataChannel, controlChannel, doneChannel)

	// Send some data
	go func() {
		for i := 0; i < 5; i++ {
			dataChannel <- fmt.Sprintf("DataItem-%d", i+1)
			time.Sleep(70 * time.Millisecond)
		}
	}()

	// Send an urgent control signal later
	go func() {
		time.Sleep(300 * time.Millisecond)
		controlChannel <- "pause"
		time.Sleep(200 * time.Millisecond)
		controlChannel <- "status_report"
		time.Sleep(400 * time.Millisecond)
		controlChannel <- "stop" // This should cause the worker to exit
	}()

	// Wait for the worker to signal completion
	<-doneChannel
	fmt.Println("Main: Worker has completed its task.")
	close(dataChannel)
	close(controlChannel)
	close(doneChannel) // Not strictly necessary after receive, but good practice
	time.Sleep(50 * time.Millisecond) // Give time for goroutines to clean up
	fmt.Println("Main: Application finished.")
}