package main

import (
	"fmt"
	"sync"
	"time"
)

// worker simulates a task that takes some time
func worker(id int, semaphore chan struct{}, wg *sync.WaitGroup) {
	defer wg.Done()

	// Acquire a slot from the semaphore
	semaphore <- struct{}{} 
	fmt.Printf("Worker %d: Acquired semaphore, starting task...
", id)

	// Simulate work
	time.Sleep(time.Duration(2 + (id % 3)) * time.Second) // 2, 3, or 4 seconds

	fmt.Printf("Worker %d: Task finished.
", id)
	// Release the slot back to the semaphore
	<-semaphore 
}

func main() {
	const maxConcurrency = 3
	const totalTasks = 10

	// Create a buffered channel to act as a semaphore
	// Its capacity limits the number of concurrent goroutines
	semaphore := make(chan struct{}, maxConcurrency)
	var wg sync.WaitGroup

	fmt.Printf("Main: Starting %d tasks with a maximum concurrency of %d.
", totalTasks, maxConcurrency)

	for i := 1; i <= totalTasks; i++ {
		wg.Add(1)
		go worker(i, semaphore, &wg)
	}

	wg.Wait() // Wait for all workers to complete

	fmt.Println("Main: All tasks completed.")
}