package main

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

// simulateWork simulates a task that takes some time.
func simulateWork(id int, wg *sync.WaitGroup) {
	defer wg.Done()
	fmt.Printf("Worker %d starting...
", id)
	time.Sleep(time.Duration(id%3+1) * 100 * time.Millisecond) // Simulate varying work
	fmt.Printf("Worker %d finished.
", id)
}

func main() {
	maxConcurrency := 3 // Limit to 3 concurrent goroutines
	semaphore := make(chan struct{}, maxConcurrency)
	var wg sync.WaitGroup

	fmt.Printf("Starting %d tasks with max concurrency of %d.
", 10, maxConcurrency)

	for i := 1; i <= 10; i++ {
		semaphore <- struct{}{} // Acquire a slot in the semaphore (blocks if full)
		wg.Add(1)
		go func(taskID int) {
			defer func() {
				<-semaphore // Release the slot after the goroutine finishes
			}()
			simulateWork(taskID, &wg)
		}(i)
	}

	wg.Wait() // Wait for all tasks to complete
	fmt.Println("All tasks completed.")
}