package main

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

// worker simulates a task that takes some time to complete
func worker(id int) {
    fmt.Printf("Worker %d starting\n", id)
    
    // Simulate expensive work
    time.Sleep(time.Second)
    
    fmt.Printf("Worker %d done\n", id)
}

func main() {
    // WaitGroup is used to wait for all goroutines launched here to finish
    var wg sync.WaitGroup

    // Launch 5 worker goroutines
    for i := 1; i <= 5; i++ {
        // Increment the WaitGroup counter BEFORE starting the goroutine
        wg.Add(1)

        // Wrap the worker call in a closure to handle the WaitGroup
        go func(id int) {
            // Defer Done() to ensure it runs even if the worker panics
            defer wg.Done()
            worker(id)
        }(i)
    }

    fmt.Println("Main: Waiting for workers to finish...")
    
    // Block until the WaitGroup counter goes back to 0
    wg.Wait()
    
    fmt.Println("Main: All workers completed")
}