package main

import (
	"fmt"
	"log"
	"time"

	"github.com/hsblhsn/singleflight"
)

func main() {
	g := singleflight.NewGroup[int]()
	inputs := []int{0, 1, 1, 1, 2, 2, 2, 3, 3, 3}
	for _, v := range inputs {
		go func(input int) {
			key := fmt.Sprintf("key-%d", input)
			result, _, _ := g.Do(key, func() (int, error) {
				// simulate a slow function
				time.Sleep(time.Second)
				log.Println("[SLOW_FUNCTION_CALL]", input)
				return input * input, nil
			})
			log.Println("[OUTPUT]", input, result)
		}(v)
	}
	// wait for all goroutines to finish.
	// in real world this should be done by a sync.WaitGroup or similar.
	time.Sleep(2 * time.Second)
}