package main

import (
	"context"
	"os"
	"os/signal"
	"syscall"
)

func concatSlices[T any](slices ...[]T) []T {
	var totalLen int

	for _, s := range slices {
		totalLen += len(s)
	}

	result := make([]T, totalLen)

	var i int

	for _, s := range slices {
		i += copy(result[i:], s)
	}

	return result
}

var shutdownSignals = []os.Signal{os.Interrupt, syscall.SIGTERM}

// newShutdownSignalContext returns a copy of the parent context that is marked done
// (its Done channel is closed) when one of the shutdownSignals arrives.
func newShutdownSignalContext(parent context.Context) (context.Context, context.CancelFunc) {
	return signal.NotifyContext(parent, shutdownSignals...)
}

func waitForShutdownSignal(ctx context.Context) {
	ctx, cancel := newShutdownSignalContext(ctx)
	defer cancel()
	<-ctx.Done()
}