package app

import (
	"syscall"
	"testing"
	"time"
)

// TestParentExitKillsDescendants verifies that when a parent process
// exits, every still-live process that was spawned under it is signaled
// and dies, recursively through the tree.
func TestParentExitKillsDescendants(t *testing.T) {
	sess := NewSession(t.TempDir(), "test")

	// Use a tiny pause-then-trap shell so the children survive long
	// enough for the parent to die first; SIGTERM should terminate them.
	sleepArgv := []string{"sh", "-c", "trap 'exit 0' TERM; sleep 30"}

	parent, err := sess.Spawn(SpawnSpec{
		Kind: KindTerminal,
		Argv: []string{"sh", "-c", "sleep 30"},
	}, 80, 24)
	if err != nil {
		t.Fatalf("spawn parent: %v", err)
	}

	childA, err := sess.Spawn(SpawnSpec{
		Kind:     KindCommand,
		Argv:     sleepArgv,
		ParentID: parent.ID,
	}, 80, 24)
	if err != nil {
		t.Fatalf("spawn childA: %v", err)
	}
	grandchild, err := sess.Spawn(SpawnSpec{
		Kind:     KindCommand,
		Argv:     sleepArgv,
		ParentID: childA.ID,
	}, 80, 24)
	if err != nil {
		t.Fatalf("spawn grandchild: %v", err)
	}

	// Wait for everyone to be running.
	waitUntilLive(t, parent)
	waitUntilLive(t, childA)
	waitUntilLive(t, grandchild)

	// Kill the parent. Its reapChild should cascade to childA, whose
	// reapChild should in turn cascade to grandchild.
	if err := parent.signal(syscall.SIGTERM); err != nil {
		t.Fatalf("signal parent: %v", err)
	}

	waitUntilNotLive(t, parent)
	waitUntilNotLive(t, childA)
	waitUntilNotLive(t, grandchild)
}

func waitUntilLive(t *testing.T, c *Child) {
	t.Helper()
	deadline := time.Now().Add(5 * time.Second)
	for time.Now().Before(deadline) {
		if c.IsLive() {
			return
		}
		time.Sleep(20 * time.Millisecond)
	}
	t.Fatalf("child %s never went live", c.ID)
}

func waitUntilNotLive(t *testing.T, c *Child) {
	t.Helper()
	deadline := time.Now().Add(5 * time.Second)
	for time.Now().Before(deadline) {
		if !c.IsLive() {
			return
		}
		time.Sleep(20 * time.Millisecond)
	}
	t.Fatalf("child %s still live after parent died (status=%s)", c.ID, c.Status())
}