package tentacle

import (
	"context"
	"encoding/json"
	"os"
	"os/exec"
	"path/filepath"
	"testing"
	"time"
)

func TestDelegationHelper(t *testing.T) {
	if len(os.Args) < 3 {
		return
	}
	mode, path := os.Args[len(os.Args)-2], os.Args[len(os.Args)-1]
	if mode == "delegation-guardian" {
		if err := RunGuardian(os.Stdin, os.Stdout, path); err != nil {
			os.Exit(1)
		}
		os.Exit(0)
	}
	if mode != "delegation-owner" {
		return
	}
	executable, _ := os.Executable()
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	delegation, err := StartDelegation(ctx, []string{executable, "-test.run=^TestDelegationHelper$", "--", "delegation-guardian"})
	if err != nil {
		t.Fatal(err)
	}
	manager, err := NewDelegatedManager(delegation)
	if err != nil {
		t.Fatal(err)
	}
	session, err := manager.Start(ctx, child_spec(t, "spawn", "spawn"))
	if err != nil {
		t.Fatal(err)
	}
	select {
	case <-session.Ready():
	case <-ctx.Done():
		t.Fatal(ctx.Err())
	}
	if err := session.Activate(); err != nil {
		t.Fatal(err)
	}
	result, err := session.Invoke(ctx, "echo", nil)
	if err != nil {
		t.Fatal(err)
	}
	value := <-result
	if value.Err != nil {
		t.Fatal(value.Err)
	}
	var pid int
	if err := json.Unmarshal(value.Value, &pid); err != nil || pid <= 0 {
		t.Fatalf("descendant: %s %v", value.Value, err)
	}
	if err := os.WriteFile(path, []byte(delegation.Parent), 0600); err != nil {
		t.Fatal(err)
	}
	// Simulate abrupt reader death: no Stop, Shutdown, Close, or deferred cleanup.
	os.Exit(0)
}

func TestNativeDelegationReaderDeath(t *testing.T) {
	if os.Getenv("CTHULHU_TENTACLE_MANAGED") != "1" {
		t.Skip("requires a systemd user manager and cgroup v2")
	}
	executable, _ := os.Executable()
	marker := filepath.Join(t.TempDir(), "group")
	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
	defer cancel()
	command := exec.CommandContext(ctx, executable, "-test.run=^TestDelegationHelper$", "--", "delegation-owner", marker)
	if output, err := command.CombinedOutput(); err != nil {
		t.Fatalf("owner: %v %s", err, output)
	}
	parent, err := os.ReadFile(marker)
	if err != nil {
		t.Fatal(err)
	}
	timer := time.NewTimer(6 * time.Second)
	defer timer.Stop()
	ticker := time.NewTicker(10 * time.Millisecond)
	defer ticker.Stop()
	for {
		if _, err := os.Stat(string(parent)); os.IsNotExist(err) {
			return
		}
		select {
		case <-ticker.C:
		case <-timer.C:
			t.Fatal("reader death left its service/descendants alive")
		}
	}
}