package namespace

import (
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"testing"
)

func TestLifecycleReferenceCounting(t *testing.T) {
	// Use a temporary directory to avoid polluting the system
	tmpDir := t.TempDir()
	SetRuntimeBaseDir(tmpDir)

	profile := "test-vpn"

	t.Run("RegisterAndUnregister", func(t *testing.T) {
		err := RegisterProcess(profile)
		if err != nil {
			t.Fatalf("failed to register: %v", err)
		}

		pidsDir := GetPidsDirPath(profile)
		pidFile := filepath.Join(pidsDir, strconv.Itoa(os.Getpid()))
		if _, err := os.Stat(pidFile); os.IsNotExist(err) {
			t.Errorf("PID file should exist at %s", pidFile)
		}

		err = UnregisterProcess(profile)
		if err != nil {
			t.Fatalf("failed to unregister: %v", err)
		}

		if _, err := os.Stat(pidFile); err == nil {
			t.Errorf("PID file should have been removed at %s", pidFile)
		}
	})

	t.Run("PruneStalePids", func(t *testing.T) {
		pidsDir := GetPidsDirPath(profile)
		if err := os.MkdirAll(pidsDir, 0755); err != nil {
			t.Fatal(err)
		}

		// Create a fake PID file for a process that definitely doesn't exist
		// Using a very high PID or -1 usually works, but let's use a known invalid one.
		fakePid := "9999999" 
		fakePidFile := filepath.Join(pidsDir, fakePid)
		if err := os.WriteFile(fakePidFile, []byte(""), 0644); err != nil {
			t.Fatal(err)
		}

		// Also register the current process so it stays
		RegisterProcess(profile)

		err := PruneStalePids(profile)
		if err != nil {
			t.Fatalf("prune failed: %v", err)
		}

		if _, err := os.Stat(fakePidFile); err == nil {
			t.Errorf("Stale PID file %s should have been pruned", fakePidFile)
		}

		// Current process should still be there
		currentPidFile := filepath.Join(pidsDir, strconv.Itoa(os.Getpid()))
		if _, err := os.Stat(currentPidFile); os.IsNotExist(err) {
			t.Errorf("Current PID file %s should not have been pruned", currentPidFile)
		}
		
		UnregisterProcess(profile)
	})

	t.Run("IsLastProcess", func(t *testing.T) {
		pidsDir := GetPidsDirPath(profile)
		os.RemoveAll(pidsDir) // Reset

		// Case 1: No processes (should return true as it's a clean state)
		isLast, err := IsLastProcess(profile)
		if err != nil || !isLast {
			t.Errorf("Expected IsLastProcess to be true for empty profile, got %v, err: %v", isLast, err)
		}

		// Case 2: Only ourselves
		RegisterProcess(profile)
		isLast, err = IsLastProcess(profile)
		if err != nil || !isLast {
			t.Errorf("Expected IsLastProcess to be true for single process, got %v, err: %v", isLast, err)
		}

		// Case 3: Ourselves + another active process
		// To test this, we'll actually start a dummy process.
		cmd := exec.Command("sleep", "1")
		if err := cmd.Start(); err != nil {
			t.Fatalf("failed to start sleep process: %v", err)
		}
		defer cmd.Process.Kill()

		// Manually add the sleep process PID to the tracking
		os.WriteFile(filepath.Join(pidsDir, strconv.Itoa(cmd.Process.Pid)), []byte(""), 0644)

		isLast, err = IsLastProcess(profile)
		if err != nil || isLast {
			t.Errorf("Expected IsLastProcess to be false with two active processes, got %v, err: %v", isLast, err)
		}

		UnregisterProcess(profile)
	})
}