package e2e

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

// TestLifecycleRace proves that a new process joining an existing namespace
// can have that namespace unpinned if an exiting process incorrectly
// thinks it's the last one out.
func TestLifecycleRace(t *testing.T) {
	binaryPath, err := GetBinaryPath()
	if err != nil {
		t.Skipf("Skipping test: %v", err)
	}

	tmpRuntimeDir := t.TempDir()
	profile := "race-test"
	pidsDir := filepath.Join(tmpRuntimeDir, "profiles", profile, "pids")

	// Setup a valid profile config to ensure tunneling starts
	tmpConfigDir := t.TempDir()
	profilesDir := filepath.Join(tmpConfigDir, "wg-wrap", "profiles")
	if err := os.MkdirAll(profilesDir, 0755); err != nil {
		t.Fatal(err)
	}
	profileConfPath := filepath.Join(profilesDir, profile+".conf")
	conf := `[Interface]
Address = 10.0.0.2/24
PrivateKey = 0000000000000000000000000000000000000000000000000000000000000000
DNS = 1.1.1.1

[Peer]
PublicKey = 0000000000000000000000000000000000000000000000000000000000000000
AllowedIPs = 0.0.0.0/0
Endpoint = 1.1.1.1:51820
`
	if err := os.WriteFile(profileConfPath, []byte(conf), 0644); err != nil {
		t.Fatal(err)
	}

	// We use a a long-running sleep for Process A to keep the namespace active.
	// Process A is the "Victim".
	cmdA := exec.Command(binaryPath, "--profile", profile, "--", "sleep", "10")
	cmdA.Env = append(os.Environ(),
		fmt.Sprintf("XDG_RUNTIME_DIR=%s", tmpRuntimeDir),
		fmt.Sprintf("XDG_CONFIG_HOME=%s", tmpConfigDir),
	)
	if err := cmdA.Start(); err != nil {
		t.Fatalf("Failed to start Process A: %v", err)
	}
	defer func() { _ = cmdA.Process.Kill() }()

	// Wait for Process A to establish the namespace and register PID
	waitForPids(t, pidsDir, 1)

	// Process B is the "Saboteur". It will join and then exit.
	// We will loop this to increase the chance of hitting the race window.
	for i := 0; i < 5; i++ {
		cmdB := exec.Command(binaryPath, "--profile", profile, "--", "sleep", "0.1")
		cmdB.Env = append(os.Environ(),
			fmt.Sprintf("XDG_RUNTIME_DIR=%s", tmpRuntimeDir),
			fmt.Sprintf("XDG_CONFIG_HOME=%s", tmpConfigDir),
		)
		if err := cmdB.Start(); err != nil {
			t.Fatalf("Failed to start Process B (iteration %d): %v", i, err)
		}

		// Wait for Process B to register
		waitForPids(t, pidsDir, 2)

		// Let Process B exit. The defer block in ExecuteCommand will:
		// 1. Unregister Process B
		// 2. Check IsLastProcess() -> might return true if Process A's PID is stale or miscounted
		// 3. UnpinNamespace()
		if err := cmdB.Wait(); err != nil {
			t.Fatalf("Process B failed: %v", err)
		}

		// After B exits, Process A should still be the only remaining process.
		// We check if the namespace pin file was accidentally deleted by B.
		nsPath := filepath.Join(tmpRuntimeDir, "profiles", profile+".ns")
		if _, err := os.Stat(nsPath); os.IsNotExist(err) {
			t.Errorf("BUG: Namespace pin file was deleted by exiting Process B, despite Process A still running!")
			return
		}

		// Wait for the PID count to drop back to 1
		waitForPids(t, pidsDir, 1)
	}
}