//go:build linux

package console

import (
	"fmt"
	"os"
	"strings"
	"sync"
	"testing"
	"time"
)

func TestPlan9Fix1ReportIdentityIsStableAcrossProcFailures(t *testing.T) {
	priorRead, priorIdentity := hostReportProcReadFile, hostReportProcessIdentity
	t.Cleanup(func() { hostReportProcReadFile, hostReportProcessIdentity = priorRead, priorIdentity })
	hostReportProcessIdentity = sync.OnceValue(readHostReportProcessIdentity)
	before := hostReportProcessID("boot")
	hostReportProcReadFile = func(string) ([]byte, error) { return nil, os.ErrPermission }
	after := hostReportProcessID("boot")
	if before != after {
		t.Fatalf("one process changed its report identity: %q -> %q", before, after)
	}
}

func TestPlan9Fix1ReportCannotProveAnotherPIDNamespaceDead(t *testing.T) {
	bootRaw, err := os.ReadFile("/proc/sys/kernel/random/boot_id")
	if err != nil {
		t.Fatal(err)
	}
	boot := strings.TrimSpace(string(bootRaw))
	next := hostReportProcessID(boot)
	old := fmt.Sprintf("%s:foreign-pid-namespace:999999999:1", boot)
	if err := hostReportCollision(plan9Report(old, time.Now()), plan9Report(next, time.Now()), time.Now()); err == nil {
		t.Fatal("absence in our PID namespace proved another namespace's process dead")
	}
}

func TestPlan9Fix1HiddenProcEntryDoesNotProveLivePIDDead(t *testing.T) {
	bootRaw, err := os.ReadFile("/proc/sys/kernel/random/boot_id")
	if err != nil {
		t.Fatal(err)
	}
	boot := strings.TrimSpace(string(bootRaw))
	namespace, err := hostReportPIDNamespace()
	if err != nil {
		t.Fatal(err)
	}
	current := fmt.Sprintf("%s:%s:%d:1", boot, namespace, os.Getpid())
	prior := hostReportProcReadFile
	t.Cleanup(func() { hostReportProcReadFile = prior })
	hostReportProcReadFile = func(path string) ([]byte, error) {
		if path == fmt.Sprintf("/proc/%d/stat", os.Getpid()) {
			return nil, os.ErrNotExist
		}
		return prior(path)
	}
	if hostReportProcessGone(current, current) {
		t.Fatal("hidden /proc entry treated as a dead live PID")
	}
}