//go:build !windows

package backup

import (
	"os"
	"path/filepath"
	"syscall"
	"testing"
)

const restoreRuntimeUID = 10001

func TestReplaceRestoreFilePreservesExistingOwner(t *testing.T) {
	requireRootForRestoreOwnershipTest(t)

	target := filepath.Join(t.TempDir(), "trust.json")
	if err := os.WriteFile(target, []byte("before"), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.Chown(target, restoreRuntimeUID, restoreRuntimeUID); err != nil {
		t.Fatal(err)
	}

	if err := replaceRestoreFile(target, []byte("after"), 0o600); err != nil {
		t.Fatal(err)
	}
	assertRestoreOwner(t, target, restoreRuntimeUID, restoreRuntimeUID)
}

func TestReplaceRestoreFileUsesParentOwnerForNewTarget(t *testing.T) {
	requireRootForRestoreOwnershipTest(t)

	parent := filepath.Join(t.TempDir(), "agent")
	if err := os.Mkdir(parent, 0o700); err != nil {
		t.Fatal(err)
	}
	if err := os.Chown(parent, restoreRuntimeUID, restoreRuntimeUID); err != nil {
		t.Fatal(err)
	}
	target := filepath.Join(parent, "trust.json")

	if err := replaceRestoreFile(target, []byte("restored"), 0o600); err != nil {
		t.Fatal(err)
	}
	assertRestoreOwner(t, target, restoreRuntimeUID, restoreRuntimeUID)
}

func requireRootForRestoreOwnershipTest(t *testing.T) {
	t.Helper()
	if os.Geteuid() != 0 {
		t.Skip("numeric ownership assertions require root")
	}
}

func assertRestoreOwner(t *testing.T, path string, uid, gid uint32) {
	t.Helper()
	info, err := os.Stat(path)
	if err != nil {
		t.Fatal(err)
	}
	status, ok := info.Sys().(*syscall.Stat_t)
	if !ok {
		t.Fatal("restored file has no Unix stat metadata")
	}
	if status.Uid != uid || status.Gid != gid {
		t.Fatalf("restored owner = %d:%d, want %d:%d", status.Uid, status.Gid, uid, gid)
	}
}