// Copyright (c) 2026 Storm Dragon
// SPDX-License-Identifier: GPL-3.0-or-later

package control

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

func socket_pair(t *testing.T, path string) (*net.UnixConn, *net.UnixConn) {
	t.Helper()
	listener, err := net.ListenUnix("unix", &net.UnixAddr{Name: path, Net: "unix"})
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { listener.Close() })
	client := connect_remote(t, path)
	server, err := listener.AcceptUnix()
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { server.Close() })
	return client, server
}

func TestHandoffReadsOriginalCallerBytesAndRejectsInvalidDescriptors(t *testing.T) {
	options := private_options(t)
	caller, original := socket_pair(t, filepath.Join(options.Directory, "caller.sock"))
	if _, err := io.WriteString(caller, "COMMAND SAY original\n"); err != nil {
		t.Fatal(err)
	}
	file, err := original.File()
	if err != nil {
		t.Fatal(err)
	}
	defer file.Close()
	ordinary, err := os.CreateTemp(options.Directory, "ordinary-")
	if err != nil {
		t.Fatal(err)
	}
	defer ordinary.Close()
	for _, trial := range []struct {
		name, header string
		fds          []int
		valid        bool
	}{
		{"original", handoffMarker + "COMMAND SAY substituted\n", []int{int(file.Fd())}, true},
		{"file", handoffMarker, []int{int(ordinary.Fd())}, false},
		{"multiple", handoffMarker, []int{int(file.Fd()), int(file.Fd())}, false},
		{"header", "INVALID\n", []int{int(file.Fd())}, false},
	} {
		t.Run(trial.name, func(t *testing.T) {
			sender, receiver := socket_pair(t, filepath.Join(options.Directory, trial.name+".sock"))
			if _, _, err := sender.WriteMsgUnix([]byte(trial.header), syscall.UnixRights(trial.fds...), nil); err != nil {
				t.Fatal(err)
			}
			_ = sender.CloseWrite()
			_, forwarded, err := receive_request(receiver)
			if !trial.valid {
				if forwarded != nil {
					forwarded.Close()
				}
				if err == nil {
					t.Fatal("accepted malformed handoff")
				}
				return
			}
			if err != nil || forwarded == nil {
				t.Fatal("valid handoff rejected", err)
			}
			defer forwarded.Close()
			pid, uid, err := peer(forwarded)
			if err != nil || pid != os.Getpid() || uid != os.Geteuid() {
				t.Fatal("caller credentials changed", pid, uid, err)
			}
			text, err := read_request(forwarded, nil)
			if err != nil || text != "COMMAND SAY original" {
				t.Fatal("handoff substituted caller bytes", text, err)
			}
		})
	}
}