// Fenrir console screen reader.
// Copyright (c) 2026 Storm Dragon
// SPDX-License-Identifier: GPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
// more details.
//
// You should have received a copy of the GNU General Public License along with
// this program. If not, see <https://www.gnu.org/licenses/gpl-3.0.html>.

//go:build linux && cgo

package console

import (
	"net"
	"syscall"
	"testing"
	"time"
)

// TCP urgent data exercises the same kernel POLLPRI/acknowledge/rearm contract
// as VCSA without requiring a real console, privileges or physical input.
func TestPriorityReadinessAcknowledgementAndRearm(t *testing.T) {
	listener, err := net.ListenTCP("tcp", &net.TCPAddr{IP: net.IPv4(127, 0, 0, 1)})
	if err != nil {
		t.Fatal(err)
	}
	defer listener.Close()
	writer, err := net.DialTCP("tcp", nil, listener.Addr().(*net.TCPAddr))
	if err != nil {
		t.Fatal(err)
	}
	defer writer.Close()
	reader, err := listener.AcceptTCP()
	if err != nil {
		t.Fatal(err)
	}
	defer reader.Close()
	readControl, err := reader.SyscallConn()
	if err != nil {
		t.Fatal(err)
	}
	writeControl, err := writer.SyscallConn()
	if err != nil {
		t.Fatal(err)
	}
	watcher, err := newReadinessWatcher(syscall.EPOLLPRI)
	if err != nil {
		t.Fatal(err)
	}
	defer watcher.close()
	var operationErr error
	if err := readControl.Control(func(fd uintptr) { operationErr = watcher.add(int(fd)) }); err != nil {
		t.Fatal(err)
	}
	if operationErr != nil {
		t.Fatal(operationErr)
	}
	for range 2 {
		if err := writeControl.Control(func(fd uintptr) {
			operationErr = syscall.Sendto(int(fd), []byte{1}, syscall.MSG_OOB, nil)
		}); err != nil {
			t.Fatal(err)
		}
		if operationErr != nil {
			t.Fatal(operationErr)
		}
		select {
		case err := <-watcher.events:
			if err != nil {
				t.Fatal(err)
			}
		case <-time.After(time.Second):
			t.Fatal("priority data did not wake the watcher")
		}
		if err := readControl.Control(func(fd uintptr) {
			var data [1]byte
			_, _, operationErr = syscall.Recvfrom(int(fd), data[:], syscall.MSG_OOB)
			if operationErr == nil {
				operationErr = watcher.arm(int(fd))
			}
		}); err != nil {
			t.Fatal(err)
		}
		if operationErr != nil {
			t.Fatal(operationErr)
		}
	}
}