//go:build linux

/*
 * ============================================================================
 * Projekt.....: rs2322tcp
 * Datei.......: internal/client/virtual_port_manager_linux_test.go
 * Copyright (C) 2026 Dieter Lang
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 * Beschreibung:
 * Linux-spezifische Tests für die Erzeugung und Verwaltung virtueller
 * rs2322tcp-Ports.
 * ============================================================================
 */
package client

import (
	"os"
	"testing"

	"git.lang-dieter.de/rs2322tcp/internal/config"
)

///////////////////////////////////////////////////////////////////////////////
// Tests
///////////////////////////////////////////////////////////////////////////////

func TestVirtualPortManagerOpen(t *testing.T) {
	tempHome := t.TempDir()
	t.Setenv("HOME", tempHome)

	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  199,
		},
	)

	port, err := manager.Open()
	if err != nil {
		t.Fatalf("Open() failed: %v", err)
	}

	if port == nil {
		t.Fatal("Open() returned nil")
	}

	if port.Path() != "/dev/ttyUSB100" {
		t.Errorf(
			"Path() = %q, want %q",
			port.Path(),
			"/dev/ttyUSB100",
		)
	}

	linkPath, err := virtualPortLinkPath(port.Path())
	if err != nil {
		t.Fatalf("virtualPortLinkPath() failed: %v", err)
	}

	target, err := os.Readlink(linkPath)
	if err != nil {
		t.Fatalf("Readlink() failed: %v", err)
	}

	if target == "" {
		t.Fatal("internal virtual port link has empty target")
	}

	if err := port.Close(); err != nil {
		t.Fatalf("Close() failed: %v", err)
	}

	targetAfterClose, err := os.Readlink(linkPath)
	if err != nil {
		t.Fatalf(
			"internal link does not exist after Close(): %q: %v",
			linkPath,
			err,
		)
	}

	if targetAfterClose != target {
		t.Errorf(
			"internal link target after Close() = %q, want %q",
			targetAfterClose,
			target,
		)
	}
}

func TestVirtualPortManagerOpenSpecific(t *testing.T) {
	tempHome := t.TempDir()
	t.Setenv("HOME", tempHome)

	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  199,
		},
	)

	port, err := manager.OpenSpecific(150)
	if err != nil {
		t.Fatalf("OpenSpecific(150) failed: %v", err)
	}

	if port == nil {
		t.Fatal("OpenSpecific(150) returned nil")
	}

	if port.Path() != "/dev/ttyUSB150" {
		t.Errorf(
			"Path() = %q, want %q",
			port.Path(),
			"/dev/ttyUSB150",
		)
	}

	linkPath, err := virtualPortLinkPath(port.Path())
	if err != nil {
		t.Fatalf("virtualPortLinkPath() failed: %v", err)
	}

	target, err := os.Readlink(linkPath)
	if err != nil {
		t.Fatalf("Readlink() failed: %v", err)
	}

	if target == "" {
		t.Fatal("internal virtual port link has empty target")
	}

	if err := port.Close(); err != nil {
		t.Fatalf("Close() failed: %v", err)
	}

	targetAfterClose, err := os.Readlink(linkPath)
	if err != nil {
		t.Fatalf(
			"internal link does not exist after Close(): %q: %v",
			linkPath,
			err,
		)
	}

	if targetAfterClose != target {
		t.Errorf(
			"internal link target after Close() = %q, want %q",
			targetAfterClose,
			target,
		)
	}
}

func TestVirtualPortManagerOpenUsesNextPort(t *testing.T) {
	tempHome := t.TempDir()
	t.Setenv("HOME", tempHome)

	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  101,
		},
	)

	first, err := manager.Open()
	if err != nil {
		t.Fatalf("first Open() failed: %v", err)
	}

	second, err := manager.Open()
	if err != nil {
		_ = first.Close()
		t.Fatalf("second Open() failed: %v", err)
	}

	if first.Path() != "/dev/ttyUSB100" {
		t.Errorf(
			"first.Path() = %q, want %q",
			first.Path(),
			"/dev/ttyUSB100",
		)
	}

	if second.Path() != "/dev/ttyUSB101" {
		t.Errorf(
			"second.Path() = %q, want %q",
			second.Path(),
			"/dev/ttyUSB101",
		)
	}

	if err := first.Close(); err != nil {
		t.Fatalf("first Close() failed: %v", err)
	}

	if err := second.Close(); err != nil {
		t.Fatalf("second Close() failed: %v", err)
	}
}

func TestVirtualPortManagerOpenReusesReleasedPort(t *testing.T) {
	tempHome := t.TempDir()
	t.Setenv("HOME", tempHome)

	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  100,
		},
	)

	first, err := manager.Open()
	if err != nil {
		t.Fatalf("first Open() failed: %v", err)
	}

	if first.Path() != "/dev/ttyUSB100" {
		t.Fatalf(
			"first.Path() = %q, want %q",
			first.Path(),
			"/dev/ttyUSB100",
		)
	}

	if err := first.Close(); err != nil {
		t.Fatalf("first Close() failed: %v", err)
	}

	second, err := manager.Open()
	if err != nil {
		t.Fatalf("second Open() failed: %v", err)
	}

	if second.Path() != "/dev/ttyUSB100" {
		t.Errorf(
			"second.Path() = %q, want %q",
			second.Path(),
			"/dev/ttyUSB100",
		)
	}

	if err := second.Close(); err != nil {
		t.Fatalf("second Close() failed: %v", err)
	}
}

func TestVirtualPortManagerOpenNoFreePort(t *testing.T) {
	tempHome := t.TempDir()
	t.Setenv("HOME", tempHome)

	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  100,
		},
	)

	port, err := manager.Open()
	if err != nil {
		t.Fatalf("first Open() failed: %v", err)
	}

	defer port.Close()

	if _, err := manager.Open(); err == nil {
		t.Fatal("second Open() succeeded, want no-free-port error")
	}
}

func TestManagedVirtualPortDataPath(t *testing.T) {
	tempHome := t.TempDir()
	t.Setenv("HOME", tempHome)

	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  100,
		},
	)

	port, err := manager.Open()
	if err != nil {
		t.Fatalf("Open() failed: %v", err)
	}

	defer port.Close()

	data := []byte{0x46, 0x41, 0x00, 0x10, 0x0D}

	if _, err := port.Write(data); err != nil {
		t.Fatalf("Write() failed: %v", err)
	}
}