/*
 * ============================================================================
 * Projekt.....: rs2322tcp
 * Datei.......: internal/client/application_test.go
 * Copyright (C) 2026 Dieter Lang
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 * Beschreibung:
 * Tests für die Anwendungsschicht des rs2322tcp-Clients.
 *
 * Die Tests prüfen den Lebenszyklus der Application und die lokale
 * Konfigurationsverwaltung, ohne dafür eine echte Serververbindung
 * aufbauen zu müssen.
 *
 * Insbesondere wird sichergestellt, dass eine neu erzeugte Application
 * ihre lokale Konfiguration bereits kennt, obwohl noch keine Verbindung
 * zum Server besteht.
 * ============================================================================
 */

package client

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

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

///////////////////////////////////////////////////////////////////////////////
// Test helpers
///////////////////////////////////////////////////////////////////////////////

// writeTestConfig creates a temporary client configuration file.
func writeTestConfig(t *testing.T) string {
	t.Helper()

	dir := t.TempDir()
	filename := filepath.Join(dir, "client.json")

	content := `{
		"server": {
			"address": "127.0.0.1",
			"port": 5000
		},
		"virtual_port_range": {
			"first": 100,
			"last": 199
		},
		"virtual_ports": [
			{
				"port": "/dev/ttyUSB100",
				"remote_device": "radio"
			},
			{
				"port": "/dev/ttyUSB101",
				"remote_device": "rotor"
			}
		]
	}`

	if err := os.WriteFile(
		filename,
		[]byte(content),
		0600,
	); err != nil {
		t.Fatalf("write test configuration: %v", err)
	}

	return filename
}

///////////////////////////////////////////////////////////////////////////////
// NewApplication
///////////////////////////////////////////////////////////////////////////////

// TestNewApplicationRejectsEmptyConfigFile verifies that an empty
// configuration-file path is rejected.
func TestNewApplicationRejectsEmptyConfigFile(t *testing.T) {
	t.Helper()

	application, err := NewApplication("")
	if err == nil {
		t.Fatal("NewApplication with empty config file returned no error")
	}

	if application != nil {
		t.Fatal("NewApplication with empty config file returned an application")
	}
}

// TestNewApplication verifies that a valid configuration-file path creates
// an application and loads the local configuration without starting the
// network connection.
func TestNewApplication(t *testing.T) {
	t.Helper()

	configFile := writeTestConfig(t)

	application, err := NewApplication(configFile)
	if err != nil {
		t.Fatalf("NewApplication: %v", err)
	}

	if application == nil {
		t.Fatal("NewApplication returned nil application")
	}

	if application.Running() {
		t.Fatal("new application reports running")
	}

	cfg := application.Config()
	if cfg == nil {
		t.Fatal("new application returned no configuration")
	}

	if len(cfg.VirtualPorts) != 2 {
		t.Fatalf(
			"new application returned %d virtual ports, want 2",
			len(cfg.VirtualPorts),
		)
	}

	if cfg.VirtualPorts[0].Port != "/dev/ttyUSB100" {
		t.Errorf(
			"virtual port 0 = %q, want %q",
			cfg.VirtualPorts[0].Port,
			"/dev/ttyUSB100",
		)
	}

	if cfg.VirtualPorts[0].RemoteDevice != "radio" {
		t.Errorf(
			"remote device 0 = %q, want %q",
			cfg.VirtualPorts[0].RemoteDevice,
			"radio",
		)
	}

	if cfg.VirtualPorts[1].Port != "/dev/ttyUSB101" {
		t.Errorf(
			"virtual port 1 = %q, want %q",
			cfg.VirtualPorts[1].Port,
			"/dev/ttyUSB101",
		)
	}

	if cfg.VirtualPorts[1].RemoteDevice != "rotor" {
		t.Errorf(
			"remote device 1 = %q, want %q",
			cfg.VirtualPorts[1].RemoteDevice,
			"rotor",
		)
	}

	if devices := application.Devices(); len(devices) != 0 {
		t.Fatalf(
			"new application returned %d devices, want 0",
			len(devices),
		)
	}
}

///////////////////////////////////////////////////////////////////////////////
// Configuration copy
///////////////////////////////////////////////////////////////////////////////

// TestApplicationConfigReturnsCopy verifies that modifying the returned
// configuration does not modify the Application's internal configuration.
func TestApplicationConfigReturnsCopy(t *testing.T) {
	t.Helper()

	configFile := writeTestConfig(t)

	application, err := NewApplication(configFile)
	if err != nil {
		t.Fatalf("NewApplication: %v", err)
	}

	cfg := application.Config()
	if cfg == nil {
		t.Fatal("Config returned nil")
	}

	cfg.VirtualPorts[0].Port = "/dev/ttyUSB999"
	cfg.VirtualPorts[0].RemoteDevice = "changed"

	current := application.Config()
	if current == nil {
		t.Fatal("second Config returned nil")
	}

	if current.VirtualPorts[0].Port != "/dev/ttyUSB100" {
		t.Errorf(
			"internal port changed to %q",
			current.VirtualPorts[0].Port,
		)
	}

	if current.VirtualPorts[0].RemoteDevice != "radio" {
		t.Errorf(
			"internal remote device changed to %q",
			current.VirtualPorts[0].RemoteDevice,
		)
	}
}

///////////////////////////////////////////////////////////////////////////////
// Close
///////////////////////////////////////////////////////////////////////////////

// TestApplicationCloseBeforeStart verifies that Close can safely be called
// before the application has been started and that the local configuration
// remains available.
func TestApplicationCloseBeforeStart(t *testing.T) {
	t.Helper()

	configFile := writeTestConfig(t)

	application, err := NewApplication(configFile)
	if err != nil {
		t.Fatalf("NewApplication: %v", err)
	}

	if err := application.Close(); err != nil {
		t.Fatalf("Close before Start: %v", err)
	}

	if application.Running() {
		t.Fatal("application reports running after Close")
	}

	if cfg := application.Config(); cfg == nil {
		t.Fatal("configuration was lost after Close")
	}
}

// TestApplicationCloseIsIdempotent verifies that Close can be called more
// than once without producing an error and without losing the local
// configuration.
func TestApplicationCloseIsIdempotent(t *testing.T) {
	t.Helper()

	configFile := writeTestConfig(t)

	application, err := NewApplication(configFile)
	if err != nil {
		t.Fatalf("NewApplication: %v", err)
	}

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

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

	if application.Running() {
		t.Fatal("application reports running after repeated Close")
	}

	if cfg := application.Config(); cfg == nil {
		t.Fatal("configuration was lost after repeated Close")
	}
}

///////////////////////////////////////////////////////////////////////////////
// Invalid configuration
///////////////////////////////////////////////////////////////////////////////

// TestNewApplicationRejectsInvalidConfiguration verifies that an invalid
// configuration file is rejected immediately.
func TestNewApplicationRejectsInvalidConfiguration(t *testing.T) {
	t.Helper()

	dir := t.TempDir()
	filename := filepath.Join(dir, "invalid.json")

	if err := os.WriteFile(
		filename,
		[]byte(`{"invalid": true}`),
		0600,
	); err != nil {
		t.Fatalf("write invalid configuration: %v", err)
	}

	application, err := NewApplication(filename)
	if err == nil {
		t.Fatal("NewApplication with invalid configuration returned no error")
	}

	if application != nil {
		t.Fatal(
			"NewApplication with invalid configuration returned an application",
		)
	}
}

///////////////////////////////////////////////////////////////////////////////
// Nil receiver
///////////////////////////////////////////////////////////////////////////////

// TestNilApplication verifies that the public lifecycle methods behave
// safely when called on a nil Application receiver.
//
// This is deliberately a small defensive test. The GUI should normally
// never operate on a nil Application.
func TestNilApplication(t *testing.T) {
	t.Helper()

	var application *Application

	if err := application.Start(); err == nil {
		t.Fatal("nil Application Start returned no error")
	}

	if err := application.Reconnect(); err == nil {
		t.Fatal("nil Application Reconnect returned no error")
	}

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

	if application.Running() {
		t.Fatal("nil Application reports running")
	}

	if application.Config() != nil {
		t.Fatal("nil Application returned a configuration")
	}

	if devices := application.Devices(); devices != nil {
		t.Fatal("nil Application returned devices")
	}
}

// Keep config imported explicitly so the test documents that the temporary
// file represents the normal ClientConfig structure.
var _ config.ClientConfig