PalladiumWallet/src/App/ViewModels/MainWindowViewModel.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Avalonia.Threading;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using NBitcoin;
using PalladiumWallet.Core.Chain;
using PalladiumWallet.Core.Crypto;
using PalladiumWallet.Core.Net;
using PalladiumWallet.Core.Spv;
using PalladiumWallet.Core.Storage;
using PalladiumWallet.Core.Wallet;

namespace PalladiumWallet.App.ViewModels;

/// <summary>Riga dello storico transazioni per la vista.</summary>
public sealed record HistoryRow(string Conferma, string Importo, string Txid, string Verificata);

/// <summary>Riga della vista indirizzi (stile Electrum): saldo e uso per indirizzo.</summary>
public sealed record AddressRow(string Tipo, int Indice, string Indirizzo, string Saldo, string NumTx);

/// <summary>
/// ViewModel unico dell'applicazione (wizard §15 ridotto + dashboard):
/// pannello di setup (crea/ripristina/apri) e pannello wallet
/// (saldo, ricevi, storico, invia, server).
/// </summary>
public partial class MainWindowViewModel : ViewModelBase
{
    private WalletDocument? _doc;
    private HdAccount? _account;
    private string? _walletPath;
    private string? _password;
    private ElectrumClient? _client;
    private WalletSynchronizer? _synchronizer;
    private IReadOnlyDictionary<string, Transaction>? _lastTransactions;
    private BuiltTransaction? _pendingSend;

    /// <summary>Notifica arrivata durante una sync: si risincronizza appena finita.</summary>
    private bool _resyncRequested;

    /// <summary>File in attesa di password (apertura da menu File → Apri).</summary>
    private string? _pendingOpenPath;

    /// <summary>Dopo la prima connessione riuscita il timer riconnette da solo.</summary>
    private bool _autoReconnect;

    private readonly DispatcherTimer _keepAliveTimer;

    // ---- selezione rete e stato pannelli ----

    public string[] Networks { get; } = ["mainnet", "testnet", "regtest"];

    [ObservableProperty]
    private string selectedNetwork = "mainnet";

    [ObservableProperty]
    [NotifyPropertyChangedFor(nameof(IsSetupVisible))]
    private bool isWalletOpen;

    public bool IsSetupVisible => !IsWalletOpen;

    [ObservableProperty]
    private bool walletFileExists;

    [ObservableProperty]
    private string statusMessage = "";

    // ---- wizard di setup (§15): un passo alla volta ----

    public const string StepStart = "start";
    public const string StepOpen = "open";
    public const string StepShowSeed = "show-seed";
    public const string StepConfirmSeed = "confirm-seed";
    public const string StepWords = "words";
    public const string StepPassphrase = "passphrase";
    public const string StepPassword = "password";

    [ObservableProperty]
    [NotifyPropertyChangedFor(nameof(IsStepStart))]
    [NotifyPropertyChangedFor(nameof(IsStepOpen))]
    [NotifyPropertyChangedFor(nameof(IsStepShowSeed))]
    [NotifyPropertyChangedFor(nameof(IsStepConfirmSeed))]
    [NotifyPropertyChangedFor(nameof(IsStepWords))]
    [NotifyPropertyChangedFor(nameof(IsStepPassphrase))]
    [NotifyPropertyChangedFor(nameof(IsStepPassword))]
    private string setupStep = StepStart;

    public bool IsStepStart => SetupStep == StepStart;
    public bool IsStepOpen => SetupStep == StepOpen;
    public bool IsStepShowSeed => SetupStep == StepShowSeed;
    public bool IsStepConfirmSeed => SetupStep == StepConfirmSeed;
    public bool IsStepWords => SetupStep == StepWords;
    public bool IsStepPassphrase => SetupStep == StepPassphrase;
    public bool IsStepPassword => SetupStep == StepPassword;

    /// <summary>True quando il flusso è "ripristina" (parole inserite dall'utente).</summary>
    private bool _isRestoreFlow;

    [ObservableProperty]
    private string mnemonicInput = "";

    [ObservableProperty]
    private string confirmMnemonicInput = "";

    [ObservableProperty]
    private string passphraseInput = "";

    [ObservableProperty]
    private string passwordInput = "";

    // ---- pannello wallet ----

    [ObservableProperty]
    private string balanceText = "—";

    [ObservableProperty]
    private string unconfirmedText = "";

    [ObservableProperty]
    private string networkInfo = "";

    [ObservableProperty]
    private string receiveAddress = "";

    [ObservableProperty]
    private string serverInput = "";

    [ObservableProperty]
    private bool useSsl;

    [ObservableProperty]
    private string connectionStatus = "non connesso";

    [ObservableProperty]
    private bool isConnected;

    [ObservableProperty]
    private bool isSyncing;

    public ObservableCollection<KnownServer> KnownServers { get; } = [];

    [ObservableProperty]
    private KnownServer? selectedKnownServer;

    public ObservableCollection<HistoryRow> History { get; } = [];

    public ObservableCollection<AddressRow> Addresses { get; } = [];

    // ---- pannello invia ----

    [ObservableProperty]
    private string sendTo = "";

    [ObservableProperty]
    private string sendAmount = "";

    [ObservableProperty]
    private string sendFeeRate = "1";

    [ObservableProperty]
    private bool sendAll;

    [ObservableProperty]
    private string sendPreview = "";

    [ObservableProperty]
    private bool hasPendingSend;

    public MainWindowViewModel()
    {
        RefreshSetupState();
        // Aggiornamenti continui (§9): ping periodico per tenere viva la
        // connessione e accorgersi subito della caduta; se cade, riconnette
        // e risincronizza da solo. Le notifiche push restano la via principale.
        _keepAliveTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(20) };
        _keepAliveTimer.Tick += async (_, _) => await KeepAliveTickAsync();
        _keepAliveTimer.Start();
    }

    private async Task KeepAliveTickAsync()
    {
        if (!IsWalletOpen || IsSyncing)
            return;
        if (_client is { IsConnected: true })
        {
            try
            {
                await _client.PingAsync();
            }
            catch
            {
                // La caduta viene gestita dall'evento Disconnected.
            }
        }
        else if (_autoReconnect)
        {
            ConnectionStatus = "riconnessione…";
            await ConnectAndSync();
        }
    }

    private NetKind Net => Enum.Parse<NetKind>(SelectedNetwork, ignoreCase: true);
    private ChainProfile Profile => ChainProfiles.For(Net);

    partial void OnSelectedNetworkChanged(string value) => RefreshSetupState();

    private ServerRegistry Registry => new(Profile, AppPaths.ServersPath(Net));

    private void RefreshSetupState()
    {
        SetupStep = StepStart;
        MnemonicInput = ConfirmMnemonicInput = PassphraseInput = PasswordInput = "";
        WalletFileExists = WalletStore.Exists(AppPaths.DefaultWalletPath(Net));
        StatusMessage = WalletFileExists
            ? "Trovato un wallet esistente su questa rete: aprilo, oppure creane un altro."
            : "Benvenuto: crea un nuovo wallet o ripristina da seed.";
        RefreshServers();
    }

    private void RefreshServers()
    {
        KnownServers.Clear();
        foreach (var server in Registry.All)
            KnownServers.Add(server);
        SelectedKnownServer = KnownServers.FirstOrDefault();
        if (SelectedKnownServer is null)
            ServerInput = $"127.0.0.1:{Profile.DefaultTcpPort}";
    }

    partial void OnSelectedKnownServerChanged(KnownServer? value)
    {
        if (value is not null)
            ServerInput = $"{value.Host}:{value.PortFor(UseSsl)}";
    }

    partial void OnUseSslChanged(bool value)
    {
        if (SelectedKnownServer is { } server)
            ServerInput = $"{server.Host}:{server.PortFor(value)}";
    }

    // ---------- comandi del wizard (§15): un passo alla volta ----------

    [RelayCommand]
    private void WizardStartOpen()
    {
        PasswordInput = "";
        SetupStep = StepOpen;
        StatusMessage = "Inserisci la password del file (lascia vuoto se non impostata).";
    }

    [RelayCommand]
    private void WizardStartNew()
    {
        _isRestoreFlow = false;
        MnemonicInput = Bip39.Generate(MnemonicLength.Twelve).ToString();
        SetupStep = StepShowSeed;
        StatusMessage = "Scrivi le 12 parole SU CARTA, nell'ordine. Sono l'unico backup del wallet.";
    }

    [RelayCommand]
    private void WizardStartRestore()
    {
        _isRestoreFlow = true;
        MnemonicInput = "";
        SetupStep = StepWords;
        StatusMessage = "Inserisci la mnemonica BIP39 (12 o 24 parole separate da spazi).";
    }

    [RelayCommand]
    private void WizardNextFromShowSeed()
    {
        ConfirmMnemonicInput = "";
        SetupStep = StepConfirmSeed;
        StatusMessage = "Reinserisci le 12 parole per confermare di averle scritte.";
    }

    [RelayCommand]
    private void WizardNextFromConfirmSeed()
    {
        var normalized = string.Join(' ',
            ConfirmMnemonicInput.Split(' ', StringSplitOptions.RemoveEmptyEntries));
        if (!string.Equals(normalized, MnemonicInput, StringComparison.OrdinalIgnoreCase))
        {
            StatusMessage = "Le parole non corrispondono: ricontrolla quello che hai scritto su carta.";
            return;
        }
        GoToPassphraseStep();
    }

    [RelayCommand]
    private void WizardNextFromWords()
    {
        if (!Bip39.TryParse(MnemonicInput, out _))
        {
            StatusMessage = "Mnemonica non valida (parole o checksum errati): ricontrolla.";
            return;
        }
        GoToPassphraseStep();
    }

    private void GoToPassphraseStep()
    {
        PassphraseInput = "";
        SetupStep = StepPassphrase;
        StatusMessage = "Passphrase BIP39 opzionale: cambia completamente il wallet. " +
            "Se la usi, annotala A PARTE dal seed; se la perdi i fondi sono irrecuperabili. " +
            "Lascia vuoto per non usarla.";
    }

    [RelayCommand]
    private void WizardNextFromPassphrase()
    {
        PasswordInput = "";
        SetupStep = StepPassword;
        StatusMessage = "Password di cifratura del file wallet su disco (consigliata). " +
            "Non sostituisce il seed: serve solo a proteggere il file.";
    }

    [RelayCommand]
    private void WizardBack()
    {
        SetupStep = SetupStep switch
        {
            StepOpen or StepShowSeed or StepWords => StepStart,
            StepConfirmSeed => StepShowSeed,
            StepPassphrase => _isRestoreFlow ? StepWords : StepConfirmSeed,
            StepPassword => StepPassphrase,
            _ => StepStart,
        };
        if (SetupStep == StepStart)
            RefreshSetupState();
    }

    [RelayCommand]
    private void CreateOrRestore()
    {
        try
        {
            var (doc, account) = WalletLoader.NewFromMnemonic(
                MnemonicInput,
                string.IsNullOrEmpty(PassphraseInput) ? null : PassphraseInput,
                ScriptKind.NativeSegwit,
                Profile);
            // Mai sovrascrivere un wallet esistente: si cerca il primo nome libero.
            var path = AppPaths.DefaultWalletPath(Net);
            for (var n = 2; WalletStore.Exists(path); n++)
                path = Path.Combine(AppPaths.WalletsDir(Net), $"wallet-{n}.wallet.json");
            var password = string.IsNullOrEmpty(PasswordInput) ? null : PasswordInput;
            WalletStore.Save(doc, path, password);
            OpenLoaded(doc, account, path, password);
        }
        catch (Exception ex)
        {
            StatusMessage = $"Errore: {ex.Message}";
        }
    }

    [RelayCommand]
    private void OpenExisting()
    {
        try
        {
            var path = _pendingOpenPath ?? AppPaths.DefaultWalletPath(Net);
            var password = string.IsNullOrEmpty(PasswordInput) ? null : PasswordInput;
            var doc = WalletStore.Load(path, password);
            _pendingOpenPath = null;
            OpenLoaded(doc, WalletLoader.ToAccount(doc), path, password);
        }
        catch (WrongPasswordException)
        {
            StatusMessage = "Password errata.";
        }
        catch (Exception ex)
        {
            StatusMessage = $"Errore: {ex.Message}";
        }
    }

    /// <summary>Apertura di un file wallet qualunque (menu File → Apri, multi-wallet §8).</summary>
    public void OpenFromPath(string path)
    {
        try
        {
            if (IsWalletOpen)
                CloseWallet();
            var doc = WalletStore.Load(path);
            OpenLoaded(doc, WalletLoader.ToAccount(doc), path, password: null);
        }
        catch (WrongPasswordException)
        {
            // Cifrato: si chiede la password nel passo di apertura del wizard.
            if (IsWalletOpen)
                CloseWallet();
            _pendingOpenPath = path;
            WalletFileExists = true;
            PasswordInput = "";
            SetupStep = StepOpen;
            StatusMessage = $"Il wallet \"{Path.GetFileName(path)}\" è cifrato: inserisci la password e premi Apri.";
        }
        catch (Exception ex)
        {
            StatusMessage = $"Errore: {ex.Message}";
        }
    }

    /// <summary>Torna al pannello di setup per creare/ripristinare un altro wallet.</summary>
    [RelayCommand]
    private void NewWallet()
    {
        if (IsWalletOpen)
            CloseWallet();
        _pendingOpenPath = null;
        StatusMessage = "Crea un nuovo wallet o ripristina da seed. ATTENZIONE: sovrascrive il wallet di default della rete selezionata.";
    }

    private void OpenLoaded(WalletDocument doc, HdAccount account, string path, string? password)
    {
        // La rete del wallet comanda (registry, pin TLS, indirizzi).
        SelectedNetwork = doc.Network;
        _doc = doc;
        _account = account;
        _walletPath = path;
        _password = password;
        MnemonicInput = ConfirmMnemonicInput = PassphraseInput = PasswordInput = "";
        SetupStep = StepStart;

        NetworkInfo = $"{doc.Network} · {doc.ScriptKind} · m/{doc.AccountPath}"
            + (doc.IsWatchOnly ? " · watch-only" : "");
        ApplyCache(doc.Cache);
        IsWalletOpen = true;
        StatusMessage = "Wallet aperto: connessione al server…";
        // Come Electrum: ci si connette da soli al server selezionato,
        // senza aspettare un click.
        _ = ConnectAndSync();
    }

    private void ApplyCache(SyncCache? cache)
    {
        if (_account is null)
            return;
        if (cache is null)
        {
            BalanceText = $"0.00000000 {Profile.CoinUnit}";
            UnconfirmedText = "";
            ReceiveAddress = _account.GetReceiveAddress(0).ToString();
            History.Clear();
            // Prima della sincronizzazione si mostrano i primi indirizzi derivati.
            Addresses.Clear();
            for (var i = 0; i < 10; i++)
                Addresses.Add(new AddressRow("ricezione", i,
                    _account.GetReceiveAddress(i).ToString(), "—", "—"));
            return;
        }
        BalanceText = CoinAmount.Format(cache.ConfirmedSats, Profile.CoinUnit);
        // Saldo in attesa: somma delle tx in mempool (può essere negativo per
        // gli invii in uscita non ancora confermati). Non è spendibile finché
        // non conferma: la TransactionFactory usa solo UTXO confermati.
        var pending = cache.History.Where(t => t.Height <= 0).Sum(t => t.DeltaSats);
        UnconfirmedText = pending != 0
            ? $"in attesa di conferma: {(pending > 0 ? "+" : "")}{CoinAmount.Format(pending)} — non ancora spendibile"
            : "";
        ReceiveAddress = _account.GetReceiveAddress(cache.NextReceiveIndex).ToString();
        History.Clear();
        foreach (var tx in cache.History)
            History.Add(new HistoryRow(
                tx.Height > 0 ? tx.Height.ToString() : "mempool",
                (tx.DeltaSats >= 0 ? "+" : "") + CoinAmount.Format(tx.DeltaSats),
                tx.Txid,
                tx.Verified ? "✓ SPV" : "—"));

        Addresses.Clear();
        foreach (var a in cache.Addresses)
            Addresses.Add(new AddressRow(
                a.IsChange ? "change" : "ricezione",
                a.Index,
                a.Address,
                a.BalanceSats > 0 ? CoinAmount.Format(a.BalanceSats) : (a.TxCount > 0 ? "0" : "—"),
                a.TxCount > 0 ? a.TxCount.ToString() : "—"));
    }

    // ---------- comandi wallet ----------

    [RelayCommand]
    private async Task ConnectAndSync()
    {
        if (_account is null || _doc is null)
            return;
        if (IsSyncing)
        {
            _resyncRequested = true;
            return;
        }
        IsSyncing = true;
        StatusMessage = "";
        try
        {
            if (_client is null || !_client.IsConnected)
            {
                var (host, port) = ParseServer();
                ConnectionStatus = $"connessione a {host}:{port}…";
                var pins = new CertificatePinStore(AppPaths.CertificatePinsPath(Net));
                _client = await ElectrumClient.ConnectAsync(host, port, UseSsl, pins);
                _client.NotificationReceived += OnServerNotification;
                _client.Disconnected += _ => Dispatcher.UIThread.Post(() =>
                {
                    IsConnected = false;
                    ConnectionStatus = "disconnesso";
                });
                IsConnected = true;
                _autoReconnect = true;
                ConnectionStatus = $"connesso a {host}:{port}{(UseSsl ? " (TLS)" : "")}";
                // Synchronizer per connessione: conserva la cache di tx e
                // prove verificate, così le risincronizzazioni sono incrementali.
                _synchronizer = new WalletSynchronizer(_account, _client, _doc.GapLimit);
                _synchronizer.Progress += msg => Dispatcher.UIThread.Post(() => StatusMessage = msg);
            }

            // Se durante la sync arrivano notifiche, si ripete subito: nessun
            // aggiornamento del server va perso (modello Electrum).
            do
            {
                _resyncRequested = false;
                var result = await _synchronizer!.SyncOnceAsync();
                _lastTransactions = result.Transactions;

                _doc.Cache = new SyncCache
                {
                    TipHeight = result.TipHeight,
                    ConfirmedSats = result.ConfirmedSats,
                    UnconfirmedSats = result.UnconfirmedSats,
                    NextReceiveIndex = result.NextReceiveIndex,
                    NextChangeIndex = result.NextChangeIndex,
                    History = [.. result.History],
                    Utxos = [.. result.Utxos],
                    Addresses = [.. result.AddressRows],
                };
                WalletStore.Save(_doc, _walletPath!, _password);
                ApplyCache(_doc.Cache);
                StatusMessage = $"Sincronizzato: altezza {result.TipHeight}, " +
                    $"{result.History.Count} transazioni verificate SPV. Aggiornamento in tempo reale attivo.";
            } while (_resyncRequested);
        }
        catch (CertificatePinMismatchException ex)
        {
            IsConnected = false;
            ConnectionStatus = "certificato cambiato";
            StatusMessage = ex.Message;
        }
        catch (Exception ex)
        {
            IsConnected = _client?.IsConnected == true;
            ConnectionStatus = IsConnected ? ConnectionStatus : "errore di connessione";
            StatusMessage = $"Errore: {ex.Message}";
        }
        finally
        {
            IsSyncing = false;
        }
    }

    /// <summary>Scopre nuovi server dai peer annunciati dal server connesso (§9).</summary>
    [RelayCommand]
    private async Task DiscoverServers()
    {
        if (_client is null || !_client.IsConnected)
        {
            StatusMessage = "Connettiti a un server prima di cercare i peer.";
            return;
        }
        try
        {
            var added = await Registry.DiscoverAsync(_client);
            var selected = SelectedKnownServer;
            RefreshServers();
            SelectedKnownServer = KnownServers.FirstOrDefault(s => s.Host == selected?.Host)
                ?? KnownServers.FirstOrDefault();
            StatusMessage = added > 0
                ? $"Trovati {added} nuovi server dai peer (totale {KnownServers.Count})."
                : $"Nessun nuovo server annunciato (totale {KnownServers.Count}).";
        }
        catch (Exception ex)
        {
            StatusMessage = $"Errore nella scoperta peer: {ex.Message}";
        }
    }

    private void OnServerNotification(string method, System.Text.Json.JsonElement payload)
    {
        // Cambiamento su un nostro indirizzo o nuovo blocco: risincronizza.
        // Se una sync è già in corso, si accoda (il loop in ConnectAndSync la
        // ripete subito dopo): nessuna notifica viene persa.
        if (method is "blockchain.scripthash.subscribe" or "blockchain.headers.subscribe")
            Dispatcher.UIThread.Post(() =>
            {
                if (IsSyncing)
                    _resyncRequested = true;
                else
                    _ = ConnectAndSync();
            });
    }

    [RelayCommand]
    private void ResetCertificates()
    {
        new CertificatePinStore(AppPaths.CertificatePinsPath(Net)).ResetAll();
        StatusMessage = "Certificati SSL azzerati: riprova la connessione.";
    }

    [RelayCommand]
    private async Task PrepareSend()
    {
        if (_account is null || _doc?.Cache is null)
        {
            SendPreview = "Sincronizza prima di inviare.";
            return;
        }
        try
        {
            if (_lastTransactions is null)
            {
                SendPreview = "Connettiti al server e sincronizza prima di inviare.";
                return;
            }

            var destination = BitcoinAddress.Create(SendTo.Trim(), PalladiumNetworks.For(Net));
            long amount = 0;
            if (!SendAll && !CoinAmount.TryParseCoins(SendAmount, out amount))
            {
                SendPreview = "Importo non valido.";
                return;
            }
            if (!decimal.TryParse(SendFeeRate, out var feeRate) || feeRate <= 0)
            {
                SendPreview = "Fee rate non valido.";
                return;
            }

            _pendingSend = new TransactionFactory(_account).Build(
                _doc.Cache.Utxos, _lastTransactions, destination, amount, feeRate,
                _doc.Cache.NextChangeIndex, SendAll);

            SendPreview = $"txid {_pendingSend.Txid[..16]}… · " +
                $"fee {CoinAmount.Format(_pendingSend.Fee.Satoshi, Profile.CoinUnit)} " +
                $"({_pendingSend.Transaction.GetVirtualSize()} vB)" +
                (_pendingSend.Signed ? "" : " · NON firmata (watch-only)");
            HasPendingSend = _pendingSend.Signed;
        }
        catch (Exception ex)
        {
            _pendingSend = null;
            HasPendingSend = false;
            SendPreview = $"Errore: {ex.Message}";
        }
        await Task.CompletedTask;
    }

    [RelayCommand]
    private async Task ConfirmSend()
    {
        if (_pendingSend is null || _client is null)
            return;
        try
        {
            var txid = await _client.BroadcastAsync(_pendingSend.ToHex());
            SendPreview = $"Trasmessa: {txid}";
            SendTo = SendAmount = "";
            _pendingSend = null;
            HasPendingSend = false;
            await ConnectAndSync();
        }
        catch (Exception ex)
        {
            SendPreview = $"Errore broadcast: {ex.Message}";
        }
    }

    [RelayCommand]
    private void CloseWallet()
    {
        _ = _client?.DisposeAsync().AsTask();
        _client = null;
        _synchronizer = null;
        _autoReconnect = false;
        _resyncRequested = false;
        _doc = null;
        _account = null;
        _lastTransactions = null;
        _pendingSend = null;
        HasPendingSend = false;
        History.Clear();
        IsWalletOpen = false;
        IsConnected = false;
        ConnectionStatus = "non connesso";
        RefreshSetupState();
    }

    private (string Host, int Port) ParseServer()
    {
        var parts = ServerInput.Trim().Split(':');
        var host = parts[0];
        var port = parts.Length > 1 && int.TryParse(parts[1], out var p)
            ? p
            : UseSsl ? Profile.DefaultSslPort : Profile.DefaultTcpPort;
        return (host, port);
    }
}