using System.Collections.ObjectModel;
using System.Windows.Input;
using AgentWikiUi.Core;

namespace AgentWikiUi.Gui;

class MessageVm(string role, string text)
{
    public string Role { get; } = role;
    public string Text { get; } = text;
    public bool IsUser => Role == "user";
    public bool IsAi => Role == "ai";
    public bool IsErr => Role == "err";
}

class ChatItem(string id, string title, DateTime updated, bool active)
{
    public string Id { get; } = id;
    public string Title { get; } = title;
    public string When { get; } = updated.ToString("d MMM HH:mm");
    public bool IsActive { get; } = active;
}

record Suggestion(string Title, string Subtitle, string Prompt);

class MainViewModel : ObservableObject
{
    static readonly ModelOption Default = new("Predefinito", "");
    static readonly ModelOption Custom = new("Altro ID…", "__custom");

    public ObservableCollection<MessageVm> Messages { get; } = [];
    public ObservableCollection<ChatItem> Chats { get; } = [];
    public ModelOption[] ModelChoices { get; } = [Default, .. Catalog.Models, Custom];
    public string[] EffortChoices { get; } = ["Predefinito", .. Catalog.Efforts];

    public Suggestion[] Suggestions { get; } =
    [
        new("Spiega il progetto", "Panoramica e struttura", "Spiega cosa fa questo progetto e come è organizzato."),
        new("Scrivi uno script", "PowerShell, Python, C#…", "Scrivi uno script PowerShell che "),
        new("Rivedi del codice", "Bug, leggibilità, prestazioni", "Rivedi questo codice e suggerisci miglioramenti:\n\n"),
        new("Riassumi un testo", "Punti chiave in breve", "Riassumi in modo chiaro questo testo:\n\n"),
    ];

    public ICommand NewChatCommand => newChat;
    public ICommand CopyCommand { get; }
    public ICommand SendCommand { get; }
    public ICommand OpenCommand { get; }
    public ICommand DeleteCommand { get; }
    public ICommand SuggestCommand { get; }
    public ICommand ToggleSidebarCommand { get; }

    /// <summary>Conferma di eliminazione, fornita dalla finestra.</summary>
    /// <summary>Copia negli appunti, fornita dalla finestra.</summary>
    public Func<string, Task> CopyText { get; set; } = _ => Task.CompletedTask;
    public Func<Task<bool>> ConfirmDelete { get; set; } = () => Task.FromResult(true);
    /// <summary>Chiesto alla finestra di rimettere il fuoco sul campo messaggio.</summary>
    public event Action? FocusInput;

    string sessionId = Guid.NewGuid().ToString();
    bool started; // true dopo il primo messaggio riuscito: da lì in poi --resume
    List<Msg> history = [];

    string input = "";
    bool busy, sidebarOpen = true;
    ModelOption selectedModel = Default;
    string customModel = "";
    string selectedEffort = "Predefinito";
    readonly RelayCommand<object> send, newChat;

    public MainViewModel()
    {
        send = new(_ => _ = SendAsync(), () => CanSend);
        SendCommand = send;
        newChat = new(_ => NewChat(), () => !busy);
        CopyCommand = new RelayCommand<string>(t => { if (t is not null) _ = CopyText(t); });
        OpenCommand = new RelayCommand<ChatItem>(c => { if (c is not null) OpenChat(c.Id); });
        DeleteCommand = new RelayCommand<ChatItem>(c => { if (c is not null) _ = DeleteAsync(c); });
        SuggestCommand = new RelayCommand<Suggestion>(s => { if (s is not null) { Input = s.Prompt; FocusInput?.Invoke(); } });
        ToggleSidebarCommand = new RelayCommand<object>(_ => SidebarOpen = !SidebarOpen);
        Messages.CollectionChanged += (_, _) => { Raise(nameof(HasMessages)); Raise(nameof(ShowEmpty)); };

        // all'avvio riapre la chat più recente
        if (ChatStore.List().FirstOrDefault() is { } last) OpenChat(last.Id); else RefreshChats();
    }

    public bool HasMessages => Messages.Count > 0;
    public bool ShowEmpty => Messages.Count == 0;
    public bool CanSend => !busy && !string.IsNullOrWhiteSpace(input);

    public string Input
    {
        get => input;
        set { if (Set(ref input, value)) { Raise(nameof(CanSend)); send.Refresh(); } }
    }

    public bool IsBusy
    {
        get => busy;
        private set { if (Set(ref busy, value)) { Raise(nameof(CanSend)); send.Refresh(); newChat.Refresh(); } }
    }

    public bool SidebarOpen { get => sidebarOpen; set => Set(ref sidebarOpen, value); }
    public ModelOption SelectedModel
    {
        get => selectedModel;
        set { if (Set(ref selectedModel, value)) Raise(nameof(IsCustomModel)); }
    }
    public bool IsCustomModel => selectedModel == Custom;
    public string CustomModel { get => customModel; set => Set(ref customModel, value); }
    public string SelectedEffort { get => selectedEffort; set => Set(ref selectedEffort, value); }

    void RefreshChats()
    {
        Chats.Clear();
        foreach (var c in ChatStore.List()) Chats.Add(new(c.Id, c.Title, c.Updated, c.Id == sessionId));
    }

    void Show(List<Msg> msgs)
    {
        Messages.Clear();
        foreach (var m in msgs) Messages.Add(new(m.Role, m.Text));
    }

    void NewChat()
    {
        sessionId = Guid.NewGuid().ToString(); started = false; history = [];
        Show(history); RefreshChats(); FocusInput?.Invoke();
    }

    void OpenChat(string id)
    {
        if (busy) return;
        if (ChatStore.Load(id) is not { } chat) { RefreshChats(); return; }
        sessionId = chat.Id; started = chat.Started; history = chat.Messages;
        Show(history); RefreshChats();
    }

    async Task DeleteAsync(ChatItem c)
    {
        if (busy || !await ConfirmDelete()) return;
        ChatStore.Delete(c.Id);
        if (c.Id == sessionId) NewChat(); else RefreshChats();
    }

    async Task SendAsync()
    {
        if (!CanSend) return;
        var text = input.Trim();
        var model = IsCustomModel ? customModel.Trim() : selectedModel.Id;
        var effort = selectedEffort == "Predefinito" ? "" : selectedEffort;

        Input = ""; IsBusy = true;
        Add("user", text);
        Persist(); // il messaggio non va perso se l'app si chiude durante l'attesa
        RefreshChats();
        try
        {
            var r = await Claude.RunCapturedAsync(text, sessionId, started, model, effort);
            if (r.Code == 0) { started = true; Add("ai", r.Out); }
            else Add("err", $"claude è uscito con codice {r.Code}\n{r.Err}".Trim());
        }
        catch (System.ComponentModel.Win32Exception) { Add("err", "'claude' non trovato nel PATH."); }
        catch (Exception ex) { Add("err", ex.Message); }
        finally
        {
            IsBusy = false;
            Persist();
            RefreshChats();
            FocusInput?.Invoke();
        }
    }

    void Add(string role, string text) { history.Add(new(role, text)); Messages.Add(new(role, text)); }

    void Persist()
    {
        try { ChatStore.Save(sessionId, started, history); }
        catch (IOException) { } // la chat resta a schermo anche se il salvataggio fallisce
    }
}