using System;
using System.Threading.Tasks;
using System.Windows.Input;
using ytLive.Helpers;
using ytLive.Models;

namespace ytLive.Services;

/// <summary>
/// TASK 41 — the Test Stream pull-out (the "TEST" tab at the bottom of the Live
/// screen's right rail). Drives a private test broadcast's chat tooling:
/// Mock Chat Input sends a REAL liveChat/messages.insert (round-tripping through
/// the normal ~2s poll and the live overlay path), and the simulated-event buttons
/// inject synthetic member / SuperChat / subscriber rows through the exact
/// MessageReceived seam the real poll uses — local-only, never sent to YouTube
/// (the insert API only creates text). The broadcast itself runs through the real
/// private go-live pipeline; this VM only owns the dock.
/// </summary>
public sealed class TestSessionViewModel : ViewModelBase
{
    private readonly YouTubeStreamService _stream;
    private readonly YouTubeChatService _chat;
    private readonly Action? _onEndStream;

    private bool _isDrawerOpen;
    private bool _isTestSession;
    private string? _broadcastId;
    private string? _liveChatId;
    private string _sendMessageText = string.Empty;
    private bool _isSending;
    private string? _lastEventText;
    private int _eventCounter;

    /// <summary>Fake viewer names for simulated events — several backs make the
    /// rows look like a real muted room.</summary>
    private static readonly string[] SimulatedViewers = { "PixelPasta", "NightskyNick", "LunaGlow", "CactusFox" };

    public TestSessionViewModel(
        YouTubeStreamService stream,
        YouTubeChatService chat,
        Action? onEndStream = null)
    {
        _stream = stream;
        _chat = chat;
        _onEndStream = onEndStream;

        SendTestMessageCommand = new RelayCommand(_ => _ = SendTestMessageAsync(), _ => CanSendTestMessage);
        SimulateSubscriberCommand = new RelayCommand(_ => Simulate(SimulatedSubscriber()));
        SimulateMemberCommand = new RelayCommand(_ => Simulate(SimulatedMember()));
        SimulateSuperChatCommand = new RelayCommand(_ => Simulate(SimulatedSuperChat()));
        EndTestCommand = new RelayCommand(_ => _onEndStream?.Invoke());
        ToggleDrawerCommand = new RelayCommand(_ => IsDrawerOpen = !IsDrawerOpen);
        CloseDrawerCommand = new RelayCommand(_ => IsDrawerOpen = false);
    }

    public ICommand SendTestMessageCommand { get; }
    public RelayCommand SimulateSubscriberCommand { get; }
    public RelayCommand SimulateMemberCommand { get; }
    public RelayCommand SimulateSuperChatCommand { get; }
    public RelayCommand EndTestCommand { get; }
    public RelayCommand ToggleDrawerCommand { get; }
    public RelayCommand CloseDrawerCommand { get; }

    public bool IsDrawerOpen
    {
        get => _isDrawerOpen;
        set => SetProperty(ref _isDrawerOpen, value);
    }

    /// <summary>Whether a test broadcast is currently live (ended by BeginTest /
    /// EndTestSilently; EndTestCommand asks the app to stop, which routes back here).</summary>
    public bool IsTestSession
    {
        get => _isTestSession;
        private set
        {
            if (SetProperty(ref _isTestSession, value))
            {
                OnPropertyChanged(nameof(SessionCaption));
                OnPropertyChanged(nameof(ChatIdLine));
                OnPropertyChanged(nameof(CanSendTestMessage));
            }
        }
    }

    public string? BroadcastId => _broadcastId;

    public string ChatIdLine => _liveChatId == null ? "liveChatId: —" : $"liveChatId: {_liveChatId}";

    public string SessionCaption => IsTestSession
        ? "Test stream is live — private to you, zero notifications, real chat."
        : "No test in progress — hit the Test button in the top bar to start a private broadcast and check your chat overlay.";

    public string SendMessageText
    {
        get => _sendMessageText;
        set
        {
            if (SetProperty(ref _sendMessageText, value))
                OnPropertyChanged(nameof(CanSendTestMessage));
        }
    }

    public bool IsSending
    {
        get => _isSending;
        private set
        {
            if (SetProperty(ref _isSending, value))
                OnPropertyChanged(nameof(CanSendTestMessage));
        }
    }

    public bool CanSendTestMessage => IsTestSession && !IsSending && _liveChatId != null
        && !string.IsNullOrWhiteSpace(SendMessageText);

    /// <summary>Feedback line for the last send / simulated event (null = nothing yet).</summary>
    public string? LastEventText
    {
        get => _lastEventText;
        private set => SetProperty(ref _lastEventText, value);
    }

    /// <summary>Called once by MainViewModel when the test broadcast is live and its
    /// liveChatId resolved — opens the dock so the chat tools are immediately usable.</summary>
    public void BeginTest(string broadcastId, string? liveChatId)
    {
        _broadcastId = broadcastId;
        _liveChatId = string.IsNullOrWhiteSpace(liveChatId) ? null : liveChatId;
        SendMessageText = string.Empty;
        LastEventText = _liveChatId == null
            ? "Chat polling couldn't start — Mock Chat Input is disabled."
            : null;
        IsTestSession = true;
        IsDrawerOpen = true;
    }

    /// <summary>Called by MainViewModel's stop path when the broadcast ends — the
    /// dock forgets the ended session (idempotent).</summary>
    public void EndTestSilently()
    {
        _broadcastId = null;
        _liveChatId = null;
        IsTestSession = false;
        IsSending = false;
    }

    /// <summary>Mock Chat Input: real liveChat/messages.insert. The inserted text
    /// arrives through the normal poll and renders via the live overlay path — the
    /// whole point is that the round-trip is the real one.</summary>
    public async Task SendTestMessageAsync()
    {
        if (!CanSendTestMessage || _liveChatId == null) return;
        var text = SendMessageText.Trim();
        IsSending = true;
        SendMessageText = string.Empty;
        LastEventText = null;
        try
        {
            var error = await _stream.InsertChatMessageAsync(_liveChatId, text);
            LastEventText = error == null
                ? $"Sent — “{text}” should appear on the chat overlay within a couple of seconds."
                : $"Couldn't send: {error}";
        }
        catch (Exception ex)
        {
            AppLog.Write($"Test chat message send failed: {ex.Message}");
            LastEventText = "Couldn't send that message — try again.";
        }
        finally
        {
            IsSending = false;
        }
    }

    private void Simulate(ChatMessage message)
    {
        if (!IsTestSession) return;
        _chat.InjectSimulatedMessage(message);
        _eventCounter++;
        LastEventText = $"Fired #{_eventCounter}: {Describe(message)} — renders on any visible chat overlay.";
        AppLog.Write($"Test chat simulation {_eventCounter} injected");
    }

    /// <summary>Subscriptions aren't chat events on YouTube, so a "subscriber" row
    /// is a plain text-shaped message carrying the count — honest: the chat overlay
    /// shows it as a regular row, which is exactly what a sub looks like in chat.
    /// It carries <see cref="ChatEventKind.None"/> on purpose: no alert animation
    /// fires for free subs — the chat mention is the announcement (creator ruling).</summary>
    private ChatMessage SimulatedSubscriber()
    {
        var author = NextViewer();
        return NewSimulated(author, "New subscriber — welcome to the herd! 🦙 (simulated subscribe)");
    }

    private ChatMessage SimulatedMember()
    {
        var author = NextViewer();
        var message = NewSimulated(author, $"🎉 {author} became a member!");
        message.IsMember = true;
        message.MembershipLevel = "New member";
        message.Kind = ChatEventKind.NewMember;
        return message;
    }

    private ChatMessage SimulatedSuperChat()
    {
        var author = NextViewer();
        var message = NewSimulated(author, "Keep the streams flowing, llama power 🦙");
        message.IsSuperChat = true;
        message.SuperChatAmount = 5.00;
        message.SuperChatCurrency = "$";
        message.SuperChatDisplayString = "$5.00";
        message.Kind = ChatEventKind.SuperChat;
        return message;
    }

    private ChatMessage NewSimulated(string author, string text)
    {
        return new ChatMessage
        {
            AuthorName = author,
            Message = text,
            Timestamp = DateTime.Now,
            IsSimulated = true,
        };
    }

    private string NextViewer() => SimulatedViewers[_eventCounter % SimulatedViewers.Length];

    private static string Describe(ChatMessage m)
    {
        if (m.IsSuperChat) return $"{m.AuthorName} pledged {m.SuperChatCurrency}{m.SuperChatAmount:0.00} in a Super Chat";
        if (m.IsMember) return $"{m.AuthorName} just became a member ({m.MembershipLevel})";
        return $"{m.AuthorName} subscribed";
    }
}