using System.Diagnostics;
using System.Windows.Input;
using ytLive.Helpers;
using ytLive.Models;

namespace ytLive.Services;

/// <summary>
/// Backing VM for the YPP pull-out (the "YPP" tab below Stream Settings on the
/// Live screen's right edge). Shows the connected channel's current position
/// toward the YPP tier thresholds (subscribers + 90-day uploads via the Data
/// API), a compliance checklist (2FA/AdSense self-reported — channel standing is
/// NOT exposed to ordinary apps, so the drawer deep-links to the Earn page for it)
/// and the "what counts" education the creator would otherwise have to leave the
/// app to find. Snapshots are appended to SQLite on every refresh so a later
/// analytics slice can compute velocity/ETA from history.
/// Drawer open/close lives here (mirrors LiveBroadcastFormViewModel).
/// </summary>
public sealed class YppTrackerViewModel : ViewModelBase
{
    private const double BarMaxWidth = 220;

    private readonly Func<LayoutStore> _store;
    private readonly Func<ChannelStatsService> _stats;
    private readonly Func<bool> _isConnected;
    private readonly Func<string?> _displayName;

    private bool _isDrawerOpen;
    private bool _isLoading;
    private bool _isRefreshing;
    private string? _loadError;
    private string _displayNameText = string.Empty;
    private long _subscriberCount;
    private long _videoCount;
    private long _totalViews;
    private int _uploadsLast90Days;
    private bool _hasSnapshot;
    private bool _twoFactorEnabled;
    private bool _adsenseLinked;
    private DateTime? _lastRefreshedAtUtc;

    public YppTrackerViewModel(
        Func<LayoutStore> store,
        Func<ChannelStatsService> stats,
        Func<bool> isConnected,
        Func<string?> displayName)
    {
        _store = store;
        _stats = stats;
        _isConnected = isConnected;
        _displayName = displayName;

        RefreshCommand = new RelayCommand(_ => _ = RefreshAsync());
        ToggleDrawerCommand = new RelayCommand(_ => IsDrawerOpen = !IsDrawerOpen);
        CloseDrawerCommand = new RelayCommand(_ => IsDrawerOpen = false);
        OpenEarnCommand = new RelayCommand(_ => OpenUrl(EarnUrl));
        OpenTwoStepCommand = new RelayCommand(_ => OpenUrl(TwoStepVerificationUrl));
        OpenAdsenseCommand = new RelayCommand(_ => OpenUrl(AdsenseGuideUrl));

        (_twoFactorEnabled, _adsenseLinked) = _store().LoadYppChecklist();
        _lastRefreshedAtUtc = _store().LoadYppLastRefreshedAtUtc();
    }

    // Deep links — the parts of the checklist YouTube does NOT expose to any API
    // resolve in the browser; everything API-derived stays in-app.
    private const string EarnUrl = "https://www.youtube.com/earn";
    private const string TwoStepVerificationUrl = "https://myaccount.google.com/signinoptions/two-step-verification";
    private const string AdsenseGuideUrl = "https://support.google.com/youtube/answer/72851";

    public RelayCommand RefreshCommand { get; }
    public RelayCommand ToggleDrawerCommand { get; }
    public RelayCommand CloseDrawerCommand { get; }
    public RelayCommand OpenEarnCommand { get; }
    public RelayCommand OpenTwoStepCommand { get; }
    public RelayCommand OpenAdsenseCommand { get; }

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

    public bool IsLoading
    {
        get => _isLoading;
        private set => SetProperty(ref _isLoading, value);
    }

    public bool IsSignedOut => !_isConnected();

    public string? LoadError
    {
        get => _loadError;
        private set => SetProperty(ref _loadError, value);
    }

    public string DisplayName => _displayNameText;

    // ─── Live numbers (from the Data API snapshot) ───

    public long SubscriberCount => _subscriberCount;
    public long VideoCount => _videoCount;
    public long TotalViews => _totalViews;
    public int UploadsLast90Days => _uploadsLast90Days;

    /// <summary>True once a snapshot has successfully captured at least once this
    /// session (drives the standing detail text's "sign in to load" state).</summary>
    public bool HasSnapshot => _hasSnapshot;

    // ─── Manual checklist (2FA / AdSense — no API exposes them) ───

    public bool TwoFactorEnabled
    {
        get => _twoFactorEnabled;
        set
        {
            if (SetProperty(ref _twoFactorEnabled, value))
                PersistChecklist();
        }
    }

    public bool AdSenseLinked
    {
        get => _adsenseLinked;
        set
        {
            if (SetProperty(ref _adsenseLinked, value))
                PersistChecklist();
        }
    }

    // ─── Progress rows (subscribers is fixed; uploads is a 3/90d bar) ───

    public double Tier1SubsProgress => Progress(SubscriberCount, YppThresholds.Tier1.Subscribers);
    public double Tier2SubsProgress => Progress(SubscriberCount, YppThresholds.Tier2Now.Subscribers);
    public double UploadsProgress => Progress(UploadsLast90Days, YppThresholds.UploadsRequiredPer90Days);

    public double Tier1SubsBarWidth => Progress(SubscriberCount, YppThresholds.Tier1.Subscribers) * BarMaxWidth;
    public double Tier2SubsBarWidth => Progress(SubscriberCount, YppThresholds.Tier2Now.Subscribers) * BarMaxWidth;
    public double UploadsBarWidth => Progress(UploadsLast90Days, YppThresholds.UploadsRequiredPer90Days) * BarMaxWidth;

    public string Tier1SubsText => $"{SubscriberCount:N0} / {YppThresholds.Tier1.Subscribers:N0}";
    public string Tier2SubsText => $"{SubscriberCount:N0} / {YppThresholds.Tier2Now.Subscribers:N0}";
    public string UploadsText => $"{UploadsLast90Days} / {YppThresholds.UploadsRequiredPer90Days} in the last 90 days";

    public string StandingDetailText
    {
        get
        {
            if (!HasSnapshot) return "Sign in to load your channel's progress from YouTube.";
            return "Channel standing isn't exposed to YouTube apps — check the Earn page for your live status.";
        }
    }

    public string LastUpdatedText
    {
        get
        {
            if (_lastRefreshedAtUtc == null) return "Not refreshed yet";
            var local = _lastRefreshedAtUtc.Value.ToLocalTime();
            return local.Date == DateTime.Today
                ? $"Updated today at {local:HH:mm}"
                : $"Updated {local:g}";
        }
    }

    public string WhatCountsText { get; } =
        "Long-form watch hours: valid public VODs and livestreams watched in the trailing 12 " +
        "months — Shorts-feed views don't count, and private, unlisted, deleted or ad-campaign " +
        "time is excluded. Shorts views: valid public Shorts viewed in the Shorts feed over 90 " +
        "days. Uploads: valid public long-form videos posted in the last 90 days. Zero active " +
        "Community Guidelines strikes, 2-Step Verification switched on, and a linked AdSense " +
        "account complete the checklist. Figures here are API-derived and close to — but not " +
        "identical to — YouTube Studio's Earn tab.";

    /// <summary>Account sign-in/out changed (fires from MainViewModel): reset the
    /// signed-out state and refresh when a session now exists.</summary>
    public void OnAccountChanged()
    {
        OnPropertyChanged(nameof(IsSignedOut));
        OnPropertyChanged(nameof(DisplayName));
        if (_hasSnapshot && !_isConnected())
        {
            _hasSnapshot = false;
            OnPropertyChanged(nameof(HasSnapshot));
        }
        if (_isConnected())
            _ = EnsureLoadedAsync();
    }

    /// <summary>Loads once per session/day (quota-honest: the analytics slice that
    /// gives watch-hours/shorts has a thin targeted-query budget, so this gate is
    /// baked in now). A manual "Refresh" always goes to the wire.</summary>
    public async Task EnsureLoadedAsync()
    {
        if (!_isConnected() || _hasSnapshot) return;
        var last = _store().LoadYppLastRefreshedAtUtc();
        if (last != null && DateTime.UtcNow - last.Value < TimeSpan.FromHours(24)) return;
        await RefreshAsync();
    }

    public async Task RefreshAsync()
    {
        if (_isRefreshing) return;
        _isRefreshing = true;
        IsLoading = true;
        LoadError = null;
        try
        {
            if (!_isConnected())
            {
                _lastRefreshedAtUtc = null;
                OnPropertyChanged(nameof(LastUpdatedText));
                return;
            }

            var snapshot = await _stats().CaptureCurrentAsync();
            if (snapshot == null)
            {
                LoadError = "Couldn't reach YouTube — try again.";
                return;
            }

            ApplySnapshot(snapshot);
            _store().SaveYppSnapshot(snapshot);
            _lastRefreshedAtUtc = snapshot.CapturedAtUtc;
            _store().SaveYppLastRefreshedAtUtc(snapshot.CapturedAtUtc);
            OnPropertyChanged(nameof(LastUpdatedText));
        }
        catch (Exception ex)
        {
            AppLog.Write($"YPP refresh failed: {ex}");
            LoadError = "Refresh failed — try again.";
        }
        finally
        {
            _isRefreshing = false;
            IsLoading = false;
        }
    }

    private void ApplySnapshot(YppStatSnapshot snapshot)
    {
        _displayNameText = _displayName() ?? string.Empty;
        _subscriberCount = snapshot.SubscriberCount;
        _videoCount = snapshot.VideoCount;
        _totalViews = snapshot.TotalViews;
        _uploadsLast90Days = snapshot.UploadsLast90Days;
        _hasSnapshot = true;

        OnPropertyChanged(nameof(DisplayName));
        OnPropertyChanged(nameof(SubscriberCount));
        OnPropertyChanged(nameof(VideoCount));
        OnPropertyChanged(nameof(TotalViews));
        OnPropertyChanged(nameof(UploadsLast90Days));
        OnPropertyChanged(nameof(HasSnapshot));
        OnPropertyChanged(nameof(Tier1SubsProgress));
        OnPropertyChanged(nameof(Tier2SubsProgress));
        OnPropertyChanged(nameof(UploadsProgress));
        OnPropertyChanged(nameof(Tier1SubsBarWidth));
        OnPropertyChanged(nameof(Tier2SubsBarWidth));
        OnPropertyChanged(nameof(UploadsBarWidth));
        OnPropertyChanged(nameof(Tier1SubsText));
        OnPropertyChanged(nameof(Tier2SubsText));
        OnPropertyChanged(nameof(UploadsText));
        OnPropertyChanged(nameof(StandingDetailText));
    }

    private void PersistChecklist() => _store().SaveYppChecklist(TwoFactorEnabled, AdSenseLinked);

    private static double Progress(long current, long target)
        => target <= 0 ? 0 : Math.Clamp((double)current / target, 0, 1);

    private static void OpenUrl(string url)
    {
        Process.Start(new ProcessStartInfo(url) { UseShellExecute = true });
    }
}