using System.Collections.ObjectModel;
using System.Linq;
using System.Windows.Threading;
using ytLive.Helpers;

namespace ytLive.ViewModels;

public partial class MainViewModel
{
    private const int VisibleLogEntryLimit = 500;
    private readonly ObservableCollection<AppLogEntry> _currentLaunchLogEntries = new();
    private readonly ObservableCollection<AppLogEntry> _pinnedLogEntries = new();
    private DispatcherTimer? _currentLaunchLogTimer;
    private long _lastCurrentLaunchLogSequence;
    private bool _isLogsTabSelected;

    public ObservableCollection<AppLogEntry> CurrentLaunchLogEntries => _currentLaunchLogEntries;
    public ObservableCollection<AppLogEntry> PinnedLogEntries => _pinnedLogEntries;
    public bool HasPinnedLogEntries => _pinnedLogEntries.Count > 0;
    public RelayCommand<AppLogEntry> AcknowledgeLogEntryCommand => new(AcknowledgeLogEntry);

    public bool IsLiveChatTabSelected
    {
        get => !_isLogsTabSelected;
        set
        {
            if (value)
                SelectLogsTab(false);
            else if (!_isLogsTabSelected)
                OnPropertyChanged(nameof(IsLiveChatTabSelected));
        }
    }

    public bool IsLogsTabSelected
    {
        get => _isLogsTabSelected;
        set
        {
            if (value)
                SelectLogsTab(true);
            else if (_isLogsTabSelected)
                OnPropertyChanged(nameof(IsLogsTabSelected));
        }
    }

    private void InitializeCurrentLaunchLogs()
    {
        var entries = AppLog.SnapshotCurrentLaunch()
            .OrderByDescending(entry => entry.Sequence)
            .Take(VisibleLogEntryLimit)
            .ToArray();
        foreach (var entry in entries)
        {
            if (entry.ErrorClass.HasValue)
                InsertPinnedLogEntry(entry);
            else
                _currentLaunchLogEntries.Add(entry);
        }

        _lastCurrentLaunchLogSequence = entries.FirstOrDefault()?.Sequence ?? 0;
        _currentLaunchLogTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(250) };
        _currentLaunchLogTimer.Tick += (_, _) => RefreshCurrentLaunchLogs();
    }

    private void SelectLogsTab(bool selected)
    {
        if (_isLogsTabSelected == selected)
        {
            OnPropertyChanged(nameof(IsLiveChatTabSelected));
            OnPropertyChanged(nameof(IsLogsTabSelected));
            return;
        }

        _isLogsTabSelected = selected;
        OnPropertyChanged(nameof(IsLiveChatTabSelected));
        OnPropertyChanged(nameof(IsLogsTabSelected));
        if (selected)
        {
            RefreshCurrentLaunchLogs();
            _currentLaunchLogTimer?.Start();
        }
        else
        {
            _currentLaunchLogTimer?.Stop();
        }
    }

    internal void RefreshCurrentLaunchLogs()
    {
        var newEntries = AppLog.SnapshotCurrentLaunch()
            .Where(entry => entry.Sequence > _lastCurrentLaunchLogSequence)
            .OrderBy(entry => entry.Sequence)
            .ToArray();

        foreach (var entry in newEntries)
        {
            if (entry.ErrorClass.HasValue)
                InsertPinnedLogEntry(entry);
            else
                InsertChronologicalLogEntry(entry);
            _lastCurrentLaunchLogSequence = entry.Sequence;
        }
    }

    private void InsertPinnedLogEntry(AppLogEntry entry)
    {
        var index = 0;
        while (index < _pinnedLogEntries.Count)
        {
            var current = _pinnedLogEntries[index];
            var currentClass = (int)current.ErrorClass!.Value;
            var entryClass = (int)entry.ErrorClass!.Value;
            if (currentClass < entryClass
                || (currentClass == entryClass && current.Sequence > entry.Sequence))
                index++;
            else
                break;
        }

        _pinnedLogEntries.Insert(index, entry);
        OnPropertyChanged(nameof(HasPinnedLogEntries));
    }

    private void AcknowledgeLogEntry(AppLogEntry? entry)
    {
        if (entry?.ErrorClass == null || !_pinnedLogEntries.Remove(entry)) return;
        InsertChronologicalLogEntry(entry);
        OnPropertyChanged(nameof(HasPinnedLogEntries));
    }

    private void InsertChronologicalLogEntry(AppLogEntry entry)
    {
        var index = 0;
        while (index < _currentLaunchLogEntries.Count
               && _currentLaunchLogEntries[index].Sequence > entry.Sequence)
            index++;
        _currentLaunchLogEntries.Insert(index, entry);
        if (_currentLaunchLogEntries.Count > VisibleLogEntryLimit)
            _currentLaunchLogEntries.RemoveAt(_currentLaunchLogEntries.Count - 1);
    }

    private void StopCurrentLaunchLogFeed()
        => _currentLaunchLogTimer?.Stop();
}