using System;
using System.Collections.Generic;
using System.Linq;
using MareSynchronos.Services.Mediator;
using MareSynchronos.MareConfiguration;
using MareSynchronos.MareConfiguration.Configurations;
using MareSynchronos.MareConfiguration.Models;

namespace MareSynchronos.Services.Notifications;

public enum NotificationCategory
{
    AutoDetect,
    Syncshell,
}

public sealed record NotificationEntry(NotificationCategory Category, string Id, string Title, string? Description, DateTime CreatedAt)
{
    public static NotificationEntry AutoDetect(string uid, string displayName)
        => new(NotificationCategory.AutoDetect, uid, displayName, "Nouvelle demande d'appairage via AutoDetect.", DateTime.UtcNow);

    public static NotificationEntry SyncshellPublic(string gid, string aliasOrGid)
        => new(NotificationCategory.Syncshell, gid, $"Syncshell publique: {aliasOrGid}", "La Syncshell est désormais visible via AutoDetect.", DateTime.UtcNow);

    public static NotificationEntry SyncshellNotPublic(string gid, string aliasOrGid)
        => new(NotificationCategory.Syncshell, gid, $"Syncshell non publique: {aliasOrGid}", "La Syncshell n'est plus visible via AutoDetect.", DateTime.UtcNow);
}

public sealed class NotificationTracker
{
    private const int MaxStored = 100;

    private readonly MareMediator _mediator;
    private readonly NotificationsConfigService _configService;
    private readonly Dictionary<(NotificationCategory Category, string Id), NotificationEntry> _entries = new();
    private readonly object _lock = new();

    public NotificationTracker(MareMediator mediator, NotificationsConfigService configService)
    {
        _mediator = mediator;
        _configService = configService;
        LoadPersisted();
        PublishState();
    }

    public void Upsert(NotificationEntry entry)
    {
        lock (_lock)
        {
            _entries[(entry.Category, entry.Id)] = entry;
            TrimIfNecessary_NoLock();
            Persist_NoLock();
        }
        PublishState();
    }

    public void Remove(NotificationCategory category, string id)
    {
        lock (_lock)
        {
            _entries.Remove((category, id));
            Persist_NoLock();
        }
        PublishState();
    }

    public IReadOnlyList<NotificationEntry> GetEntries()
    {
        lock (_lock)
        {
            return _entries.Values
                .OrderBy(e => e.CreatedAt)
                .ToList();
        }
    }

    public int Count
    {
        get
        {
            lock (_lock)
            {
                return _entries.Count;
            }
        }
    }

    private void PublishState()
    {
        _mediator.Publish(new NotificationStateChanged(Count));
    }

    private void LoadPersisted()
    {
        try
        {
            var list = _configService.Current.Notifications ?? new List<StoredNotification>();
            foreach (var s in list)
            {
                if (!Enum.TryParse<NotificationCategory>(s.Category, out var cat)) continue;
                var entry = new NotificationEntry(cat, s.Id, s.Title, s.Description, s.CreatedAtUtc);
                _entries[(entry.Category, entry.Id)] = entry;
            }
            TrimIfNecessary_NoLock();
        }
        catch
        {
            // ignore load errors, start empty
        }
    }

    private void Persist_NoLock()
    {
        try
        {
            var stored = _entries.Values
                .OrderBy(e => e.CreatedAt)
                .Select(e => new StoredNotification
                {
                    Category = e.Category.ToString(),
                    Id = e.Id,
                    Title = e.Title,
                    Description = e.Description,
                    CreatedAtUtc = e.CreatedAt
                })
                .ToList();
            _configService.Current.Notifications = stored;
            _configService.Save();
        }
        catch
        {
            // ignore persistence errors
        }
    }

    private void TrimIfNecessary_NoLock()
    {
        if (_entries.Count <= MaxStored) return;
        foreach (var kv in _entries.Values.OrderByDescending(v => v.CreatedAt).Skip(MaxStored).ToList())
        {
            _entries.Remove((kv.Category, kv.Id));
        }
    }
}