using Microsoft.Extensions.Localization;

using MongoDB.Entities;

using PrivaPub.ClientModels;
using PrivaPub.ClientModels.Post;
using PrivaPub.ClientModels.Social;
using PrivaPub.Domain.Privacy;
using PrivaPub.Models.Post;
using PrivaPub.Models.Social;
using PrivaPub.Resources;
using PrivaPub.StaticServices;

namespace PrivaPub.Domain.Timelines
{
	public interface ITimelineService
	{
		Task<WebResult> Home(string rootUserId, string avatarId, string maxId, int limit, CancellationToken token);
		Task<WebResult> Notifications(string rootUserId, string avatarId, string maxId, int limit, CancellationToken token);
		Task<WebResult> MarkNotificationsRead(string rootUserId, string avatarId, CancellationToken token);
	}

	public class TimelineService : ITimelineService
	{
		const int MaxLimit = 40;

		readonly DbEntities _dbEntities;
		readonly IStringLocalizer<GenericRes> _localizer;

		public TimelineService(DbEntities dbEntities, IStringLocalizer<GenericRes> localizer)
		{
			_dbEntities = dbEntities;
			_localizer = localizer;
		}

		public async Task<WebResult> Home(string rootUserId, string avatarId, string maxId, int limit, CancellationToken token)
		{
			var result = new WebResult();
			if (!await Owns(rootUserId, avatarId, token))
				return result.Invalidate(_localizer["Avatar not found."], StatusCodes.Status404NotFound);

			var query = _dbEntities.TimelineEntries.Match(e => e.AvatarId == avatarId);
			if (!string.IsNullOrEmpty(maxId))
				query.Match(f => f.Lt(e => e.PostId, maxId));
			var entries = await query.Sort(e => e.PostId, Order.Descending).Limit(Math.Clamp(limit, 1, MaxLimit)).ExecuteAsync(token);

			var ids = entries.Select(e => e.PostId).Concat(entries.Where(e => e.ReblogOfPostId != default).Select(e => e.ReblogOfPostId)).Distinct().ToList();
			var posts = ids.Count == 0
				? new Dictionary<string, Post>()
				: (await _dbEntities.Posts.Match(p => ids.Contains(p.ID)).Match(VisibilityPolicy.IsShown).ExecuteAsync(token)).ToDictionary(p => p.ID);

			result.Data = entries
				.Where(e => posts.ContainsKey(e.PostId) && (e.ReblogOfPostId == default || posts.ContainsKey(e.ReblogOfPostId)))
				.Select(e =>
				{
					var view = ToView(posts[e.PostId]);
					if (e.ReblogOfPostId != default)
						view.ReblogOf = ToView(posts[e.ReblogOfPostId]);
					return view;
				})
				.ToList();
			return result;
		}

		public async Task<WebResult> Notifications(string rootUserId, string avatarId, string maxId, int limit, CancellationToken token)
		{
			var result = new WebResult();
			if (!await Owns(rootUserId, avatarId, token))
				return result.Invalidate(_localizer["Avatar not found."], StatusCodes.Status404NotFound);

			var query = _dbEntities.Notifications.Match(n => n.AvatarId == avatarId);
			if (!string.IsNullOrEmpty(maxId))
				query.Match(f => f.Lt(n => n.ID, maxId));
			result.Data = (await query.Sort(n => n.ID, Order.Descending).Limit(Math.Clamp(limit, 1, MaxLimit)).ExecuteAsync(token))
				.Select(n => new ViewNotification
				{
					Id = n.ID,
					Type = n.Type.ToString(),
					FromAccountId = n.FromAccountId,
					FromActorURI = n.FromActorURI,
					PostId = n.PostId,
					IsRead = n.IsRead,
					CreatedAt = n.CreatedAt
				})
				.ToList();
			return result;
		}

		public async Task<WebResult> MarkNotificationsRead(string rootUserId, string avatarId, CancellationToken token)
		{
			var result = new WebResult();
			if (!await Owns(rootUserId, avatarId, token))
				return result.Invalidate(_localizer["Avatar not found."], StatusCodes.Status404NotFound);
			await DB.Default.Update<Notification>().Match(n => n.AvatarId == avatarId && !n.IsRead).Modify(n => n.IsRead, true).ExecuteAsync(token);
			return result;
		}

		async Task<bool> Owns(string rootUserId, string avatarId, CancellationToken token) =>
			!string.IsNullOrEmpty(rootUserId) && !string.IsNullOrEmpty(avatarId)
			&& await _dbEntities.RootToAvatars.Match(ra => ra.RootId == rootUserId && ra.AvatarId == avatarId).ExecuteAnyAsync(token);

		static ViewPost ToView(Post post) => new()
		{
			Id = post.ID,
			ObjectURI = post.ObjectURI,
			AuthorAvatarId = post.IsFederatedCopy ? default : post.GroupUserId,
			AuthorActorURI = post.ActorURI,
			GroupId = post.GroupId,
			DmGroupId = post.ConversationId,
			Visibility = post.Visibility.ToString(),
			AnsweringToPostId = post.AnsweringToPostId,
			Title = post.Title,
			Text = post.Text,
			ContentHtml = post.ContentHtml,
			HasContentWarning = post.HasContentWarning,
			IsFederatedCopy = post.IsFederatedCopy,
			CreationDate = post.CreationDate
		};
	}
}