using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Caching.Memory;

using MongoDB.Entities;

using PrivaPub.Api.Mastodon.Entities;
using PrivaPub.Api.Mastodon.Infrastructure;
using PrivaPub.Api.Mastodon.Mappers;
using PrivaPub.Domain.Privacy;
using PrivaPub.Domain.Statuses;
using PrivaPub.Models.Post;
using PrivaPub.StaticServices;

using PostEntity = PrivaPub.Models.Post.Post;

namespace PrivaPub.Api.Mastodon.Controllers
{
	public class StatusesController : MastodonController
	{
		const int MaxContext = 200;

		readonly IStatusService _statuses;
		readonly MastodonMapper _mapper;
		readonly DbEntities _dbEntities;
		readonly IMemoryCache _cache;

		public StatusesController(IStatusService statuses, MastodonMapper mapper, DbEntities dbEntities, IMemoryCache cache)
		{
			_statuses = statuses;
			_mapper = mapper;
			_dbEntities = dbEntities;
			_cache = cache;
		}

		[HttpPost("/api/v1/statuses"), Scope("write:statuses")]
		public async Task<IActionResult> Create(CancellationToken token)
		{
			var idempotency = Request.Headers["Idempotency-Key"].ToString();
			var cacheKey = string.IsNullOrEmpty(idempotency) ? default : $"idempotency:{MyId}:{idempotency}";
			if (cacheKey != default && _cache.TryGetValue(cacheKey, out string earlier))
			{
				var existing = await _dbEntities.Posts.MatchID(earlier).ExecuteFirstAsync(token);
				if (existing != default)
					return Json(await _mapper.Status(existing, MyId, token));
			}
			if (Params.List("media_ids").Count > 0)
				return Error(StatusCodes.Status422UnprocessableEntity, "Validation failed: Media attachments are not supported yet");
			if (Params.Has("poll[options]"))
				return Error(StatusCodes.Status422UnprocessableEntity, "Validation failed: Polls are not supported yet");

			var outcome = await _statuses.Publish(Me, new StatusDraft
			{
				Text = Params.Get("status"),
				PlainText = true,
				SpoilerText = Params.Get("spoiler_text"),
				Sensitive = Params.Bool("sensitive") ?? Me.Settings.DefaultSensitive,
				Visibility = Visibility(Params.Get("visibility") ?? Me.Settings.DefaultVisibility),
				InReplyTo = Params.Get("in_reply_to_id"),
				Language = Params.Get("language") ?? Me.Settings.DefaultLanguage
			}, token);
			if (!outcome.Ok)
				return Error(outcome.Status, outcome.Error);
			if (cacheKey != default)
				_cache.Set(cacheKey, outcome.Post.ID, TimeSpan.FromHours(1));
			return Json(await _mapper.Status(outcome.Post, MyId, token));
		}

		[HttpGet("/api/v1/statuses"), Scope("read:statuses", requiresUser: false), Microsoft.AspNetCore.Authorization.AllowAnonymous]
		public async Task<IActionResult> Many(CancellationToken token)
		{
			var ids = Params.List("id").Take(20).ToList();
			var posts = await _dbEntities.Posts.Match(p => ids.Contains(p.ID) && !p.DeletedAt.HasValue).ExecuteAsync(token);
			var visible = new List<PostEntity>();
			foreach (var post in posts)
				if (await VisibilityPolicy.CanSee(post, MyId, token))
					visible.Add(post);
			return Json(await _mapper.Statuses(visible, MyId, token));
		}

		[HttpGet("/api/v1/statuses/{id}"), Scope("read:statuses", requiresUser: false), Microsoft.AspNetCore.Authorization.AllowAnonymous]
		public async Task<IActionResult> Get(string id, CancellationToken token)
		{
			var post = await Visible(id, token);
			return post == default ? NotFoundError() : Json(await _mapper.Status(post, MyId, token));
		}

		[HttpPut("/api/v1/statuses/{id}"), Scope("write:statuses")]
		public async Task<IActionResult> Edit(string id, CancellationToken token)
		{
			if (Params.List("media_ids").Count > 0)
				return Error(StatusCodes.Status422UnprocessableEntity, "Validation failed: Media attachments are not supported yet");
			var outcome = await _statuses.Edit(Me, id, new StatusDraft
			{
				Text = Params.Get("status"),
				PlainText = true,
				SpoilerText = Params.Get("spoiler_text"),
				Sensitive = Params.Bool("sensitive") ?? false,
				Language = Params.Get("language")
			}, token);
			return outcome.Ok ? Json(await _mapper.Status(outcome.Post, MyId, token)) : Error(outcome.Status, outcome.Error);
		}

		[HttpDelete("/api/v1/statuses/{id}"), Scope("write:statuses")]
		public async Task<IActionResult> Delete(string id, CancellationToken token)
		{
			var before = await _dbEntities.Posts.Match(p => p.ID == id && p.GroupUserId == MyId && !p.IsFederatedCopy && !p.DeletedAt.HasValue).ExecuteFirstAsync(token);
			if (before == default)
				return NotFoundError();
			var status = await _mapper.Status(before, MyId, token);
			var outcome = await _statuses.Remove(Me, id, token);
			if (!outcome.Ok)
				return Error(outcome.Status, outcome.Error);
			if (status != default)
			{
				status.Text = before.Text;
				status.SpoilerText = before.SpoilerText ?? string.Empty;
			}
			return Json(status);
		}

		[HttpGet("/api/v1/statuses/{id}/context"), Scope("read:statuses", requiresUser: false), Microsoft.AspNetCore.Authorization.AllowAnonymous]
		public async Task<IActionResult> Context(string id, CancellationToken token)
		{
			var post = await Visible(id, token);
			if (post == default)
				return NotFoundError();

			var ancestors = new List<PostEntity>();
			var cursor = post;
			while (!string.IsNullOrEmpty(cursor.AnsweringToPostId) && ancestors.Count < MaxContext)
			{
				cursor = await _dbEntities.Posts.MatchID(cursor.AnsweringToPostId).ExecuteFirstAsync(token);
				if (cursor == default || cursor.DeletedAt.HasValue || !await VisibilityPolicy.CanSee(cursor, MyId, token))
					break;
				ancestors.Insert(0, cursor);
			}

			var descendants = new List<PostEntity>();
			var frontier = new List<string> { post.ID };
			while (frontier.Count > 0 && descendants.Count < MaxContext)
			{
				var parents = frontier;
				var children = await _dbEntities.Posts.Match(p => parents.Contains(p.AnsweringToPostId) && !p.DeletedAt.HasValue && p.ReblogOfPostId == null)
					.Sort(p => p.ID, Order.Ascending).Limit(MaxContext).ExecuteAsync(token);
				frontier = new List<string>();
				foreach (var child in children)
					if (await VisibilityPolicy.CanSee(child, MyId, token))
					{
						descendants.Add(child);
						frontier.Add(child.ID);
					}
			}
			return Json(new Context
			{
				Ancestors = await _mapper.Statuses(ancestors, MyId, token),
				Descendants = await _mapper.Statuses(descendants.OrderBy(d => d.ID, StringComparer.Ordinal).ToList(), MyId, token)
			});
		}

		[HttpGet("/api/v1/statuses/{id}/history"), Scope("read:statuses", requiresUser: false), Microsoft.AspNetCore.Authorization.AllowAnonymous]
		public async Task<IActionResult> History(string id, CancellationToken token)
		{
			var post = await Visible(id, token);
			if (post == default)
				return NotFoundError();
			var account = await _mapper.Account(MastodonMapper.AuthorOf(post), token);
			var edits = post.Revisions.Select(r => new StatusEdit
			{
				Content = r.ContentHtml ?? string.Empty,
				SpoilerText = r.SpoilerText ?? string.Empty,
				Sensitive = r.HasContentWarning,
				CreatedAt = MastodonJson.Time(r.EditedAt),
				Account = account
			}).ToList();
			edits.Add(new StatusEdit
			{
				Content = MastodonMapper.Content(post),
				SpoilerText = post.SpoilerText ?? string.Empty,
				Sensitive = post.HasContentWarning,
				CreatedAt = MastodonJson.Time(post.EditedAt ?? post.CreationDate),
				Account = account
			});
			return Json(edits);
		}

		[HttpGet("/api/v1/statuses/{id}/source"), Scope("read:statuses")]
		public async Task<IActionResult> Source(string id, CancellationToken token)
		{
			var post = await _dbEntities.Posts.Match(p => p.ID == id && p.GroupUserId == MyId && !p.IsFederatedCopy && !p.DeletedAt.HasValue).ExecuteFirstAsync(token);
			return post == default ? NotFoundError() : Json(new StatusSource { Id = post.ID, Text = post.Text ?? string.Empty, SpoilerText = post.SpoilerText ?? string.Empty });
		}

		[HttpPost("/api/v1/statuses/{id}/favourite"), Scope("write:favourites")]
		public Task<IActionResult> Favourite(string id, CancellationToken token) => Toggle(_statuses.Favourite(Me, id, true, token), id, token);

		[HttpPost("/api/v1/statuses/{id}/unfavourite"), Scope("write:favourites")]
		public Task<IActionResult> Unfavourite(string id, CancellationToken token) => Toggle(_statuses.Favourite(Me, id, false, token), id, token);

		[HttpPost("/api/v1/statuses/{id}/reblog"), Scope("write:statuses")]
		public async Task<IActionResult> Reblog(string id, CancellationToken token)
		{
			var outcome = await _statuses.Reblog(Me, id, true, Visibility(Params.Get("visibility")), token);
			return outcome.Ok ? Json(await _mapper.Status(outcome.Post, MyId, token)) : Error(outcome.Status, outcome.Error);
		}

		[HttpPost("/api/v1/statuses/{id}/unreblog"), Scope("write:statuses")]
		public Task<IActionResult> Unreblog(string id, CancellationToken token) => Toggle(_statuses.Reblog(Me, id, false, PostVisibility.Public, token), id, token);

		[HttpGet("/api/v1/statuses/{id}/favourited_by"), Scope("read:accounts", requiresUser: false), Microsoft.AspNetCore.Authorization.AllowAnonymous]
		public async Task<IActionResult> FavouritedBy(string id, CancellationToken token)
		{
			if (await Visible(id, token) == default)
				return NotFoundError();
			var favourites = await _dbEntities.Favourites.Match(f => f.PostId == id).Sort(f => f.ID, Order.Descending).Limit(Limit(40, 80)).ExecuteAsync(token);
			var accounts = await _mapper.Accounts(favourites.Select(f => f.AccountId), token);
			return Json(favourites.Select(f => accounts.GetValueOrDefault(f.AccountId)).Where(a => a != default).ToList());
		}

		[HttpGet("/api/v1/statuses/{id}/reblogged_by"), Scope("read:accounts", requiresUser: false), Microsoft.AspNetCore.Authorization.AllowAnonymous]
		public async Task<IActionResult> RebloggedBy(string id, CancellationToken token)
		{
			if (await Visible(id, token) == default)
				return NotFoundError();
			var reblogs = await _dbEntities.Posts.Match(p => p.ReblogOfPostId == id && !p.DeletedAt.HasValue).Sort(p => p.ID, Order.Descending).Limit(Limit(40, 80)).ExecuteAsync(token);
			var accounts = await _mapper.Accounts(reblogs.Select(MastodonMapper.AuthorOf), token);
			return Json(reblogs.Select(r => accounts.GetValueOrDefault(MastodonMapper.AuthorOf(r))).Where(a => a != default).ToList());
		}

		[HttpPost("/api/v1/statuses/{id}/bookmark"), Scope("write:bookmarks")]
		public Task<IActionResult> Bookmark(string id, CancellationToken token) => Unchanged(id, token);

		[HttpPost("/api/v1/statuses/{id}/unbookmark"), Scope("write:bookmarks")]
		public Task<IActionResult> Unbookmark(string id, CancellationToken token) => Unchanged(id, token);

		[HttpPost("/api/v1/statuses/{id}/mute"), Scope("write:mutes")]
		public Task<IActionResult> Mute(string id, CancellationToken token) => Unchanged(id, token);

		[HttpPost("/api/v1/statuses/{id}/unmute"), Scope("write:mutes")]
		public Task<IActionResult> Unmute(string id, CancellationToken token) => Unchanged(id, token);

		[HttpPost("/api/v1/statuses/{id}/pin"), Scope("write:accounts")]
		public IActionResult Pin(string id) => Error(StatusCodes.Status422UnprocessableEntity, "Validation failed: Pinning is not supported yet");

		[HttpPost("/api/v1/statuses/{id}/unpin"), Scope("write:accounts")]
		public Task<IActionResult> Unpin(string id, CancellationToken token) => Unchanged(id, token);

		async Task<IActionResult> Toggle(Task<StatusOutcome> action, string id, CancellationToken token)
		{
			var outcome = await action;
			if (!outcome.Ok)
				return Error(outcome.Status, outcome.Error);
			var post = await _dbEntities.Posts.MatchID(id).ExecuteFirstAsync(token);
			return Json(await _mapper.Status(post, MyId, token));
		}

		async Task<IActionResult> Unchanged(string id, CancellationToken token)
		{
			var post = await Visible(id, token);
			return post == default ? NotFoundError() : Json(await _mapper.Status(post, MyId, token));
		}

		async Task<PostEntity> Visible(string id, CancellationToken token)
		{
			var post = await _dbEntities.Posts.Match(p => p.ID == id && !p.DeletedAt.HasValue).ExecuteFirstAsync(token);
			return post != default && post.Visibility != PostVisibility.LocalGeo && await VisibilityPolicy.CanSee(post, MyId, token) ? post : default;
		}

		static PostVisibility Visibility(string value) => value?.ToLowerInvariant() switch
		{
			"unlisted" => PostVisibility.Unlisted,
			"private" => PostVisibility.FollowersOnly,
			"direct" => PostVisibility.Direct,
			_ => PostVisibility.Public
		};
	}
}