using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Localization;

using MongoDB.Driver;
using MongoDB.Entities;

using PrivaPub.ClientModels;
using PrivaPub.ClientModels.Admin;
using PrivaPub.Domain.Content;
using PrivaPub.Domain.Media;
using PrivaPub.Domain.Moderation;
using PrivaPub.Extensions;
using PrivaPub.Federation.Actors;
using PrivaPub.Models;
using PrivaPub.Models.Post;
using PrivaPub.Models.Social;
using PrivaPub.Models.User;
using PrivaPub.Resources;

namespace PrivaPub.Controllers.ClientToServer
{
	// The server's custom emoji from the administrator's page (completion program R7): listed, added, changed and deleted
	// by an administrator, checked again against the database. Every act is kept in the staff's log (emoji.insert,
	// emoji.update, emoji.delete). An emoji is never renamed: its shortcode is its id on other servers (/grimaces/{shortcode}).
	[ApiController,
		Route("clientapi/admin/emoji"),
		Authorize(Policy = Policies.IsAdmin)]
	public class EmojiAdminController : ControllerBase
	{
		// a picture up to a megabyte reaches EmojiImage, which refuses one over 256 KB with its reason
		const long MaxRequestBytes = 1024 * 1024;

		readonly IModerationLog _log;
		readonly IStringLocalizer _localizer;
		readonly IMediaService _media;
		readonly ILocalActorService _localActors;

		public EmojiAdminController(IModerationLog log, IStringLocalizer<GenericRes> localizer, IMediaService media, ILocalActorService localActors)
		{
			_log = log;
			_localizer = localizer;
			_media = media;
			_localActors = localActors;
		}

		// the token says administrator; the database has the last word
		async Task<RootUser> Administrator(CancellationToken token)
		{
			var root = await DB.Default.Find<RootUser>().MatchID(User.GetUserId()).ExecuteFirstAsync(token);
			return root is { IsBanned: false, DeletedAt: null } && root.Policies.Contains(Policies.IsAdmin) ? root : default;
		}

		IActionResult Refused(int status, string message) => StatusCode(status, new WebResult().Invalidate(_localizer[message], status));

		[HttpGet, Route("list")]
		public async Task<IActionResult> List(CancellationToken token)
		{
			if (await Administrator(token) == default)
				return Forbid();
			var emojis = await DB.Default.Find<LocalEmoji>().Match(e => e.DeletedAt == null).Sort(e => e.Key, Order.Ascending).ExecuteAsync(token);
			return Ok(emojis.Select(View).ToList());
		}

		// a new emoji; a shortcode deleted before comes back as it was written, with its new picture (the same id elsewhere)
		[HttpPost, Route("insert"), RequestSizeLimit(MaxRequestBytes), RequestFormLimits(MultipartBodyLengthLimit = MaxRequestBytes)]
		public async Task<IActionResult> Insert([FromForm] LocalEmojiForm form, CancellationToken token)
		{
			var admin = await Administrator(token);
			if (admin == default)
				return Forbid();
			var key = form.Shortcode.ToLowerInvariant();
			var existing = await DB.Default.Find<LocalEmoji>().Match(e => e.Key == key).ExecuteFirstAsync(token);
			if (existing != default && (existing.DeletedAt == default || existing.Shortcode != form.Shortcode))
				return Refused(StatusCodes.Status409Conflict, "This shortcode is taken.");
			var outcome = await _media.EmojiImage(form.Shortcode, await Picture(token), token);
			if (!outcome.Ok)
				return StatusCode(outcome.Status, new WebResult().Invalidate(outcome.Error, outcome.Status));

			var now = DateTime.UtcNow;
			var emoji = existing ?? new LocalEmoji { Shortcode = form.Shortcode, Key = key, CreatedAt = now };
			emoji.Category = Clean(form.Category);
			emoji.VisibleInPicker = form.VisibleInPicker;
			emoji.Disabled = form.Disabled;
			emoji.DeletedAt = default;
			emoji.UpdatedAt = now;
			Picture(emoji, outcome.Attachment, now);
			var saved = true;
			if (existing == default)
				try
				{
					await DB.Default.SaveAsync(emoji, token);
				}
				catch (MongoWriteException ex) when (ex.WriteError?.Category == ServerErrorCategory.DuplicateKey)
				{
					saved = false;//the same shortcode added at the same moment
				}
			else
				saved = (await DB.Default.Update<LocalEmoji>().Match(e => e.ID == existing.ID && e.DeletedAt != null).ModifyWith(emoji).ExecuteAsync(token))
					.ModifiedCount > 0;
			if (!saved)
			{
				await _media.Trash(m => m.ID == outcome.Attachment.ID, "emoji not saved", token);
				return Refused(StatusCodes.Status409Conflict, "This shortcode is taken.");
			}
			await LocalEmojis.Reload(CancellationToken.None);
			var notes = new[] { existing != default ? "added again" : default, emoji.Disabled ? "disabled" : default, Animated(emoji) }.Where(n => n != default).ToList();
			await _log.Write(admin.ID, AdminActions.EmojiInsert, AdminTargets.Emoji, emoji.ID, $":{emoji.Shortcode}:",
				note: notes.Count > 0 ? string.Join(", ", notes) : default, token: token);
			return Ok(View(emoji));
		}

		// the emoji with that shortcode as it should be now: its category, the picker, disabled or not, and a new picture if
		// one is sent
		[HttpPost, Route("update"), RequestSizeLimit(MaxRequestBytes), RequestFormLimits(MultipartBodyLengthLimit = MaxRequestBytes)]
		public async Task<IActionResult> Update([FromForm] LocalEmojiForm form, CancellationToken token)
		{
			var admin = await Administrator(token);
			if (admin == default)
				return Forbid();
			var emoji = await Live(form.Shortcode, token);
			if (emoji == default)
				return NotFound();
			var changed = new List<string>();
			var category = Clean(form.Category);
			if (emoji.Category != category)
				changed.Add("category");
			if (emoji.VisibleInPicker != form.VisibleInPicker)
				changed.Add(form.VisibleInPicker ? "in the picker" : "out of the picker");
			if (emoji.Disabled != form.Disabled)
				changed.Add(form.Disabled ? "disabled" : "enabled");
			emoji.Category = category;
			emoji.VisibleInPicker = form.VisibleInPicker;
			emoji.Disabled = form.Disabled;

			var image = await Picture(token);
			var previous = (MediaId: emoji.MediaId, Url: emoji.Url);
			var now = DateTime.UtcNow;
			MediaOutcome outcome = default;
			if (image != default)
			{
				outcome = await _media.EmojiImage(emoji.Shortcode, image, token);
				if (!outcome.Ok)
					return StatusCode(outcome.Status, new WebResult().Invalidate(outcome.Error, outcome.Status));
				Picture(emoji, outcome.Attachment, now);
				changed.Add("image");
			}
			if (changed.Count == 0)
				return Ok(View(emoji));
			emoji.UpdatedAt = now;
			if ((await DB.Default.Update<LocalEmoji>().Match(e => e.ID == emoji.ID && e.DeletedAt == null).ModifyWith(emoji).ExecuteAsync(token)).ModifiedCount == 0)
			{
				if (outcome != default)
					await _media.Trash(m => m.ID == outcome.Attachment.ID, "emoji not saved", token);
				return NotFound();//deleted meanwhile
			}
			if (outcome != default)
			{
				var use = LocalEmojis.ServerUse(emoji.Shortcode);
				if (previous.MediaId != default)
					await _media.Trash(m => m.ID == previous.MediaId && m.ServerUse == use, "emoji image replaced", token);
				// the reactions made with it show the picture it has now
				if (previous.Url != default)
				{
					await DB.Default.Update<Reaction>().Match(r => r.Emoji == emoji.Shortcode && r.EmojiURL == previous.Url)
						.Modify(r => r.EmojiURL, emoji.Url).ExecuteAsync(token);
					await DB.Default.Update<Notification>().Match(n => n.Emoji == emoji.Shortcode && n.EmojiURL == previous.Url)
						.Modify(n => n.EmojiURL, emoji.Url).ExecuteAsync(token);
				}
			}
			await LocalEmojis.Reload(CancellationToken.None);
			await _log.Write(admin.ID, AdminActions.EmojiUpdate, AdminTargets.Emoji, emoji.ID, $":{emoji.Shortcode}:", note: string.Join(", ", changed), token: token);
			return Ok(View(emoji));
		}

		// deleted: offered nowhere, left out of what posts and profiles render, its picture trashed, and its id answers 410.
		// No other server is told (Mastodon tells none either); they keep their copy until they read a post again.
		[HttpPost, Route("delete")]
		public async Task<IActionResult> Delete([FromQuery] string shortcode, CancellationToken token)
		{
			var admin = await Administrator(token);
			if (admin == default)
				return Forbid();
			var emoji = await Live(shortcode, token);
			if (emoji == default)
				return NotFound();
			var now = DateTime.UtcNow;
			if ((await DB.Default.Update<LocalEmoji>().Match(e => e.ID == emoji.ID && e.DeletedAt == null)
					.Modify(e => e.DeletedAt, now).Modify(e => e.UpdatedAt, now).ExecuteAsync(token)).ModifiedCount == 0)
				return NotFound();
			var use = LocalEmojis.ServerUse(emoji.Shortcode);
			await _media.Trash(m => m.ID == emoji.MediaId && m.ServerUse == use, "emoji deleted", token);
			await LocalEmojis.Reload(CancellationToken.None);
			await _log.Write(admin.ID, AdminActions.EmojiDelete, AdminTargets.Emoji, emoji.ID, $":{emoji.Shortcode}:", token: token);
			return Ok();
		}

		static async Task<LocalEmoji> Live(string shortcode, CancellationToken token)
		{
			if (!LocalEmojis.IsShortcode(shortcode))
				return default;
			var key = shortcode.ToLowerInvariant();
			var emoji = await DB.Default.Find<LocalEmoji>().Match(e => e.Key == key && e.DeletedAt == null).ExecuteFirstAsync(token);
			return emoji?.Shortcode == shortcode ? emoji : default;
		}

		// the picture sent as `image` (or `file`, as the thumbnail's route names it)
		async Task<IFormFile> Picture(CancellationToken token) =>
			Request.HasFormContentType && await Request.ReadFormAsync(token) is { } form ? form.Files["image"] ?? form.Files["file"] : default;

		void Picture(LocalEmoji emoji, Models.Media.MediaAttachment attachment, DateTime now)
		{
			emoji.MediaId = attachment.ID;
			emoji.Url = _media.Url(attachment.FilePath);
			emoji.StaticUrl = attachment.PreviewPath == default ? emoji.Url : _media.Url(attachment.PreviewPath);
			emoji.ContentType = attachment.ContentType;
			emoji.Width = attachment.Width;
			emoji.Height = attachment.Height;
			emoji.Size = attachment.Size;
			emoji.ImageUpdatedAt = now;
		}

		static string Animated(LocalEmoji emoji) => emoji.ContentType == "image/gif" ? "animated" : default;

		static string Clean(string text) => string.IsNullOrWhiteSpace(text) ? default : text.Trim();

		ViewLocalEmoji View(LocalEmoji emoji) => new()
		{
			Id = emoji.ID,
			Shortcode = emoji.Shortcode,
			Category = emoji.Category,
			VisibleInPicker = emoji.VisibleInPicker,
			Disabled = emoji.Disabled,
			Url = emoji.Url,
			StaticUrl = emoji.StaticUrl ?? emoji.Url,
			ContentType = emoji.ContentType,
			Width = emoji.Width,
			Height = emoji.Height,
			Size = emoji.Size,
			Uri = LocalEmojis.Uri(_localActors.BaseAddress, emoji.Shortcode),
			CreatedAt = emoji.CreatedAt,
			UpdatedAt = emoji.UpdatedAt,
			ImageUpdatedAt = emoji.ImageUpdatedAt
		};
	}
}