module PublishHelperBot.Handlers

open System.Threading.Tasks
open PublishHelperBot.Environment
open Telegram.Bot
open Telegram.Bot.Types
open Telegram.Bot.Types.Enums

type BaseHandlerArgs = Update * BotConfig
type HandlerArgs = Update * BotConfig * ITelegramBotClient
type HandlerRequirements = BaseHandlerArgs -> bool
type Handler = HandlerArgs -> Task

// Utils
let UpdateIsAMessage (x: Update) = x.Type = UpdateType.Message
let FromAdminChat (x: Message, c: BotConfig) = x.Chat.Id = c.adminChatId
let HasReply (x: Message) = not(isNull x.ReplyToMessage) 
let ExtractPhotoFromMessage (x: Message) = Array.map (fun (p: PhotoSize) -> p.FileId) x.Photo
let UrlsAsAlbumInputMedia (urls: string[]): IAlbumInputMedia[] =
  Array.map (fun (x: string) -> InputMediaPhoto(x)) urls

// Post (Relay) command
type RelayCaptionMode = WithAuthor | Anonymous | Unknown
let RelaySupportedContent (x: Message) =
  match x.Type with
  | MessageType.Text -> true
  | MessageType.Photo -> true
  | MessageType.Video -> true
  | _ -> false

let RelayCaptionType (command: string) =
  match command with
  | _ when command.StartsWith "\\post anon" -> Anonymous
  | _ when command.StartsWith "\\post" -> WithAuthor
  | _ -> Unknown

let RelayCaption (name: string, url: string) = $"<a href=\"{url}\">Прислал</a> {name}"
let RelayParseMode = ParseMode.Html;

let RelayResolveCaption (mode: RelayCaptionMode, username: string, linkUrl: string) =
  match mode with
  | WithAuthor -> RelayCaption(username, linkUrl)
  | _ -> null

let public RelayMatch: HandlerRequirements = fun (u, c) ->
  UpdateIsAMessage u &&
  FromAdminChat <| (u.Message, c) &&
  HasReply u.Message &&
  RelaySupportedContent u.Message.ReplyToMessage &&
  not (RelayCaptionType u.Message.Text = RelayCaptionMode.Unknown)

let public RelayHandler: Handler = fun (u, c, tg) ->
  let reply = u.Message.ReplyToMessage
  let channelId = c.chanelId
  let author = $"{reply.From.FirstName} {reply.From.LastName}"
  let captionMode = RelayCaptionType u.Message.Text
  
  let photoMedia = lazy Array.get (ExtractPhotoFromMessage reply) 0
  let caption = lazy RelayResolveCaption(captionMode, author, c.relayUrl)
  
  match reply.Type with
  | MessageType.Text -> tg.ForwardMessageAsync(channelId, reply.Chat.Id, reply.MessageId)
  | MessageType.Photo -> tg.SendPhotoAsync(channelId, photoMedia.Value, caption = caption.Value,
                                           parseMode = RelayParseMode)
  | MessageType.Video -> tg.SendVideoAsync(channelId, reply.Video.FileId, caption = caption.Value,
                                           parseMode = RelayParseMode)
  | _ -> Task.CompletedTask


// Youtube repost

let public YoutubeRepostMatch: HandlerRequirements = fun (u, c) ->
  UpdateIsAMessage u &&
  FromAdminChat <| (u.Message, c) &&
  u.Message.Text.StartsWith("\\yt") &&
  u.Message.Text.Split(' ').Length = 2