open Async
open Core
open Disml
open Models

(* Client object will be stored here after creation. *)
let client = Ivar.create ()

(* Define a function to handle message_create *)
let check_command (Event.MessageCreate.{message}) =
    (* Split content on space and return list head, list tail as tuple *)
    let cmd, rest = match String.split ~on:' ' message.content with
    | hd::tl -> hd, tl
    | [] -> "", []
    (* Match against the command portion *)
    in match cmd with
    | "!ping" ->
        (* Reply with "Pong!" and bind to the response, new message is the created one *)
        Message.reply message "Pong!" >>> begin function
        | Ok message ->
            (* Get the time difference between now and the timestamp of the reply *)
            let diff = Time.diff (Time.now ()) (Time.of_string message.timestamp) in
            (* Edit the reply to include the timestamp as rounded milliseconds. Ignore result *)
            Message.set_content message (Printf.sprintf "Pong! `%d ms`" (Time.Span.to_ms diff |> Float.abs |> Float.to_int)) >>> ignore
        | Error e -> Error.raise e
        end
    | "!spam" ->
        (* Convert first arg to an integer, defaulting to 0 *)
        let count = Option.((List.hd rest >>| Int.of_string) |> value ~default:0) in
        (* Generate a list, and send each element to discord as unique message, ignoring the results. Not recommended to use this, but I have it for ratelimit tests *)
        List.range 0 count
        |> List.iter ~f:(fun i -> Message.reply message (string_of_int i) >>> ignore)
    | "!list" ->
        (* Convert first arg to an integer, defaulting to 0 *)
        let count = Option.((List.hd rest >>| Int.of_string) |> value ~default:0) in
        (* Generate a list and convert to an sexp string *)
        let list = List.range 0 count
        |> List.sexp_of_t Int.sexp_of_t
        |> Sexp.to_string_hum in
        (* Send list as a message and bind the result, printing to console *)
        Message.reply message list >>> begin function
        | Ok msg -> print_endline msg.content
        | Error err -> print_endline (Error.to_string_hum err)
        end
    | "!fold" ->
        (* Convert first arg to an integer, defaulting to 0 *)
        let count = Option.((List.hd rest >>| Int.of_string) |> value ~default:0) in
        (* Generate a list and sum the count before sending the result to discord. pretty useless lol *)
        let list = List.range 0 count
        |> List.fold ~init:0 ~f:(+)
        |> Int.to_string in
        Message.reply message list >>> ignore
    | "!embed" ->
        (* Example of setting pretty much everything in an embed using the Embed module builders *)
        let image_url = "https://cdn.discordapp.com/avatars/345316276098433025/17ccdc992814cc6e21a9e7d743a30e37.png" in
        let embed = Embed.(default
            |> title "Foo"
            |> description "Bar"
            |> url "https://gitlab.com/Mishio595/disml"
            |> timestamp Time.(now () |> to_string_iso8601_basic ~zone:Time.Zone.utc)
            |> colour 0xff
            |> footer (fun f -> footer_text "boop" f)
            |> image image_url
            |> thumbnail image_url
            |> author (fun a -> a
                |> author_name "Adelyn"
                |> author_icon image_url
                |> author_url "https://gitlab.com/Mishio595/disml")
            |> field ("field 3", "test", true)
            |> field ("field 2", "test", true)
            |> field ("field 1", "test", true)
        ) in
        Message.reply_with ~embed message >>> ignore
    | "!status" ->
        (* Concat all args into a string *)
        let status = List.fold ~init:"" ~f:(fun a v -> a ^ " " ^ v) rest in
        (* Ensure the client is started by binding to the Ivar *)
        Ivar.read client >>> fun client ->
        (* Set the status as a simple string *)
        Client.set_status ~status:(`String status) client
        >>> fun _ ->
        (* Upon response, let the user know we updated the status *)
        Message.reply message "Updated status" >>> ignore
    | "!test" ->
        (* Basic send message to channel ID, can use any ID as `Channel_id some_snowflake *)
        Channel_id.say "Testing..." message.channel_id >>> ignore
    | "!echo" ->
        (* Fetch a message by ID in the current channel, or default to message ID *)
        let `Message_id id = message.id in
        let id = Option.((List.hd rest >>| Int.of_string) |> value ~default:id) in
        Channel_id.get_message ~id message.channel_id >>> begin function
        (* If successful, convert to sexp and send to discord *)
        | Ok msg -> Message.reply message (Printf.sprintf "```lisp\n%s```" (Message.sexp_of_t msg |> Sexp.to_string_hum)) >>> ignore
        | _ -> ()
        end
    | _ -> ()

(* Example logs setup *)
let setup_logger () =
    Logs.set_reporter (Logs_fmt.reporter ());
    Logs.set_level ~all:true (Some Logs.Debug)

let main () =
    (* Call the logger setup *)
    setup_logger ();
    (* Set some event handlers *)
    Client.message_create := check_command;
    Client.ready := (fun _ -> Logs.info (fun m -> m "Ready!"));
    (* Pull token from env var *)
    let token = match Sys.getenv "DISCORD_TOKEN" with
    | Some t -> t
    | None -> failwith "No token in env"
    in
    (* Start client with no special options *)
    Client.start token
    >>> fun c ->
    (* Fill that ivar once its done *)
    Ivar.fill client c

(* Lastly, we have to register this to the Async Scheduler for anything to work *)
let _ =
    Scheduler.go_main ~main ()