open Brr
module PM = Prosemirror
module Js = Js_of_ocaml.Js

module Actions = Editor_actions

(** Create a new editor view

    [build_view element state] will create the editor and attach it to [element].

*)
let build_view
  : PM.t -> Jstr.t option -> El.t -> PM.View.editor_view Js.t * float
  = fun pm page_id editor ->

    (* Remove all the elements if any *)
    El.set_children editor [];

    (* TODO
       This could be improved, instead of creating a new schema, just fetch
       the node and marks from the plungin *)
    let custom_schema =
      Plugins.Footnotes.footnote_schema
        pm
        (PM.SchemaBasic.schema pm) in

    (* Recreate the full schema by adding all the nodes and marks from the
       plugings *)
    let specs = PM.Model.schema_spec
        (PM.SchemaList.add_list_nodes
           pm
           (custom_schema##.spec##.nodes)
           (Jstr.v "paragraph block*")
           (Some (Jstr.v "block")))
        (Some custom_schema##.spec##.marks)
        None in
    let full_schema = PM.Model.schema pm specs in
    let stored_content = State.Storage.load page_id in

    (* This variable contains the last update time, either because it is
       stored, or because it is the date where we create the first page. *)
    let last_backup = Js.Opt.get
        stored_content##.date
        (fun () -> (new%js Js.date_now)##getTime) in

    let props = PM.View.direct_editor_props () in
    props##.state := State.state_of_storage pm stored_content full_schema;

    (* Add the custom nodes *)
    props##.nodeViews := PM.O.init
        [| ( "footnote", (Plugins.Footnotes.footnote_view pm))
        |];

    let view = PM.View.editor_view
        pm
        editor
        props in
    view, last_backup

module Store = struct
  type t = El.t

  let update
    : t -> State.t -> State.t
    = fun title_element state ->
      let title = El.prop (El.Prop.value) title_element in

      let new_date = (new%js Js.date_now)##getTime in
      let content_obj = object%js
        val content = Js.some @@ Jv.Id.to_jv (state.view##.state##toJSON ())
        val title = Js.some title
        val date = Js.some new_date
      end in
      let save = State.Storage.save
          content_obj
          state.page_id
          (* There three date here :
             - The actual date at the time we save the note
             - The date associated with the note when we loaded it first time
             - The date associated with the note at the time we want to update it

             The two last may differ if the note has been updated in another one tab. *)
          ~check:(fun ~previous ~update ->
              let _ = update in
              Js.Opt.case previous##.date
                (fun () -> true)
                (fun date ->
                   (* I do not figure how the previous date could be older
                      than the last backup. It could be either :

                      - equal (if we are the only one to update it)
                      - more recent (if the content has been updated elsewhere)

                      but older shoud be a bug. *)
                   let is_ok = date <= state.last_backup in
                   if (not is_ok) then (
                     let open Console in
                     log
                       [ Jstr.v "Last backup date is "
                       ; new%js Js.date_fromTimeValue state.last_backup
                       ; Jstr.v " but date is "
                       ; new%js Js.date_fromTimeValue date] );
                   is_ok)) in
      begin match save with
        | Ok true -> { state with last_backup = new_date }
        | Ok false ->
          Console.(log [Jstr.v "Didn't save"]);
          state
        | Error other ->
          (* TODO In case of error, notify the user *)
          Console.(log [Jstr.v "Couldn't save" ; other]);
          state
      end
end


let app id content =

  let title_element = Document.find_el_by_id G.document (Jstr.v "title") in
  (* Check the pre-requisite *)
  match title_element, (Jv.is_none id), (Jv.is_none content), Blog.Sidebar.get () with
  | Some title, false, false, Some sidebar ->

    let () = Blog.Sidebar.clean sidebar in

    let pm = PM.v () in
    let editor:El.t = Jv.Id.of_jv id in
    (* Load the cache for the given page *)
    let page_id = State.Storage.page_id () in
    let view, last_backup = build_view pm page_id editor in

    let init_state = State.init pm view last_backup page_id in

    (* Initialize the buttons actions and get the associated events.
       At this point, the HTML element is not yet created, and cannot be
       inserted in the document.
     *)
    let side_elements = Editor_actions.build pm in
    let btn_events = Editor_actions.get_event side_elements in

    (* Create the main event loop with all the collected events *)
    let app_state = State.run
        ~eq:State.eq
        init_state
        (Note.E.select
           [ Brr_note.Evr.on_els Ev.focusout
               (fun _ _ ->
                  State.E
                    ( title
                    , (module Store:State.Event with type t = Store.t)))
               [ editor ; title ]
           ; btn_events
           ]) in

    (* Get the html element associated with the buttons, and add it in the
       page.

       The state event is already created, and can be given in the html
       creation in order to update the elements when the state change.
    *)
    let childs = Editor_actions.complete side_elements app_state in
    let () = El.append_children sidebar childs in
    let _ = Note.(Logr.hold (S.log app_state (fun _ -> ()))) in
    ()

  | _ ->
    Console.(error [str "No element with id '%s' '%s' found"; id ; content])

let () =

  let open Jv in
  let editor = obj
      [| "attach_prosemirror", (repr app)
      |] in

  set global "editor" editor