type document = {
  hash: string;
  owner: address;
}

(*
    @signs - Need for finding user storage
    @documents -Need for access document by hash
    @access -Need for check use access for document
*)
type storage = {
  signs : (address, string set) map;
  documents : (string, document) map;
  access : (address, string set) map;
}

let%init storage = {
  signs= Map;
  documents= Map;
  access= Map;
}

(*
  withdraw access for document can only owner
*)
let%entry removeAccess ((fileHash : string),(user : address)) storage =
  let userAddress  = Current.sender() in
  let document =  match Map.find fileHash storage.documents with
    | None -> failwith ("Document not found")
    | Some document -> document
  in

  if document.owner <> userAddress then failwith("you not owner");

  let userAccessStorage = match Map.find userAddress storage.access with
    | None -> Set
    | Some userAccessStorage ->
        if not(Set.mem document.hash userAccessStorage) then
          failwith ("access not found");
        userAccessStorage
  in

  let userAccessStorage = Set.remove fileHash userAccessStorage in
  let storage = storage.access <- Map.add user userAccessStorage storage.access in
  [],storage

(*
  add access for document can only owner
*)
let%entry addAccess ((fileHash : string),(user : address)) storage =
  let userAddress  = Current.sender() in
  let document =  match Map.find fileHash storage.documents with
    | None -> failwith ("Document not found")
    | Some document -> document
  in

  if document.owner <> userAddress then failwith("you not owner");

  let userAccessStorage = match Map.find userAddress storage.access with
    | None -> Set
    | Some userAccessStorage ->
        if Set.mem document.hash userAccessStorage then
          failwith ("access already granted");
        userAccessStorage
  in

  let userAccessStorage = Set.add fileHash userAccessStorage in
  let storage = storage.access <- Map.add user userAccessStorage storage.access in
  [],storage

let%entry signFile (fileHash : string) storage =
  let userAddress  = Current.sender() in
  let existDocument =  Map.mem fileHash storage.documents in
  let userSignsStorage = match Map.find userAddress storage.signs with
    | None -> Set
    | Some userSigns -> userSigns
  in

  if existDocument then

    let document =  match Map.find fileHash storage.documents with
      | None -> failwith ("Exist document not found")
      | Some document -> document
    in

    if Set.mem document.hash userSignsStorage then failwith "document now signed";

    if document.owner = userAddress then failwith ("document signed");

    begin match Map.find userAddress storage.access with
      | None -> failwith ("sign not allowed")
      | Some access ->
          if not(Set.mem document.hash access) then
            failwith ("sign not allowed");
    end;

    let userSignsStorage = Set.add document.hash userSignsStorage in
    let storage = storage.signs <- Map.add userAddress userSignsStorage storage.signs in
    [],storage

  else

    let document = { hash = fileHash; owner = userAddress } in
    let storage = storage.documents <- Map.add fileHash document storage.documents in
    let userSignsStorage = Set.add fileHash userSignsStorage in
    let storage = storage.signs <- Map.add userAddress userSignsStorage storage.signs in

    [],storage

let%entry main (fileHash : string) storage =
  ([], storage)