;;
;;  TON NFT Item Smart Contract v2
;;  support ownership_assigned on minting nft
;;

{-

    NOTE that this tokens can be transferred within the same workchain.

    This is suitable for most tokens, if you need tokens transferable between workchains there are two solutions:

    1) use more expensive but universal function below to calculate message forward fee for arbitrary destination (see `misc/forward-fee-calc.cs`)

    2) use token holder proxies in target workchain (that way even 'non-universal' token can be used from any workchain)

-}

#include "imports/stdlib.fc";
#include "imports/op-codes.fc";
#include "imports/params.fc";

int min_tons_for_storage() asm "50000000 PUSHINT"; ;; 0.05 TON

;;
;;  Storage
;;
;;  uint64 index
;;  MsgAddressInt collection_address
;;  MsgAddressInt owner_address
;;  cell content
;;

(int, int, slice, slice, cell) load_data() {
    slice ds = get_data().begin_parse();
    var (index, collection_address) = (ds~load_uint(64), ds~load_msg_addr());
    if (ds.slice_bits() > 0) {
      return (-1, index, collection_address, ds~load_msg_addr(), ds~load_ref());
    } else {
      return (0, index, collection_address, null(), null()); ;; nft not initialized yet
    }
}

() store_data(int index, slice collection_address, slice owner_address, cell content) impure {
    set_data(
        begin_cell()
            .store_uint(index, 64)
            .store_slice(collection_address)
            .store_slice(owner_address)
            .store_ref(content)
            .end_cell()
    );
}

() send_msg(slice to_address, int amount, int op, int query_id, builder payload, int send_mode) impure inline {
  var msg = begin_cell()
    .store_uint(0x10, 6) ;; nobounce - int_msg_info$0 ihr_disabled:Bool bounce:Bool bounced:Bool src:MsgAddress -> 011000
    .store_slice(to_address)
    .store_coins(amount)
    .store_uint(0, 1 + 4 + 4 + 64 + 32 + 1 + 1)
    .store_uint(op, 32)
    .store_uint(query_id, 64);

  if (~ builder_null?(payload)) {
    msg = msg.store_builder(payload);
  }

  send_raw_message(msg.end_cell(), send_mode);
}

() transfer_ownership(int my_balance, int index, slice collection_address, slice owner_address, cell content, slice sender_address, int query_id, slice in_msg_body, int fwd_fees) impure inline {
    throw_unless(401, equal_slices(sender_address, owner_address));

    slice new_owner_address = in_msg_body~load_msg_addr();
    force_chain(new_owner_address);
    slice response_destination = in_msg_body~load_msg_addr();
    in_msg_body~load_int(1); ;; this nft don't use custom_payload
    int forward_amount = in_msg_body~load_coins();

    int rest_amount = my_balance - min_tons_for_storage();
    if (forward_amount) {
      rest_amount -= (forward_amount + fwd_fees);
    }
    int need_response = response_destination.preload_uint(2) != 0; ;; if NOT addr_none: 00
    if (need_response) {
      rest_amount -= fwd_fees;
    }

    throw_unless(402, rest_amount >= 0); ;; base nft spends fixed amount of gas, will not check for response

    if (forward_amount) {
      send_msg(new_owner_address, forward_amount, op::ownership_assigned(), query_id, begin_cell().store_slice(owner_address).store_slice(in_msg_body), 1);  ;; paying fees, revert on errors
    }
    if (need_response) {
      force_chain(response_destination);
      send_msg(response_destination, rest_amount, op::excesses(), query_id, null(), 1); ;; paying fees, revert on errors
    }

    store_data(index, collection_address, new_owner_address, content);
}

() recv_internal(int my_balance, int msg_value, cell in_msg_full, slice in_msg_body) impure {
    if (in_msg_body.slice_empty?()) { ;; ignore empty messages
        return ();
    }

    slice cs = in_msg_full.begin_parse();
    int flags = cs~load_uint(4);

    if (flags & 1) { ;; ignore all bounced messages
        return ();
    }
    slice sender_address = cs~load_msg_addr();

    cs~load_msg_addr(); ;; skip dst
    cs~load_coins(); ;; skip value
    cs~skip_bits(1); ;; skip extracurrency collection
    cs~load_coins(); ;; skip ihr_fee
    int fwd_fee = muldiv(cs~load_coins(), 3, 2); ;; we use message fwd_fee for estimation of forward_payload costs


    (int init?, int index, slice collection_address, slice owner_address, cell content) = load_data();
    if (~ init?) {
      throw_unless(405, equal_slices(collection_address, sender_address));
      var new_owner_address = in_msg_body~load_msg_addr();
      store_data(index, collection_address, new_owner_address, in_msg_body~load_ref());
      if (in_msg_body.slice_data_empty?() == false) {
        var forward_amount = in_msg_body~load_coins();
        if (forward_amount) {
          send_msg(new_owner_address, forward_amount, op::ownership_assigned(), 0, begin_cell().store_slice(collection_address).store_slice(in_msg_body), 3); ;; paying fees, ignore errors
        }
      }
      return ();
    }

    int op = in_msg_body~load_uint(32);
    int query_id = in_msg_body~load_uint(64);

    if (op == op::transfer()) {
      transfer_ownership(my_balance, index, collection_address, owner_address, content, sender_address, query_id, in_msg_body, fwd_fee);
      return ();
    }
    if (op == op::get_static_data()) {
      send_msg(sender_address, 0, op::report_static_data(), query_id, begin_cell().store_uint(index, 256).store_slice(collection_address), 64);  ;; carry all the remaining value of the inbound message
      return ();
    }
    throw(0xffff);
}

;;
;;  GET Methods
;;

(int, int, slice, slice, cell) get_nft_data() method_id {
  (int init?, int index, slice collection_address, slice owner_address, cell content) = load_data();
  return (init?, index, collection_address, owner_address, content);
}