SSIDNS_v0.5.scilla

(* SSI DNS v0.5
SSI Domain Name System that integrates the Zilliqa-Reference-Contract #6 standard (which has an SPDX-License-Identifier: MIT)
Self-Sovereign Identity Protocol
Copyright Tyron Mapu Community Interest Company 2022. All rights reserved.
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Subject to the limited license below, you may not (and you may not permit anyone else to) distribute, publish, copy, modify, merge, combine with another program, create derivative works of, reverse engineer, decompile or otherwise attempt to extract the source code of, the Program or any part thereof, except that you may contribute to this repository.
You are granted a non-exclusive, non-transferable, non-sublicensable license to distribute, publish, copy, modify, merge, combine with another program or create derivative works of the Program (such resulting program, collectively, the Resulting Program) solely for Non-Commercial Use as long as you:
1. give prominent notice (Notice) with each copy of the Resulting Program that the Program is used in the Resulting Program and that the Program is the copyright of Tyron; and
2. subject the Resulting Program and any distribution, publication, copy, modification, merger therewith, combination with another program or derivative works thereof to the same Notice requirement and Non-Commercial Use restriction set forth herein.
Non-Commercial Use means each use as described in clauses (1)-(3) below, as reasonably determined by Tyron in its sole discretion:
1. personal use for research, personal study, private entertainment, hobby projects or amateur pursuits, in each case without any anticipated commercial application;
2. use by any charitable organization, educational institution, public research organization, public safety or health organization, environmental protection organization or government institution; or
3. the number of monthly active users of the Resulting Program across all versions thereof and platforms globally do not exceed 10,000 at any time.
You will not use any trade mark, service mark, trade name, logo of Tyron or any other company or organization in a way that is likely or intended to cause confusion about the owner or authorized user of such marks, names or logos.
If you have any questions, comments or interest in pursuing any other use cases, please reach out to us at tyron@ssiprotocol.com.*)

scilla_version 0

(***************************************************)
(*               Associated library                *)
(***************************************************)
import BoolUtils ListUtils IntUtils PairUtils
library NonfungibleToken

type Operation =
| Add
| Sub

(* Global variables *)
let zero_address = 0x0000000000000000000000000000000000000000
let zero_bystr32 = 0x0000000000000000000000000000000000000000000000000000000000000000
let false = False
let true = True
let zero = Uint256 0
let zero_128 = Uint128 0
let one = Uint256 1
let empty_string = ""
let zilID = "zil"

let add_operation = Add
let sub_operation = Sub
let min_fee_bps = Uint128 1
let max_fee_bps = Uint128 10000

(* Library functions *)
let one_msg = 
  fun (msg: Message) => 
    let nil_msg = Nil {Message} in
    Cons {Message} msg nil_msg

let two_msgs =
  fun (msg1: Message) =>
  fun (msg2: Message) =>
    let msgs_tmp = one_msg msg2 in
    Cons {Message} msg1 msgs_tmp

let get_bal =
  fun (maybe_bal: Option Uint256) =>
    match maybe_bal with
    | None => zero
    | Some bal => bal
    end

(* Error exception *)
type Error =
  | NotPausedError
  | PausedError
  | SelfError
  | NotContractOwnerError
  | NotContractOwnershipRecipientError
  | NotTokenOwnerError
  | NotOwnerOrOperatorError
  | SpenderFoundError
  | OperatorNotFoundError
  | OperatorFoundError
  | NotAllowedToTransferError
  | TokenNotFoundError
  | InvalidFeeBPSError
  | ZeroAddressDestinationError
  | ThisAddressDestinationError
  | DomainNotValidError
  | DomainTakenError

let make_error =
  fun (result: Error) =>
    let result_code = 
      match result with
      | NotPausedError                     => Int32 -1
      | PausedError                        => Int32 -2
      | SelfError                          => Int32 -3
      | NotContractOwnerError              => Int32 -4
      | NotTokenOwnerError                 => Int32 -5
      | NotOwnerOrOperatorError            => Int32 -7
      | SpenderFoundError                  => Int32 -10
      | OperatorNotFoundError              => Int32 -11
      | OperatorFoundError                 => Int32 -12
      | NotAllowedToTransferError          => Int32 -13
      | TokenNotFoundError                 => Int32 -14
      | InvalidFeeBPSError                 => Int32 -15
      | ZeroAddressDestinationError        => Int32 -16
      | ThisAddressDestinationError        => Int32 -17
      | NotContractOwnershipRecipientError => Int32 -18
      | DomainNotValidError                => Int32 -19
      | DomainTakenError                   => Int32 -20
      end
    in
    { _exception: "Error"; code: result_code }

  let option_value = tfun 'A => fun( default: 'A ) => fun( input: Option 'A) =>
    match input with
    | Some v => v
    | None => default end
  let option_bystr20_value = let f = @option_value ByStr20 in f zero_address
  let option_bystr32_value = let f = @option_value ByStr32 in f zero_bystr32
  
(***************************************************)
(*             The contract definition             *)
(***************************************************)

contract NonfungibleToken
(
  init: ByStr20 with contract field dApp: ByStr20 with contract
    field implementation: ByStr20 with contract
      field utility: Map String Map String Uint128 end,
    field did_dns: Map String ByStr20 with contract
      field services: Map String ByStr20 end end end,
  initial_contract_owner: ByStr20,
  (* Initial Base URI. e.g. 'https://creatures-api.zilliqa.com/api/creature/' *)
  initial_base_uri: String,
  name: String,
  symbol: String,
  init_dns: Map ByStr32 ByStr20
)

(* Contract constraints *)
with
  (* 'initial_contract_owner' must not be the zero address *)
  let is_contract_owner_invalid = builtin eq initial_contract_owner zero_address in
  (* 'name' must not be an empty string *)
  let is_name_invalid = builtin eq name empty_string in
  (* 'symbol' must not be an empty string *)
  let is_symbol_invalid = builtin eq symbol empty_string in
  (* Check if any parameter is invalid *)
  let is_name_or_symbol_invalid = orb is_name_invalid is_symbol_invalid in

  let is_invalid = orb is_contract_owner_invalid is_name_or_symbol_invalid in
  negb is_invalid
=>

(* Mutable fields *)

(* Emergency stop mechanism *)
(* Defaults to False *)
field is_paused: Bool = false
field is_paused_zil: Bool = false

(* Token Name *)
(* Defaults to 'name' *)
(* No need to mutate this field since this is for remote fetch to retrieve the immutable parameter. *)
field token_name: String = name

(* Token Symbol *)
(* Defaults to 'symbol' *)
(* No need to mutate this field since this is for remote fetch to retrieve the immutable parameter. *)
field token_symbol: String = symbol

(* Contract Owner *)
(* Defaults to 'initial_contract_owner' *)
field contract_owner: ByStr20 = initial_contract_owner

(* Contract ownership recipient *)
(* Defaults to 'zero_address' *)
field contract_ownership_recipient: ByStr20 = zero_address

(* Address to send royalties to *)
(* Defaults to 'initial_contract_owner' *)
field royalty_recipient: ByStr20 = initial_contract_owner

(* Royalty fee BPS *)
(* e.g. 1 = 0.01%, 10000 = 100% *)
(* Defaults to 1000 *)
field royalty_fee_bps: Uint128 = Uint128 1000

(* Base URI *)
(* Defaults to 'initial_base_uri' *)
field base_uri: String = initial_base_uri

(* Token URIs *)
field token_uris: Map Uint256 String = Emp Uint256 String

(* NFT domains per token ID *)
field token_domains: Map Uint256 ByStr32 = Emp Uint256 ByStr32

(* Mapping from token ID to its owner *)
field token_owners: Map Uint256 ByStr20 = Emp Uint256 ByStr20
field nft_domain_names: Map ByStr32 Uint256 = Emp ByStr32 Uint256
field nft_dns: Map ByStr32 ByStr20 = init_dns (* Emp ByStr32 ByStr20 *)

(* The total number of tokens minted *)
field token_id_count: Uint256 = Uint256 0

(* The total number of existing tokens *)
field total_supply: Uint256 = Uint256 0

(* Mapping from token owner to the number of existing tokens *)
field balances: Map ByStr20 Uint256 = Emp ByStr20 Uint256

(* Set for minters *)
(* 'initial_contract_owner' is a minter by default *)
field minters: Map ByStr20 Bool =
    let emp_map = Emp ByStr20 Bool in
    builtin put emp_map initial_contract_owner true

(* Mapping from token ID to a spender *)
field spenders: Map Uint256 ByStr20 = Emp Uint256 ByStr20

(* Mapping from token owner to operators authorized by the token owner *)
field operators: Map ByStr20 (Map ByStr20 Bool) = Emp ByStr20 (Map ByStr20 Bool)

field version: String = "SSIDNS_0.5.0" (* @xalkan *)

(* Emit Errors *)
procedure Throw(error: Error)
  e = make_error error;
  throw e
end

procedure RequireNotPaused()
  (* Reference: *)
  (* https://consensys.github.io/smart-contract-best-practices/general_philosophy/#prepare-for-failure *)
  paused <- is_paused;
  match paused with
  | False =>
  | True =>
    (* Contract is paused *)
    error = PausedError;
    Throw error
  end
end

procedure RequireNotPausedZil()
  paused <- is_paused_zil; match paused with
    | False => | True => e = { _exception : "SSIDNS-ZilDomainIsPaused" }; throw e
  end
end

procedure RequireNotTaken(domain_id: ByStr32)
  is_empty = 
    let null = 0x0000000000000000000000000000000000000000000000000000000000000000 in 
    builtin eq domain_id null;
  match is_empty with 
  | True => 
    error = DomainNotValidError;
    Throw error
  | False => end;
  is_taken <- exists nft_domain_names[domain_id];
  match is_taken with
  | True => (* The NFT Domain Name has an owner *)
    error = DomainTakenError;
    Throw error
  | False =>
  end
end

procedure RequireValidRoyaltyFee(fee_bps: Uint128)
  is_gte_min = uint128_ge fee_bps min_fee_bps;
  is_lte_max = uint128_le fee_bps max_fee_bps;
  
  is_valid = andb is_gte_min is_lte_max;
  match is_valid with 
    | True => 
    | False =>
      error = InvalidFeeBPSError;
      Throw error
  end
end

procedure RequireContractOwner()
  cur_owner <- contract_owner;
  is_contract_owner = builtin eq cur_owner _sender;
  match is_contract_owner with
  | True => 
  | False =>
    error = NotContractOwnerError;
    Throw error
  end
end

procedure RequireNotSelf(address_a: ByStr20, address_b: ByStr20)
  is_self = builtin eq address_a address_b;
  match is_self with
  | False =>
  | True =>
    error = SelfError;
    Throw error
  end
end

procedure RequireExistingToken(token_id: Uint256)
  has_token <- exists token_owners[token_id];
  match has_token with
  | True =>
  | False =>
    error = TokenNotFoundError;
    Throw error
  end
end

procedure RequireValidDestination(to: ByStr20)
  (* Reference: https://github.com/ConsenSys/smart-contract-best-practices/blob/master/docs/tokens.md *)
  is_zero_address = builtin eq to zero_address;
  match is_zero_address with
  | False =>
  | True =>
    error = ZeroAddressDestinationError;
    Throw error
  end;

  is_this_address = builtin eq to _this_address;
  match is_this_address with
  | False =>
  | True =>
    error = ThisAddressDestinationError;
    Throw error
  end
end

procedure RequireOwnerOrOperator(address: ByStr20)
  is_owner = builtin eq _sender address;
  has_operator <- exists operators[address][_sender];
  is_allowed = orb is_owner has_operator;
  match is_allowed with
  | True =>
  | False =>
    error = NotOwnerOrOperatorError;
    Throw error
  end
end

procedure RequireAccessToTransfer(token_owner: ByStr20, token_id: Uint256)  
  (* check if _sender is token owner *)
  is_token_owner = builtin eq token_owner _sender;
  
  (* check if _sender is spender *)
  maybe_spender <- spenders[token_id];
  is_spender = match maybe_spender with
    | None => False
    | Some spender => 
      builtin eq spender _sender
    end;

  (* check if _sender is operator *)
  is_operator <- exists operators[token_owner][_sender];
  
  is_spender_or_operator = orb is_spender is_operator;
  is_allowed = orb is_spender_or_operator is_token_owner;
  match is_allowed with
  | True =>
  | False =>
    error = NotAllowedToTransferError;
    Throw error
  end
end

procedure UpdateBalance(operation: Operation, address: ByStr20)
  match operation with
  | Add =>
    maybe_count <- balances[address];
    new_count = 
      let cur_count = get_bal maybe_count in
      (* if overflow occurs, it throws CALL_CONTRACT_FAILED *)
      builtin add cur_count one;
    balances[address] := new_count
  | Sub =>
    maybe_count <- balances[address];
    new_count = 
      let cur_count = get_bal maybe_count in
      (* if underflow occurs, it throws CALL_CONTRACT_FAILED *)
      builtin sub cur_count one;
    balances[address] := new_count
  end
end

procedure HandlePayment(id: Pair String String)
  payment_id = let fst_element = @fst String String in fst_element id;
  txID = let snd_element = @snd String String in snd_element id;
  current_init <-& init.dApp; current_impl <-& current_init.implementation;
  get_fee <-& current_impl.utility[payment_id][txID]; match get_fee with
  | None => e = { _exception : "SSIDNS-FeeIsNull" }; throw e
  | Some fee =>
    cur_owner <- contract_owner;
    is_zil = builtin eq payment_id zilID; match is_zil with
      | True =>
        not_enough = builtin lt _amount fee; match not_enough with
          | True => e = { _exception : "SSIDNS-InsufficientZIL" }; throw e
          | False =>
            accept; msg = let m = { _tag: "AddFunds"; _recipient: cur_owner; _amount: fee } in one_msg m; send msg;
            refund = builtin sub _amount fee; is_zero = builtin eq refund zero_128; match is_zero with
            | True => | False => rmsg = let m = { _tag: "AddFunds"; _recipient: _sender; _amount: refund } in one_msg m; send rmsg end end
      | False =>
        initId = "init"; get_impl_did <-& current_init.did_dns[initId]; match get_impl_did with
          | None => e = { _exception: "SSIDNS-InitDidIsNull" }; throw e
          | Some did_ =>
            get_token_addr <-& did_.services[payment_id]; token_addr = option_bystr20_value get_token_addr;
            msg = let m = { _tag: "TransferFrom"; _recipient: token_addr; _amount: zero_128;
              from: _sender;
              to: cur_owner;
              amount: fee } in one_msg m; send msg end end end end

transition TransferFromSuccessCallBack(
  initiator: ByStr20,
  sender: ByStr20,
  recipient: ByStr20,
  amount: Uint128
  )
  RequireNotPaused;
  is_valid = builtin eq initiator _this_address; match is_valid with
    | True => | False => e = { _exception : "SSIDNS-WrongInitiator" }; throw e end end

procedure HandleBatchPayment(payment_id: String, txID: String, counter: Uint32 )
  current_init <-& init.dApp; current_impl <-& current_init.implementation;
  get_fee <-& current_impl.utility[payment_id][txID]; match get_fee with
  | None => e = { _exception : "SSIDNS-FeeIsNull" }; throw e
  | Some fee_ =>
    get_counter = builtin to_uint128 counter; counter_ = match get_counter with
    | Some c => c
    | None => Uint128 0 (* should never happen *)
    end;
    fee = builtin mul fee_ counter_;
    cur_owner <- contract_owner;
    is_zil = builtin eq payment_id zilID; match is_zil with
      | True =>
        not_enough = builtin lt _amount fee; match not_enough with
          | True => e = { _exception : "SSIDNS-InsufficientZIL" }; throw e
          | False =>
            accept; msg = let m = { _tag: "AddFunds"; _recipient: cur_owner; _amount: fee } in one_msg m; send msg;
            refund = builtin sub _amount fee; is_zero = builtin eq refund zero_128; match is_zero with
            | True => | False => rmsg = let m = { _tag: "AddFunds"; _recipient: _sender; _amount: refund } in one_msg m; send rmsg end end
      | False =>
        initId = "init"; get_impl_did <-& current_init.did_dns[initId]; match get_impl_did with
          | None => e = { _exception: "SSIDNS-InitDidIsNull" }; throw e
          | Some did_ =>
            get_token_addr <-& did_.services[payment_id]; token_addr = option_bystr20_value get_token_addr;
            msg = let m = { _tag: "TransferFrom"; _recipient: token_addr; _amount: zero_128;
              from: _sender;
              to: cur_owner;
              amount: fee } in one_msg m; send msg end end end end

(* @Requirements: *)
(* - 'to' must not be the zero address. Otherwise, it must throw 'ZeroAddressDestinationError' *)
(* - 'to' must not be '_this_address'. Otherwise, it must throw 'ThisAddressDestinationError' *)
(* - '_sender' must be a minter. Otherwise, it must throw 'NotMinterError' *)
procedure MintToken(to: ByStr20)
  RequireValidDestination to;

  (*IsMinter _sender;*)

  (* generate ID *)
  current_token_id_count <- token_id_count;
  new_token_id_count = builtin add current_token_id_count one;
  token_id_count := new_token_id_count;
  
  (* mint a new token *)
  token_owners[new_token_id_count] := to;

  (* add one to the token owner balance *)
  UpdateBalance add_operation to;
  
  (* add one to the total supply *)
  current_supply <- total_supply;
  new_supply = builtin add current_supply one;
  total_supply := new_supply
end

procedure SetTokenURI(token_id: Uint256, token_uri: String)
  is_empty_string = builtin eq token_uri empty_string;
  match is_empty_string with 
  | True => 
    (* noop *)
  | False =>
    token_uris[token_id] := token_uri
  end
end

procedure HandleMint(info: Pair ByStr20 String)
  match info with
  | Pair to token_uri =>
    domain_id = builtin sha256hash token_uri;
    RequireNotTaken domain_id;
    MintToken to;
    token_id <- token_id_count;
    token_domains[token_id] := domain_id; 
    SetTokenURI token_id token_uri;
    nft_domain_names[domain_id] := token_id;
    nft_dns[domain_id] := to
  end
end

(* @Requirements: *)
(* - 'token_id' must exist. Otherwise, it must throw 'TokenNotFoundError' *)
(* - '_sender' must be a token owner or an operator. Otherwise, it must throw 'NotOwnerOrOperatorError' *)
procedure BurnToken(token_id: Uint256)
  (* Check if token exists *)
  maybe_token_owner <- token_owners[token_id];
  match maybe_token_owner with
  | None =>
    error = TokenNotFoundError;
    Throw error
  | Some token_owner =>
    RequireOwnerOrOperator token_owner;
    (* Destroy existing token *)
    delete token_owners[token_id];
    delete token_uris[token_id];
    delete spenders[token_id];

    get_token_domain <- token_domains[token_id]; token_domain = option_bystr32_value get_token_domain;
    delete nft_domain_names[token_domain];
    delete nft_dns[token_domain];
    delete token_domains[token_id];

    (* subtract one from the balance *)
    UpdateBalance sub_operation token_owner;
    (* subtract one from the total supply *)
    current_supply <- total_supply;
    new_supply = builtin sub current_supply one;
    total_supply := new_supply;

    e = {
      _eventname: "Burn";
      token_owner: token_owner;
      token_id: token_id
    };
    event e
  end
end

(* @Requirements: *)
(* - 'to' must not be the zero address. Otherwise, it must throw 'ZeroAddressDestinationError' *)
(* - 'to' must not be '_this_address'. Otherwise, it must throw 'ThisAddressDestinationError' *)
(* - 'token_id' must exist. Otherwise, it must throw 'TokenNotFoundError' *)
(* - '_sender' must be a token owner, spender, or operator. Otherwise, it must throw 'NotAllowedToTransferError' *)
(* - '_sender' must not be 'to'. Otherwise, it must throw 'SelfError' *)
procedure TransferToken(to: ByStr20, token_id: Uint256)
  RequireValidDestination to;

  maybe_token_owner <- token_owners[token_id];
  match maybe_token_owner with
  | None =>
    error = TokenNotFoundError;
    Throw error
  | Some token_owner =>
    RequireAccessToTransfer token_owner token_id;
    RequireNotSelf token_owner to;
    
    (* change token_owner for that token_id *)
    token_owners[token_id] := to;

    delete spenders[token_id];

    (* subtract one from previous token owner balance *)
    UpdateBalance sub_operation token_owner;
    (* add one to the new token owner balance *)
    UpdateBalance add_operation to;

    e = {
      _eventname: "TransferFrom"; 
      from: token_owner;
      to: to;
      token_id: token_id
    };
    event e
  end
end

procedure HandleTransfer(info: Pair ByStr20 Uint256)
  match info with
  | Pair to token_id =>
    TransferToken to token_id
  end
end

(* Pauses the contract. Use this when things are going wrong ('circuit breaker'). *)
(* @Requirements: *)
(* - The contract must not be paused. Otherwise, it must throw 'PausedError' *)
(* - '_sender' must be the contract owner. Otherwise, it must throw 'NotContractOwnerError' *)
transition Pause()
  RequireNotPaused;
  RequireContractOwner;

  is_paused := true;
  e = {
    _eventname: "Pause";
    is_paused: true
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_PauseCallback";
    _recipient: _sender;
    _amount: Uint128 0;
    is_paused: true
  };
  msgs = one_msg msg_to_sender;
  send msgs
end

transition PauseZil()
  RequireNotPaused;
  RequireContractOwner;

  is_paused_zil := true;
  e = {
    _eventname: "PauseZil";
    is_paused_zil: true
  };
  event e
end

(* Unpauses the contract. *)
(* @Requirements: *)
(* - The contract must be paused. Otherwise, it must throw 'NotPausedError' *)
(* - '_sender' must be the contract owner. Otherwise, it must throw 'NotContractOwnerError' *)
transition Unpause()
  paused <- is_paused;
  match paused with
  | True =>
  | False =>
    error = NotPausedError;
    Throw error
  end;
  RequireContractOwner;

  is_paused := false;
  e = {
    _eventname: "Unpause";
    is_paused: false
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_UnpauseCallback";
    _recipient: _sender;
    _amount: Uint128 0;
    is_paused: false
  };
  msgs = one_msg msg_to_sender;
  send msgs
end

transition UnpauseZil()
  paused <- is_paused_zil;
  match paused with
  | True =>
  | False =>
    error = NotPausedError;
    Throw error
  end;
  RequireContractOwner;

  is_paused_zil := false;
  e = {
    _eventname: "UnpauseZil";
    is_paused_zil: false
  };
  event e
end

(* Sets 'to' as the royalty recipient. *)
(* @param: to - Royalty recipient address  *)
(* @Requirements: *)
(* - '_sender' must be the contract owner. Otherwise, it must throw 'NotContractOwnerError' *)
(* - 'to' must not be the zero address. Otherwise, it must throw 'ZeroAddressDestinationError' *)
(* - 'to' must not be '_this_address'. Otherwise, it must throw 'ThisAddressDestinationError' *)
transition SetRoyaltyRecipient(to: ByStr20)
  RequireContractOwner;
  RequireValidDestination to;
  
  royalty_recipient := to;
  
  e = { 
    _eventname: "SetRoyaltyRecipient";
    to: to
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_SetRoyaltyRecipientCallback"; 
    _recipient: _sender;
    _amount: Uint128 0;
    to: to
  };
  msgs = one_msg msg_to_sender;
  send msgs  
end

(* Sets 'fee_bps' as royalty fee bps. *)
(* @param: fee_bps - Royalty fee BPS *)
(* @Requirements: *)
(* - '_sender' must be the contract owner. Otherwise, it must throw 'NotContractOwnerError' *)
(* - 'fee_bps' must be in the range of 1 and 10000. Otherwise, it must throw 'InvalidFeeBPSError' *)
transition SetRoyaltyFeeBPS(fee_bps: Uint128)
  RequireContractOwner;
  RequireValidRoyaltyFee fee_bps;
  royalty_fee_bps := fee_bps;
  
  e = { 
    _eventname: "SetRoyaltyFeeBPS";
    royalty_fee_bps: fee_bps
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_SetRoyaltyFeeBPSCallback"; 
    _recipient: _sender;
    _amount: Uint128 0;
    royalty_fee_bps: fee_bps
  };
  msgs = one_msg msg_to_sender;
  send msgs
end

(* Sets 'uri' as the base URI. *)
(* @Requirements: *)
(* - '_sender' must be the contract owner. Otherwise, it must throw 'NotContractOwnerError' *)
transition SetBaseURI(uri: String)
  RequireContractOwner;
  base_uri := uri;

  e = { 
    _eventname: "SetBaseURI";
    base_uri: uri
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_SetBaseURICallback"; 
    _recipient: _sender;
    _amount: Uint128 0;
    base_uri: uri
  };
  msgs = one_msg msg_to_sender;
  send msgs  
end

(* Mints a token with a specific 'token_uri' and transfers it to 'to'. *)
(* Pass empty string to 'token_uri' to use the concatenated token URI. i.e. '<base_uri><token_id>'. *)
(* @param: to - Address of the token recipient *)
(* @param: token_uri - URI of a token *)
(* @Requirements: *)
(* - The contract must not be paused. Otherwise, it must throw 'PausedError' *)
transition Mint(to: ByStr20, token_uri: String)
  RequireNotPaused;
  domain_id = builtin sha256hash token_uri;
  maybe_dns <- nft_dns[domain_id]; match maybe_dns with
    | None =>
      id_ = let txID = "BuyNftUsername" in Pair {String String} zilID txID;
      HandlePayment id_
    | Some address =>
      RequireNotPausedZil;
      is_owner = builtin eq _sender address; match is_owner with 
        | True => | False => e = { _exception : "SSIDNS-ZilDomainIsTaken" }; throw e end end;
  MintToken to;
  token_id <- token_id_count;
  token_domains[token_id] := domain_id;
  SetTokenURI token_id token_uri;
  nft_domain_names[domain_id] := token_id;
  nft_dns[domain_id] := to;

  e = {
    _eventname: "Mint";
    to: to;
    token_id: token_id;
    token_uri: token_uri
  };
  event e;
  msg_to_recipient = {
    _tag: "ZRC6_RecipientAcceptMint";
    _recipient: to;
    _amount: Uint128 0
  };
  msg_to_sender = {
    _tag: "ZRC6_MintCallback";
    _recipient: _sender;
    _amount: Uint128 0;
    to: to;
    token_id: token_id;
    token_uri: token_uri
  };
  msgs = two_msgs msg_to_recipient msg_to_sender;
  send msgs
end

(* Mints a token with a specific 'token_uri' and transfers it to 'to'. *)
(* Pass empty string to 'token_uri' to use the concatenated token URI. i.e. '<base_uri><token_id>'. *)
(* @param: to - Address of the token recipient *)
(* @param: token_uri - URI of a token *)
(* @Requirements: *)
(* - The contract must not be paused. Otherwise, it must throw 'PausedError' *)
transition MintTyron(to: ByStr20, token_uri: ByStr32, id: String)
  RequireNotPaused; domain_id = token_uri;
  maybe_dns <- nft_dns[domain_id]; match maybe_dns with
    | None =>
      id_ = let txID = "BuyNftUsername" in Pair {String String} id txID;
      HandlePayment id_
    | Some address =>
      RequireNotPausedZil;
      is_owner = builtin eq _sender address; match is_owner with 
        | True => | False => e = { _exception : "SSIDNS-ZilDomainIsTaken" }; throw e end end;
  MintToken to;
  token_id <- token_id_count;
  token_domains[token_id] := domain_id;
  nft_domain_names[domain_id] := token_id;
  nft_dns[domain_id] := to;

  e = {
    _eventname: "MintTyron";
    to: to;
    token_id: token_id;
    token_uri: token_uri
  };
  event e;
  msg_to_recipient = {
    _tag: "ZRC6_RecipientAcceptMint";
    _recipient: to;
    _amount: Uint128 0
  };
  msg_to_sender = {
    _tag: "ZRC6_MintCallback";
    _recipient: _sender;
    _amount: Uint128 0;
    to: to;
    token_id: token_id;
    token_uri: empty_string
  };
  msgs = two_msgs msg_to_recipient msg_to_sender;
  send msgs
end

(* Mints multiple tokens with 'token_uri's and transfers them to multiple 'to's. *)
(* Pass empty string to 'token_uri' to use the concatenated token URI. i.e. '<base_uri><token_id>'. *)
(* @param: to_token_uri_pair_list - List of Pair (to, token_uri). *)
(* @Requirements: *)
(* - The contract must not be paused. Otherwise, it must throw 'PausedError' *)
transition BatchMint(to_token_uri_pair_list: List (Pair ByStr20 String))
  RequireNotPaused;
  cur_id <- token_id_count;
  start_id = builtin add cur_id one;
  txID = "BuyNftUsername";
  counter = let list_length = @list_length (Pair ByStr20 String) in list_length to_token_uri_pair_list;
  HandleBatchPayment zilID txID counter;
  forall to_token_uri_pair_list HandleMint;
  end_id <- token_id_count;
  e = {
    _eventname: "BatchMint";
    to_token_uri_pair_list: to_token_uri_pair_list;
    start_id: start_id;
    end_id: end_id
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_BatchMintCallback";
    _recipient: _sender;
    _amount: Uint128 0
  };
  msgs = one_msg msg_to_sender;
  send msgs
end

(* Mints multiple tokens with 'token_uri's and transfers them to multiple 'to's. *)
(* Pass empty string to 'token_uri' to use the concatenated token URI. i.e. '<base_uri><token_id>'. *)
(* @param: to_token_uri_pair_list - List of Pair (to, token_uri). *)
(* @Requirements: *)
(* - The contract must not be paused. Otherwise, it must throw 'PausedError' *)
transition BatchMintTyron(to_token_uri_pair_list: List (Pair ByStr20 String), id: String)
  RequireNotPaused;
  cur_id <- token_id_count;
  start_id = builtin add cur_id one;
  txID = "BuyNftUsername";
  counter = let list_length = @list_length (Pair ByStr20 String) in list_length to_token_uri_pair_list;
  HandleBatchPayment id txID counter;
  forall to_token_uri_pair_list HandleMint;
  end_id <- token_id_count;
  e = {
    _eventname: "BatchMint";
    to_token_uri_pair_list: to_token_uri_pair_list;
    start_id: start_id;
    end_id: end_id
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_BatchMintCallback";
    _recipient: _sender;
    _amount: Uint128 0
  };
  msgs = one_msg msg_to_sender;
  send msgs
end

(* Destroys 'token_id'. *)
(* @param: token_id - Unique ID of the NFT to be destroyed *)
(* @Requirements: *)
(* - The contract must not be paused. Otherwise, it must throw 'PausedError' *)
transition Burn(token_id: Uint256)
  RequireNotPaused;
  (* Check if token exists *)
  maybe_token_owner <- token_owners[token_id];
  match maybe_token_owner with
  | None =>
    error = TokenNotFoundError;
    Throw error
  | Some token_owner =>
    BurnToken token_id;
    msg_to_sender = {
      _tag: "ZRC6_BurnCallback";
      _recipient: _sender;
      _amount: Uint128 0;
      token_owner: token_owner;
      token_id: token_id
    };
    msgs = one_msg msg_to_sender;
    send msgs
  end
end

(* Destroys 'token_id_list'. *)
(* @param: token_id_list - List of unique IDs of the NFT to be destroyed *)
(* @Requirements: *)
(* - The contract must not be paused. Otherwise, it must throw 'PausedError' *)
transition BatchBurn(token_id_list: List Uint256)
  RequireNotPaused;
  forall token_id_list BurnToken;
  msg_to_sender = {
    _tag: "ZRC6_BatchBurnCallback";
    _recipient: _sender;
    _amount: Uint128 0
  };
  msgs = one_msg msg_to_sender;
  send msgs
end

(* Adds 'minter'. *)
(* @Requirements: *)
(* - '_sender' must be the contract owner. Otherwise, it must throw 'NotContractOwnerError' *)
(* - 'minter' must not be already a minter. Otherwise, it must throw 'MinterFoundError' *)
(*
transition AddMinter(minter: ByStr20)
  RequireContractOwner;
  has_minter <- exists minters[minter];
  match has_minter with
  | True => 
    error = MinterFoundError;
    Throw error
  | False =>
    (* Add minter *)
    minters[minter] := true
  end;
  e = { 
    _eventname: "AddMinter";
    minter: minter
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_AddMinterCallback";
    _recipient: _sender;
    _amount: Uint128 0;
    minter: minter
  };
  msgs = one_msg msg_to_sender;
  send msgs
end
*)

(* Removes 'minter'. *)
(* @Requirements: *)
(* - '_sender' must be the contract owner. Otherwise, it must throw 'NotContractOwnerError' *)
(* - 'minter' must be already a minter. Otherwise, it must throw 'MinterNotFoundError' *)
(*
transition RemoveMinter(minter: ByStr20)
  RequireContractOwner;
  has_minter <- exists minters[minter];
  match has_minter with
  | False =>
    error = MinterNotFoundError;
    Throw error
  | True => 
    delete minters[minter]
  end;
  e = { 
    _eventname: "RemoveMinter";
    minter: minter
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_RemoveMinterCallback";
    _recipient: _sender;
    _amount: Uint128 0;
    minter: minter
  };
  msgs = one_msg msg_to_sender;
  send msgs
end
*)

(* Sets 'spender' for 'token_id'. *)
(* To remove 'spender' for a token, use 'zero_address'. *)
(* i.e., '0x0000000000000000000000000000000000000000' *)
(* @Requirements: *)
(* - 'token_id' must exist. Otherwise, it must throw 'TokenNotFoundError' *)
(* - '_sender' must be a token owner or an operator. Otherwise, it must throw 'NotOwnerOrOperatorError' *)
(* - '_sender' must not be 'spender'. Otherwise, it must throw 'SelfError' *)
(* - 'spender' must not be already a spender. Otherwise, it must throw 'SpenderFoundError' *)
transition SetSpender(spender: ByStr20, token_id: Uint256)
  RequireNotSelf spender _sender;
  
  maybe_token_owner <- token_owners[token_id];
  match maybe_token_owner with
  | None =>
    error = TokenNotFoundError;
    Throw error
  | Some token_owner =>
    RequireOwnerOrOperator token_owner;
    
    (* Check if the spender exists *)
    maybe_spender <- spenders[token_id];
    match maybe_spender with
      | None =>
      | Some cur_spender =>
        has_spender = builtin eq cur_spender spender;
        match has_spender with 
        | False =>
        | True => 
          error = SpenderFoundError;
          Throw error
        end
    end;
      
    spenders[token_id] := spender;

    e = {
      _eventname: "SetSpender";
      token_owner: token_owner;
      spender: spender;
      token_id: token_id
    };
    event e;
    msg_to_sender = {
      _tag: "ZRC6_SetSpenderCallback";
      _recipient: _sender;
      _amount: Uint128 0;
      spender: spender;
      token_id: token_id
    };
    msgs = one_msg msg_to_sender;
    send msgs
  end
end

(* Adds 'operator' for '_sender'. *)
(* @Requirements: *)
(* - '_sender' must be the token owner. Otherwise, it must throw 'NotTokenOwnerError' *)
(* - '_sender' must not be 'operator'. Otherwise, it must throw 'SelfError' *)
(* - 'operator' must not be already an operator. Otherwise, it must throw 'OperatorFoundError' *)
transition AddOperator(operator: ByStr20)
  RequireNotSelf operator _sender;
  
  maybe_bal <- balances[_sender];
  balance = get_bal maybe_bal;
  
  is_balance_zero = builtin eq zero balance;
  (* _sender must have at least 1 token *)
  match is_balance_zero with 
  | True =>    
    error = NotTokenOwnerError;
    Throw error
  | False =>
    has_operator <- exists operators[_sender][operator];
    match has_operator with
    | False =>
      (* Add operator *)
      operators[_sender][operator] := true
    | True =>
      error = OperatorFoundError;
      Throw error
    end;
    e = {
      _eventname: "AddOperator";
      token_owner: _sender;
      operator: operator
    };
    event e;
    msg_to_sender = {
      _tag: "ZRC6_AddOperatorCallback";
      _recipient: _sender;
      _amount: Uint128 0;
      operator: operator
    };
    msgs = one_msg msg_to_sender;
    send msgs
  end
end

(* Removes 'operator' for '_sender'. *)
(* @Requirements:  *)
(* - 'operator' must be already an operator of '_sender'. Otherwise, it must throw 'OperatorNotFoundError' *)
transition RemoveOperator(operator: ByStr20)
  has_operator <- exists operators[_sender][operator];
  match has_operator with
  | False =>
    error = OperatorNotFoundError;
    Throw error
  | True =>
    (* Remove operator *)
    delete operators[_sender][operator]
  end;
  e = {
    _eventname: "RemoveOperator";
    token_owner: _sender;
    operator: operator
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_RemoveOperatorCallback";
    _recipient: _sender;
    _amount: Uint128 0;
    operator: operator
  };
  msgs = one_msg msg_to_sender;
  send msgs
end

(* Transfers 'token_id' from the token owner to 'to'.  *)
(* @Requirements: *)
(* - The contract must not be paused. Otherwise, it must throw 'PausedError' *)
transition TransferFrom(to: ByStr20, token_id: Uint256)
  RequireNotPaused;
  maybe_token_owner <- token_owners[token_id];
  match maybe_token_owner with
  | None =>
    error = TokenNotFoundError;
    Throw error
  | Some token_owner =>
    TransferToken to token_id;
    msg_to_recipient = {
      _tag: "ZRC6_RecipientAcceptTransferFrom";
      _recipient: to;
      _amount: Uint128 0;
      from: token_owner;
      to: to;
      token_id: token_id
    };
    msg_to_sender = {
      _tag: "ZRC6_TransferFromCallback";
      _recipient: _sender;
      _amount: Uint128 0;
      from: token_owner;
      to: to;
      token_id: token_id
    };
    msgs = two_msgs msg_to_recipient msg_to_sender;
    send msgs
  end
end

(* Transfers multiple 'token_id' to multiple 'to'. *)
(* @param: to_token_id_pair_list - List of Pair (to, token_id). *)
(* @Requirements: *)
(* - The contract must not be paused. Otherwise, it must throw 'PausedError' *)
transition BatchTransferFrom(to_token_id_pair_list: List (Pair ByStr20 Uint256))
  RequireNotPaused;
  forall to_token_id_pair_list HandleTransfer;
  msg_to_sender = {
    _tag: "ZRC6_BatchTransferFromCallback";
    _recipient: _sender;
    _amount: Uint128 0
  };
  msgs = one_msg msg_to_sender;
  send msgs
end

(* Sets 'to' as the contract ownership recipient. *)
(* To reset 'contract_ownership_recipient', use 'zero_address'. *)
(* i.e., '0x0000000000000000000000000000000000000000' *)
(* @param: to - Address of contract ownership recipient *)
(* @Requirements: *)
(* - '_sender' must be the contract owner. Otherwise, it must throw 'NotContractOwnerError' *)
(* - '_sender' must not be 'to'. Otherwise, it must throw 'SelfError' *)
transition SetContractOwnershipRecipient(to: ByStr20)
  RequireContractOwner;
  RequireNotSelf to _sender;
  
  contract_ownership_recipient := to;

  e = {
    _eventname: "SetContractOwnershipRecipient";
    to: to
  };
  event e;
  msg_to_sender = {
    _tag: "ZRC6_SetContractOwnershipRecipientCallback";
    _recipient: _sender;
    _amount: Uint128 0;
    to: to
  };
  msgs = one_msg msg_to_sender;
  send msgs
end

(* Sets 'contract_ownership_recipient' as the contract owner. *)
(* @Requirements: *)
(* - '_sender' must be the contract ownership recipient. Otherwise, it must throw 'NotContractOwnershipRecipientError' *)
transition AcceptContractOwnership()
  recipient <- contract_ownership_recipient;

  is_recipient = builtin eq _sender recipient;
  match is_recipient with
  | False =>
    error = NotContractOwnershipRecipientError;
    Throw error
  | True =>
    contract_owner := _sender;
    contract_ownership_recipient := zero_address;

    e = {
      _eventname: "AcceptContractOwnership";
      contract_owner: _sender
    };
    event e;
    msg_to_sender = {
      _tag: "ZRC6_AcceptContractOwnershipCallback";
      _recipient: _sender;
      _amount: Uint128 0;
      contract_owner: _sender
    };
    msgs = one_msg msg_to_sender;
    send msgs
  end
end

(* Shall change the current permalink for a new one. *)
transition UpdateTokenURI(token_id: Uint256, token_uri: String)
  RequireNotPaused;
  (* Check if token exists *)
  maybe_token_owner <- token_owners[token_id];
  match maybe_token_owner with
  | None =>
    error = TokenNotFoundError;
    Throw error
  | Some token_owner =>
      RequireOwnerOrOperator token_owner;
      SetTokenURI token_id token_uri;
      msg_to_sender = {
        _tag: "SSIDNS_UpdateDomainCallback";
        _recipient: _sender;
        _amount: Uint128 0;
        token_owner: token_owner;
        token_id: token_id
      };
      msgs = one_msg msg_to_sender;
      send msgs
  end
end

(* Sets the domain address for a certain token. *)
transition UpdateDomainAddress(token_id: Uint256, new_addr: ByStr20)
  RequireNotPaused;
  (* Check if token exists *)
  maybe_token_owner <- token_owners[token_id];
  match maybe_token_owner with
  | None =>
    error = TokenNotFoundError;
    Throw error
  | Some token_owner =>
      RequireOwnerOrOperator token_owner;
      get_token_domain <- token_domains[token_id]; token_domain = option_bystr32_value get_token_domain;
      nft_dns[token_domain] := new_addr;
      msg_to_sender = {
        _tag: "SSIDNS_UpdateDomainCallback";
        _recipient: _sender;
        _amount: Uint128 0;
        token_owner: token_owner;
        token_id: token_id
      };
      msgs = one_msg msg_to_sender;
      send msgs
  end
end