// Generic value in accordance with ICRC-3.
// Reference: https://github.com/dfinity/ICRC-1/tree/main/standards/ICRC-3
type Value = variant {
    Blob : blob;
    Text : text;
    Nat : nat;
    Int : int;
    Array : vec Value;
    Map : vec record { text; Value };
};

// Account in accordance with ICRC-1.
type Subaccount = blob;
type Account = record { owner : principal; subaccount : opt Subaccount };

type TransferArg = record {
    from_subaccount: opt blob;
    to : Account;
    token_id : nat;
    memo : opt blob;
    created_at_time : opt nat64;
};

type TransferResult = variant {
    Ok : nat;
    Err : TransferError;
};

type TransferError = variant {
    NonExistingTokenId;
    InvalidRecipient;
    Unauthorized;
    TooOld;
    CreatedInFuture : record { ledger_time: nat64 };
    Duplicate : record { duplicate_of : nat };
    GenericError : record { error_code : nat; message : text };
    GenericBatchError : record { error_code : nat; message : text };
};

service : () -> {
    // Returns all the collection-level metadata of the NFT collection in a single query.
    icrc7_collection_metadata : () -> (vec record { text; Value } ) query;
    // Returns the token symbol of the NFT collection (e.g., MS).
    icrc7_symbol : () -> (text) query;
    // Returns the name of the NFT collection (e.g., My Super NFT).
    icrc7_name : () -> (text) query;
    // Returns the text description of the collection.
    icrc7_description : () -> (opt text) query;
    // Returns a link to the logo of the collection.
    // It may be a DataURL that contains the logo image itself.
    icrc7_logo : () -> (opt text) query;

    // Returns the total number of NFTs on all accounts.
    icrc7_total_supply : () -> (nat) query;
    // Returns the maximum number of NFTs possible for this collection.
    // Any attempt to mint more NFTs than this supply cap shall be rejected.
    icrc7_supply_cap : () -> (opt nat) query;

    // Returns the maximum batch size for batch query calls this ledger implementation supports.
    icrc7_max_query_batch_size : () -> (opt nat) query;
    // Returns the maximum number of token ids allowed for being used as input in a batch update method.
    icrc7_max_update_batch_size : () -> (opt nat) query;
    // Returns the default parameter the ledger uses for `take` in case the parameter is null in paginated queries.
    icrc7_default_take_value : () -> (opt nat) query;
    // Returns the maximum `take` value for paginated query calls this ledger implementation supports.
    // The value applies to all paginated calls the ledger exposes.
    icrc7_max_take_value : () -> (opt nat) query;

    // Returns the maximum size of memos as supported by an implementation.
    icrc7_max_memo_size : () -> (opt nat) query;

    // Returns true if and only if batch transfers of the ledger are executed atomically,
    // i.e., either all transfers execute or none, false otherwise.
    icrc7_atomic_batch_transfers : () -> (opt bool) query;
    // Returns the time window in seconds during which transactions can be deduplicated. Corresponds to the parameter
    // `TX_WINDOW` as specified in the section on transaction deduplication.
    icrc7_tx_window : () -> (opt nat) query;
    // Returns the time duration in seconds by which the transaction deduplication window can be extended. Corresponds
    // to the parameter PERMITTED_DRIFT as specified in the section on transaction deduplication.
    icrc7_permitted_drift : () -> (opt nat) query;

    // Returns the token metadata for token_ids, a list of token ids. Each tuple in the response vector comprises an
    // optional metadata element with the metadata expressed as vector of text and Value pairs. In case a token does
    // not exist, a null element corresponding to it is returned in the response. If a token does not have metadata,
    // its associated metadata vector is the empty vector.
    icrc7_token_metadata : (token_ids : vec nat) -> (vec opt vec record { text; Value }) query;

    // Returns the owner Account of each token in a list token_ids of token ids. The ordering of the response elements
    // corresponds to that of the request elements.
    icrc7_owner_of : (token_ids : vec nat) -> (vec opt Account) query;
    // Returns the balance of the account provided as an argument, i.e., the number of tokens held by the account.
    // For a non-existing account, the value 0 is returned.
    icrc7_balance_of : (vec Account) -> (vec nat) query;

    // Returns the list of tokens in this ledger, sorted by their token id.
    icrc7_tokens : (prev : opt nat, take : opt nat) -> (vec nat) query;

    // Returns a vector of token_ids of all tokens held by account, sorted by token_id. The token ids in the response
    // are sorted in any consistent sorting order used by the ledger. The result is paginated, the mechanics of
    // pagination are analogous to icrc7_tokens using prev and take to control pagination.
    icrc7_tokens_of : (account : Account, prev : opt nat, take : opt nat) -> (vec nat) query;

    // Performs a batch of token transfers. Each of those transfers transfers a token `token_id` from the account
    // defined by the caller principal and the specified `from_subaccount` to the `to` account. A `null` for the
    // `from_subaccount` refers to the default subaccount comprising all zeroes. A `memo` and `created_at_time` can be
    // given optionally. The transfer can only be initiated by the holder of the tokens.
    icrc7_transfer : (vec TransferArg) -> (vec opt TransferResult);
}