Contract to fetch single NFT

flake.nix

@@ -12,7 +12,8 @@
       repo = "cardano-transaction-lib";
       # should be same rev as in packages.dhall
       # Oh update, do `spago2nix generate`
-      rev = "b7614b4e11a57b5b366b65509b86eb4b086bb1ce";
+      # https://github.com/Plutonomicon/cardano-transaction-lib/pull/702/commits/6592f4188850ca4b2adab0c593c6a971087a54ba
+      rev = "6592f4188850ca4b2adab0c593c6a971087a54ba";
     };
     nixpkgs.follows = "cardano-transaction-lib/nixpkgs";
   };

index.d.ts

@@ -2,6 +2,13 @@ export function callMarketPlaceBuy(config: Config, args: BuyNftArgs):
     Promise<void>
 export function callMarketPlaceListNft(config: Config):
     Promise<Array<NftListing>>
+/**
+ * Fetch the info for a single NFT. Returns null if the given
+ * transaction input has been spent (for example if the NFT has been
+ * bought).
+ */
+export function callMarketPlaceFetchNft(config: Config, args: FetchNftArgs):
+    Promise<NftListing?>
 export function connectWallet(): Promise<any>
 export function getWalletBalance(): Promise<any>
 
@@ -36,6 +43,8 @@ export type BuyNftArgs = {
 
 }
 
+export type FetchNftArgs = Input
+
 export type NftCollectionArgs = {
     // CurrencySymbol of nft collection
     collectionNftCs: string,
@@ -66,8 +75,8 @@ export type NftListing = {
 }
 
 export type Input = {
-    transaction_id: String,
-    input_index: number
+    transactionId: String,
+    inputIndex: number
 }
 
 export type Output = {

index.js

@@ -27,6 +27,11 @@ exports.callMarketPlaceListNft = async (config) => {
   return sb.callMarketPlaceListNft(config)();
 };
 
+exports.callMarketPlaceFetchNft = async (config, args) => {
+  const sb = await seabug;
+  return sb.callMarketPlaceFetchNft(config)(args)();
+};
+
 
 /**
  * Returns a promise containing the connected wallet's balance.

packages.dhall

@@ -328,9 +328,7 @@ let additions =
             ]
         , repo = "https://github.com/Plutonomicon/cardano-transaction-lib.git"
           -- should be same rev as in flake.nix
-          -- https://github.com/Plutonomicon/cardano-transaction-lib/pull/696
-          -- PR: Return error if no utxo is specified for a tx input & Fix transaction inputs locking
-        , version = "b7614b4e11a57b5b366b65509b86eb4b086bb1ce"
+        , version = "6592f4188850ca4b2adab0c593c6a971087a54ba"
         }
       }
 in upstream // additions

spago.dhall

@@ -27,6 +27,7 @@ You can edit this file as you like.
   , "monad-logger"
   , "mote"
   , "newtype"
+  , "nullable"
   , "ordered-collections"
   , "parallel"
   , "partial"

src/Seabug/CallContract.purs

@@ -1,7 +1,8 @@
 module Seabug.CallContract
   ( callMarketPlaceBuy
-  , callMarketPlaceListNft
   , callMarketPlaceBuyTest
+  , callMarketPlaceFetchNft
+  , callMarketPlaceListNft
   ) where
 
 import Contract.Prelude
@@ -16,12 +17,9 @@ import Contract.Monad
   , runContract_
   )
 import Contract.Numeric.Natural (toBigInt)
-import Contract.Prim.ByteArray
-  ( byteArrayToHex
-  , hexToByteArray
-  )
+import Contract.Prim.ByteArray (byteArrayToHex, hexToByteArray)
 import Contract.Transaction
-  ( TransactionInput(TransactionInput)
+  ( TransactionInput(..)
   , TransactionOutput(TransactionOutput)
   )
 import Contract.Value
@@ -38,19 +36,22 @@ import Control.Promise (Promise)
 import Control.Promise as Promise
 import Data.BigInt (BigInt)
 import Data.BigInt as BigInt
+import Data.Log.Level (LogLevel(..))
+import Data.Nullable (Nullable, notNull, null)
 import Data.Tuple.Nested ((/\))
 import Data.UInt as UInt
 import Effect (Effect)
 import Effect.Aff (error)
 import Effect.Class (liftEffect)
-import Data.Log.Level (LogLevel(..))
 import Effect.Exception (Error)
-import Seabug.Metadata.Types (SeabugMetadata(SeabugMetadata))
-import Seabug.Metadata.Share (unShare)
 import Partial.Unsafe (unsafePartial)
 import Plutus.Conversion (fromPlutusAddress)
+import Seabug.Contract.Common (NftResult)
 import Seabug.Contract.MarketPlaceBuy (marketplaceBuy)
-import Seabug.Contract.MarketPlaceListNft (ListNftResult, marketPlaceListNft)
+import Seabug.Contract.MarketPlaceFetchNft (marketPlaceFetchNft)
+import Seabug.Contract.MarketPlaceListNft (marketPlaceListNft)
+import Seabug.Metadata.Share (unShare)
+import Seabug.Metadata.Types (SeabugMetadata(SeabugMetadata))
 import Seabug.Types
   ( NftCollection(NftCollection)
   , NftData(NftData)
@@ -63,14 +64,26 @@ import Serialization.Hash
   , scriptHashFromBech32
   , scriptHashToBech32Unsafe
   )
+import Types.BigNum as BigNum
 import Types.Natural as Nat
 import Wallet (mkNamiWalletAff)
-import Types.BigNum as BigNum
 
 -- | Exists temporarily for testing purposes
 callMarketPlaceBuyTest :: String -> Effect (Promise String)
 callMarketPlaceBuyTest = Promise.fromAff <<< pure
 
+callMarketPlaceFetchNft
+  :: ContractConfiguration
+  -> TransactionInputOut
+  -> Effect (Promise (Nullable ListNftResultOut))
+callMarketPlaceFetchNft cfg args = Promise.fromAff do
+  contractConfig <- buildContractConfig cfg
+  txInput <- liftEffect $ liftEither $ buildTransactionInput args
+  runContract contractConfig (marketPlaceFetchNft txInput) >>= case _ of
+    Nothing -> pure null
+    Just nftResult -> pure $ notNull $
+      buildNftList (unwrap contractConfig).networkId nftResult
+
 -- | Calls Seabugs marketplaceBuy and takes care of converting data types.
 --   Returns a JS promise holding no data.
 callMarketPlaceBuy
@@ -123,12 +136,14 @@ type BuyNftArgs =
       }
   }
 
+type TransactionInputOut = { transactionId :: String, inputIndex :: Int }
+
 -- Placeholder for types I'm not sure how should we represent on frontend.
 type ValueOut = Array
   { currencySymbol :: String, tokenName :: String, amount :: BigInt }
 
 type ListNftResultOut =
-  { input :: { transactionId :: String, inputIndex :: Int }
+  { input :: TransactionInputOut
   , output :: { address :: String, value :: ValueOut, dataHash :: String }
   , metadata ::
       { seabugMetadata ::
@@ -193,7 +208,7 @@ stringToLogLevel "Warn" = Just Warn
 stringToLogLevel "Error" = Just Error
 stringToLogLevel _ = Nothing
 
-buildNftList :: NetworkId -> ListNftResult -> ListNftResultOut
+buildNftList :: NetworkId -> NftResult -> ListNftResultOut
 buildNftList
   network
   { input: TransactionInput input, output: TransactionOutput output, metadata } =
@@ -298,3 +313,13 @@ buildNftData { nftCollectionArgs, nftIdArgs } = do
       , daoScript
       , daoShare
       }
+
+buildTransactionInput :: TransactionInputOut -> Either Error TransactionInput
+buildTransactionInput input = do
+  transactionId <-
+    note (error $ "Invalid transaction id: " <> input.transactionId)
+      $ wrap
+      <$> hexToByteArray input.transactionId
+  index <- note (error $ "Invalid input index: " <> show input.inputIndex) $
+    UInt.fromInt' input.inputIndex
+  pure $ wrap { transactionId, index }

src/Seabug/Contract/Common.purs

@@ -0,0 +1,12 @@
+module Seabug.Contract.Common
+  ( NftResult
+  ) where
+
+import Contract.Transaction (TransactionInput, TransactionOutput)
+import Seabug.Metadata (FullSeabugMetadata)
+
+type NftResult =
+  { input :: TransactionInput
+  , output :: TransactionOutput
+  , metadata :: FullSeabugMetadata
+  }

src/Seabug/Contract/MarketPlaceFetchNft.purs

@@ -0,0 +1,38 @@
+-- | Contract to fetch a single NFT
+module Seabug.Contract.MarketPlaceFetchNft
+  ( marketPlaceFetchNft
+  ) where
+
+import Contract.Prelude
+
+import Contract.Monad (Contract, liftContractM, liftedE, liftedM, logWarn')
+import Contract.PlutusData (fromData, getDatumByHash)
+import Contract.Transaction (TransactionInput, TransactionOutput(..))
+import Contract.Utxos (getUtxo)
+import Control.Monad.Reader (asks)
+import Seabug.Contract.Common (NftResult)
+import Seabug.Metadata (getFullSeabugMetadataWithBackoff)
+import Seabug.Types (MarketplaceDatum(..))
+
+-- | Fetch the info for a single NFT identified by a utxo
+-- | (`TransactionInput`). Returns `Nothing` if the given transaction
+-- | input has been spent (for example if the NFT has been bought).
+marketPlaceFetchNft
+  :: forall (r :: Row Type)
+   . TransactionInput
+  -> Contract (projectId :: String | r) (Maybe NftResult)
+marketPlaceFetchNft ref = do
+  getUtxo ref >>= case _ of
+    Nothing -> do
+      logWarn' "Could not find NFT utxo, it may have been spent"
+      pure Nothing
+    Just output@(TransactionOutput nftTxOut) -> do
+      datumHash <- liftContractM "Datum hash not available for NFT"
+        nftTxOut.dataHash
+      MarketplaceDatum { getMarketplaceDatum: datum } <-
+        liftedM "Could not get datum for NFT" $ getDatumByHash datumHash <#>
+          (_ >>= unwrap >>> fromData)
+      projectId <- asks $ unwrap >>> _.projectId
+      metadata <- liftedE $ liftAff $
+        getFullSeabugMetadataWithBackoff datum projectId
+      pure $ Just { input: ref, output, metadata }

src/Seabug/Contract/MarketPlaceListNft.purs

@@ -1,18 +1,14 @@
 -- | Helper to list the utxo with relevant NFT at the market validator script
 module Seabug.Contract.MarketPlaceListNft
-  ( ListNftResult
-  , marketPlaceListNft
+  ( marketPlaceListNft
   ) where
 
 import Contract.Prelude
 
 import Contract.Address (getNetworkId, typedValidatorEnterpriseAddress)
 import Contract.Monad (Contract, liftContractE, liftedM)
 import Contract.PlutusData (fromData, getDatumsByHashes)
-import Contract.Transaction
-  ( TransactionInput
-  , TransactionOutput(TransactionOutput)
-  )
+import Contract.Transaction (TransactionOutput(TransactionOutput))
 import Contract.Utxos (utxosAt)
 import Contract.Value (valueOf)
 import Control.Alternative (guard)
@@ -21,22 +17,17 @@ import Control.Monad.Reader (asks)
 import Control.Parallel (parTraverse)
 import Data.Array (catMaybes, mapMaybe)
 import Data.Map as Map
+import Seabug.Contract.Common (NftResult)
 import Seabug.MarketPlace (marketplaceValidator)
-import Seabug.Metadata (FullSeabugMetadata, getFullSeabugMetadataWithBackoff)
+import Seabug.Metadata (getFullSeabugMetadataWithBackoff)
 import Seabug.Types (MarketplaceDatum(MarketplaceDatum))
 
-type ListNftResult =
-  { input :: TransactionInput
-  , output :: TransactionOutput
-  , metadata :: FullSeabugMetadata
-  }
-
 -- | Lists the utxos at the script address that contain a datum of type
 -- | `MarketplaceDatum` with unit value. It currently doesn't have any logic
 -- | on matching `CurrencySymbol` and `TokenName`.
 marketPlaceListNft
   :: forall (r :: Row Type)
-   . Contract (projectId :: String | r) (Array ListNftResult)
+   . Contract (projectId :: String | r) (Array NftResult)
 marketPlaceListNft = do
   marketplaceValidator' <- unwrap <$> liftContractE marketplaceValidator
   networkId <- getNetworkId

src/Seabug/Seabug.purs

@@ -7,5 +7,6 @@ import Seabug.CallContract
   ( callMarketPlaceBuy
   , callMarketPlaceBuyTest
   , callMarketPlaceListNft
+  , callMarketPlaceFetchNft
   )
 import QueryM.Utxos (getWalletBalance)