From f0854dcf2fcf27bb452238bb46050379f766f876 Mon Sep 17 00:00:00 2001
From: Jay Taylor <taylorjay098@gmail.com>
Date: Wed, 24 Jul 2024 18:16:09 +1000
Subject: [PATCH] feat: Blockfrost provider returns UTxOs with datums and
 script refs (#91)

---
 .changeset/sour-panthers-double.md     |   5 +
 examples/blockfrost/index.js           |  18 ++++
 packages/blaze-query/src/blockfrost.ts | 143 +++++++++++++++++++------
 3 files changed, 133 insertions(+), 33 deletions(-)
 create mode 100644 .changeset/sour-panthers-double.md

diff --git a/.changeset/sour-panthers-double.md b/.changeset/sour-panthers-double.md
new file mode 100644
index 0000000..8bbfa7c
--- /dev/null
+++ b/.changeset/sour-panthers-double.md
@@ -0,0 +1,5 @@
+---
+"@blaze-cardano/query": patch
+---
+
+feat: Blockfrost provider returns UTxOs with datums and script refs
diff --git a/examples/blockfrost/index.js b/examples/blockfrost/index.js
index 68b7939..ab493a6 100644
--- a/examples/blockfrost/index.js
+++ b/examples/blockfrost/index.js
@@ -92,6 +92,14 @@ const txIns = [
     "74baf638a18a6ab54798cac310112af61cb1f1d6eacb8c893a10b6877cf71a8d",
     1,
   ),
+  new TransactionInput(
+    "036ed48c89169a9c4e475e08a6d22ea1e09ba8a6a6cfbabfa4f1deefd269652c",
+    0,
+  ),
+  new TransactionInput(
+    "ad54aa407df81404ab74343a4fca56e51c4ab488c54f12c4bc43e8b093c976a5",
+    1,
+  ),
 ];
 
 const resolvedOutputs = await provider.resolveUnspentOutputs(txIns);
@@ -110,6 +118,16 @@ for (const utxo of resolvedOutputs) {
 
     console.log(`Amount of ${assetName}: ${amount}`);
   }
+
+  if (utxo.output().datum()) {
+    console.log("Datum:");
+    console.log(utxo.output().datum().toCore());
+  }
+
+  if (utxo.output().scriptRef()) {
+    console.log("Reference Script:");
+    console.log(utxo.output().scriptRef().hash());
+  }
 }
 
 const datumHash =
diff --git a/packages/blaze-query/src/blockfrost.ts b/packages/blaze-query/src/blockfrost.ts
index d0efe5a..753a86b 100644
--- a/packages/blaze-query/src/blockfrost.ts
+++ b/packages/blaze-query/src/blockfrost.ts
@@ -2,9 +2,9 @@ import type {
   AssetId as AssetIdType,
   CostModels,
   Credential,
-  DatumHash,
   ProtocolParameters,
   Redeemer,
+  ScriptHash,
   TokenMap,
   Transaction,
 } from "@blaze-cardano/core";
@@ -12,12 +12,18 @@ import {
   Address,
   AddressType,
   AssetId,
+  Datum,
+  DatumHash,
   ExUnits,
   fromHex,
+  Hash28ByteBase16,
   HexBlob,
   PlutusData,
+  PlutusV1Script,
+  PlutusV2Script,
   Redeemers,
   RedeemerTag,
+  Script,
   TransactionId,
   TransactionInput,
   TransactionOutput,
@@ -147,7 +153,7 @@ export class Blockfrost implements Provider {
             paymentPart: address.toCore(),
           }).toBech32();
 
-    const buildTxUnspentOutput = buildTransactionUnspentOutput(
+    const buildTxUnspentOutput = this.buildTransactionUnspentOutput(
       Address.fromBech32(bech32),
     );
 
@@ -173,7 +179,7 @@ export class Blockfrost implements Provider {
       }
 
       for (const blockfrostUTxO of response) {
-        results.add(buildTxUnspentOutput(blockfrostUTxO));
+        results.add(await buildTxUnspentOutput(blockfrostUTxO));
       }
 
       if (response.length < maxPageCount) {
@@ -212,7 +218,7 @@ export class Blockfrost implements Provider {
             paymentPart: address.toCore(),
           }).toBech32();
 
-    const buildTxUnspentOutput = buildTransactionUnspentOutput(
+    const buildTxUnspentOutput = this.buildTransactionUnspentOutput(
       Address.fromBech32(bech32),
     );
 
@@ -242,7 +248,7 @@ export class Blockfrost implements Provider {
       }
 
       for (const blockfrostUTxO of response) {
-        results.add(buildTxUnspentOutput(blockfrostUTxO));
+        results.add(await buildTxUnspentOutput(blockfrostUTxO));
       }
 
       if (response.length < maxPageCount) {
@@ -349,11 +355,11 @@ export class Blockfrost implements Provider {
         // Blockfrost API does not return tx hash, so it must be manually set
         blockfrostUTxO.tx_hash = txIn.transactionId();
 
-        const buildTxUnspentOutput = buildTransactionUnspentOutput(
+        const buildTxUnspentOutput = this.buildTransactionUnspentOutput(
           Address.fromBech32(blockfrostUTxO.address),
         );
 
-        results.add(buildTxUnspentOutput(blockfrostUTxO));
+        results.add(await buildTxUnspentOutput(blockfrostUTxO));
       }
     }
 
@@ -584,6 +590,103 @@ export class Blockfrost implements Provider {
       Array.from(evaledRedeemers).map((x) => x.toCore()),
     );
   }
+
+  private async getScriptRef(scriptHash: ScriptHash): Promise<Script> {
+    const typeQuery = `/scripts/${scriptHash}`;
+    const typeJson = await fetch(`${this.url}${typeQuery}`, {
+      headers: this.headers(),
+    }).then((resp) => resp.json());
+
+    if (!typeJson) {
+      throw new Error("getScriptRef: Could not parse response json");
+    }
+
+    const typeResponse = typeJson as BlockfrostResponse<{
+      type: "timelock" | "plutusV1" | "plutusV2";
+    }>;
+
+    if ("message" in typeResponse) {
+      throw new Error(
+        `getScriptRef: Blockfrost threw "${typeResponse.message}"`,
+      );
+    }
+
+    const type = typeResponse.type;
+    if (type == "timelock") {
+      throw new Error("getScriptRef: Native scripts are not yet supported.");
+    }
+
+    const cborQuery = `/scripts/${scriptHash}/cbor`;
+    const cborJson = await fetch(`${this.url}${cborQuery}`, {
+      headers: this.headers(),
+    }).then((resp) => resp.json());
+
+    if (!cborJson) {
+      throw new Error("getScriptRef: Could not parse response json");
+    }
+
+    const cborResponse = cborJson as BlockfrostResponse<{
+      cbor: string;
+    }>;
+
+    if ("message" in cborResponse) {
+      throw new Error(
+        `getScriptRef: Blockfrost threw "${cborResponse.message}"`,
+      );
+    }
+
+    const cbor = HexBlob(cborResponse.cbor);
+
+    switch (type) {
+      case "plutusV1":
+        return Script.newPlutusV1Script(new PlutusV1Script(cbor));
+      case "plutusV2":
+        return Script.newPlutusV2Script(new PlutusV2Script(cbor));
+    }
+  }
+
+  // Partially applies address in order to avoid sending it
+  // as argument repeatedly when building TransactionUnspentOutput
+  private buildTransactionUnspentOutput(
+    address: Address,
+  ): (blockfrostUTxO: BlockfrostUTxO) => Promise<TransactionUnspentOutput> {
+    return async (blockfrostUTxO) => {
+      const txIn = new TransactionInput(
+        TransactionId(blockfrostUTxO.tx_hash),
+        BigInt(blockfrostUTxO.output_index),
+      );
+      // No tx output CBOR available from Blockfrost,
+      // so TransactionOutput must be manually constructed.
+      const tokenMap: TokenMap = new Map<AssetId, bigint>();
+      let lovelace = 0n;
+      for (const { unit, quantity } of blockfrostUTxO.amount) {
+        if (unit === "lovelace") {
+          lovelace = BigInt(quantity);
+        } else {
+          tokenMap.set(unit as AssetId, BigInt(quantity));
+        }
+      }
+      const txOut = new TransactionOutput(
+        address,
+        new Value(lovelace, tokenMap),
+      );
+      const datum = blockfrostUTxO.inline_datum
+        ? Datum.newInlineData(
+            PlutusData.fromCbor(HexBlob(blockfrostUTxO.inline_datum)),
+          )
+        : blockfrostUTxO.data_hash
+          ? Datum.newDataHash(DatumHash(blockfrostUTxO.data_hash))
+          : undefined;
+      if (datum) txOut.setDatum(datum);
+      if (blockfrostUTxO.reference_script_hash)
+        txOut.setScriptRef(
+          await this.getScriptRef(
+            Hash28ByteBase16(blockfrostUTxO.reference_script_hash),
+          ),
+        );
+      return new TransactionUnspentOutput(txIn, txOut);
+    };
+  }
 }
 
 // builds proper type from string result from Blockfrost API
@@ -606,32 +709,6 @@ function purposeFromTag(tag: string): RedeemerTag {
   }
 }
 
-// Partially applies address in order to avoid sending it
-// as argument repeatedly when building TransactionUnspentOutput
-function buildTransactionUnspentOutput(
-  address: Address,
-): (blockfrostUTxO: BlockfrostUTxO) => TransactionUnspentOutput {
-  return (blockfrostUTxO) => {
-    const txIn = new TransactionInput(
-      TransactionId(blockfrostUTxO.tx_hash),
-      BigInt(blockfrostUTxO.output_index),
-    );
-    // No tx output CBOR available from Blockfrost,
-    // so TransactionOutput must be manually constructed.
-    const tokenMap: TokenMap = new Map<AssetId, bigint>();
-    let lovelace = 0n;
-    for (const { unit, quantity } of blockfrostUTxO.amount) {
-      if (unit === "lovelace") {
-        lovelace = BigInt(quantity);
-      } else {
-        tokenMap.set(unit as AssetId, BigInt(quantity));
-      }
-    }
-    const txOut = new TransactionOutput(address, new Value(lovelace, tokenMap));
-    return new TransactionUnspentOutput(txIn, txOut);
-  };
-}
-
 type BlockfrostLanguageVersions = "PlutusV1" | "PlutusV2" | "PlutusV3";
 export const fromBlockfrostLanguageVersion = (
   x: BlockfrostLanguageVersions,