feat: decoding extrinsics within blocks (#136)

_deps/scale.ts

@@ -1 +1,3 @@
-export * from "https://deno.land/x/scale@v0.2.1/mod.ts";
+export * from "https://raw.githubusercontent.com/paritytech/parity-scale-codec-ts/7b40cffaf930bf945b09b39a6a4196509d6cd262/mod.ts";
+// TODO: replace line above with line below (with new version) upon release with bit sequence codec
+// export * from "https://deno.land/x/scale@v0.2.1/mod.ts";

core/Block.ts

@@ -1,3 +1,4 @@
+import { read } from "../runtime/mod.ts";
 import { HashHexString } from "../util/mod.ts";
 import { Chain } from "./Chain.ts";
 import { NodeBase } from "./common.ts";
@@ -9,4 +10,8 @@ export class Block<C extends Chain = Chain> extends NodeBase<"Block"> {
   ) {
     super("Block");
   }
+
+  read(): Promise<unknown> {
+    return read(this);
+  }
 }

examples/block.ts

@@ -0,0 +1,5 @@
+import { polkadot } from "../known/mod.ts";
+
+const result = await polkadot.block().read();
+
+console.log({ result });

frame_metadata/Codec.ts

@@ -139,7 +139,7 @@ export function DeriveCodec(metadata: M.Metadata): DeriveCodec {
       return $.compact;
     },
     BitSequence: () => {
-      return $.never as unknown as $.Codec<any>;
+      return $.bitSequence;
     },
     visit: (i) => {
       if (cache[i]) {

frame_metadata/Extrinsic.ts

@@ -24,8 +24,8 @@ interface ExtrinsicCodecProps {
   sign: (value: Uint8Array) => Signature;
 }
 
-export function $extrinsic(args: ExtrinsicCodecProps): $.Codec<Extrinsic> {
-  const { metadata, sign, deriveCodec, hashers: { Blake2_256 } } = args;
+export function $extrinsic(props: ExtrinsicCodecProps): $.Codec<Extrinsic> {
+  const { metadata, sign, deriveCodec, hashers: { Blake2_256 } } = props;
   const { signedExtensions } = metadata.extrinsic;
   const $sig = deriveCodec(findExtrinsicTypeParam("Signature")!);
   const $address = deriveCodec(findExtrinsicTypeParam("Address")!);
@@ -97,7 +97,7 @@ export function $extrinsic(args: ExtrinsicCodecProps): $.Codec<Extrinsic> {
   });
 
   return $.createCodec({
-    _metadata: [$extrinsic, args],
+    _metadata: [$extrinsic, props],
     _staticSize: $.nCompact._staticSize,
     _encode(buffer, extrinsic) {
       const encoded = $baseExtrinsic.encode(extrinsic);

runtime/read.ts

@@ -4,7 +4,7 @@ import * as M from "../frame_metadata/mod.ts";
 import * as U from "../util/mod.ts";
 import { globalContext } from "./Context.ts";
 
-export type ReadTarget = C.Entry | C.KeyPage | C.Metadata | C.Header;
+export type ReadTarget = C.Entry | C.KeyPage | C.Metadata | C.Header | C.Block;
 
 export async function read<Target extends ReadTarget = ReadTarget>(
   target: Target,
@@ -78,5 +78,31 @@ export async function read<Target extends ReadTarget = ReadTarget>(
       }
       throw new Error(); // TODO
     }
+    case "Block": {
+      const raw = await chain.rpcClient.call("chain_getBlock", [target.hash]);
+      if (raw.result) {
+        const { block, justifications } = raw.result;
+        const { extrinsics, header } = block;
+        const $extrinsic = M.$extrinsic({
+          deriveCodec: group.deriveCodec,
+          hashers: await Hashers(),
+          metadata: group.metadata,
+          sign: undefined!,
+        });
+        await chain.release();
+        return {
+          justifications,
+          block: {
+            header,
+            extrinsics: extrinsics.map((extrinsic) => {
+              const trimmed = extrinsic.substring(2);
+              const bytes = U.hex.decode(trimmed);
+              return $extrinsic.decode(bytes);
+            }),
+          },
+        };
+      }
+      throw new Error();
+    }
   }
 }