Added missing block header API (#630)

* header API frontend

* Block Header API endpoint added to Node.js backend

* updated package-lock.json

Co-authored-by: Rishabh <rishabh@Rajeshs-MacBook-Pro.local>

backend/src/api/bitcoin/bitcoin-api-abstract-factory.ts

@@ -6,6 +6,7 @@ export interface AbstractBitcoinApi {
   $getBlockHeightTip(): Promise<number>;
   $getTxIdsForBlock(hash: string): Promise<string[]>;
   $getBlockHash(height: number): Promise<string>;
+  $getBlockHeader(hash: string): Promise<string>;
   $getBlock(hash: string): Promise<IEsploraApi.Block>;
   $getAddress(address: string): Promise<IEsploraApi.Address>;
   $getAddressTransactions(address: string, lastSeenTxId: string): Promise<IEsploraApi.Transaction[]>;

backend/src/api/bitcoin/bitcoin-api.ts

@@ -60,6 +60,10 @@ class BitcoinApi implements AbstractBitcoinApi {
     return this.bitcoindClient.getBlockHash(height);
   }
 
+  $getBlockHeader(hash: string): Promise<string> {
+    return this.bitcoindClient.getBlockHeader(hash,false);
+  }
+
   async $getBlock(hash: string): Promise<IEsploraApi.Block> {
     const foundBlock = blocks.getBlocks().find((block) => block.id === hash);
     if (foundBlock) {

backend/src/api/bitcoin/esplora-api.ts

@@ -35,6 +35,11 @@ class ElectrsApi implements AbstractBitcoinApi {
       .then((response) => response.data);
   }
 
+  $getBlockHeader(hash: string): Promise<string> {
+    return axios.get<string>(config.ESPLORA.REST_API_URL + '/block/' + hash + '/header', this.axiosConfig)
+      .then((response) => response.data);
+  }
+
   $getBlock(hash: string): Promise<IEsploraApi.Block> {
     return axios.get<IEsploraApi.Block>(config.ESPLORA.REST_API_URL + '/block/' + hash, this.axiosConfig)
       .then((response) => response.data);