For non Bitcoin network, run legacy API code, but keep the same endpoint

backend/src/routes.ts

@@ -722,14 +722,52 @@ class Routes {
 
   public async getBlocks(req: Request, res: Response) {
     try {
-      const height = req.params.height === undefined ? undefined : parseInt(req.params.height, 10);
-      res.setHeader('Expires', new Date(Date.now() + 1000 * 60).toUTCString());
-      res.json(await blocks.$getBlocks(height, 15));
+      if (['mainnet', 'testnet', 'signet', 'regtest'].includes(config.MEMPOOL.NETWORK)) { // Bitcoin
+        const height = req.params.height === undefined ? undefined : parseInt(req.params.height, 10);
+        res.setHeader('Expires', new Date(Date.now() + 1000 * 60).toUTCString());
+        res.json(await blocks.$getBlocks(height, 15));
+      } else { // Liquid, Bisq
+        return await this.getLegacyBlocks(req, res);
+      }
     } catch (e) {
       res.status(500).send(e instanceof Error ? e.message : e);
     }
   }
 
+  public async getLegacyBlocks(req: Request, res: Response) {
+    try {
+      const returnBlocks: IEsploraApi.Block[] = [];
+      const fromHeight = parseInt(req.params.height, 10) || blocks.getCurrentBlockHeight();
+
+      // Check if block height exist in local cache to skip the hash lookup
+      const blockByHeight = blocks.getBlocks().find((b) => b.height === fromHeight);
+      let startFromHash: string | null = null;
+      if (blockByHeight) {
+        startFromHash = blockByHeight.id;
+      } else {
+        startFromHash = await bitcoinApi.$getBlockHash(fromHeight);
+      }
+
+      let nextHash = startFromHash;
+      for (let i = 0; i < 10 && nextHash; i++) {
+        const localBlock = blocks.getBlocks().find((b) => b.id === nextHash);
+        if (localBlock) {
+          returnBlocks.push(localBlock);
+          nextHash = localBlock.previousblockhash;
+        } else {
+          const block = await bitcoinApi.$getBlock(nextHash);
+          returnBlocks.push(block);
+          nextHash = block.previousblockhash;
+        }
+      }
+
+      res.setHeader('Expires', new Date(Date.now() + 1000 * 60).toUTCString());
+      res.json(returnBlocks);
+    } catch (e) {
+      res.status(500).send(e instanceof Error ? e.message : e);
+    }
+  }
+  
   public async getBlockTransactions(req: Request, res: Response) {
     try {
       loadingIndicators.setProgress('blocktxs-' + req.params.hash, 0);