Add endpoint for difficulty adjustment by height

backend/src/api/mining/mining-routes.ts

@@ -30,6 +30,7 @@ class MiningRoutes {
       .get(config.MEMPOOL.API_URL_PREFIX + 'mining/blocks/fee-rates/:interval', this.$getHistoricalBlockFeeRates)
       .get(config.MEMPOOL.API_URL_PREFIX + 'mining/blocks/sizes-weights/:interval', this.$getHistoricalBlockSizeAndWeight)
       .get(config.MEMPOOL.API_URL_PREFIX + 'mining/difficulty-adjustments/:interval', this.$getDifficultyAdjustments)
+      .get(config.MEMPOOL.API_URL_PREFIX + 'mining/difficulty-adjustment/:height', this.$getDifficultyAdjustment)
       .get(config.MEMPOOL.API_URL_PREFIX + 'mining/blocks/predictions/:interval', this.$getHistoricalBlocksHealth)
       .get(config.MEMPOOL.API_URL_PREFIX + 'mining/blocks/audit/scores', this.$getBlockAuditScores)
       .get(config.MEMPOOL.API_URL_PREFIX + 'mining/blocks/audit/scores/:height', this.$getBlockAuditScores)
@@ -297,6 +298,18 @@ class MiningRoutes {
     }
   }
 
+  private async $getDifficultyAdjustment(req: Request, res: Response) {
+    try {
+      const adjustment = await DifficultyAdjustmentsRepository.$getAdjustmentAtHeight(parseInt(req.params.height, 10));
+      res.header('Pragma', 'public');
+      res.header('Cache-control', 'public');
+      res.setHeader('Expires', new Date(Date.now() + 1000 * 300).toUTCString());
+      res.json(adjustment);
+    } catch (e) {
+      res.status(e instanceof Error && e.message === 'not found' ? 204 : 500).send(e instanceof Error ? e.message : e);
+    }
+  }
+
   private async $getRewardStats(req: Request, res: Response) {
     try {
       const response = await mining.$getRewardStats(parseInt(req.params.blockCount, 10));

backend/src/repositories/DifficultyAdjustmentsRepository.ts

@@ -88,6 +88,22 @@ class DifficultyAdjustmentsRepository {
     }
   }
 
+  public async $getAdjustmentAtHeight(height: number): Promise<IndexedDifficultyAdjustment> {
+    try {
+      if (isNaN(height)) {
+        throw new Error(`argument must be a number`);
+      }
+      const [rows] = await DB.query(`SELECT * FROM difficulty_adjustments WHERE height = ?`, [height]);
+      if (!rows[0]) {
+        throw new Error(`not found`);
+      }
+      return rows[0] as IndexedDifficultyAdjustment;
+    } catch (e: any) {
+      logger.err(`Cannot get difficulty adjustment from the database. Reason: ${e instanceof Error ? e.message : e}`, logger.tags.mining);
+      throw e;
+    }
+  }
+
   public async $getAdjustmentsHeights(): Promise<number[]> {
     try {
       const [rows]: any[] = await DB.query(`SELECT height FROM difficulty_adjustments`);

frontend/src/app/services/api.service.ts

@@ -315,6 +315,12 @@ export class ApiService {
       );
   }
 
+  getDifficultyAdjustmentByHeight$(height: number): Observable<any> {
+    return this.httpClient.get<any>(
+      this.apiBaseUrl + this.apiBasePath + `/api/v1/mining/difficulty-adjustment/${height}`
+    );
+  }
+
   getHistoricalHashrate$(interval: string | undefined): Observable<any> {
     return this.httpClient.get<any[]>(
         this.apiBaseUrl + this.apiBasePath + `/api/v1/mining/hashrate` +