feat(tvl): Use Zapper API as TVL fallback (#579)

src/stats/tvl/tvl.service.ts

@@ -1,21 +1,62 @@
-import { Inject, Injectable } from '@nestjs/common';
+import { Inject, Injectable, NotFoundException } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import Axios, { AxiosInstance } from 'axios';
 
 import { AppService } from '~app/app.service';
 import { Network } from '~types/network.interface';
 
 import { TvlFetcherRegistry } from './tvl-fetcher.registry';
 
+type AppTvl = {
+  appId: string;
+  appName: string;
+  network: Network;
+  tvl: number;
+};
+
 @Injectable()
 export class TvlService {
+  private readonly axios: AxiosInstance;
+
   constructor(
     @Inject(TvlFetcherRegistry) private readonly tvlFetcherRegistry: TvlFetcherRegistry,
     @Inject(AppService) private readonly appService: AppService,
-  ) {}
+    @Inject(ConfigService) private readonly configService: ConfigService,
+  ) {
+    this.axios = Axios.create({
+      baseURL: this.configService.get('zapperApi.url'),
+      params: { api_key: this.configService.get('zapperApi.key') },
+    });
+  }
+
+  private async getTvlFromApi({ appId, network }: { appId: string; network: Network }) {
+    try {
+      const { data } = await this.axios.get<AppTvl>(`/v1/apps/${appId}/tvl`, {
+        params: {
+          network,
+        },
+      });
+      return data;
+    } catch (e) {
+      return undefined;
+    }
+  }
 
-  async getTvl({ appId, network }: { appId: string; network: Network }) {
+  private async getTvlLocally({ appId, network }: { appId: string; network: Network }) {
     const app = this.appService.getApp(appId);
     const tvlFetcher = this.tvlFetcherRegistry.get({ network, appId: app.id });
-    const tvl = tvlFetcher ? await tvlFetcher.getTvl() : 0;
+    const tvl = (await tvlFetcher?.getTvl()) ?? 0;
+
     return { appId: appId, appName: app.name, network, tvl };
   }
+
+  async getTvl({ appId, network }: { appId: string; network: Network }): Promise<AppTvl> {
+    try {
+      return await this.getTvlLocally({ appId, network });
+    } catch (e) {
+      const apiTvl = await this.getTvlFromApi({ appId, network });
+      if (!apiTvl) throw new NotFoundException('No TVL registered on Studio and on Zapper API');
+      return apiTvl;
+    }
+  }
 }