From b2bb6705951b3bbb9f6e8174fa45f26c2b10ce2d Mon Sep 17 00:00:00 2001
From: Marc Velmer <marc1987@gmail.com>
Date: Tue, 12 Sep 2023 14:24:20 +0200
Subject: [PATCH] Added supported chains endpoint in Census3

---
 CHANGELOG.md               |  6 ++++++
 src/api/census3/index.ts   |  1 +
 src/api/census3/service.ts | 35 +++++++++++++++++++++++++++++++++++
 src/census3.ts             | 10 ++++++++++
 4 files changed, 52 insertions(+)
 create mode 100644 src/api/census3/service.ts

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a77df450..527fe576 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+
+- Census3 supported chains information.
+
 ## [0.2.0] - 2023-09-04
 
 ### Fixed
diff --git a/src/api/census3/index.ts b/src/api/census3/index.ts
index b0e94979..f9e04d2d 100644
--- a/src/api/census3/index.ts
+++ b/src/api/census3/index.ts
@@ -1,4 +1,5 @@
 export * from './census';
 export * from './strategy';
+export * from './service';
 export * from './token';
 export * from './errors';
diff --git a/src/api/census3/service.ts b/src/api/census3/service.ts
new file mode 100644
index 00000000..bd0d1154
--- /dev/null
+++ b/src/api/census3/service.ts
@@ -0,0 +1,35 @@
+import axios from 'axios';
+import { Census3API } from './api';
+
+enum Census3ServiceAPIMethods {
+  INFO = '/info',
+}
+
+export interface ICensus3ServiceInfoResponse {
+  /**
+   * The list of supported chains
+   */
+  chainIDs: Array<number>;
+}
+
+export abstract class Census3ServiceAPI extends Census3API {
+  /**
+   * Cannot be constructed.
+   */
+  private constructor() {
+    super();
+  }
+
+  /**
+   * Fetches supported chains from the service
+   *
+   * @param {string} url API endpoint URL
+   * @returns {Promise<ICensus3ServiceInfoResponse>}
+   */
+  public static info(url: string): Promise<ICensus3ServiceInfoResponse> {
+    return axios
+      .get<ICensus3ServiceInfoResponse>(url + Census3ServiceAPIMethods.INFO)
+      .then((response) => response.data)
+      .catch(this.isApiError);
+  }
+}
diff --git a/src/census3.ts b/src/census3.ts
index 07f0b347..e9e2f93d 100644
--- a/src/census3.ts
+++ b/src/census3.ts
@@ -2,6 +2,7 @@ import { CENSUS3_URL } from './util/constants';
 import { ClientOptions } from './client';
 import {
   Census3CensusAPI,
+  Census3ServiceAPI,
   Census3StrategyAPI,
   Census3TokenAPI,
   ICensus3CensusResponse,
@@ -43,6 +44,15 @@ export class VocdoniCensus3Client {
     return Census3TokenAPI.list(this.url).then((list) => list.tokens ?? []);
   }
 
+  /**
+   * Returns a list of supported chain identifiers
+   *
+   * @returns {Promise<number[]>} Supported chain list
+   */
+  getSupportedChains(): Promise<number[]> {
+    return Census3ServiceAPI.info(this.url).then((info) => info.chainIDs ?? []);
+  }
+
   /**
    * Returns a list of supported tokens type
    *