From 7a37a8d13757c00f3965c1c63bbe6eb89c66c337 Mon Sep 17 00:00:00 2001
From: patrick-zippenfenig <patrick@zippenfenig.de>
Date: Wed, 1 Nov 2023 09:27:40 +0100
Subject: [PATCH] fix: add retry and error handling

---
 src/index.ts       | 52 +++++++++++++++++++++++++++++++++++++++-------
 test/index.spec.ts | 47 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 92 insertions(+), 7 deletions(-)

diff --git a/src/index.ts b/src/index.ts
index da9515d..a40b7b1 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,18 +1,56 @@
 import { ByteBuffer } from 'flatbuffers';
 import { WeatherApiResponse } from '@openmeteo/sdk/weather-api-response';
 
+const sleep = (ms: number) => new Promise(r => setTimeout(r, ms));
+
+async function fetchRetried(
+  url: string,
+  retries = 3,
+  backoffFactor = 0.5,
+  backoffMax = 2
+): Promise<Response> {
+  const statusToRetry = [500, 502, 504];
+  const statusWithJsonError = [400, 429];
+  let currentTry = 0;
+  let response = await fetch(url);
+
+  while (statusToRetry.includes(response.status)) {
+    currentTry++;
+    if (currentTry >= retries) {
+      throw new Error(response.statusText);
+    }
+    const sleepMs =
+      Math.min(backoffFactor * 2 ** currentTry, backoffMax) * 1000;
+    await sleep(sleepMs);
+    response = await fetch(url);
+  }
+
+  if (statusWithJsonError.includes(response.status)) {
+    const json = await response.json();
+    if ('reason' in json) {
+      throw new Error((json as { reason: string }).reason);
+    }
+    throw new Error(response.statusText);
+  }
+  return response;
+}
+
 async function fetchWeatherApi(
   url: string,
-  params: any
+  params: any,
+  retries = 3,
+  backoffFactor = 0.2,
+  backoffMax = 2
 ): Promise<WeatherApiResponse[]> {
   const urlParams = new URLSearchParams(params);
   urlParams.set('format', 'flatbuffers');
-  //console.log(`${url}?${urlParams.toString()}`);
-  const response = await fetch(`${url}?${urlParams.toString()}`);
-  const bb = await response.arrayBuffer();
-  const fb = new ByteBuffer(new Uint8Array(bb));
-
-  // TODO: retry, error handling
+  const response = await fetchRetried(
+    `${url}?${urlParams.toString()}`,
+    retries,
+    backoffFactor,
+    backoffMax
+  );
+  const fb = new ByteBuffer(new Uint8Array(await response.arrayBuffer()));
 
   const results: WeatherApiResponse[] = [];
   let pos = 0;
diff --git a/test/index.spec.ts b/test/index.spec.ts
index 58d7d1f..280a312 100644
--- a/test/index.spec.ts
+++ b/test/index.spec.ts
@@ -7,6 +7,7 @@ describe('openmeteo', () => {
       // 2 location data, with hourly temp and precip
       global.fetch = jest.fn(() =>
         Promise.resolve({
+          status: 200,
           arrayBuffer: () =>
             Promise.resolve(
               new Uint8Array([
@@ -92,3 +93,49 @@ describe('openmeteo', () => {
     });
   });
 });
+
+describe('openmeteo', () => {
+  describe('client', () => {
+    test('test_error', async () => {
+      global.fetch = jest.fn(() =>
+        Promise.resolve({
+          status: 400,
+          json: () => Promise.resolve({ reason: 'Some error' }),
+        })
+      ) as jest.Mock;
+      await expect(fetchWeatherApi('', {})).rejects.toThrow('Some error');
+    });
+  });
+});
+
+describe('openmeteo', () => {
+  describe('client', () => {
+    test('test_unknown_error', async () => {
+      global.fetch = jest.fn(() =>
+        Promise.resolve({
+          status: 400,
+          statusText: 'Other error',
+          json: () => Promise.resolve({}),
+        })
+      ) as jest.Mock;
+      await expect(fetchWeatherApi('', {})).rejects.toThrow('Other error');
+    });
+  });
+});
+
+describe('openmeteo', () => {
+  describe('client', () => {
+    test('test_retry', async () => {
+      global.fetch = jest.fn(() =>
+        Promise.resolve({
+          status: 500,
+          statusText: 'Internal server error',
+        })
+      ) as jest.Mock;
+      await expect(fetchWeatherApi('', {})).rejects.toThrow(
+        'Internal server error'
+      );
+      expect(fetch).toHaveBeenCalledTimes(3);
+    });
+  });
+});