feat: Add Ensembl class for Ensembl REST API inter

src/Snps/Ensembl.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace Dna\Snps;
+
+use Exception;
+use Symfony\Component\HttpClient\HttpClient;
+use Symfony\Contracts\HttpClient\Exception\ClientExceptionInterface;
+use Symfony\Contracts\HttpClient\Exception\RedirectionExceptionInterface;
+use Symfony\Contracts\HttpClient\Exception\ServerExceptionInterface;
+use Symfony\Contracts\HttpClient\Exception\TransportExceptionInterface;
+
+class Ensembl
+{
+    private string $server;
+    private int $reqs_per_sec;
+    private int $req_count;
+    private float $last_req;
+
+    public function __construct(string $server = "https://rest.ensembl.org", int $reqs_per_sec = 15)
+    {
+        $this->server = $server;
+        $this->reqs_per_sec = $reqs_per_sec;
+        $this->req_count = 0;
+        $this->last_req = microtime(true);
+    }
+
+    public function performRestAction(string $endpoint, ?array $hdrs = null, ?array $params = null): ?array
+    {
+        if ($hdrs === null) {
+            $hdrs = [];
+        }
+
+        if (!array_key_exists("Content-Type", $hdrs)) {
+            $hdrs["Content-Type"] = "application/json";
+        }
+
+        if ($params) {
+            $endpoint .= "?" . http_build_query($params);
+        }
+
+        $this->rateLimit();
+
+        $client = HttpClient::create();
+        $url = $this->server . $endpoint;
+        $options = [
+            'headers' => $hdrs,
+            'query' => $params,
+        ];
+
+        try {
+            $response = $client->request('GET', $url, $options);
+            $statusCode = $response->getStatusCode();
+
+            if ($statusCode === 200) {
+                return $response->toArray();
+            } elseif ($statusCode == 429) {
+                $retryAfter = $response->getHeaders()['retry-after'][0] ?? 1;
+                sleep($retryAfter);
+                return $this->performRestAction($endpoint, $hdrs, $params);
+            } else {
+                throw new Exception("HTTP request failed with status code {$statusCode}.");
+            }
+        } catch (ClientExceptionInterface | RedirectionExceptionInterface | ServerExceptionInterface | TransportExceptionInterface $e) {
+            error_log("Request failed for {$endpoint}: " . $e->getMessage());
+            return null;
+        }
+    }
+
+    private function rateLimit(): void
+    {
+        if ($this->req_count >= $this->reqs_per_sec) {
+            $delta = microtime(true) - $this->last_req;
+            if ($delta < 1) {
+                usleep((1 - $delta) * 1000000);
+            }
+            $this->last_req = microtime(true);
+            $this->req_count = 0;
+        } else {
+            $this->req_count++;
+        }
+    }
+}
+?>