Merge pull request #15 from ilazaridis/feature/file-cache

Add file cache implementation

cache.php

@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+class FileCache {
+    private $cacheDir;
+    private $defaultExpiration;
+
+    public function __construct($cacheDir = 'cache', $defaultExpiration = 60) {
+        $this->cacheDir = $cacheDir;
+        $this->defaultExpiration = $defaultExpiration;
+        // Create the cache directory if it doesn't exist
+        if (!file_exists($this->cacheDir)) {
+            mkdir($this->cacheDir, 0755, true);
+        }
+    }
+
+    public function get($key, $expiration = null)
+    {
+        $file = $this->cacheDir . '/' . md5($key) . '.cache';
+        if (file_exists($file)) {
+            $expiration = $expiration ?? $this->defaultExpiration;
+            if (time() - filemtime($file) < $expiration) {
+                $data = file_get_contents($file);
+                return unserialize($data);
+            } else {
+                unlink($file);
+            }
+        }
+        return null;
+    }
+
+    public function set($key, $data): void
+    {
+        $file = $this->cacheDir . '/' . md5($key) . '.cache';
+        file_put_contents($file, serialize($data));
+    }
+
+    public function delete($key): void
+    {
+        $file = $this->cacheDir . '/' . md5($key) . '.cache';
+        if (file_exists($file)) {
+            unlink($file);
+        }
+    }
+
+    public function clear()
+    {
+        array_map('unlink', glob($this->cacheDir . '/*.cache'));
+    }
+
+    public function getOrSet($key, callable $callback, ?int $expiration = null)
+    {
+        $data = $this->get($key, $expiration);
+        if ($data === null) {
+            $data = $callback(); // Execute the callback to get the data
+            $this->set($key, $data);
+        }
+        return $data;
+    }
+}

coingecko.php

@@ -6,14 +6,16 @@ date_default_timezone_set('Europe/Berlin');
 // Define currencies that should *not* be included in the list
 $excludedCurrencies = ['bits', 'sats'];
 
+require_once __DIR__ . '/cache.php';
+
 // Fetch JSON data from a file and decode it
 function fetchJson($filename) {
     return json_decode(file_get_contents($filename), true);
 }
 
-function fetchCache(string $key, string $url)
+function fetchCache(string $key, string $url, FileCache $cache)
 {
-    return apcu_entry($key, function() use ($url) {
+    return $cache->getOrSet($key, function() use ($url) {
         return makeApiRequest($url);
     }, 60);
 }
@@ -78,8 +80,9 @@ function fetchAvailableCurrencies() {
 
 // Fetch currency data from CoinGecko API
 function fetchCurrencyData($currencies) {
+    $cache = new FileCache(__DIR__ . '/cache');
     $apiUrl = getCoinGeckoApiUrl('simple/price', ['ids' => 'monero', 'vs_currencies' => implode(',', array_map('strtolower', $currencies))]);
-    return fetchCache('currency_data', $apiUrl);
+    return fetchCache('currency_data', $apiUrl, $cache);
 }
 
 $currencyFile = 'coingecko.json';