feat: add auth and cache to currency route

lib/cache.ts

@@ -0,0 +1,108 @@
+export type CacheKey = string
+export type CacheEntry<T> = {
+  value: T
+  timestamp: number
+}
+
+export class PoorManCache<T> {
+  private cache: Map<CacheKey, CacheEntry<T>>
+  private duration: number
+
+  /**
+   * Create a new cache instance
+   * @param duration Cache duration in milliseconds
+   */
+  constructor(duration: number) {
+    this.cache = new Map<CacheKey, CacheEntry<T>>()
+    this.duration = duration
+  }
+
+  /**
+   * Get a value from the cache
+   * @param key Cache key
+   * @returns The cached value or undefined if not found or expired
+   */
+  get(key: CacheKey): T | undefined {
+    const entry = this.cache.get(key)
+
+    if (!entry) {
+      return undefined
+    }
+
+    // Check if entry is expired
+    if (Date.now() - entry.timestamp > this.duration) {
+      this.cache.delete(key)
+      return undefined
+    }
+
+    return entry.value
+  }
+
+  /**
+   * Set a value in the cache
+   * @param key Cache key
+   * @param value Value to cache
+   */
+  set(key: CacheKey, value: T): void {
+    this.cache.set(key, {
+      value,
+      timestamp: Date.now(),
+    })
+  }
+
+  /**
+   * Check if a key exists in the cache and is not expired
+   * @param key Cache key
+   * @returns True if the key exists and is not expired
+   */
+  has(key: CacheKey): boolean {
+    const entry = this.cache.get(key)
+
+    if (!entry) {
+      return false
+    }
+
+    // Check if entry is expired
+    if (Date.now() - entry.timestamp > this.duration) {
+      this.cache.delete(key)
+      return false
+    }
+
+    return true
+  }
+
+  /**
+   * Remove a key from the cache
+   * @param key Cache key
+   */
+  delete(key: CacheKey): void {
+    this.cache.delete(key)
+  }
+
+  /**
+   * Clear all expired entries from the cache
+   */
+  cleanup(): void {
+    const now = Date.now()
+    for (const [key, entry] of this.cache.entries()) {
+      if (now - entry.timestamp > this.duration) {
+        this.cache.delete(key)
+      }
+    }
+  }
+
+  /**
+   * Get the current size of the cache
+   * @returns Number of entries in the cache
+   */
+  size(): number {
+    return this.cache.size
+  }
+
+  /**
+   * Clear all entries from the cache
+   */
+  clear(): void {
+    this.cache.clear()
+  }
+}