Replace forked cache by official npm (#21)

* Replace forked cache by official npm

* Follow the same validation as @action/cache

* Remove debug log

src/utils/actionUtils.ts

@@ -0,0 +1,47 @@
+import * as core from "@actions/core"
+
+import { Outputs, RefKey, State } from "../constants"
+
+export function isExactKeyMatch(key: string, cacheKey?: string): boolean {
+  return !!(
+    cacheKey &&
+    cacheKey.localeCompare(key, undefined, {
+      sensitivity: "accent",
+    }) === 0
+  )
+}
+
+export function setCacheState(state: string): void {
+  core.saveState(State.CacheMatchedKey, state)
+}
+
+export function setCacheHitOutput(isCacheHit: boolean): void {
+  core.setOutput(Outputs.CacheHit, isCacheHit.toString())
+}
+
+export function setOutputAndState(key: string, cacheKey?: string): void {
+  setCacheHitOutput(isExactKeyMatch(key, cacheKey))
+  // Store the matched cache key if it exists
+  cacheKey && setCacheState(cacheKey)
+}
+
+export function getCacheState(): string | undefined {
+  const cacheKey = core.getState(State.CacheMatchedKey)
+  if (cacheKey) {
+    core.debug(`Cache state/key: ${cacheKey}`)
+    return cacheKey
+  }
+
+  return undefined
+}
+
+export function logWarning(message: string): void {
+  const warningPrefix = "[warning]"
+  core.info(`${warningPrefix}${message}`)
+}
+
+// Cache token authorized for all events that are tied to a ref
+// See GitHub Context https://help.github.com/actions/automating-your-workflow-with-github-actions/contexts-and-expression-syntax-for-github-actions#github-context
+export function isValidEvent(): boolean {
+  return RefKey in process.env && Boolean(process.env[RefKey])
+}