firebase functions Android レシートデータを検証してlatest_receiptを返す

purchase.js

const PACKAGE_NAME_ANDROID = "(PUT YOUR APP PACKAGE NAME. ex. com.example.your.app)";

const RECEIPT_VERIFICATION_ENDPOINT_FRO_ANDROID = "https://androidpublisher.googleapis.com/androidpublisher/v3/applications/";

const SERVICE_CLIENT_EMAIL_FOR_ANDROID = "(PUT YOUR CLIENT EMAIL)";
const SERVICE_PRIVATE_KEY_FOR_ANDROID = "(PUT YOUR PRIVATE KEY)"

// Android検証用のAuthClient
const authClient = new google.auth.JWT({
 email: SERVICE_CLIENT_EMAIL_FOR_ANDROID,
 key: SERVICE_PRIVATE_KEY_FOR_ANDROID,
 scopes: ["https://www.googleapis.com/auth/androidpublisher"],
});

async function verifyReceiptAndroid(verificationData, auth) {
 try {
   const decodedReceipt = JSON.parse(verificationData);

   // サブスク商品であることを確認する
   if (!decodedReceipt["autoRenewing"]) {
     return null;
   }

   const credential = await authClient.authorize();

   const url =
     RECEIPT_VERIFICATION_ENDPOINT_FRO_ANDROID +
     PACKAGE_NAME_ANDROID +
     "/purchases/subscriptions/" +
     decodedReceipt["productId"] +
     "/tokens/" +
     decodedReceipt["purchaseToken"] +
     "?access_token=" +
     credential.access_token;

   const response = await axios.get(url);

   const verifiedData = response.data;
   if (!verifiedData) {
     return null;
   }
   return verifiedData;
 } catch (err) {
   return null;
 }
}