# API CALL #1 - Fetch Purchases from backend
# REQUEST:
# - GET /android/purchases/:app_id/:user_id
# PARAMS:
# - requires "user_id", type: String, regexp: /[a-zA-Z0-9_.\-@+]*/, desc: "Android device/user id (e.g. com.google_xxx_xxx@gmail.com)"
# - requires "app_id",  type: String, regexp: /[a-zA-Z0-9_.\-]*/,   desc: "Magazine App id (e.g. com.chuj.magazine)"
# DESCRIPTION:
# - Fetch all purchased issues (single issue purchase) and subscription information
# - This request is sent when the app launches, and whenever the issue shelf refreshes
# LOGIC:
# - First, create an empty array of strings ($issue_id_array) that will be filled with purchased issue product ids.
# - Next, check if there is any active subscription available for this user_id and app_id. If so, append all issue ids within the subscription period to $issue_id_array
# - Next, fetch all individual issue purchases that have been made for this user_id and app_id. Append them to $issue_id_array
# - Finally, return a json response as below
# RESPONSE:
# - JSON: {"issues":["issue_product_id_1","issue_product_id_2"],"subscribed":true}

# API CALL #2 - Verify purchase receipts and register purchased issues/subscriptions
# REQUEST:
# - POST /android/verify_multi/:app_id/:user_id
# PARAMS:
# - requires "purchases",       type: Array,   desc: "Array containing purchase information from google play"
# - > requires "data",          type: String,  desc: "Product data"
# - > requires "order_id",      type: String,  desc: "Product order id"
# - > requires "package_name",  type: String,  desc: "Product package name / app_id"
# - > requires "payload",       type: String,  desc: "Product payload"
# - > requires "signature",     type: String,  desc: "Product signature"
# - > requires "sku",           type: String,  desc: "Product sku"
# - > requires "state",         type: String,  desc: "Product state"
# - > requires "token",         type: String,  desc: "Product token"
# - > requires "time",          type: Integer, desc: "Product time"
# - > requires "purchase_type", type: String,  desc: "Purchase type", values: ["product", "subscription"]
# - requires "user_id",         type: String,  regexp: /[a-zA-Z0-9_.\-@+]*/, desc: "Android device/user id (e.g. com.google_XXXX_xxx@gmail.com)"
# - requires "app_id",          type: String,  regexp: /[a-zA-Z0-9_.\-]*/,   desc: "Magazine App id (e.g. com.chuj.magazine)"
# DESCRIPTION:
# - Verify purchases made from google play with the backend
# - This request is sent when the app launches, and whenever the issue shelf refreshes
# - The backend should verify and store the receipt information and register receipts and purchases in the database
# LOGIC:
# - First, verify the receipt information by testing signature and payload
# - Store the purchase information (= receipt data) in the database
# - Find the related issues or subscriptions and unlock them for the provided user_id (e.g. tables "purchased_issues", "purchased_subscriptions")
# - Finally, return a json response as below
# RESPONSE:
# - STATUS 204 (Success, no body)