StoreLog.swift

//
//  StoreLog.swift
//  StoreHelper
//
//  Created by Russell Archer on 16/06/2021.
//

import Foundation
import os.log

/// We use Apple's unified logging system to log errors, notifications and general messages.
/// This system works on simulators and real devices for both debug and release builds.
/// You can view the logs in the Console app by selecting the test device in the left console pane.
/// If running on the simulator, select the machine the simulator is running on. Type your app's
/// bundle identifier into the search field and then narrow the results by selecting "SUBSYSTEM"
/// from the search field's filter. Logs also appear in Xcode's console in the same manner as
/// print statements.
///
/// When running the app on a real device that's not attached to the Xcode debugger,
/// dynamic strings (i.e. the error, event or message parameter you send to the event() function)
/// will not be publicly viewable. They're automatically redacted with the word "private" in the
/// console. This prevents the accidental logging of potentially sensistive user data. Because
/// we know in advance that StoreNotificaton enums do NOT contain sensitive information, we let the
/// unified logging system know it's OK to log these strings through the use of the "%{public}s"
/// keyword. However, we don't know what the event(message:) function will be used to display,
/// so its logs will be redacted.
@available(iOS 15.0, macOS 12.0, *)
public struct StoreLog {
    /// Set to `true` if you want to log detailed events each time a product's isPurchased state is checked.
    public static var logIsPurchasedEvents = false
    
    private static let storeLog = OSLog(subsystem: Bundle.main.bundleIdentifier!, category: "STORE")
    
    /// Logs a StoreNotification. Note that the text (shortDescription) of the log entry will be
    /// publically available in the Console app.
    /// - Parameter event: A StoreNotification.
    public static func event(_ event: StoreNotification) { logEvent(event) }
    
    /// Logs an StoreNotification. Note that the text (shortDescription) and the productId for the
    /// log entry will be publically available in the Console app.
    /// - Parameters:
    ///   - event:      A StoreNotification.
    ///   - productId:  A ProductId associated with the event.
    public static func event(_ event: StoreNotification, productId: ProductId, transactionId: String? = nil) {
        logEvent(event, productId: productId, transactionId: transactionId)
    }
    
    /// Logs an StoreNotification. Note that the text (shortDescription) and the productId for the
    /// log entry will be publically available in the Console app.
    /// - Parameters:
    ///   - event:      A StoreNotification.
    ///   - productId:  A ProductId associated with the event.
    ///   - webOrderLineItemId: A unique ID that identifies subscription purchase events across devices, including subscription renewals
    public static func event(_ event: StoreNotification, productId: ProductId, webOrderLineItemId: String?, transactionId: String? = nil) {
        logEvent(event, productId: productId, webOrderLineItemId: webOrderLineItemId, transactionId: transactionId)
    }
    
    public static var transactionLog: Set<TransactionLog> = []
    
    /// Logs a StoreNotification as a transaction. Multiple transactions for the same event, product id and transaction id will only be logged once.
    /// Note that the text (shortDescription) and the productId for the log entry will be publically available in the Console app.
    /// - Parameters:
    ///   - event:      A StoreNotification.
    ///   - productId:  A ProductId associated with the event.
    public static func transaction(_ event: StoreNotification, productId: ProductId, transactionId: String? = nil) {
        
        let t = TransactionLog(notification: event, productId: productId)
        if transactionLog.contains(t) { return }
        transactionLog.insert(t)
        
        #if DEBUG
        print("\(event.shortDescription()) for product \(productId) \(transactionId == nil ? "" : "with transaction id \(transactionId!)")")
        #else
        os_log("%{public}s for product %{public}s", log: storeLog, type: .default, event.shortDescription(), productId)
        #endif
    }
    
    /// Logs a StoreException. Note that the text (shortDescription) and the productId for the
    /// log entry will be publically available in the Console app.
    /// - Parameters:
    ///   - exception:  A StoreException.
    ///   - productId:  A ProductId associated with the event.
    public static func exception(_ exception: StoreException, productId: ProductId, transactionId: String? = nil) {
        #if DEBUG
        print("\(exception.shortDescription()). For product \(productId) \(transactionId == nil ? "" : "with transaction id \(transactionId!)")")
        #else
        os_log("%{public}s for product %{public}s", log: storeLog, type: .default, exception.shortDescription(), productId)
        #endif
    }
    
    /// Logs a message.
    /// - Parameter message: The message to log.
    public static func event(_ message: String) {
        #if DEBUG
        print(message)
        #else
        os_log("%s", log: storeLog, type: .info, message)
        #endif
    }
    
    private static func logEvent(_ event: StoreNotification) {
        #if DEBUG
        var doLog = true
        if event.isNotificationPurchaseState(), !logIsPurchasedEvents { doLog = false }
        if doLog { print(event.shortDescription()) }
        #else
        var doLog = true
        if event.isNotificationPurchaseState(), !logIsPurchasedEvents { doLog = false }
        if doLog { os_log("%{public}s", log: storeLog, type: .default, event.shortDescription()) }
        #endif
    }
    
    private static func logEvent(_ event: StoreNotification, productId: ProductId, transactionId: String? = nil) {
        #if DEBUG
        var doLog = true
        if event.isNotificationPurchaseState(), !logIsPurchasedEvents { doLog = false }
        if doLog { print("\(event.shortDescription()) for product \(productId) \(transactionId == nil ? "" : "with transaction id \(transactionId!)")") }
        #else
        var doLog = true
        if event.isNotificationPurchaseState(), !logIsPurchasedEvents { doLog = false }
        if doLog { os_log("%{public}s for product %{public}s", log: storeLog, type: .default, event.shortDescription(), productId) }
        #endif
    }
    
    private static func logEvent(_ event: StoreNotification, productId: ProductId, webOrderLineItemId: String?, transactionId: String? = nil) {
        #if DEBUG
        var doLog = true
        if event.isNotificationPurchaseState(), !logIsPurchasedEvents { doLog = false }
        if doLog { print("\(event.shortDescription()) for product \(productId) with webOrderLineItemId \(webOrderLineItemId ?? "none") \(transactionId == nil ? "" : "and transaction id \(transactionId!)")") }
        #else
        var doLog = true
        if event.isNotificationPurchaseState(), !logIsPurchasedEvents { doLog = false }
        if doLog { os_log("%{public}s for product %{public}s with webOrderLineItemId %{public}s",
                          log: storeLog,
                          type: .default,
                          event.shortDescription(),
                          productId,
                          webOrderLineItemId ?? "none") }
        #endif
    }
}

public struct TransactionLog: Hashable {
    let notification: StoreNotification
    let productId: ProductId
    
    public static func == (lhs: TransactionLog, rhs: TransactionLog) -> Bool { return (lhs.productId == rhs.productId) && (lhs.notification == rhs.notification) }
}