Paywalls: extracted configuration processing into a new `TemplateVi…

…ewConfiguration` (#2830)

### Changes:
- Created `TemplateViewConfiguration` to encapsulate all processed
configuration for a paywall
- Created `TemplateViewConfiguration.PackageSetting` and
`TemplateViewConfiguration.PackageConfiguration` to represent paywalls
that support 1 or N packages
- Taken all common logic out of `Example1Template`
- Added new `PaywallViewMode` for upcoming "ramps" views

RevenueCatUI/Data/PaywallViewMode.swift

@@ -0,0 +1,16 @@
+//
+//  PaywallViewMode.swift
+//  
+//
+//  Created by Nacho Soto on 7/17/23.
+//
+
+import RevenueCat
+
+/// The mode for how a paywall is rendered.
+public enum PaywallViewMode {
+
+    /// Paywall is displayed full-screen, with as much information as available.
+    case fullScreen
+
+}

RevenueCatUI/Data/TemplateError.swift

@@ -0,0 +1,46 @@
+//
+//  TemplateError.swift
+//  
+//
+//  Created by Nacho Soto on 7/17/23.
+//
+
+import Foundation
+import RevenueCat
+
+/// Error produced when processing `PaywallData`.
+enum TemplateError: Error {
+
+    /// No packages available to create a paywall.
+    case noPackages
+
+    /// Paywall configuration contained no package types.
+    case emptyPackageList
+
+    /// No packages from the `PackageType` list could be found.
+    case couldNotFindAnyPackages(expectedTypes: [PackageType])
+
+}
+
+extension TemplateError: CustomNSError {
+
+    var errorUserInfo: [String: Any] {
+        return [
+            NSLocalizedDescriptionKey: self.description
+        ]
+    }
+
+    private var description: String {
+        switch self {
+        case .noPackages:
+            return "Attempted to display paywall with no packages."
+
+        case .emptyPackageList:
+            return "Paywall configuration contains no packages."
+
+        case let .couldNotFindAnyPackages(expectedTypes):
+            return "Couldn't find any requested packages: \(expectedTypes)"
+        }
+    }
+
+}

RevenueCatUI/Data/TemplateViewConfiguration.swift

@@ -0,0 +1,153 @@
+//
+//  TemplateViewConfiguration.swift
+//  
+//
+//  Created by Nacho Soto on 7/17/23.
+//
+
+import Foundation
+import RevenueCat
+
+/// The processed data necessary to render a `TemplateViewType`.
+@available(iOS 16.0, macOS 13.0, tvOS 16.0, *)
+struct TemplateViewConfiguration {
+
+    let mode: PaywallViewMode
+    let packages: PackageConfiguration
+    let configuration: PaywallData.Configuration
+    let colors: PaywallData.Configuration.Colors
+    let headerImageURL: URL
+
+}
+
+// MARK: - Packages
+
+@available(iOS 16.0, macOS 13.0, tvOS 16.0, *)
+extension TemplateViewConfiguration {
+
+    /// A `Package` with its processed localized strings.
+    struct Package {
+
+        let content: RevenueCat.Package
+        let localization: ProcessedLocalizedConfiguration
+
+    }
+
+    /// Whether a template displays 1 or multiple packages.
+    enum PackageSetting {
+
+        case single
+        case multiple
+
+    }
+
+    /// Describes the possible displayed packages in a paywall.
+    /// See `create(with:filter:setting:)` for how to create these.
+    enum PackageConfiguration {
+
+        case single(Package)
+        case multiple([Package])
+
+    }
+
+}
+
+// MARK: - Properties
+
+@available(iOS 16.0, macOS 13.0, tvOS 16.0, *)
+extension TemplateViewConfiguration.PackageConfiguration {
+
+    /// Returns a single package, useful for templates that expect a single package.
+    var single: TemplateViewConfiguration.Package {
+        switch self {
+        case let .single(package):
+            return package
+        case let .multiple(packages):
+            guard let package = packages.first else {
+                // `create()` makes this impossible.
+                fatalError("Unexpectedly found no packages in `PackageConfiguration.multiple`")
+            }
+
+            return package
+        }
+    }
+
+    /// Returns all packages, useful for templates that expect multiple packages
+    var all: [TemplateViewConfiguration.Package] {
+        switch self {
+        case let .single(package):
+            return [package]
+        case let .multiple(packages):
+            return packages
+        }
+    }
+
+}
+
+// MARK: - Creation
+
+@available(iOS 16.0, macOS 13.0, tvOS 16.0, *)
+extension TemplateViewConfiguration.PackageConfiguration {
+
+    /// Creates a `PackageConfiguration` based on `setting`.
+    /// - Throws: `TemplateError`
+    static func create(
+        with packages: [RevenueCat.Package],
+        filter: [PackageType],
+        localization: PaywallData.LocalizedConfiguration,
+        setting: TemplateViewConfiguration.PackageSetting
+    ) throws -> Self {
+        guard !packages.isEmpty else { throw TemplateError.noPackages }
+        guard !filter.isEmpty else { throw TemplateError.emptyPackageList }
+
+        let filtered = TemplateViewConfiguration
+            .filter(packages: packages, with: filter)
+            .map { package in
+                TemplateViewConfiguration.Package(
+                    content: package,
+                    localization: localization.processVariables(with: package))
+            }
+
+        guard let firstPackage = filtered.first else {
+            throw TemplateError.couldNotFindAnyPackages(expectedTypes: filter)
+        }
+
+        switch setting {
+        case .single:
+            return .single(firstPackage)
+        case .multiple:
+            return .multiple(filtered)
+        }
+    }
+
+}
+
+@available(iOS 16.0, macOS 13.0, tvOS 16.0, *)
+extension TemplateViewConfiguration {
+
+    /// Filters `packages`, extracting only the values corresponding to `list`.
+    static func filter(packages: [RevenueCat.Package], with list: [PackageType]) -> [RevenueCat.Package] {
+        // Only subscriptions are supported at the moment
+        let subscriptions = packages.filter { $0.storeProduct.productCategory == .subscription }
+        let map = Dictionary(grouping: subscriptions) { $0.packageType }
+
+        return list.compactMap { type in
+            if let packages = map[type] {
+                switch packages.count {
+                case 0:
+                    // This isn't actually possible because of `Dictionary(grouping:by:)
+                    return nil
+                case 1:
+                    return packages.first
+                default:
+                    Logger.warning("Found multiple \(type) packages. Will use the first one.")
+                    return packages.first
+                }
+            } else {
+                Logger.warning("Couldn't find '\(type)'")
+                return nil
+            }
+        }
+    }
+
+}

RevenueCatUI/PaywallView.swift

@@ -8,15 +8,17 @@ import SwiftUI
 @available(macCatalyst, unavailable, message: "RevenueCatUI does not support Catalyst yet")
 public struct PaywallView: View {
 
+    private let mode: PaywallViewMode
     private let offering: Offering
     private let paywall: PaywallData
     private let introEligibility: TrialOrIntroEligibilityChecker?
     private let purchaseHandler: PurchaseHandler?
 
     /// Create a view for the given offering and paywal.
     /// - Warning: `Purchases` must have been configured prior to displaying it.
-    public init(offering: Offering, paywall: PaywallData) {
+    public init(mode: PaywallViewMode, offering: Offering, paywall: PaywallData) {
         self.init(
+            mode: mode,
             offering: offering,
             paywall: paywall,
             introEligibility: Purchases.isConfigured ? .init() : nil,
@@ -25,11 +27,13 @@ public struct PaywallView: View {
     }
 
     init(
+        mode: PaywallViewMode = .fullScreen,
         offering: Offering,
         paywall: PaywallData,
         introEligibility: TrialOrIntroEligibilityChecker?,
         purchaseHandler: PurchaseHandler?
     ) {
+        self.mode = mode
         self.offering = offering
         self.paywall = paywall
         self.introEligibility = introEligibility
@@ -40,7 +44,7 @@ public struct PaywallView: View {
     public var body: some View {
         if let checker = self.introEligibility, let purchaseHandler = self.purchaseHandler {
             self.paywall
-                .createView(for: self.offering)
+                .createView(for: self.offering, mode: self.mode)
                 .environmentObject(checker)
                 .environmentObject(purchaseHandler)
         } else {
@@ -64,6 +68,7 @@ struct PaywallView_Previews: PreviewProvider {
 
         if let paywall = offering.paywall {
             PaywallView(
+                mode: .fullScreen,
                 offering: offering,
                 paywall: paywall,
                 introEligibility: TrialOrIntroEligibilityChecker