Add GoogleSignInKit (iOS)

- Set available platforms in Package.swift
- Documentation (README.md)
- Source code files

Author: Tibimac

Package.swift

@@ -5,6 +5,9 @@ import PackageDescription
 
 let package = Package(
     name: "GoogleSignInKit",
+    platforms: [
+        .iOS(.v9)
+    ],
     products: [
         // Products define the executables and libraries a package produces, and make them visible to other packages.
         .library(

README.md

@@ -1,3 +1,32 @@
 # GoogleSignInKit
 
-A description of this package.
+<img src="https://camo.githubusercontent.com/86f8561418bbd6240d5c39dbf80b83a3dc1e85e69fe58da808f0168194dcc0d3/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f5377696674504d2d436f6d70617469626c652d627269676874677265656e2e737667" alt="SwiftPM Compatible" data-canonical-src="https://img.shields.io/badge/SwiftPM-Compatible-brightgreen.svg" style="max-width:100%;">
+
+⚠️ In its v1.0.0 this module is intended to be use in an iOS app only.
+
+This module is intended to be used to do a "Google Sign-In" for your app.
+Using this module will give you ability to authenticate a user and either create him an account or log him to an existing account.
+What we call "sign-in" is composed in two parts :
+- First part is authenticating user and let him choose which Google account to use for sign-in. This is done on a Google dedicated web page.
+- Second part is retrieving credentials for the user-choosen account. This is done by doing a request on Google API.
+Let's see how it works (it's very easy 😉).
+
+Depending on how you want to use this module you have two possible flows.
+
+## First flow
+Start by configuring the module by giving it a configuration (`GoogleSignInKit.Manager.Configuration`) through a call to the function `configure(configuration:)`.
+This is only needed once in your app lifecycle. So you can do it from your AppDelegate or at init of you login view controller.
+
+Then once sign-in is required call the function `signIn(overrideConfig:completion:)`. 
+Through this function you can override some parameters of the module configuration (but not the client ID) just for the time of the authentication by giving an optional `GoogleSignInKit.Configuration` struct.
+And of course give your completion block in which you'll receive the `GoogleSignInKit.Credentials` struct with all you need to do the account creation / sign-in.
+If you need do repeat the sign-in you can call this function again. 
+
+## Second flow
+When sign-in is required just call the function `signIn(configuration:completion:)`.
+Through this single function you can set the module configuration and start sign-in. 
+As a second paramter of course give your completion block in which you'll receive the  `GoogleSignInKit.Credentials` struct with all you need to do the account creation / sign-in.
+If you need do repeat the sign-in you can either call this function again or call `signIn(overrideConfig:completion:)`, it's up to you.
+
+## Need Demo ?
+Here's a [GoogleSignInKit-Demo project](https://github.com/Tibimac/GoogleSignInKit-Demo)

Sources/GoogleSignInKit/AuthenticationRequest.swift

@@ -0,0 +1,36 @@
+//
+//  AuthenticationRequest.swift
+//  GoogleSignInKit
+//
+//  Created by Thibault Le Cornec on 25/05/2021.
+//
+
+import Foundation
+
+extension GoogleSignInKit {
+    
+    internal enum AuthenticationRequest {
+        internal static let baseURLString: String = "https://accounts.google.com/o/oauth2/v2/auth"
+        
+        /* This struct is for internal use only. Used to store info from callback URL
+         after the authentication consent on Google accounts webpage.
+         Example :
+         "SCHEME://?state=STRING&code=4/0AY0e-g7lmiIocD...4CMbiOA&authuser=0&prompt=consent&scope=email%20profile%20https://www.googleapis.com/auth/userinfo.email%20https://www.googleapis.com/auth/userinfo.profile%20openid
+         */
+        internal struct Result {
+            let code: String?
+            let state: String?
+            let scopes: String?
+            let prompt: String?
+            let authUser: String?
+            
+            init(from dictionary: [String: String]) {
+                code = dictionary["code"]
+                state = dictionary["state"]
+                scopes = dictionary["scope"]
+                prompt = dictionary["prompt"]
+                authUser = dictionary["authuser"]
+            }
+        }
+    }
+}

Sources/GoogleSignInKit/Error.swift

@@ -0,0 +1,26 @@
+//
+//  GoogleSignInError.swift
+//  GoogleSignInKit
+//
+//  Created by Thibault Le Cornec on 25/05/2021.
+//
+
+import Foundation
+
+extension GoogleSignInKit {
+    
+    public enum Error: CustomNSError {
+        case unknown
+        case canceled
+        case noConfiguration
+        case failedToSetupAuthenticationRequest
+        case cannotStartAuthentication
+        case authenticationRequestFailed
+        case failedToSetupCredentialsRequest
+        case credentialsRequestFailed
+        
+        public static var errorDomain: String {
+            return "GoogleSignInKit.GoogleSignInKit"
+        }
+    }
+}

Sources/GoogleSignInKit/Extensions/CharacterSet+Extensions.swift

@@ -0,0 +1,20 @@
+//
+//  CharacterSet+Extensions.swift
+//  GoogleSignInKit
+//
+//  Created by Thibault Le Cornec on 25/05/2021.
+//
+
+import Foundation
+
+extension CharacterSet {
+    
+    static let urlQueryValueAllowed: CharacterSet = {
+        let generalDelimitersToEncode = ":#[]@" // Does not include "?" or "/" due to RFC 3986 - Section 3.4
+        let subDelimitersToEncode = "!$&'()*+,;="
+        
+        var allowed = CharacterSet.urlQueryAllowed
+        allowed.remove(charactersIn: "\(generalDelimitersToEncode)\(subDelimitersToEncode)")
+        return allowed
+    }()
+}

Sources/GoogleSignInKit/Extensions/Dictionary+Extensions.swift

@@ -0,0 +1,21 @@
+//
+//  Dictionary+Extensions.swift
+//  GoogleSignInKit
+//
+//  Created by Thibault Le Cornec on 25/05/2021.
+//
+
+import Foundation
+
+extension Dictionary where Value: Any {
+    
+    func percentEncoded() -> Data? {
+        return map { key, value in
+            let escapedKey = "\(key)".addingPercentEncoding(withAllowedCharacters: .urlQueryValueAllowed) ?? ""
+            let escapedValue = "\(value)".addingPercentEncoding(withAllowedCharacters: .urlQueryValueAllowed) ?? ""
+            return escapedKey + "=" + escapedValue
+        }
+        .joined(separator: "&")
+        .data(using: .utf8)
+    }
+}

Sources/GoogleSignInKit/Extensions/URL+Extensions.swift

@@ -0,0 +1,25 @@
+//
+//  URL+Extensions.swift
+//  GoogleSignInKit
+//
+//  Created by Thibault Le Cornec on 25/05/2021.
+//
+
+import Foundation
+
+extension URL {
+    
+    var queryDictionary: [String: String]? {
+        guard let query = self.query else { return nil }
+        var queryStrings = [String: String]()
+        for pair in query.components(separatedBy: "&") {
+            let key = pair.components(separatedBy: "=")[0]
+            let value = pair
+                .components(separatedBy:"=")[1]
+                .replacingOccurrences(of: "+", with: " ")
+                .removingPercentEncoding ?? ""
+            queryStrings[key] = value
+        }
+        return queryStrings
+    }
+}