(core) Adding GristConnect login system

Summary:
New login system to allow simple SSO flow that is based on Discourse description that is available at:
https://meta.discourse.org/t/discourseconnect-official-single-sign-on-for-discourse-sso/13045

Test Plan: New core test.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D3418

app/gen-server/entity/User.ts

@@ -47,6 +47,9 @@ export class User extends BaseEntity {
   @Column({name: 'options', type: nativeValues.jsonEntityType, nullable: true})
   public options: UserOptions | null;
 
+  @Column({name: 'connect_id', type: String, nullable: true})
+  public connectId: string | null;
+
   /**
    * Get user's email.  Returns undefined if logins has not been joined, or no login
    * is available

app/gen-server/lib/HomeDBManager.ts

@@ -476,6 +476,60 @@ export class HomeDBManager extends EventEmitter {
     return result;
   }
 
+  /**
+   * Ensures that user with external id exists and updates its profile and email if necessary.
+   *
+   * @param profile External profile
+   */
+  public async ensureExternalUser(profile: UserProfile) {
+    await this._connection.transaction(async manager => {
+      // First find user by the connectId from the profile
+      const existing = await manager.findOne(User, { connectId: profile.connectId}, {relations: ["logins"]});
+
+      // If a user does not exist, create it with data from the external profile.
+      if (!existing) {
+        const newUser = await this.getUserByLoginWithRetry(profile.email, {
+          profile,
+          manager
+        });
+        if (!newUser) {
+          throw new ApiError("Unable to create user", 500);
+        }
+        // No need to survey this user.
+        newUser.isFirstTimeUser = false;
+        await newUser.save();
+      } else {
+        // Else update profile and login information from external profile.
+        let updated = false;
+        let login: Login = existing.logins[0]!;
+        const properEmail = normalizeEmail(profile.email);
+
+        if (properEmail !== existing.loginEmail) {
+          login = login ?? new Login();
+          login.email = properEmail;
+          login.displayEmail = profile.email;
+          existing.logins.splice(0, 1, login);
+          login.user = existing;
+          updated = true;
+        }
+
+        if (profile?.name && profile?.name !== existing.name) {
+          existing.name = profile.name;
+          updated = true;
+        }
+
+        if (profile?.picture && profile?.picture !== existing.picture) {
+          existing.picture = profile.picture;
+          updated = true;
+        }
+
+        if (updated) {
+          await manager.save([existing, login]);
+        }
+      }
+    });
+  }
+
   public async updateUser(userId: number, props: UserProfileChange): Promise<void> {
     let isWelcomed: boolean = false;
     let user: User|undefined;
@@ -601,6 +655,12 @@ export class HomeDBManager extends EventEmitter {
         login.displayEmail = profile.email;
         needUpdate = true;
       }
+
+      if (profile?.connectId && profile?.connectId !== user.connectId) {
+        user.connectId = profile.connectId;
+        needUpdate = true;
+      }
+
       if (!login.displayEmail) {
         // Save some kind of display email if we don't have anything at all for it yet.
         // This could be coming from how someone wrote it in a UserManager dialog, for

app/gen-server/migration/1652277549983-UserConnectId.ts

@@ -0,0 +1,22 @@
+import {MigrationInterface, QueryRunner, TableColumn, TableIndex} from "typeorm";
+
+export class UserConnectId1652277549983 implements MigrationInterface {
+  public async up(queryRunner: QueryRunner): Promise<any> {
+    await queryRunner.addColumn("users", new TableColumn({
+      name: "connect_id",
+      type: 'varchar',
+      isNullable: true,
+      isUnique: true,
+    }));
+    await queryRunner.createIndex("users", new TableIndex({
+      name: "users_connect_id",
+      columnNames: ["connect_id"],
+      isUnique: true
+    }));
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<any> {
+    await queryRunner.dropIndex("users", "users_connect_id");
+    await queryRunner.dropColumn("users", "connect_id");
+  }
+}