Restore updateBranchProtections method for metrics purposes

We've decided to keep collecting metrics for `commitsToRepositoryWithBranchProtections`, which requires us to store data on protected branches in a repository

app/src/lib/stores/app-store.ts

@@ -74,6 +74,7 @@ import {
   getAccountForEndpoint,
   getDotComAPIEndpoint,
   IAPIOrganization,
+  IAPIBranch,
   IAPIRepository,
 } from '../api'
 import { shell } from '../app-shell'
@@ -3271,6 +3272,37 @@ export class AppStore extends TypedBaseStore<IAppState> {
     return updatedRepository
   }
 
+  private async updateBranchProtectionsFromAPI(repository: Repository) {
+    if (
+      repository.gitHubRepository === null ||
+      repository.gitHubRepository.dbID === null
+    ) {
+      return
+    }
+
+     const { owner, name } = repository.gitHubRepository
+
+     const account = getAccountForEndpoint(
+      this.accounts,
+      repository.gitHubRepository.endpoint
+    )
+
+     if (account === null) {
+      return
+    }
+
+     const api = API.fromAccount(account)
+
+     const branches = enableBranchProtectionChecks()
+      ? await api.fetchProtectedBranches(owner.login, name)
+      : new Array<IAPIBranch>()
+
+     await this.repositoriesStore.updateBranchProtections(
+      repository.gitHubRepository,
+      branches
+    )
+  }
+
   private async matchGitHubRepository(
     repository: Repository
   ): Promise<IMatchedGitHubRepository | null> {

app/src/lib/stores/repositories-store.ts

@@ -2,13 +2,15 @@ import {
   RepositoriesDatabase,
   IDatabaseGitHubRepository,
   IDatabaseOwner,
+  IDatabaseProtectedBranch,
 } from '../databases/repositories-database'
 import { Owner } from '../../models/owner'
 import { GitHubRepository } from '../../models/github-repository'
 import { Repository } from '../../models/repository'
 import { fatalError } from '../fatal-error'
-import { IAPIRepository } from '../api'
+import { IAPIRepository, IAPIBranch } from '../api'
 import { BaseStore } from './base-store'
+import { enableBranchProtectionChecks } from '../feature-flag'
 
 /** The store for local repositories. */
 export class RepositoriesStore extends BaseStore {
@@ -453,6 +455,70 @@ export class RepositoriesStore extends BaseStore {
     )
   }
 
+  /** Add or update the branch protections associated with a GitHub repository. */
+
+  public async updateBranchProtections(
+    gitHubRepository: GitHubRepository,
+    protectedBranches: ReadonlyArray<IAPIBranch>
+  ): Promise<void> {
+    if (!enableBranchProtectionChecks()) {
+      return
+    }
+
+    const dbID = gitHubRepository.dbID
+    if (!dbID) {
+      return fatalError(
+        '`updateBranchProtections` can only update a GitHub repository for a repository which has been added to the database.'
+      )
+    }
+
+    await this.db.transaction('rw', this.db.protectedBranches, async () => {
+      // This update flow is organized into two stages:
+      //
+      // - update the in-memory cache
+      // - update the underyling database state
+      //
+      // This should ensure any stale values are not being used, and avoids
+      // the need to query the database while the results are in memory.
+
+      const prefix = getKeyPrefix(dbID)
+
+      for (const key of this.protectionEnabledForBranchCache.keys()) {
+        // invalidate any cached entries belonging to this repository
+        if (key.startsWith(prefix)) {
+          this.protectionEnabledForBranchCache.delete(key)
+        }
+      }
+
+      const branchRecords = protectedBranches.map<IDatabaseProtectedBranch>(
+        b => ({
+          repoId: dbID,
+          name: b.name,
+        })
+      )
+
+      // update cached values to avoid database lookup
+      for (const item of branchRecords) {
+        const key = getKey(dbID, item.name)
+        this.protectionEnabledForBranchCache.set(key, true)
+      }
+
+      await this.db.protectedBranches
+        .where('repoId')
+        .equals(dbID)
+        .delete()
+
+      const protectionsFound = branchRecords.length > 0
+      this.branchProtectionSettingsFoundCache.set(dbID, protectionsFound)
+
+      if (branchRecords.length > 0) {
+        await this.db.protectedBranches.bulkAdd(branchRecords)
+      }
+    })
+
+    this.emitUpdate()
+  }
+
   /**
    * Set's the last time the repository was checked for pruning
    *