Merge pull request desktop#15704 from desktop/pr-preview-should-alway…

…s-open

PR Preview: Handle no default branch.

app/src/lib/app-state.ts

@@ -967,7 +967,7 @@ export interface IPullRequestState {
    * The base branch of a a pull request - the branch the currently checked out
    * branch would merge into
    */
-  readonly baseBranch: Branch
+  readonly baseBranch: Branch | null
 
   /** The SHAs of commits of the pull request */
   readonly commitSHAs: ReadonlyArray<string> | null
@@ -981,7 +981,7 @@ export interface IPullRequestState {
    * repositories commit selection where the diff of all commits represents the
    * diff between the latest commit and the earliest commits parent.
    */
-  readonly commitSelection: ICommitSelection
+  readonly commitSelection: ICommitSelection | null
 
   /** The result of merging the pull request branch into the base branch */
   readonly mergeStatus: MergeTreeResult | null

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

@@ -7309,23 +7309,28 @@ export class AppStore extends TypedBaseStore<IAppState> {
   }
 
   public async _startPullRequest(repository: Repository) {
-    const { branchesState } = this.repositoryStateCache.get(repository)
-    const { defaultBranch, tip } = branchesState
+    const { tip, defaultBranch } =
+      this.repositoryStateCache.get(repository).branchesState
 
-    if (defaultBranch === null || tip.kind !== TipState.Valid) {
+    if (tip.kind !== TipState.Valid) {
+      // Shouldn't even be able to get here if so - just a type check
       return
     }
+
     const currentBranch = tip.branch
     this._initializePullRequestPreview(repository, defaultBranch, currentBranch)
   }
 
   private async _initializePullRequestPreview(
     repository: Repository,
-    baseBranch: Branch,
+    baseBranch: Branch | null,
     currentBranch: Branch
   ) {
-    const { branchesState, localCommitSHAs } =
-      this.repositoryStateCache.get(repository)
+    if (baseBranch === null) {
+      this.showPullRequestPopupNoBaseBranch(repository, currentBranch)
+      return
+    }
+
     const gitStore = this.gitStoreCache.get(repository)
 
     const pullRequestCommits = await gitStore.getCommitsBetweenBranches(
@@ -7392,15 +7397,46 @@ export class AppStore extends TypedBaseStore<IAppState> {
       )
     }
 
+    this.showPullRequestPopup(repository, currentBranch, commitSHAs)
+  }
+
+  public showPullRequestPopupNoBaseBranch(
+    repository: Repository,
+    currentBranch: Branch
+  ) {
+    this.repositoryStateCache.initializePullRequestState(repository, {
+      baseBranch: null,
+      commitSHAs: null,
+      commitSelection: null,
+      mergeStatus: null,
+    })
+
+    this.emitUpdate()
+
+    this.showPullRequestPopup(repository, currentBranch, [])
+  }
+
+  public showPullRequestPopup(
+    repository: Repository,
+    currentBranch: Branch,
+    commitSHAs: ReadonlyArray<string>
+  ) {
     if (this.popupManager.areTherePopupsOfType(PopupType.StartPullRequest)) {
       return
     }
 
+    const { branchesState, localCommitSHAs } =
+      this.repositoryStateCache.get(repository)
     const { allBranches, recentBranches, defaultBranch, currentPullRequest } =
       branchesState
     const { imageDiffType, selectedExternalEditor, showSideBySideDiff } =
       this.getState()
 
+    const nonLocalCommitSHA =
+      commitSHAs.length > 0 && !localCommitSHAs.includes(commitSHAs[0])
+        ? commitSHAs[0]
+        : null
+
     this._showPopup({
       type: PopupType.StartPullRequest,
       allBranches,
@@ -7410,10 +7446,7 @@ export class AppStore extends TypedBaseStore<IAppState> {
       recentBranches,
       repository,
       externalEditorLabel: selectedExternalEditor ?? undefined,
-      nonLocalCommitSHA:
-        commitSHAs.length > 0 && !localCommitSHAs.includes(commitSHAs[0])
-          ? commitSHAs[0]
-          : null,
+      nonLocalCommitSHA,
       showSideBySideDiff,
       currentBranchHasPullRequest: currentPullRequest !== null,
     })
@@ -7435,7 +7468,7 @@ export class AppStore extends TypedBaseStore<IAppState> {
 
     const currentBranch = branchesState.tip.branch
     const { baseBranch, commitSHAs } = pullRequestState
-    if (commitSHAs === null) {
+    if (commitSHAs === null || baseBranch === null) {
       return
     }
 

app/src/lib/stores/repository-state-cache.ts

@@ -286,7 +286,8 @@ export class RepositoryStateCache {
     }
 
     const oldState = pullRequestState.commitSelection
-    const commitSelection = merge(oldState, fn(oldState))
+    const commitSelection =
+      oldState === null ? null : merge(oldState, fn(oldState))
     this.updatePullRequestState(repository, () => ({
       commitSelection,
     }))

app/src/ui/branches/branch-select.tsx

@@ -9,7 +9,7 @@ import { IBranchListItem } from './group-branches'
 
 interface IBranchSelectProps {
   /** The initially selected branch. */
-  readonly branch: Branch
+  readonly branch: Branch | null
 
   /**
    * See IBranchesState.defaultBranch

app/src/ui/open-pull-request/open-pull-request-dialog.tsx

@@ -83,7 +83,7 @@ export class OpenPullRequestDialog extends React.Component<IOpenPullRequestDialo
       dispatcher.showPullRequest(repository)
     } else {
       const { baseBranch } = this.props.pullRequestState
-      dispatcher.createPullRequest(repository, baseBranch)
+      dispatcher.createPullRequest(repository, baseBranch ?? undefined)
       // TODO: create pr from dialog pr stat?
       dispatcher.recordCreatePullRequest()
     }
@@ -123,6 +123,7 @@ export class OpenPullRequestDialog extends React.Component<IOpenPullRequestDialo
     return (
       <div className="open-pull-request-content">
         {this.renderNoChanges()}
+        {this.renderNoDefaultBranch()}
         {this.renderFilesChanged()}
       </div>
     )
@@ -140,6 +141,11 @@ export class OpenPullRequestDialog extends React.Component<IOpenPullRequestDialo
       nonLocalCommitSHA,
     } = this.props
     const { commitSelection } = pullRequestState
+    if (commitSelection === null) {
+      // type checking - will render no default branch message
+      return
+    }
+
     const { diff, file, changesetData, shas } = commitSelection
     const { files } = changesetData
 
@@ -167,8 +173,12 @@ export class OpenPullRequestDialog extends React.Component<IOpenPullRequestDialo
   private renderNoChanges() {
     const { pullRequestState, currentBranch } = this.props
     const { commitSelection, baseBranch, mergeStatus } = pullRequestState
-    const { shas } = commitSelection
+    if (commitSelection === null || baseBranch === null) {
+      // type checking - will render no default branch message
+      return
+    }
 
+    const { shas } = commitSelection
     if (shas.length !== 0) {
       return
     }
@@ -185,7 +195,7 @@ export class OpenPullRequestDialog extends React.Component<IOpenPullRequestDialo
       </>
     )
     return (
-      <div className="open-pull-request-no-changes">
+      <div className="open-pull-request-message">
         <div>
           <Octicon symbol={OcticonSymbol.gitPullRequest} />
           <h3>There are no changes.</h3>
@@ -195,6 +205,24 @@ export class OpenPullRequestDialog extends React.Component<IOpenPullRequestDialo
     )
   }
 
+  private renderNoDefaultBranch() {
+    const { baseBranch } = this.props.pullRequestState
+
+    if (baseBranch !== null) {
+      return
+    }
+
+    return (
+      <div className="open-pull-request-message">
+        <div>
+          <Octicon symbol={OcticonSymbol.gitPullRequest} />
+          <h3>Could not find a default branch to compare against.</h3>
+          Select a base branch above.
+        </div>
+      </div>
+    )
+  }
+
   private renderFooter() {
     const { currentBranchHasPullRequest, pullRequestState, repository } =
       this.props

app/src/ui/open-pull-request/open-pull-request-header.tsx

@@ -7,7 +7,7 @@ import { Ref } from '../lib/ref'
 
 interface IOpenPullRequestDialogHeaderProps {
   /** The base branch of the pull request */
-  readonly baseBranch: Branch
+  readonly baseBranch: Branch | null
 
   /** The branch of the pull request */
   readonly currentBranch: Branch

app/styles/ui/dialogs/_open-pull-request.scss

@@ -29,7 +29,7 @@
     flex-grow: 1;
   }
 
-  .open-pull-request-no-changes {
+  .open-pull-request-message {
     height: 100%;
     display: flex;
     align-items: center;