Fixed failure when running Githubinator with detached HEAD (#26)

Githubinator would fail because there wasn't a ref to work off when running with a detached HEAD.

Author: chdsbd

.circleci/config.yml

@@ -22,6 +22,7 @@ jobs:
           name: install
           command: |
             make install
+            sudo apt update
             sudo apt install libgtk-3-0 libxss1 libnss3 libasound2
       - save_cache:
           paths:

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed failure when running Githubinator with detached HEAD. Githubinator
+  would fail because there wasn't a ref to work off when running with a detached
+  HEAD.
+
 ## 0.2.1 - 2019-03-08
 
 ### Fixed

src/extension.ts

@@ -136,7 +136,7 @@ async function githubinator({
   if (gitDir == null) {
     return err("Could not find .git directory.")
   }
-  let headBranch: [string, string] | null = null
+  let headBranch: [string, string | null] | null = null
   if (branch) {
     const sha = await git.getSHAForBranch(gitDir, branch)
     if (sha == null) {
@@ -166,8 +166,13 @@ async function githubinator({
       remote => git.origin(gitDir, remote),
     ).getUrls({
       selection: [editor.selection.start.line, editor.selection.end.line],
-      // permalink > branch > branch from HEAD
-      head: !!permalink ? createSha(head) : createBranch(branchName),
+      // priority: permalink > branch > branch from HEAD
+      // If branchName could not be found (null) then we generate a permalink
+      // using the SHA.
+      head:
+        !!permalink || branchName == null
+          ? createSha(head)
+          : createBranch(branchName),
       relativeFilePath: getRelativeFilePath(gitDir, fileName),
     })
     if (parsedUrl != null) {

src/git.ts

@@ -64,7 +64,9 @@ export async function getSHAForBranch(
 }
 
 /** Get the current SHA and branch from HEAD for a git directory */
-export async function head(gitDir: string): Promise<[string, string] | null> {
+export async function head(
+  gitDir: string,
+): Promise<[string, string | null] | null> {
   const headPath = path.resolve(gitDir, "HEAD")
   if (!(await fs.exists(headPath))) {
     return null
@@ -73,8 +75,17 @@ export async function head(gitDir: string): Promise<[string, string] | null> {
   if (!headFileData) {
     return null
   }
-  const headInfo = headFileData.split(" ")[1].trim()
-  const branchName = headInfo.replace("refs/heads/", "")
+  // If we're not on a branch, headFileData will be of the form:
+  // `3c0cc80bbdb682f6e9f65b4c9659ca21924aad4`
+  // If we're on a branch, it will be `ref: refs/heads/my_branch_name`
+  const [maybeSha, maybeHeadInfo] = headFileData.split(" ") as [
+    string,
+    string | undefined
+  ]
+  if (maybeHeadInfo == null) {
+    return [maybeSha, null]
+  }
+  const branchName = maybeHeadInfo.trim().replace("refs/heads/", "")
   const sha = await getSHAForBranch(gitDir, branchName)
   if (sha == null) {
     return null