Add ref input parameter

src/git.ts

@@ -54,30 +54,38 @@ export async function getChangesOnHead(): Promise<File[]> {
   return parseGitDiffOutput(output)
 }
 
-export async function getChangesSinceMergeBase(base: string, ref: string, initialFetchDepth: number): Promise<File[]> {
+export async function getChangesSinceMergeBase(base: string, head: string, initialFetchDepth: number): Promise<File[]> {
   let baseRef: string | undefined
+  let headRef: string | undefined
   async function hasMergeBase(): Promise<boolean> {
-    return (
-      baseRef !== undefined && (await exec('git', ['merge-base', baseRef, ref], {ignoreReturnCode: true})).code === 0
-    )
+    if (baseRef === undefined || headRef === undefined) {
+      return false
+    }
+    return (await exec('git', ['merge-base', baseRef, headRef], {ignoreReturnCode: true})).code === 0
   }
 
   let noMergeBase = false
-  core.startGroup(`Searching for merge-base ${base}...${ref}`)
+  core.startGroup(`Searching for merge-base ${base}...${headRef}`)
   try {
     baseRef = await getFullRef(base)
+    headRef = await getFullRef(head)
     if (!(await hasMergeBase())) {
-      await exec('git', ['fetch', '--no-tags', `--depth=${initialFetchDepth}`, 'origin', base, ref])
-      if (baseRef === undefined) {
-        baseRef = await getFullRef(base)
-        if (baseRef === undefined) {
-          await exec('git', ['fetch', '--tags', '--depth=1', 'origin', base, ref], {
+      await exec('git', ['fetch', '--no-tags', `--depth=${initialFetchDepth}`, 'origin', base, head])
+      if (baseRef === undefined || headRef === undefined) {
+        baseRef = baseRef ?? (await getFullRef(base))
+        headRef = headRef ?? (await getFullRef(head))
+        if (baseRef === undefined || headRef === undefined) {
+          await exec('git', ['fetch', '--tags', '--depth=1', 'origin', base, head], {
             ignoreReturnCode: true // returns exit code 1 if tags on remote were updated - we can safely ignore it
           })
-          baseRef = await getFullRef(base)
+          baseRef = baseRef ?? (await getFullRef(base))
+          headRef = headRef ?? (await getFullRef(head))
           if (baseRef === undefined) {
             throw new Error(`Could not determine what is ${base} - fetch works but it's not a branch or tag`)
           }
+          if (headRef === undefined) {
+            throw new Error(`Could not determine what is ${head} - fetch works but it's not a branch or tag`)
+          }
         }
       }
 
@@ -85,7 +93,7 @@ export async function getChangesSinceMergeBase(base: string, ref: string, initia
       let lastCommitCount = await getCommitCount()
       while (!(await hasMergeBase())) {
         depth = Math.min(depth * 2, Number.MAX_SAFE_INTEGER)
-        await exec('git', ['fetch', `--deepen=${depth}`, 'origin', base, ref])
+        await exec('git', ['fetch', `--deepen=${depth}`, 'origin', base, head])
         const commitCount = await getCommitCount()
         if (commitCount === lastCommitCount) {
           core.info('No more commits were fetched')
@@ -103,10 +111,10 @@ export async function getChangesSinceMergeBase(base: string, ref: string, initia
     core.endGroup()
   }
 
-  let diffArg = `${baseRef}...${ref}`
+  let diffArg = `${baseRef}...${headRef}`
   if (noMergeBase) {
     core.warning('No merge base found - change detection will use direct <commit>..<commit> comparison')
-    diffArg = `${baseRef}..${ref}`
+    diffArg = `${baseRef}..${headRef}`
   }
 
   // Get changes introduced on ref compared to base

src/main.ts

@@ -19,6 +19,7 @@ async function run(): Promise<void> {
     }
 
     const token = core.getInput('token', {required: false})
+    const ref = core.getInput('ref', {required: false})
     const base = core.getInput('base', {required: false})
     const filtersInput = core.getInput('filters', {required: true})
     const filtersYaml = isPathInput(filtersInput) ? getConfigFileContent(filtersInput) : filtersInput
@@ -31,7 +32,7 @@ async function run(): Promise<void> {
     }
 
     const filter = new Filter(filtersYaml)
-    const files = await getChangedFiles(token, base, initialFetchDepth)
+    const files = await getChangedFiles(token, base, ref, initialFetchDepth)
     const results = filter.match(files)
     exportResults(results, listFiles)
   } catch (error) {
@@ -55,7 +56,7 @@ function getConfigFileContent(configPath: string): string {
   return fs.readFileSync(configPath, {encoding: 'utf8'})
 }
 
-async function getChangedFiles(token: string, base: string, initialFetchDepth: number): Promise<File[]> {
+async function getChangedFiles(token: string, base: string, ref: string, initialFetchDepth: number): Promise<File[]> {
   // if base is 'HEAD' only local uncommitted changes will be detected
   // This is the simplest case as we don't need to fetch more commits or evaluate current/before refs
   if (base === git.HEAD) {
@@ -70,18 +71,18 @@ async function getChangedFiles(token: string, base: string, initialFetchDepth: n
     core.info('Github token is not available - changes will be detected from PRs merge commit')
     return await git.getChangesInLastCommit()
   } else {
-    return getChangedFilesFromGit(base, initialFetchDepth)
+    return getChangedFilesFromGit(base, ref, initialFetchDepth)
   }
 }
 
-async function getChangedFilesFromGit(base: string, initialFetchDepth: number): Promise<File[]> {
+async function getChangedFilesFromGit(base: string, head: string, initialFetchDepth: number): Promise<File[]> {
   const defaultRef = github.context.payload.repository?.default_branch
 
   const beforeSha =
     github.context.eventName === 'push' ? (github.context.payload as Webhooks.WebhookPayloadPush).before : null
 
   const ref =
-    git.getShortName(github.context.ref) ||
+    git.getShortName(head || github.context.ref) ||
     (core.warning(`'ref' field is missing in event payload - using current branch, tag or commit SHA`),
     await git.getCurrentRef())