From db5f2e1edee666a4b862a3bde6c8882708b14eae Mon Sep 17 00:00:00 2001
From: Colin Lacy <colinjlacy@gmail.com>
Date: Tue, 16 Dec 2025 14:22:26 -0500
Subject: [PATCH] Adds option to only show latest patch versions

Signed-off-by: Colin Lacy <colacy@cisco.com>
---
 __tests__/main.test.js | 21 +++++++++++++++++----
 action.yml             |  4 ++++
 src/go-versions.js     | 28 +++++++++++++++++++++++++++-
 src/main.js            |  9 ++++++++-
 4 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/__tests__/main.test.js b/__tests__/main.test.js
index bb5d110..e62dec0 100644
--- a/__tests__/main.test.js
+++ b/__tests__/main.test.js
@@ -28,13 +28,13 @@ test('test latest version', () => {
 
 test('test version matrix', () => {
   const t = JSON.parse(fs.readFileSync('__tests__/testdata/dl.json', 'utf8'))
-  const m = matrix('1.16', false, false, t)
+  const m = matrix('1.16', false, false, false, t)
   expect(m).toEqual(['1.16', '1.17', '1.18'])
 })
 
 test('test unstable version matrix', () => {
   const t = JSON.parse(fs.readFileSync('__tests__/testdata/dl.json', 'utf8'))
-  const m = matrix('1.16', true, false, t)
+  const m = matrix('1.16', true, false, false, t)
   expect(m).toEqual([
     '1.16beta1',
     '1.16rc1',
@@ -52,7 +52,7 @@ test('test unstable version matrix', () => {
 
 test('test patch level version matrix', () => {
   const t = JSON.parse(fs.readFileSync('__tests__/testdata/dl.json', 'utf8'))
-  const m = matrix('1.16', false, true, t)
+  const m = matrix('1.16', false, true, false, t)
   expect(m).toEqual([
     '1.16',
     '1.16.1',
@@ -85,7 +85,7 @@ test('test patch level version matrix', () => {
 
 test('test patch level, unstable version matrix', () => {
   const t = JSON.parse(fs.readFileSync('__tests__/testdata/dl.json', 'utf8'))
-  const m = matrix('1.16', true, true, t)
+  const m = matrix('1.16', true, true, false, t)
   expect(m).toEqual([
     '1.16beta1',
     '1.16rc1',
@@ -123,3 +123,16 @@ test('test patch level, unstable version matrix', () => {
     '1.18'
   ])
 })
+
+test('test patch level with latest patches only', () => {
+  const t = JSON.parse(fs.readFileSync('__tests__/testdata/dl.json', 'utf8'))
+  const m = matrix('1.16', false, true, true, t)
+  expect(m).toEqual(['1.16.15', '1.17.8', '1.18'])
+})
+
+test('test patch level with latest patches only and unstable throws error', () => {
+  const t = JSON.parse(fs.readFileSync('__tests__/testdata/dl.json', 'utf8'))
+  expect(() => {
+    matrix('1.16', true, true, true, t)
+  }).toThrow('The options "unstable" and "latest-patches-only" cannot be used together')
+})
diff --git a/action.yml b/action.yml
index a1c4cd8..2b054b4 100644
--- a/action.yml
+++ b/action.yml
@@ -22,6 +22,10 @@ inputs:
     description: Include the patch levels on the versions (default is major.minor)
     required: false
     default: 'false'
+  latest-patches-only:
+    description: When patch-level is true, only include the latest patch version of each major.minor version in the matrix. Does nothing if patch-level is false. Cannot be used with unstable.
+    required: false
+    default: 'false'
 outputs:
   go-mod-version:
     description: The Go version specified by go.mod
diff --git a/src/go-versions.js b/src/go-versions.js
index 6e98369..9642341 100644
--- a/src/go-versions.js
+++ b/src/go-versions.js
@@ -41,11 +41,16 @@ const getVersions = async withUnsupported => {
   return result
 }
 
-const matrix = (min, withUnstable, withPatchLevel, tags) => {
+const matrix = (min, withUnstable, withPatchLevel, withLatestPatches, tags) => {
   const minClean = semverCoerce(min)
   if (minClean === null) {
     throw new Error(`Minimal version isn't quite right: ${min}`)
   }
+  if (withUnstable && withLatestPatches) {
+    throw new Error(
+      'The options "unstable" and "latest-patches-only" cannot be used together'
+    )
+  }
   if (!withUnstable) {
     tags = tags.filter(tag => tag.stable === true)
   }
@@ -63,6 +68,27 @@ const matrix = (min, withUnstable, withPatchLevel, tags) => {
       const parts = version.split('.')
       return `${parts[0]}.${parts[1]}`
     })
+  } else if (withLatestPatches) {
+    // Group by major.minor and keep only the latest patch version
+    const grouped = {}
+    versions.forEach(version => {
+      const parts = version.split('.')
+      const majorMinor = `${parts[0]}.${parts[1]}`
+      if (!grouped[majorMinor]) {
+        grouped[majorMinor] = []
+      }
+      grouped[majorMinor].push(version)
+    })
+    versions = Object.values(grouped).map(group => {
+      return group.reduce((acc, val) => {
+        const a = semverCoerce(acc)
+        const v = semverCoerce(val)
+        if (v !== null && a !== null && semverGte(v, a)) {
+          return val
+        }
+        return acc
+      })
+    })
   }
   versions = [...new Set(versions)]
   return versions.reverse()
diff --git a/src/main.js b/src/main.js
index 27293f2..65a5429 100644
--- a/src/main.js
+++ b/src/main.js
@@ -21,11 +21,18 @@ async function run() {
     const withUnsupported = core.getBooleanInput('unsupported')
     const withUnstable = core.getBooleanInput('unstable')
     const withPatchLevel = core.getBooleanInput('patch-level')
+    const withLatestPatches = core.getBooleanInput('latest-patches-only')
     const content = gomod(`${workingDirectory}/go.mod`)
     const name = modulename(content)
     const goModVersion = getGoModVersion(content)
     const versions = await getVersions(withUnsupported)
-    const mat = matrix(goModVersion, withUnstable, withPatchLevel, versions)
+    const mat = matrix(
+      goModVersion,
+      withUnstable,
+      withPatchLevel,
+      withLatestPatches,
+      versions
+    )
     const lat = latest(mat)
     const min = minimal(mat)