From c6c5f0788074bcc03c5b17bc81f49a04a204b1bd Mon Sep 17 00:00:00 2001
From: Martin Habovstiak <martin.habovstiak@gmail.com>
Date: Sat, 20 Jan 2024 15:07:03 +0100
Subject: [PATCH] Add automated labeler job

Rather than modifying the labels manually, which we often forget, we can
label the PRs automatically. This will make it easier to search PRs.
---
 .github/labeler.yml             | 13 +++++++++++
 .github/workflows/manage-pr.yml | 26 ++++++++++++++++++++++
 contrib/gen_label_config.sh     | 39 +++++++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+)
 create mode 100644 .github/labeler.yml
 create mode 100644 .github/workflows/manage-pr.yml
 create mode 100755 contrib/gen_label_config.sh

diff --git a/.github/labeler.yml b/.github/labeler.yml
new file mode 100644
index 00000000..986c15a0
--- /dev/null
+++ b/.github/labeler.yml
@@ -0,0 +1,13 @@
+ci:
+  - changed-files:
+    - any-glob-to-any-file: .github/**
+test:
+  - changed-files:
+    - any-glob-to-any-file: fuzz/**
+    - any-glob-to-any-file: '*/tests/**'
+    - any-glob-to-any-file: 'dep_test'
+    - any-glob-to-any-file: 'contrib/test.sh'
+    - any-glob-to-any-file: '*/contrib/test.sh'
+doc:
+  - changed-files:
+    - any-glob-to-any-file: '**/*.md'
diff --git a/.github/workflows/manage-pr.yml b/.github/workflows/manage-pr.yml
new file mode 100644
index 00000000..1ae25001
--- /dev/null
+++ b/.github/workflows/manage-pr.yml
@@ -0,0 +1,26 @@
+name: Manage PR
+on:
+  - pull_request_target
+
+jobs:
+  labeler:
+    permissions:
+      contents: read
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout master
+        uses: actions/checkout@v4
+        with:
+          path: master
+      - name: Checkout merge commit
+        uses: actions/checkout@v4
+        with:
+          path: merge
+          ref: "refs/pull/${{ github.event.number }}/merge"
+      - name: Generate label config
+        run: cd master && SCAN_DIR=../merge ./contrib/gen_label_config.sh
+      - name: Update labels
+        uses: actions/labeler@v5
+        with:
+          configuration-path: master/.github/labeler.yml
diff --git a/contrib/gen_label_config.sh b/contrib/gen_label_config.sh
new file mode 100755
index 00000000..1f88145a
--- /dev/null
+++ b/contrib/gen_label_config.sh
@@ -0,0 +1,39 @@
+#!/bin/bash
+
+set -e
+
+# Generates the label configuration using crates in the repository.
+# The label configuration is appended to the labeler config file.
+
+config=.github/labeler.yml
+
+if [ -n "$SCAN_DIR" ];
+then
+	scan_dir="$SCAN_DIR"
+else
+	scan_dir=.
+fi
+
+if [ "$1" '!=' "--force" ] && ! git diff --exit-code "$config";
+then
+	echo "Error: $config is not committed."
+	echo "Refusing to overwrite it to prevent disaster."
+	echo "Run the script with --force to override this."
+	exit 1
+fi
+
+excluded_crates="fuzz|dep_test"
+
+CRATES="`cd "$scan_dir" && cargo metadata --no-deps --format-version 1 | jq -j -r '.packages | map(.manifest_path | rtrimstr("/Cargo.toml") | ltrimstr("'$PWD'/")) | join(" ")'`"
+
+for crate in $CRATES;
+do
+	if echo "$crate" | grep -qE "$excluded_crates";
+	then
+		continue
+	fi
+
+	echo "C-$crate:" >> "$config"
+	echo "  - changed-files:" >> "$config"
+	echo "    - any-glob-to-any-file: $crate/**" >> "$config"
+done