refactor: extract shared validation logic for git hooks

Author: Athemis

.githooks/commit-msg

@@ -3,14 +3,16 @@
 # SPDX-FileCopyrightText: 2025 Alexander Minges
 set -euo pipefail
 
+# Source shared validation logic
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/validate-commit-msg.sh"
+
 msg_file="$1"
 msg=$(head -n1 "$msg_file")
 
-# Conventional Commits pattern (type[!][scope]: subject)
-regex='^(feat|fix|docs|style|refactor|perf|test|build|ci|chore|revert)(\([^)]+\))?(!)?: .+'
-if [[ ! $msg =~ $regex ]]; then
-  echo "commit message must follow Conventional Commits, e.g., 'feat: add feature'" >&2
-  exit 1
+if ! validate_commit_msg "$msg"; then
+    print_error "$msg"
+    exit 1
 fi
 
 exit 0

.githooks/pre-push

@@ -6,12 +6,13 @@ set -euo pipefail
 # Pre-push hook to validate that all commits being pushed follow Conventional Commits
 # This prevents malformed commits that may have bypassed commit-msg hook during rebases
 
+# Source shared validation logic
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/validate-commit-msg.sh"
+
 remote="$1"
 url="$2"
 
-# Conventional Commits pattern (type[!][scope]: subject)
-regex='^(feat|fix|docs|style|refactor|perf|test|build|ci|chore|revert)(\([^)]+\))?(!)?: .+'
-
 has_errors=0
 
 # Read stdin to get the refs being pushed
@@ -31,21 +32,9 @@ while read local_ref local_sha remote_ref remote_sha; do
 
   # Get all commit messages in the range
   while IFS= read -r commit_msg; do
-    # Skip merge commits
-    if [[ "$commit_msg" =~ ^Merge ]]; then
-      continue
-    fi
-
-    # Check if commit message follows Conventional Commits
-    if [[ ! "$commit_msg" =~ $regex ]]; then
-      echo "ERROR: Invalid commit message format:" >&2
-      echo "  '$commit_msg'" >&2
-      echo >&2
-      echo "Commit messages must follow Conventional Commits specification." >&2
-      echo "Example: feat: add new feature" >&2
-      echo "         fix(ui): correct button alignment" >&2
+    if ! validate_commit_msg "$commit_msg"; then
+      print_error "$commit_msg"
       echo >&2
-      echo "Valid types: feat, fix, docs, style, refactor, perf, test, build, ci, chore, revert" >&2
       has_errors=1
     fi
   done < <(git log --format=%s "$range")

.githooks/validate-commit-msg.sh

@@ -0,0 +1,51 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: MIT
+# SPDX-FileCopyrightText: 2025 Alexander Minges
+
+# Shared validation logic for commit messages
+# Used by both commit-msg and pre-push hooks to ensure consistency
+
+set -euo pipefail
+
+# Conventional Commits pattern (type[!][scope]: subject)
+readonly COMMIT_MSG_REGEX='^(feat|fix|docs|style|refactor|perf|test|build|ci|chore|revert)(\([^)]+\))?(!)?: .+'
+
+# Valid commit types for reference
+readonly VALID_TYPES="feat, fix, docs, style, refactor, perf, test, build, ci, chore, revert"
+
+# Validate a single commit message
+# Arguments:
+#   $1 - commit message to validate
+# Returns:
+#   0 if valid, 1 if invalid
+validate_commit_msg() {
+    local msg="$1"
+
+    # Skip merge commits
+    if [[ "$msg" =~ ^Merge ]]; then
+        return 0
+    fi
+
+    # Check if commit message follows Conventional Commits
+    if [[ ! "$msg" =~ $COMMIT_MSG_REGEX ]]; then
+        return 1
+    fi
+
+    return 0
+}
+
+# Print error message for invalid commit
+# Arguments:
+#   $1 - invalid commit message
+print_error() {
+    local msg="$1"
+
+    echo "ERROR: Invalid commit message format:" >&2
+    echo "  '$msg'" >&2
+    echo >&2
+    echo "Commit messages must follow Conventional Commits specification." >&2
+    echo "Example: feat: add new feature" >&2
+    echo "         fix(ui): correct button alignment" >&2
+    echo >&2
+    echo "Valid types: $VALID_TYPES" >&2
+}