CCM-8881: Extend sync script to merge some config files rather than replacing them

Author: m-houston

scripts/config/.repository-template-sync-ignore

@@ -1,5 +1,4 @@
 # Files and folders to ignore when syncing nhs-notify-repository-template back in to this repository
-scripts/config/.repository-template-sync-ignore
 .github/workflows/
 nhs-notify-repository-template/
 

scripts/config/.repository-template-sync-merge

@@ -0,0 +1,7 @@
+# Files and folders to merge when syncing nhs-notify-repository-template back in to this repository
+scripts/config/.repository-template-sync-ignore
+scripts/config/.repository-template-sync-merge
+.tool-versions
+.gitignore
+scripts/config/vale/styles/config/vocabularies/words/accept.txt
+scripts/config/vale/styles/config/vocabularies/words/reject.txt

scripts/githooks/sync-template-repo.sh

@@ -13,13 +13,14 @@ set -euo pipefail
 
 # ==============================================================================
 
-# Command line prameters
+# Command line parameters
 new_only=${new_only:-false}
 changes_only=${changes_only:-false}
 
 # Set variables
 TEMPLATE_REPO_DIR="nhs-notify-repository-template"
 IGNORE_FILE="scripts/config/.repository-template-sync-ignore"
+MERGE_FILE="scripts/config/.repository-template-sync-merge"
 
 # Check if the template directory exists
 if [ ! -d "${TEMPLATE_REPO_DIR}" ]; then
@@ -34,11 +35,21 @@ if [ ! -f "${IGNORE_FILE}" ]; then
   echo "# Files and Folders in the template repository to disregard" >> ${IGNORE_FILE}
 fi
 
+# Check if the .template-merge file exists, create an empty one if not
+if [ ! -f "${MERGE_FILE}" ]; then
+  echo "# Files and folders to merge when syncing ${TEMPLATE_REPO_DIR} back in to this repository" > ${MERGE_FILE}
+fi
+
 # Read the .template-ignore file into an array
 while IFS= read -r line || [ -n "$line" ]; do
   IGNORED_PATHS+=("$line")
 done < "$IGNORE_FILE"
 
+# Read the .template-merge file into an array
+while IFS= read -r line || [ -n "$line" ]; do
+  MERGED_PATHS+=("$line")
+done < "$MERGE_FILE"
+
 # Check if a file is ignored.
 is_ignored() {
   local file=${1}
@@ -56,6 +67,17 @@ is_ignored() {
   return 1
 }
 
+is_merge() {
+  local file=${1}
+
+  for merged in "${MERGED_PATHS[@]}"; do
+    if [[ -n "$merged" && "$file" =~ $merged ]]; then
+      return 0
+    fi
+  done
+  return 1
+}
+
 # Navigate to the template directory
 cd "${TEMPLATE_REPO_DIR}" || exit
 FILES_ADDED=()
@@ -84,9 +106,24 @@ while IFS= read -r -d '' file; do
     # If the file exists, check if it's different
     if [ "$new_only" == false ]; then
       if ! diff -q "$file" "$target_path" > /dev/null 2>&1; then
-        echo "Merging changes from $relative_path"
-        FILES_WITH_CHANGES+=("${relative_path}")
-        cp "$file" "$target_path"
+        if is_merge "$relative_path"; then
+          echo "Merging changes from $relative_path"
+          cp "$target_path" "${target_path}.bak"
+          if git merge-file "$target_path" /dev/null "$file" --union; then
+              if ! cmp -s "$target_path" "${target_path}.bak"; then
+                  FILES_WITH_CHANGES+=("${relative_path}")
+              fi
+          else
+              echo "Merge failed for $relative_path, rolling back."
+              mv "${target_path}.bak" "$target_path"
+              diff3 "$target_path" /dev/null "$file"
+          fi
+          rm -f "${target_path}.bak"
+        else
+          echo "Copying changes from $relative_path"
+          cp "$file" "$target_path"
+          FILES_WITH_CHANGES+=("${relative_path}")
+        fi
       fi
     fi
   fi