Pre-commit hook to test if the code needs restyling (project-chip#7506)

* Pre-commit hook to test if the code needs restyling

* use diff patch to save unstaged changes

* Fix spelling

.githooks/pre-commit

@@ -0,0 +1,64 @@
+#!/bin/sh
+
+here=${0%/*}
+
+CHIP_ROOT=$(cd "$here/.." && pwd)
+
+SAVED_UNSTAGED=0
+SAVED_UNSTAGED_FILE=$(git rev-parse --short HEAD)-unstaged.diff
+
+RESTYLED=0
+
+save_unstaged() {
+    if [[ $SAVED_UNSTAGED -ne 0 ]]; then
+        git diff --output="$SAVED_UNSTAGED_FILE"
+        git apply -R "$SAVED_UNSTAGED_FILE"
+    fi
+}
+
+revert_unstaged() {
+    if [[ $SAVED_UNSTAGED -ne 0 ]]; then
+        git apply "$SAVED_UNSTAGED_FILE"
+        rm "$SAVED_UNSTAGED_FILE"
+    fi
+    SAVED_UNSTAGED=0
+}
+
+revert_restyled() {
+    if [[ $RESTYLED -ne 0 ]]; then
+        # Reset the changes introduced by restyle
+        git stash push -q --keep-index
+        git stash drop -q
+    fi
+    RESTYLED=0
+}
+
+revert_if_needed() {
+    revert_restyled
+    revert_unstaged
+}
+
+trap "revert_if_needed; exit 1" SIGINT SIGTERM SIGKILL
+
+git diff --quiet
+SAVED_UNSTAGED=$?
+
+# If there are unstaged files, save them for now
+save_unstaged
+
+# Try restyling the code
+"$CHIP_ROOT"/scripts/helpers/restyle-diff.sh
+
+git diff --quiet
+RESTYLED=$?
+FAILED_COMMIT="$RESTYLED"
+
+revert_if_needed
+
+if [[ $FAILED_COMMIT -ne 0 ]]; then
+    echo "Commit Failed: Code needs restyling before committing."
+    echo "Restyling can be done by running $CHIP_ROOT/scripts/helpers/restyle-diff.sh"
+    exit 1
+fi
+
+echo "Code doesn't need restyling. Committing."