#!/usr/bin/env bash
# Pre-push hook: runs the local Unity-version parity check in compile-only mode.
# Installed by tools/install-hooks.sh; opt-in (devs without the hook see no behavior change).
# To bypass for a single push: git push --no-verify

set -e

REPO_ROOT="$(git rev-parse --show-toplevel)"
SCRIPT="${REPO_ROOT}/tools/check-unity-versions.sh"

if [[ ! -x "$SCRIPT" ]]; then
  echo "pre-push: $SCRIPT missing or not executable; skipping Unity-version check." >&2
  exit 0
fi

# Skip if the push touches nothing relevant. We approximate "relevant" with the same path filters
# the CI workflow uses, so the hook fires for the same scope of changes.
relevant_paths='^(MCPForUnity/(Editor|Runtime)/|TestProjects/UnityMCPTests/|tools/unity-versions\.json$|\.github/workflows/unity-tests\.yml$)'

# Git's empty-tree SHA — fallback that always exists. Used when we can't find a sensible merge
# base (shallow clone, fresh fork with no origin/beta or origin/main, etc.) so the hook still
# runs the check instead of silently skipping it.
EMPTY_TREE=4b825dc642cb6eb9a060e54bf8d69288fbee4904

# stdin format from git: <local-ref> <local-sha> <remote-ref> <remote-sha> (one line per ref being pushed)
relevant=0
while read -r local_ref local_sha remote_ref remote_sha; do
  [[ -z "$local_sha" || "$local_sha" == "0000000000000000000000000000000000000000" ]] && continue

  if [[ "$remote_sha" == "0000000000000000000000000000000000000000" ]]; then
    # New branch on remote — diff against the default branch, or the empty tree as a guaranteed-valid fallback.
    base=$(git merge-base "$local_sha" origin/beta 2>/dev/null \
        || git merge-base "$local_sha" origin/main 2>/dev/null \
        || echo "$EMPTY_TREE")
  else
    base="$remote_sha"
  fi

  if git diff --name-only "$base..$local_sha" 2>/dev/null | grep -qE "$relevant_paths"; then
    relevant=1
    break
  fi
done

if [[ $relevant -eq 0 ]]; then
  echo "pre-push: no Unity-relevant changes detected; skipping check."
  exit 0
fi

exec "$SCRIPT" --pre-push