#!/usr/bin/env bash
#
# Run the accessibility audit against the oldest supported simulator runtime
# before pushing.
#
# Enable once per clone:
#     git config core.hooksPath .githooks
#
# Why pre-push and not pre-commit: the suite takes ~85s. At pre-commit that
# blocks every commit, and a hook you routinely bypass with --no-verify is worse
# than no hook, because it trains you to ignore it. Pushes are far less frequent
# and map to the unit of work that actually reaches CI.
#
# Why only the floor tier: CI already audits the newest runtime on a clean
# checkout. The GitHub image has no old runtimes, so the floor is the one thing
# CI structurally cannot cover — and it is the one this machine can. Running
# both here would just double the wait to re-check what CI already does.
#
# Skip deliberately with: git push --no-verify

set -euo pipefail

repo_root=$(git rev-parse --show-toplevel)
cd "$repo_root"

zero='0000000000000000000000000000000000000000'
changed=''

# stdin: <local ref> <local sha> <remote ref> <remote sha>, one line per ref.
while read -r _local_ref local_sha _remote_ref remote_sha; do
  [ "$local_sha" = "$zero" ] && continue  # branch deletion

  if [ "$remote_sha" = "$zero" ]; then
    # New branch: diff against the default branch rather than the whole history.
    base=$(git merge-base origin/main "$local_sha" 2>/dev/null || echo '')
    range="${base:+$base..}$local_sha"
  else
    range="$remote_sha..$local_sha"
  fi

  changed="$changed$(git diff --name-only "$range" 2>/dev/null || true)"$'\n'
done

if [ -z "$(printf '%s' "$changed" | tr -d '[:space:]')" ]; then
  exit 0
fi

# Only pay the ~85s when something could actually change the rendered UI.
if ! printf '%s' "$changed" | grep -qE '\.(swift|xcassets|xcodeproj)|\.pbxproj|xcscheme'; then
  echo "pre-push: no Swift/project changes, skipping accessibility audit"
  exit 0
fi

echo "pre-push: running accessibility audit on the floor runtime (~85s)"
echo "          skip with 'git push --no-verify'"

if ! ./Scripts/audit-a11y.sh floor; then
  echo
  echo "pre-push: audit could not run. Push aborted." >&2
  echo "          Re-run with './Scripts/audit-a11y.sh floor' to see why," >&2
  echo "          or bypass with 'git push --no-verify'." >&2
  exit 1
fi

# Note: findings are reported, not enforced, so a clean exit here does not mean
# zero findings — read the list above. Enforcement is controlled by
# AccessibilityAuditHarness.enforcedAuditTypes.
exit 0