#!/usr/bin/env bash

# ============================================================================
# Pre-push gate: runs the `stages: [pre-push]` hooks from
# .pre-commit-config.yaml (prettier, ci-mirror, pytest-coverage).
#
# Before this hook existed there was no pre-push gate at all, so those three
# never ran locally — which is how a completely absent `prettier` binary went
# unnoticed while unformatted markdown reached main.
#
# git passes the remote name/URL as $1/$2 and one line per ref on stdin:
#   <local_ref> <local_sha> <remote_ref> <remote_sha>
# ============================================================================

set -euo pipefail

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

# shellcheck source=linux_configuration/.githooks/lib/common.sh
source "${repo_root}/linux_configuration/.githooks/lib/common.sh"

readonly ZERO_SHA="0000000000000000000000000000000000000000"

# pre-commit arguments describing what to check; filled by resolve_push_range.
RANGE_ARGS=()

# Translate the refs git feeds us on stdin into a pre-commit file selector.
#
# This matters: `pre-commit run --hook-stage pre-push` with no range operates
# on *staged* files, and nothing is staged at push time — so file-scoped hooks
# like prettier would silently receive zero files and pass vacuously. Only the
# always_run hooks would really fire. Passing the range is what makes the gate
# real.
resolve_push_range() {
  local local_ref local_sha remote_ref remote_sha

  while read -r local_ref local_sha remote_ref remote_sha; do
    # Branch deletion — nothing to check.
    if [[ $local_sha == "$ZERO_SHA" ]]; then
      continue
    fi

    # New branch on the remote: no common ancestor to diff against, so check
    # every file rather than silently checking nothing.
    if [[ $remote_sha == "$ZERO_SHA" ]]; then
      printf 'Pushing a new branch (%s) — checking all files.\n' "$remote_ref"
      RANGE_ARGS=(--all-files)
      return 0
    fi

    printf 'Checking %s (%s..%s)\n' "$local_ref" "${remote_sha:0:8}" "${local_sha:0:8}"
    RANGE_ARGS=(--from-ref "$remote_sha" --to-ref "$local_sha")
    return 0
  done

  return 0
}

printf 'Verifying hook wiring and toolchain before pushing...\n'
ensure_hooks_path
verify_toolchain
printf '  ✓ toolchain complete\n'

resolve_push_range

if [[ ${#RANGE_ARGS[@]} -eq 0 ]]; then
  printf 'Nothing to check (branch deletion or empty push).\n'
  exit 0
fi

printf '\nRunning pre-push hooks (prettier, ci-mirror, pytest-coverage)...\n'

if ! pre-commit run --hook-stage pre-push "${RANGE_ARGS[@]}"; then
  printf '\nPush aborted: pre-push hooks failed.\n' >&2
  printf 'Fix the issues above and retry the push.\n' >&2
  exit 1
fi

printf 'All pre-push checks passed. Proceeding with push.\n'