#!/usr/bin/env bash
set -euo pipefail

# Hard-fails only when pushing to main: if any file covered by .pre-commit-hooks.yaml
# (the external git-hook/CI contract, see ADR-0014) changed since the last tag,
# a release must be cut before landing on main, or external consumers pinning
# `rev: <tag>` silently miss the change. Pre-commit sets PRE_COMMIT_REMOTE_BRANCH
# for pre-push hooks; on every other branch (feature work mid-review) this is a
# silent no-op — pushing WIP commits there must not be blocked on cutting a
# premature tag (see ADR-0014's repo: local vs pinned self-reference decision).
#
# Known gap: this only fires on a local `git push` through pre-commit's pre-push
# hook. A PR merged via Gitea's merge button (server-side, no local push) or a
# CI runner invoking `pre-commit run --hook-stage pre-push` directly does not set
# PRE_COMMIT_REMOTE_BRANCH and will not trigger this check — closing that
# requires a server-side CI job, which this repo does not have yet.

TARGET_BRANCH="refs/heads/main"

if [[ "${PRE_COMMIT_REMOTE_BRANCH:-}" != "$TARGET_BRANCH" ]]; then
  exit 0
fi

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

HOOKS_MANIFEST=".pre-commit-hooks.yaml"

if [[ ! -f "$HOOKS_MANIFEST" ]]; then
  exit 0
fi

# Derive release-relevant paths from .pre-commit-hooks.yaml's own entry: lines
# instead of hand-maintaining a parallel list — the manifest is the single
# source of truth for what external consumers actually pull at a pinned rev,
# so a hook added/removed/renamed there can't silently drift out of sync here.
# Everything is derived from tokens[0], the hook's script: pre-commit prefixes
# only entry[0] with the hook-repo clone path, so any later token that looks
# like a path resolves against the *consuming* repo and can never name a file
# this repo ships. A hook's bundled data therefore has to be self-located
# relative to the script — vale-wrap.sh reads its own
# <script-dir>/../assets/vale/.vale.ini plus the sibling styles/ tree — which
# makes <script-dir>/../assets release-relevant alongside the script itself.
# The ../ is normalised by stripping a path component rather than with
# `realpath -m`, which is a GNU-only extension. Two guards keep the derivation
# from inventing paths: a bundle root of "." is skipped, because a script in a
# top-level directory (scripts/skill-size-check.sh) would derive the repo's own
# shared assets/, which no hook owns and whose churn must not demand a release;
# and the directory is added only when it exists, since a hook that bundles
# nothing must not contribute a pathspec matching nothing.
RELEASE_PATHS=("$HOOKS_MANIFEST")
while IFS= read -r entry; do
  read -ra tokens <<< "$entry"
  [[ ${#tokens[@]} -eq 0 ]] && continue
  RELEASE_PATHS+=("${tokens[0]}")
  bundle_root="$(dirname "$(dirname "${tokens[0]}")")"
  if [[ "$bundle_root" != "." && -d "$bundle_root/assets" ]]; then
    RELEASE_PATHS+=("$bundle_root/assets")
  fi
done < <(sed -n 's/^[[:space:]]*entry:[[:space:]]*//p' "$HOOKS_MANIFEST")

# Only vX.Y.Z release tags count as a baseline — an incidental checkpoint or
# experiment tag reachable from HEAD must not shift the diff baseline.
LAST_TAG="$(git describe --tags --abbrev=0 --match 'v[0-9]*.[0-9]*.[0-9]*' 2>/dev/null || true)"

if [[ -z "$LAST_TAG" ]]; then
  echo "FAIL: no release tag exists yet, but .pre-commit-hooks.yaml already exposes hooks to external consumers." >&2
  echo "  Fix: cut the first release tag (e.g. v1.0.0) before this lands on main." >&2
  exit 1
fi

# No -e/existence filtering: a path deleted since $LAST_TAG is exactly the case
# that must be caught (external consumers pinning the old tag would hit a
# missing file), and `git diff` reports deletions fine without it existing at
# HEAD. A git failure (e.g. a shallow clone missing $LAST_TAG's history) must
# fail closed, not be swallowed into an empty, falsely-clean diff.
if ! CHANGED="$(git diff --name-only "$LAST_TAG"..HEAD -- "${RELEASE_PATHS[@]}")"; then
  echo "FAIL: could not diff $LAST_TAG..HEAD to check for release-relevant changes (see git error above)." >&2
  echo "  Fix: ensure full tag history is available (e.g. git fetch --unshallow) and retry." >&2
  exit 1
fi

if [[ -n "$CHANGED" ]]; then
  echo "FAIL: files covered by .pre-commit-hooks.yaml changed since $LAST_TAG:" >&2
  echo "$CHANGED" | sed 's/^/    /' >&2
  echo "  Fix: cut a new release tag — external consumers pinning rev: $LAST_TAG would miss this change." >&2
  exit 1
fi