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

# Fails a push when a skill changed without its SKILL.md `metadata.version`
# being bumped. ADR-0022 makes the field mandatory and the bump the rule; this
# is the gate that holds the rule, since skill-size-check only checks presence
# and shape.
#
# Baseline: `git merge-base <main> <pushed ref>`. Readers install skills from
# main, so "changed" means changed relative to what main ships, not relative to
# the remote branch's current tip. Diffing from PRE_COMMIT_FROM_REF would let
# the second push of a feature branch excuse a change the first push already
# carried unbumped. Unlike check-release-needed this runs on EVERY push, not
# only pushes to main: a missing bump is cheapest to fix on the branch, before
# review, and a push to main is then already covered.
#
# Scope: every skill directory plugins/<plugin>/.apm/skills/<skill>/, bin
# included. Anything under <skill>/tests/ is ignored — no agent ever loads it,
# so a test-only change ships nothing to a reader. A skill counts as changed
# when any other file under its directory differs between baseline and pushed
# ref. Renames are diffed as delete + add (--no-renames), so:
#   - a skill absent at the baseline (new, renamed-to, merged-into) is exempt;
#     it has no prior version to exceed.
#   - a skill absent at the pushed ref (deleted, renamed-from) is exempt;
#     there is nothing left to version.
# A changed skill present at both refs must carry a three-part semver
# `metadata.version` at the pushed ref (same SEMVER_RE as skill-size-check.sh,
# so pre-release suffixes are rejected here as they are there) that is
# numerically greater than the baseline's. A baseline with no parseable
# version (a skill predating ADR-0022) accepts any valid version. Versions are
# read from git objects, never the working tree.
#
# Missing baseline: if neither origin/main nor main resolves, or no merge-base
# exists (shallow clone, unrelated history), the gate FAILS closed — the same
# choice check-release-needed makes for an unreadable tag. Passing would make
# a fresh clone without main the one place the rule is silently off.
#
# Known gap: this only fires on a local `git push` through pre-commit's
# pre-push hook (or a manual `pre-commit run --hook-stage pre-push`). A PR
# merged via Gitea's merge button runs no local hook at all — closing that
# requires a server-side CI job, which this repo does not have yet.

# See check-release-needed.sh: PRE_COMMIT_TO_REF is the local sha actually
# being pushed, which is only HEAD for the common case.
PUSHED_REF="${PRE_COMMIT_TO_REF:-HEAD}"

# All-zeros sha: the push deletes a branch. Nothing ships; bail out.
if [[ "$PUSHED_REF" =~ ^0+$ ]]; then
  exit 0
fi

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

MAIN_REF=""
for candidate in origin/main main; do
  if git rev-parse --verify -q "$candidate^{commit}" > /dev/null; then
    MAIN_REF="$candidate"
    break
  fi
done

if [[ -z "$MAIN_REF" ]]; then
  echo "FAIL: neither origin/main nor main resolves, so there is no baseline to compare skill versions against." >&2
  echo "  Fix: git fetch origin main (or create a local main) and retry." >&2
  exit 1
fi

if ! BASELINE="$(git merge-base "$MAIN_REF" "$PUSHED_REF" 2>/dev/null)"; then
  echo "FAIL: no merge-base between $MAIN_REF and $PUSHED_REF, so there is no baseline to compare skill versions against." >&2
  echo "  Fix: ensure full history is available (e.g. git fetch --unshallow) and retry." >&2
  exit 1
fi

if ! CHANGED="$(git diff --no-renames --name-only "$BASELINE" "$PUSHED_REF" -- plugins)"; then
  echo "FAIL: could not diff $BASELINE..$PUSHED_REF (see git error above)." >&2
  exit 1
fi

SKILL_PATH_RE='^(plugins/[^/]+/\.apm/skills/[^/]+)/(.+)$'
SKILL_DIRS=()
while IFS= read -r path; do
  [[ "$path" =~ $SKILL_PATH_RE ]] || continue
  [[ "${BASH_REMATCH[2]}" == tests/* ]] && continue
  dir="${BASH_REMATCH[1]}"
  seen=false
  for existing in ${SKILL_DIRS[@]+"${SKILL_DIRS[@]}"}; do
    [[ "$existing" == "$dir" ]] && { seen=true; break; }
  done
  $seen || SKILL_DIRS+=("$dir")
done <<< "$CHANGED"

[[ ${#SKILL_DIRS[@]} -eq 0 ]] && exit 0

# Prints the three-part semver metadata.version from SKILL.md on stdin, or
# nothing when it is missing or malformed. Same acceptance rule as
# skill-size-check.sh: str()-coerce, strip whitespace and quotes, then
# ^\d+\.\d+\.\d+$ — so `1.0` (a YAML float) and `1.0.0-rc1` both print nothing.
read_version() {
  python3 -c '
import re, sys, yaml
text = sys.stdin.read()
m = re.match(r"^---\s*\n(.*?)\n---\s*(\n|$)", text, re.S)
if not m:
    sys.exit(0)
try:
    data = yaml.safe_load(m.group(1))
except Exception:
    sys.exit(0)
meta = data.get("metadata") if isinstance(data, dict) else None
ver = meta.get("version") if isinstance(meta, dict) else None
if ver is None:
    sys.exit(0)
ver = str(ver).strip().strip("\x27\"")
if re.match(r"^\d+\.\d+\.\d+$", ver):
    print(ver)
'
}

# Exit 0 when $1 > $2, both MAJOR.MINOR.PATCH, compared numerically so
# 1.0.10 > 1.0.9. 10# forces base 10 on a leading zero.
semver_gt() {
  local -a a b
  local i
  IFS=. read -ra a <<< "$1"
  IFS=. read -ra b <<< "$2"
  for i in 0 1 2; do
    if (( 10#${a[i]} > 10#${b[i]} )); then return 0; fi
    if (( 10#${a[i]} < 10#${b[i]} )); then return 1; fi
  done
  return 1
}

OFFENDERS=()
for dir in ${SKILL_DIRS[@]+"${SKILL_DIRS[@]}"}; do
  # Absent at baseline: new, renamed-to, or merged-into. Exempt.
  git cat-file -e "$BASELINE:$dir/SKILL.md" 2>/dev/null || continue
  # Absent at pushed ref: deleted or renamed-from. Exempt.
  [[ "$(git cat-file -t "$PUSHED_REF:$dir" 2>/dev/null)" == "tree" ]] || continue

  base_ver="$(git show "$BASELINE:$dir/SKILL.md" | read_version)"
  cur_ver="$(git show "$PUSHED_REF:$dir/SKILL.md" 2>/dev/null | read_version || true)"

  if [[ -z "$cur_ver" ]]; then
    OFFENDERS+=("$dir: metadata.version missing or not MAJOR.MINOR.PATCH at $PUSHED_REF (baseline: ${base_ver:-none})")
  elif [[ -n "$base_ver" ]] && ! semver_gt "$cur_ver" "$base_ver"; then
    OFFENDERS+=("$dir: $base_ver -> $cur_ver")
  fi
done

if [[ ${#OFFENDERS[@]} -gt 0 ]]; then
  echo "FAIL: skills changed since merge-base with $MAIN_REF without a metadata.version bump (ADR-0022):" >&2
  printf '    %s\n' ${OFFENDERS[@]+"${OFFENDERS[@]}"} >&2
  echo "  Fix: raise metadata.version in each SKILL.md above the baseline — bump PATCH at minimum." >&2
  exit 1
fi