#!/usr/bin/env bash
# pre-commit — enforces breakpilot-compliance structural guardrails.
#
# 1. Blocks commits that introduce a non-test, non-generated source file > 500 LOC.
# 2. Blocks commits that touch backend-compliance/migrations/ unless the commit message
#    contains the marker [migration-approved] (last-resort escape hatch).
# 3. Blocks edits to .claude/settings.json, scripts/check-loc.sh, or
#    .claude/rules/loc-exceptions.txt unless [guardrail-change] is in the commit message.
#
# Bypass with --no-verify is intentionally NOT supported by the team workflow.
# CI re-runs all of these on the server side anyway.

set -euo pipefail
REPO_ROOT="$(git rev-parse --show-toplevel)"

mapfile -t staged < <(git diff --cached --name-only --diff-filter=ACM)
[[ ${#staged[@]} -eq 0 ]] && exit 0

# 1. LOC budget on staged files.
loc_targets=()
for f in "${staged[@]}"; do
  [[ -f "$REPO_ROOT/$f" ]] && loc_targets+=("$REPO_ROOT/$f")
done
if [[ ${#loc_targets[@]} -gt 0 ]]; then
  if ! "$REPO_ROOT/scripts/check-loc.sh" "${loc_targets[@]}"; then
    echo
    echo "Commit blocked: file-size budget violated. See output above."
    echo "Either split the file (preferred) or add an exception with rationale to"
    echo "  .claude/rules/loc-exceptions.txt"
    exit 1
  fi
fi

# 2. Migration directories are frozen unless explicitly approved.
if printf '%s\n' "${staged[@]}" | grep -qE '(^|/)(migrations|alembic/versions)/'; then
  if ! git log --format=%B -n 1 HEAD 2>/dev/null | grep -q '\[migration-approved\]' \
     && ! grep -q '\[migration-approved\]' "$(git rev-parse --git-dir)/COMMIT_EDITMSG" 2>/dev/null; then
    echo "Commit blocked: this change touches a migrations directory."
    echo "Database schema changes require an explicit migration plan reviewed by the DB owner."
    echo "If approved, add '[migration-approved]' to your commit message."
    exit 1
  fi
fi

# 3. Guardrail files are protected.
guarded='^(\.claude/settings\.json|\.claude/rules/loc-exceptions\.txt|scripts/check-loc\.sh|scripts/githooks/pre-commit|AGENTS\.(python|go|typescript)\.md)$'
if printf '%s\n' "${staged[@]}" | grep -qE "$guarded"; then
  if ! grep -q '\[guardrail-change\]' "$(git rev-parse --git-dir)/COMMIT_EDITMSG" 2>/dev/null; then
    echo "Commit blocked: this change modifies guardrail files."
    echo "If intentional, add '[guardrail-change]' to your commit message and explain why in the body."
    exit 1
  fi
fi

exit 0