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

ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
cd "$ROOT"

ts="$(date -u +"%Y-%m-%dT%H:%M:%SZ")"
safe_ts="$(date -u +"%Y-%m-%dT%H-%M-%SZ")"
note="${1:-}"

mkdir -p out/checkpoints

echo "== running ci ==" >&2
ci_json="$(./scripts/ci.sh)"
echo "$ci_json" > "out/checkpoints/ci_${safe_ts}.json"

echo "== writing session state ==" >&2
./scripts/state.sh >/dev/null

git_branch="(unknown)"
git_head_short=""
dirty_count="0"
modified_count="0"
untracked_count="0"
diffstat=""
diffstat_lines="0"
diffstat_note=""

if git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
  git_branch="$(git rev-parse --abbrev-ref HEAD 2>/dev/null || echo "(unknown)")"
  git_head_short="$(git rev-parse --short HEAD 2>/dev/null || echo "")"
  porcelain="$(git status --porcelain=v1 2>/dev/null || true)"
  if [ -n "${porcelain}" ]; then
    dirty_count="$(printf "%s\n" "${porcelain}" | wc -l | awk '{print $1}')"
    untracked_count="$(printf "%s\n" "${porcelain}" | grep -c '^??' || true)"
    modified_count="$(printf "%s\n" "${porcelain}" | grep -vc '^??' || true)"
  fi
  diffstat="$(git diff --stat 2>/dev/null || true)"
  if [ -n "${diffstat}" ]; then
    diffstat_lines="$(printf "%s\n" "${diffstat}" | wc -l | awk '{print $1}')"
    if [ "${diffstat_lines}" -gt 200 ]; then
      diffstat="$(printf "%s\n" "${diffstat}" | head -n 200)"
      diffstat_note="(diffstat truncated to first 200 lines)"
    fi
  fi
fi

tar_path="out/checkpoints/iftypeset_checkpoint_${safe_ts}.tar.gz"
details_path="out/checkpoints/checkpoint_${safe_ts}.md"

echo "== creating snapshot ${tar_path} ==" >&2
snapshot_paths=(.forgejo .gitignore README.md STATUS.md app docs fixtures forgejo pyproject.toml requirements.txt scripts spec src tests tools)
if [ -f AGENTS.md ]; then
  snapshot_paths+=(AGENTS.md)
fi
tar \
  --exclude=".git" \
  --exclude=".venv" \
  --exclude="out" \
  -czf "$tar_path" \
  "${snapshot_paths[@]}"

sha="$(sha256sum "$tar_path" | awk '{print $1}')"

cat > "${details_path}" <<EOF
# iftypeset checkpoint

- timestamp_utc: ${ts}
- snapshot: ${tar_path}
- snapshot_sha256: ${sha}
- ci: \`out/checkpoints/ci_${safe_ts}.json\`
- git: ${git_branch} ${git_head_short}
- working_tree: dirty_paths=${dirty_count} (modified=${modified_count}, untracked=${untracked_count})
$( [ -n "${note}" ] && printf -- "- note: %s\n" "${note}" )

## Diffstat (uncommitted changes)

${diffstat_note}

\`\`\`text
${diffstat}
\`\`\`

EOF

if [ ! -s docs/CHECKPOINTS.md ]; then
  cat > docs/CHECKPOINTS.md <<'EOF'
# Checkpoints

Durable restore points for this repo (useful when chat context resets).

How to create a checkpoint:

- `./scripts/checkpoint.sh "short note about what changed"`

Each entry records the snapshot tarball path + sha256 and the CI JSON for that moment.
EOF
fi

cat >> docs/CHECKPOINTS.md <<EOF

## ${ts}

- snapshot: \`${tar_path}\`
- snapshot_sha256: \`${sha}\`
- ci_json: \`out/checkpoints/ci_${safe_ts}.json\`
- details: \`${details_path}\`
- git: \`${git_branch}\` \`${git_head_short}\`
- working_tree: dirty_paths=${dirty_count} (modified=${modified_count}, untracked=${untracked_count})
$( [ -n "${note}" ] && printf -- "- note: %s\n" "${note}" )

EOF

echo "checkpoint complete: ${tar_path} (sha256=${sha})" >&2