#!/bin/sh
# postinst — install and upgrade paths (spec §7).
#
# dpkg calls: postinst configure [most-recently-configured-version]
#   fresh install: $1 = "configure"
#   upgrade:       $1 = "configure"  (old version as $2 when available)
#
# rpm calls: %post $1 = 1 (fresh install) / 2 (upgrade)
#   (handled by packaging/rpm/post.sh)
#
# Install:  sysusers, tmpfiles, daemon-reload — nothing else (dormant).
# Upgrade:  snapshot, migration, daemon-reload, conditional timer restart.
set -eu

STORE_DIR="/var/lib/fenris"
STORE_DB="${STORE_DIR}/observations.db"
STORE_BAK="${STORE_DIR}/observations.db.bak"
VENV_PYTHON="/opt/fenris/bin/python3"

case "${1:-}" in
    configure)
        if [ -n "${2:-}" ]; then
            # Upgrade — $2 is the old version
            # Snapshot observation store (one generation)
            if [ -f "${STORE_DB}" ]; then
                cp "${STORE_DB}" "${STORE_BAK}" 2>/dev/null || true
            fi

            # Forward-only schema migration
            if [ -x "${VENV_PYTHON}" ] && [ -f "${STORE_DB}" ]; then
                "${VENV_PYTHON}" -c "
from fenris.store import migrate_to_latest
from pathlib import Path
n = migrate_to_latest(Path('${STORE_DB}'))
print(f'Fenris migration: {n} step(s) applied') if n else None
" 2>&1 || echo "Fenris: migration skipped (store not yet initialized)"
            fi

            # Restart collect timer only if unit contents changed AND it is active
            for unit in fenris-collect.timer fenris-collect.service; do
                if systemctl is-active --quiet "${unit}" 2>/dev/null; then
                    TMPFILE="$(mktemp)"
                    systemctl cat "${unit}" > "${TMPFILE}" 2>/dev/null || true
                    UNIT_PATH="/usr/lib/systemd/system/${unit}"
                    if ! diff -q "${TMPFILE}" "${UNIT_PATH}" > /dev/null 2>&1; then
                        systemctl restart "${unit}" 2>/dev/null || true
                    fi
                    rm -f "${TMPFILE}"
                fi
            done
        fi
        # Always run on both fresh install and upgrade
        systemd-sysusers  || true
        systemd-tmpfiles --create  || true
        systemctl daemon-reload  || true
        ;;
    abort-upgrade|abort-install|disappear)
        ;;
esac