#!/bin/sh
# postinst — deb install and upgrade paths (spec §7).
#
# dpkg calls: postinst configure [most-recently-configured-version]
#   fresh install: $1 = "configure", $2 = ""
#   upgrade:       $1 = "configure", $2 = old version
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 — snapshot, migration, daemon-reload, conditional timer restart
            if [ -f "${STORE_DB}" ]; then
                cp "${STORE_DB}" "${STORE_BAK}" 2>/dev/null || true
            fi
            if [ -x "${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('${STORE_DB}'))
print(f'Fenris migration: {n} step(s) applied') if n else None
" 2>&1 || echo "Fenris: migration skipped (store not yet initialized)"
            fi
            # Capture running unit content BEFORE daemon-reload (spec §7)
            RUNNING_UNITS=""
            for unit in fenris-collect.timer; do
                if systemctl is-active --quiet "${unit}" 2>/dev/null; then
                    RUNNING_UNITS="${RUNNING_UNITS} ${unit}"
                fi
            done
            systemctl daemon-reload 2>/dev/null || true
            # Restart timer only if unit contents changed AND active
            for unit in ${RUNNING_UNITS}; do
                OLD_CONTENT="$(mktemp)"
                NEW_PATH="/usr/lib/systemd/system/${unit}"
                systemctl cat "${unit}" > "${OLD_CONTENT}" 2>/dev/null || true
                if ! diff -q "${OLD_CONTENT}" "${NEW_PATH}" > /dev/null 2>&1; then
                    systemctl restart "${unit}" 2>/dev/null || true
                fi
                rm -f "${OLD_CONTENT}"
            done
        fi
        # sysusers, tmpfiles, daemon-reload (both fresh install and upgrade)
        systemd-sysusers  || true
        systemd-tmpfiles --create  || true
        systemctl daemon-reload  || true
        ;;
    abort-upgrade|abort-install|disappear)
        ;;
esac