#!/bin/sh
set -u

INTERVAL_MINUTES="${SYNC_INTERVAL:-1}"
APPLY_MODE="${DNS_SYNC_APPLY:-false}"
STATE_DB="${DNS_SYNC_STATE_DB:-/var/lib/dns-sync/state.sqlite3}"
MAX_CHANGES="${DNS_SYNC_MAX_CHANGES:-}"

case "$INTERVAL_MINUTES" in
    ''|*[!0-9]*)
        echo "ERROR: SYNC_INTERVAL must be an integer number of minutes" >&2
        exit 1
        ;;
esac

if [ "$INTERVAL_MINUTES" -lt 1 ]; then
    echo "ERROR: SYNC_INTERVAL must be at least 1 minute" >&2
    exit 1
fi

case "$(printf '%s' "$APPLY_MODE" | tr '[:upper:]' '[:lower:]')" in
    1|true|yes|on)
        APPLY_MODE=true
        ;;
    0|false|no|off)
        APPLY_MODE=false
        ;;
    *)
        echo "ERROR: DNS_SYNC_APPLY must be true or false" >&2
        exit 1
        ;;
esac

if [ -n "$MAX_CHANGES" ]; then
    case "$MAX_CHANGES" in
        *[!0-9]*)
            echo "ERROR: DNS_SYNC_MAX_CHANGES must be a non-negative integer" >&2
            exit 1
            ;;
    esac
fi

INTERVAL_SECONDS=$((INTERVAL_MINUTES * 60))
sleep_pid=""

shutdown() {
    echo "Stopping DNS sync service..."
    [ -z "$sleep_pid" ] || kill "$sleep_pid" 2>/dev/null || true
    exit 0
}

trap shutdown INT TERM

run_reconcile() {
    if [ "$APPLY_MODE" = true ]; then
        if [ -n "$MAX_CHANGES" ]; then
            python -m dns_sync reconcile \
                --state-db "$STATE_DB" \
                --apply \
                --max-changes "$MAX_CHANGES"
        else
            python -m dns_sync reconcile \
                --state-db "$STATE_DB" \
                --apply
        fi
    else
        python -m dns_sync reconcile \
            --state-db "$STATE_DB"
    fi
}

echo "DNS sync service started"
echo "Sync interval: ${INTERVAL_MINUTES} minute(s)"
echo "Reconciliation mode: $([ "$APPLY_MODE" = true ] && echo APPLY || echo READ-ONLY)"
echo "State database: ${STATE_DB}"
echo "Enabled plugins: ${ENABLED_PLUGINS:-npm}"
echo "External plugin path: ${DNS_SYNC_PLUGIN_PATH:-/plugins}"

while :; do
    echo
    echo "=== DNS reconciliation: $(date -Iseconds) ==="

    if run_reconcile; then
        echo "Reconciliation run completed successfully"
    else
        rc=$?
        echo "ERROR: Reconciliation run failed with exit code ${rc}" >&2
    fi

    sleep "$INTERVAL_SECONDS" &
    sleep_pid=$!
    wait "$sleep_pid" || true
    sleep_pid=""
done