#!/bin/sh
set -e

log() {
    # send messages to stderr so Docker logs capture them even if stdout is used by CoreDNS
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1" >&2
}

# Attempt to fetch .alt root hints from known sources
generate_alt_forwards() {
    # try hostnames first
    log "Fetching .alt hints from alt.root-servers.org (may require external DNS)"
    hints=$(curl --connect-timeout 5 --max-time 8 -fsSL https://alt.root-servers.org/hints.txt 2>/dev/null || true)
    if [ -z "$hints" ]; then
        log "hostname fetch failed, trying hard-coded IP fallback"
        hints=$(curl --connect-timeout 5 --max-time 8 -fsSL http://185.121.177.177/hints.txt 2>/dev/null || true)
    fi
    if [ -z "$hints" ]; then
        log "no hints available, leaving placeholder intact"
        return
    fi
    echo "$hints" | awk '{print "  forward . " $1 ":53"}'
}

# Replace placeholder in Corefile with actual forwards (or leave empty)
update_corefile() {
    forwards=$(generate_alt_forwards)
    if [ -n "$forwards" ]; then
        log "updating Corefile alt forwards"
        awk -v fwd="$forwards" '
        /#ALT_FORWARDS/ {
            print fwd; next
        }
        { print }
        ' /Corefile > /Corefile.new && mv /Corefile.new /Corefile
    fi
}

log "running entrypoint"
update_corefile

# Exec CoreDNS with provided arguments
exec /coredns "$@"