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

# ------------------------------------------------------------
# Optional env overrides (with safe defaults)
# ------------------------------------------------------------
: "${BUSYBOX_IMAGE:?Missing Busybox image}"
: "${NODE_IMAGE?Missing Node image; pass it empty to skip the getaddrinfo check}"

: "${DOMAIN:?Missing env DOMAIN}"

SUBDOMAIN="foo.${DOMAIN}"

section() {
  echo
  echo "------------------------------------------------------------"
  echo "$1"
  echo "------------------------------------------------------------"
}

ok()   { echo "OK:   $*"; }
fail() { echo "FAIL: $*"; exit 1; }

section "Wait for dockerd (DinD)"

for i in $(seq 1 60); do
  if [ -S /var/run/docker.sock ] && container info >/dev/null 2>&1; then
    ok "dockerd ready"
    break
  fi
  echo "waiting for dockerd... (${i}/60)" >&2
  sleep 1
done

[ -S /var/run/docker.sock ] || fail "docker.sock missing after waiting"
container info >/dev/null 2>&1 || fail "container info still failing after waiting"

section "Docker-in-Docker DNS (busybox: A + no SERVFAIL)"

container run --rm "${BUSYBOX_IMAGE}" sh -lc "
  set -e

  test_lookup_a() {
    name=\"\$1\"
    out=\$(nslookup \"\$name\" 2>&1 || true)
    echo \"\$out\"
    echo \"\$out\" | grep -qE \"^Address: [0-9]\" || {
      echo \"A lookup returned no address for \$name\"
      exit 1
    }
  }

  # We don't require AAAA, but we must never see SERVFAIL (that broke Node/getaddrinfo).
  test_lookup_no_servfail() {
    name=\"\$1\"
    out=\$(nslookup \"\$name\" 2>&1 || true)
    echo \"\$out\"
    if echo \"\$out\" | grep -q \"SERVFAIL\"; then
      echo \"DNS lookup returned SERVFAIL for \$name\"
      exit 1
    fi
  }

  test_lookup_a \"${DOMAIN}\"
  test_lookup_a \"${SUBDOMAIN}\"

  test_lookup_no_servfail \"${DOMAIN}\"
  test_lookup_no_servfail \"${SUBDOMAIN}\"
"

ok "Inner container DNS works (A present; no SERVFAIL)"

if [ -z "${NODE_IMAGE}" ]; then
  section "Docker-in-Docker DNS (node/getaddrinfo): skipped, NODE_IMAGE is empty"
else
  section "Docker-in-Docker DNS (node/getaddrinfo)"

  container run --rm "${NODE_IMAGE}" sh -lc "
    set -e
    node -e \"
      const dns = require('dns');
      dns.lookup('${DOMAIN}', { all: true }, (e, a) => {
        console.log('err', e && e.code, e && e.message);
        console.log('addrs', a);
        process.exit(e ? 1 : 0);
      });
    \"
  "

  ok "Node/getaddrinfo DNS works"
fi

echo
echo "============================================================"
echo "DNS health check completed successfully."
echo "============================================================"