feat: add nethergamesmc core install flow

lib/validation.sh

@@ -0,0 +1,73 @@
+#!/usr/bin/env bash
+
+validate_root_usage() {
+  if [[ "$(id -u)" -ne 0 ]]; then
+    fail "$(t root_required)"
+  fi
+}
+
+validate_core_support() {
+  local supported_cores="pmmp,paper,purpur,velocity,powernukkitx,nethergamesmc"
+  local supported_os="ubuntu,debian"
+  local planned_os="arch,fedora,rocky,almalinux"
+
+  case "$CORE" in
+    pmmp|paper|purpur|velocity|powernukkitx|nethergamesmc)
+      ;;
+    *)
+      fail "$(t unsupported_core "$CORE" "$supported_cores" "${SCRIPT_DIR}/manifests/cores.json")"
+      ;;
+  esac
+
+  case "$OS_ID" in
+    ubuntu|debian)
+      return 0
+      ;;
+    arch|fedora|rocky|almalinux)
+      warn "$(t os_coreplanned "$OS_ID" "${SCRIPT_DIR}/manifests/os-support.json")"
+      ;;
+    *)
+      fail "$(t unsupported_os "$OS_ID" "$supported_os" "$planned_os" "${SCRIPT_DIR}/manifests/os-support.json")"
+      ;;
+  esac
+}
+
+validate_eula() {
+  if ! is_java_core "$CORE"; then
+    return 0
+  fi
+
+  if [[ "${ACCEPT_EULA,,}" != "yes" ]]; then
+    fail "$(t eula_denied)"
+  fi
+}
+
+validate_port() {
+  local port="$1"
+  local protocol="$2"
+
+  if ! command -v ss >/dev/null 2>&1; then
+    if command -v lsof >/dev/null 2>&1; then
+      if [[ "$protocol" == "tcp" ]]; then
+        if lsof -iTCP:"$port" -sTCP:LISTEN -n -P >/dev/null 2>&1; then
+          fail "$(t tcp_port_in_use "$port")"
+        fi
+      else
+        if lsof -iUDP:"$port" -n -P >/dev/null 2>&1; then
+          fail "$(t udp_port_in_use "$port")"
+        fi
+      fi
+      return 0
+    fi
+  fi
+
+  if [[ "$protocol" == "tcp" ]]; then
+    if ss -ltn | awk '{print $4}' | grep -q ":${port}$"; then
+      fail "$(t tcp_port_in_use "$port")"
+    fi
+  else
+    if ss -lun | awk '{print $5}' | grep -q ":${port}$"; then
+      fail "$(t udp_port_in_use "$port")"
+    fi
+  fi
+}