import dns from "node:dns/promises";
import net from "node:net";

import { getConfig } from "@app/lib/config/env";
import { BadRequestError } from "@app/lib/errors";
import { isPrivateIp } from "@app/lib/ip/ipRange";
import { getDbConnectionHost } from "@app/lib/knex";

export const verifyHostInputValidity = async (host: string, isGateway = false) => {
  const appCfg = getConfig();

  if (appCfg.isDevelopmentMode) return [host];

  const reservedHosts = [appCfg.DB_HOST || getDbConnectionHost(appCfg.DB_CONNECTION_URI)].concat(
    (appCfg.DB_READ_REPLICAS || []).map((el) => getDbConnectionHost(el.DB_CONNECTION_URI)),
    getDbConnectionHost(appCfg.REDIS_URL),
    getDbConnectionHost(appCfg.AUDIT_LOGS_DB_CONNECTION_URI)
  );

  // get host db ip
  const exclusiveIps: string[] = [];
  for await (const el of reservedHosts) {
    if (el) {
      if (net.isIPv4(el)) {
        exclusiveIps.push(el);
      } else {
        try {
          const resolvedIps = await dns.resolve4(el);
          exclusiveIps.push(...resolvedIps);
        } catch (error) {
          // only try lookup if not found
          if ((error as { code: string })?.code !== "ENOTFOUND") throw error;

          const resolvedIps = (await dns.lookup(el, { all: true, family: 4 })).map(({ address }) => address);
          exclusiveIps.push(...resolvedIps);
        }
      }
    }
  }

  const normalizedHost = host.split(":")[0];
  const inputHostIps: string[] = [];
  if (net.isIPv4(host)) {
    inputHostIps.push(host);
  } else {
    if (normalizedHost === "localhost" || normalizedHost === "host.docker.internal") {
      throw new BadRequestError({ message: "Invalid db host" });
    }
    try {
      const resolvedIps = await dns.resolve4(host);
      inputHostIps.push(...resolvedIps);
    } catch (error) {
      // only try lookup if not found
      if ((error as { code: string })?.code !== "ENOTFOUND") throw error;

      const resolvedIps = (await dns.lookup(host, { all: true, family: 4 })).map(({ address }) => address);
      inputHostIps.push(...resolvedIps);
    }
  }

  if (!isGateway && !(appCfg.DYNAMIC_SECRET_ALLOW_INTERNAL_IP || appCfg.ALLOW_INTERNAL_IP_CONNECTIONS)) {
    const isInternalIp = inputHostIps.some((el) => isPrivateIp(el));
    if (isInternalIp) throw new BadRequestError({ message: "Invalid db host" });
  }

  const isAppUsedIps = inputHostIps.some((el) => exclusiveIps.includes(el));
  if (isAppUsedIps) throw new BadRequestError({ message: "Invalid db host" });
  return inputHostIps;
};