package com.sun.jndi.ldap;

import javax.naming.NamingException;
import java.util.ArrayList;
import java.util.Hashtable;
import java.util.List;
import java.util.function.BiFunction;

public class DefaultLdapDnsProvider implements
        BiFunction<String, Hashtable<?,?>, List<String>>
{

    @Override
    public List<String> apply(String url, Hashtable<?,?> env) {
        List<String> urls = new ArrayList<>();
        try {
            LdapURL ldapUrl = new LdapURL(url);
            String dn = ldapUrl.getDN();
            String host = ldapUrl.getHost();
            int port = ldapUrl.getPort();
            String[] hostports;
            String domainName = null;

            // handle a URL with no hostport (ldap:/// or ldaps:///)
            // locate the LDAP service using the URL's distinguished name
            if (host == null
                    && port == -1
                    && dn != null
                    && ServiceLocator.mapDnToDomainName(dn) != null
                    && (hostports = ServiceLocator.getLdapService(domainName, env)) != null)
            {
                // Generate new URLs that include the discovered hostports.
                // Reuse the original URL scheme.
                String scheme = ldapUrl.getScheme() + "://";
                String query = ldapUrl.getQuery();
                String urlSuffix = ldapUrl.getPath() + (query != null ? query : "");
                for (int i = 0; i < hostports.length; i++) {
                    urls.add(scheme + hostports[i] + urlSuffix);
                }
            } else {
                urls.add(url);
            }
        } catch (NamingException e) {
            // leave list of resolved urls empty
        }
        return urls;
    }

}