/*

 * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package com.sun.jndi.ldap;

import com.sun.jndi.toolkit.ctx.Continuation;

import java.util.NoSuchElementException;

import java.util.Vector;

import javax.naming.*;

import javax.naming.directory.Attributes;

import javax.naming.ldap.Control;

/**

 * Basic enumeration for NameClassPair, Binding, and SearchResults.

 */

abstract class AbstractLdapNamingEnumeration<T extends NameClassPair>

        implements NamingEnumeration<T>, ReferralEnumeration<T> {

    protected Name listArg;

    private boolean cleaned = false;

    private LdapResult res;

    private LdapClient enumClnt;

    private Continuation cont;  // used to fill in exceptions

    private Vector<LdapEntry> entries = null;

    private int limit = 0;

    private int posn = 0;

    protected LdapCtx homeCtx;

    private LdapReferralException refEx = null;

    private NamingException errEx = null;

    /*

     * Record the next set of entries and/or referrals.

     */

    AbstractLdapNamingEnumeration(LdapCtx homeCtx, LdapResult answer, Name listArg,

        Continuation cont) throws NamingException {

            // These checks are to accommodate referrals and limit exceptions

            // which will generate an enumeration and defer the exception

            // to be thrown at the end of the enumeration.

            // All other exceptions are thrown immediately.

            // Exceptions shouldn't be thrown here anyhow because

            // process_return_code() is called before the constructor

            // is called, so these are just safety checks.

            if ((answer.status != LdapClient.LDAP_SUCCESS) &&

                (answer.status != LdapClient.LDAP_SIZE_LIMIT_EXCEEDED) &&

                (answer.status != LdapClient.LDAP_TIME_LIMIT_EXCEEDED) &&

                (answer.status != LdapClient.LDAP_ADMIN_LIMIT_EXCEEDED) &&

                (answer.status != LdapClient.LDAP_REFERRAL) &&

                (answer.status != LdapClient.LDAP_PARTIAL_RESULTS)) {

                // %%% need to deal with referral

                NamingException e = new NamingException(

                                    LdapClient.getErrorMessage(

                                    answer.status, answer.errorMessage));

                throw cont.fillInException(e);

            }

            // otherwise continue

            res = answer;

            entries = answer.entries;

            limit = (entries == null) ? 0 : entries.size(); // handle empty set

            this.listArg = listArg;

            this.cont = cont;

            if (answer.refEx != null) {

                refEx = answer.refEx;

            }

            // Ensures that context won't get closed from underneath us

            this.homeCtx = homeCtx;

            homeCtx.incEnumCount();

            enumClnt = homeCtx.clnt; // remember

    }

    @Override

    public final T nextElement() {

        try {

            return next();

        } catch (NamingException e) {

            // can't throw exception

            cleanup();

            return null;

        }

    }

    @Override

    public final boolean hasMoreElements() {

        try {

            return hasMore();

        } catch (NamingException e) {

            // can't throw exception

            cleanup();

            return false;

        }

    }

    /*

     * Retrieve the next set of entries and/or referrals.

     */

    private void getNextBatch() throws NamingException {

        res = homeCtx.getSearchReply(enumClnt, res);

        if (res == null) {

            limit = posn = 0;

            return;

        }

        entries = res.entries;

        limit = (entries == null) ? 0 : entries.size(); // handle empty set

        posn = 0; // reset

        // minimize the number of calls to processReturnCode()

        // (expensive when batchSize is small and there are many results)

        if ((res.status != LdapClient.LDAP_SUCCESS) ||

            ((res.status == LdapClient.LDAP_SUCCESS) &&

                (res.referrals != null))) {

            try {

                // convert referrals into a chain of LdapReferralException

                homeCtx.processReturnCode(res, listArg);

            } catch (LimitExceededException | PartialResultException e) {

                setNamingException(e);

            }

        }

        // merge any newly received referrals with any current referrals

        if (res.refEx != null) {

            if (refEx == null) {

                refEx = res.refEx;

            } else {

                refEx = refEx.appendUnprocessedReferrals(res.refEx);

            }

            res.refEx = null; // reset

        }

        if (res.resControls != null) {

            homeCtx.respCtls = res.resControls;

        }

    }

    private boolean more = true;  // assume we have something to start with

    private boolean hasMoreCalled = false;

    /*

     * Test if unprocessed entries or referrals exist.

     */

    @Override

    public final boolean hasMore() throws NamingException {

        if (hasMoreCalled) {

            return more;

        }

        hasMoreCalled = true;

        if (!more) {

            return false;

        } else {

            return (more = hasMoreImpl());

        }

    }

    /*

     * Retrieve the next entry.

     */

    @Override

    public final T next() throws NamingException {

        if (!hasMoreCalled) {

            hasMore();

        }

        hasMoreCalled = false;

        return nextImpl();

    }

    /*

     * Test if unprocessed entries or referrals exist.

     */

    private boolean hasMoreImpl() throws NamingException {

        // when page size is supported, this

        // might generate an exception while attempting

        // to fetch the next batch to determine

        // whether there are any more elements

        // test if the current set of entries has been processed

        if (posn == limit) {

            getNextBatch();

        }

        // test if any unprocessed entries exist

        if (posn < limit) {

            return true;

        } else {

            try {

                // try to process another referral

                return hasMoreReferrals();

            } catch (LdapReferralException |

                     LimitExceededException |

                     PartialResultException e) {

                cleanup();

                throw e;

            } catch (NamingException e) {

                cleanup();

                PartialResultException pre = new PartialResultException();

                pre.setRootCause(e);

                throw pre;

            }

        }

    }

    /*

     * Retrieve the next entry.

     */

    private T nextImpl() throws NamingException {

        try {

            return nextAux();

        } catch (NamingException e) {

            cleanup();

            throw cont.fillInException(e);

        }

    }

    private T nextAux() throws NamingException {

        if (posn == limit) {

            getNextBatch();  // updates posn and limit

        }

        if (posn >= limit) {

            cleanup();

            throw new NoSuchElementException("invalid enumeration handle");

        }

        LdapEntry result = entries.elementAt(posn++);

        // gets and outputs DN from the entry

        return createItem(result.DN, result.attributes, result.respCtls);

    }

    protected final String getAtom(String dn) {

        // need to strip off all but lowest component of dn

        // so that is relative to current context (currentDN)

        try {

            Name parsed = new LdapName(dn);

            return parsed.get(parsed.size() - 1);

        } catch (NamingException e) {

            return dn;

        }

    }

    protected abstract T createItem(String dn, Attributes attrs,

        Vector<Control> respCtls) throws NamingException;

    /*

     * Append the supplied (chain of) referrals onto the

     * end of the current (chain of) referrals.

     */

    @Override

    public void appendUnprocessedReferrals(LdapReferralException ex) {

        if (refEx != null) {

            refEx = refEx.appendUnprocessedReferrals(ex);

        } else {

            refEx = ex.appendUnprocessedReferrals(refEx);

        }

    }

    final void setNamingException(NamingException e) {

        errEx = e;

    }

    protected abstract AbstractLdapNamingEnumeration<? extends NameClassPair> getReferredResults(

            LdapReferralContext refCtx) throws NamingException;

    /*

     * Iterate through the URLs of a referral. If successful then perform

     * a search operation and merge the received results with the current

     * results.

     */

    protected final boolean hasMoreReferrals() throws NamingException {

        if ((refEx != null) &&

            (refEx.hasMoreReferrals() ||

             refEx.hasMoreReferralExceptions()

                && !(errEx instanceof LimitExceededException))) {

            if (homeCtx.handleReferrals == LdapClient.LDAP_REF_THROW) {

                throw (NamingException)(refEx.fillInStackTrace());

            }

            // process the referrals sequentially

            while (true) {

                LdapReferralContext refCtx =

                    (LdapReferralContext)refEx.getReferralContext(

                    homeCtx.envprops, homeCtx.reqCtls);

                try {

                    update(getReferredResults(refCtx));

                    break;

                } catch (LdapReferralException re) {

                    // record a previous exception

                    if (errEx == null) {

                        errEx = re.getNamingException();

                    }

                    refEx = re;

                    continue;

                } finally {

                    // Make sure we close referral context

                    refCtx.close();

                }

            }

            return hasMoreImpl();

        } else {

            cleanup();

            if (errEx != null) {

                throw errEx;

            }

            return (false);

        }

    }

    /*

     * Merge the entries and/or referrals from the supplied enumeration

     * with those of the current enumeration.

     */

    protected void update(AbstractLdapNamingEnumeration<? extends NameClassPair> ne) {

        // Cleanup previous context first

        homeCtx.decEnumCount();

        // New enum will have already incremented enum count and recorded clnt

        homeCtx = ne.homeCtx;

        enumClnt = ne.enumClnt;

        // Do this to prevent referral enumeration (ne) from decrementing

        // enum count because we'll be doing that here from this

        // enumeration.

        ne.homeCtx = null;

        // Record rest of information from new enum

        posn = ne.posn;

        limit = ne.limit;

        res = ne.res;

        entries = ne.entries;

        refEx = ne.refEx;

        listArg = ne.listArg;

    }

    @SuppressWarnings("deprecation")

    protected final void finalize() {

        cleanup();

    }

    protected final void cleanup() {

        if (cleaned) return; // been there; done that

        if(enumClnt != null) {

            enumClnt.clearSearchReply(res, homeCtx.reqCtls);

        }

        enumClnt = null;

        cleaned = true;

        if (homeCtx != null) {

            homeCtx.decEnumCount();

            homeCtx = null;

        }

    }

    @Override

    public final void close() {

        cleanup();

    }

}