// Copyright (C) 2012  Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

#include <datasrc/memory/zone_data_loader.h>
#include <datasrc/memory/zone_data_updater.h>
#include <datasrc/memory/logger.h>
#include <datasrc/memory/segment_object_holder.h>

#include <dns/rdataclass.h>
#include <dns/rrset.h>
#include <dns/masterload.h>

#include <boost/foreach.hpp>
#include <boost/bind.hpp>
#include <boost/noncopyable.hpp>

#include <map>

using namespace isc::dns;
using namespace isc::dns::rdata;

namespace isc {
namespace datasrc {
namespace memory {

using detail::SegmentObjectHolder;

namespace { // unnamed namespace

// A functor type used for loading.
typedef boost::function<void(isc::dns::ConstRRsetPtr)> LoadCallback;

// A helper internal class for \c loadZoneData().  make it non-copyable
// to avoid accidental copy.
//
// The current internal implementation expects that both a normal
// (non RRSIG) RRset and (when signed) its RRSIG are added at once.
// Also in the current implementation, the input sequence of RRsets
// are grouped with their owner name (so once a new owner name is encountered,
// no subsequent RRset has the previous owner name), but the ordering
// in the same group is not fixed.  So we hold all RRsets of the same
// owner name in node_rrsets_ and node_rrsigsets_, and add the matching
// pairs of RRsets to the zone when we see a new owner name.
//
// The caller is responsible for adding the RRsets of the last group
// in the input sequence by explicitly calling flushNodeRRsets() at the
// end.  It's cleaner and more robust if we let the destructor of this class
// do it, but since we cannot guarantee the adding operation is exception free,
// we don't choose that option to maintain the common expectation for
// destructors.
class ZoneDataLoader : boost::noncopyable {
public:
    ZoneDataLoader(util::MemorySegment& mem_sgmt,
                   const isc::dns::RRClass rrclass,
                   const isc::dns::Name& zone_name, ZoneData& zone_data) :
        updater_(mem_sgmt, rrclass, zone_name, zone_data)
    {}

    void addFromLoad(const isc::dns::ConstRRsetPtr& rrset);
    void flushNodeRRsets();

private:
    typedef std::map<isc::dns::RRType, isc::dns::ConstRRsetPtr> NodeRRsets;
    typedef NodeRRsets::value_type NodeRRsetsVal;

    // A helper to identify the covered type of an RRSIG.
    static isc::dns::RRType getCoveredType
        (const isc::dns::ConstRRsetPtr& sig_rrset);
    const isc::dns::Name& getCurrentName() const;

private:
    NodeRRsets node_rrsets_;
    NodeRRsets node_rrsigsets_;
    ZoneDataUpdater updater_;
};

void
ZoneDataLoader::addFromLoad(const ConstRRsetPtr& rrset) {
    // If we see a new name, flush the temporary holders, adding the
    // pairs of RRsets and RRSIGs of the previous name to the zone.
    if ((!node_rrsets_.empty() || !node_rrsigsets_.empty()) &&
        (getCurrentName() != rrset->getName())) {
        flushNodeRRsets();
    }

    // Store this RRset until it can be added to the zone.  The current
    // implementation requires RRs of the same RRset should be added at
    // once, so we check the "duplicate" here.
    const bool is_rrsig = rrset->getType() == RRType::RRSIG();
    NodeRRsets& node_rrsets = is_rrsig ? node_rrsigsets_ : node_rrsets_;
    const RRType& rrtype = is_rrsig ? getCoveredType(rrset) : rrset->getType();
    if (!node_rrsets.insert(NodeRRsetsVal(rrtype, rrset)).second) {
        isc_throw(ZoneDataUpdater::AddError,
                  "Duplicate add of the same type of"
                  << (is_rrsig ? " RRSIG" : "") << " RRset: "
                  << rrset->getName() << "/" << rrtype);
    }

    if (rrset->getRRsig()) {
        addFromLoad(rrset->getRRsig());
    }
}

void
ZoneDataLoader::flushNodeRRsets() {
    BOOST_FOREACH(NodeRRsetsVal val, node_rrsets_) {
        // Identify the corresponding RRSIG for the RRset, if any.  If
        // found add both the RRset and its RRSIG at once.
        ConstRRsetPtr sig_rrset;
        NodeRRsets::iterator sig_it = node_rrsigsets_.find(val.first);
        if (sig_it != node_rrsigsets_.end()) {
            sig_rrset = sig_it->second;
            node_rrsigsets_.erase(sig_it);
        }
        updater_.add(val.second, sig_rrset);
    }

    // Right now, we don't accept RRSIG without covered RRsets (this
    // should eventually allowed, but to do so we'll need to update the
    // finder).
    if (!node_rrsigsets_.empty()) {
        isc_throw(ZoneDataUpdater::AddError,
                  "RRSIG is added without covered RRset for "
                  << getCurrentName());
    }

    node_rrsets_.clear();
    node_rrsigsets_.clear();
}

RRType
ZoneDataLoader::getCoveredType(const ConstRRsetPtr& sig_rrset) {
    RdataIteratorPtr it = sig_rrset->getRdataIterator();
    // Empty RRSIG shouldn't be passed either via a master file or
    // another data source iterator, but it could still happen if the
    // iterator has a bug.  We catch and reject such cases.
    if (it->isLast()) {
        isc_throw(isc::Unexpected,
                  "Empty RRset is passed in-memory loader, name: "
                  << sig_rrset->getName());
    }
    return (dynamic_cast<const generic::RRSIG&>(it->getCurrent()).
            typeCovered());
}

const Name&
ZoneDataLoader::getCurrentName() const {
    if (!node_rrsets_.empty()) {
        return (node_rrsets_.begin()->second->getName());
    }
    assert(!node_rrsigsets_.empty());
    return (node_rrsigsets_.begin()->second->getName());
}

ZoneData*
loadZoneDataInternal(util::MemorySegment& mem_sgmt,
                     const isc::dns::RRClass& rrclass,
                     const Name& zone_name,
                     boost::function<void(LoadCallback)> rrset_installer)
{
    SegmentObjectHolder<ZoneData, RRClass> holder(
        mem_sgmt, ZoneData::create(mem_sgmt, zone_name), rrclass);

    ZoneDataLoader loader(mem_sgmt, rrclass, zone_name, *holder.get());
    rrset_installer(boost::bind(&ZoneDataLoader::addFromLoad, &loader, _1));
    // Add any last RRsets that were left
    loader.flushNodeRRsets();

    const ZoneNode* origin_node = holder.get()->getOriginNode();
    const RdataSet* rdataset = origin_node->getData();
    // If the zone is NSEC3-signed, check if it has NSEC3PARAM
    if (holder.get()->isNSEC3Signed()) {
        if (RdataSet::find(rdataset, RRType::NSEC3PARAM()) == NULL) {
            LOG_WARN(logger, DATASRC_MEMORY_MEM_NO_NSEC3PARAM).
                arg(zone_name).arg(rrclass);
        }
    }

    // When an empty zone file is loaded, the origin doesn't even have
    // an SOA RR. This condition should be avoided, and hence load()
    // should throw when an empty zone is loaded.
    if (RdataSet::find(rdataset, RRType::SOA()) == NULL) {
        isc_throw(EmptyZone,
                  "Won't create an empty zone for: " << zone_name);
    }

    return (holder.release());
}

// A wrapper for dns::masterLoad used by loadZoneData() below.  Essentially it
// converts the two callback types.  Note the mostly redundant wrapper of
// boost::bind.  It converts function<void(ConstRRsetPtr)> to
// function<void(RRsetPtr)> (masterLoad() expects the latter).  SunStudio
// doesn't seem to do this conversion if we just pass 'callback'.
void
masterLoadWrapper(const char* const filename, const Name& origin,
                  const RRClass& zone_class, LoadCallback callback)
{
    masterLoad(filename, origin, zone_class, boost::bind(callback, _1));
}

// The installer called from the iterator version of loadZoneData().
void
generateRRsetFromIterator(ZoneIterator* iterator, LoadCallback callback) {
    ConstRRsetPtr rrset;
    while ((rrset = iterator->getNextRRset()) != NULL) {
        callback(rrset);
    }
}

} // end of unnamed namespace

ZoneData*
loadZoneData(util::MemorySegment& mem_sgmt,
             const isc::dns::RRClass& rrclass,
             const isc::dns::Name& zone_name,
             const std::string& zone_file)
{
     return (loadZoneDataInternal(mem_sgmt, rrclass, zone_name,
                                 boost::bind(masterLoadWrapper,
                                             zone_file.c_str(),
                                             zone_name, rrclass,
                                             _1)));
}

ZoneData*
loadZoneData(util::MemorySegment& mem_sgmt,
             const isc::dns::RRClass& rrclass,
             const isc::dns::Name& zone_name,
             ZoneIterator& iterator)
{
    return (loadZoneDataInternal(mem_sgmt, rrclass, zone_name,
                                 boost::bind(generateRRsetFromIterator,
                                             &iterator, _1)));
}

} // namespace memory
} // namespace datasrc
} // namespace isc