// Copyright (C) 2010  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 <util/memory_segment.h>

#include <dns/name.h>

#include <datasrc/memory/zone_data.h>
#include <datasrc/memory/zone_table.h>
#include <datasrc/memory/domaintree.h>

#include <cassert>

using namespace std;
using namespace isc::dns;

namespace isc {
namespace datasrc {
namespace memory {
namespace {
// A simple holder to create and use some objects in this implementation
// in an exception safe manner.   It works like std::auto_ptr but much
// more simplified.
template <typename T>
class Holder {
public:
    Holder(util::MemorySegment& mem_sgmt, T* obj) :
        mem_sgmt_(mem_sgmt), obj_(obj)
    {}
    ~Holder() {
        if (obj_ != NULL) {
            T::destroy(mem_sgmt_, obj_);
        }
    }
    T* get() { return (obj_); }
    T* release() {
        T* ret = obj_;
        obj_ = NULL;
        return (ret);
    }
private:
    util::MemorySegment& mem_sgmt_;
    T* obj_;
};
}

void
ZoneTable::ZoneDataDeleter::operator()(util::MemorySegment& mem_sgmt,
                                       ZoneData* zone_data) const
{
    ZoneData::destroy(mem_sgmt, zone_data);
}

ZoneTable*
ZoneTable::create(util::MemorySegment& mem_sgmt) {
    Holder<ZoneTableTree> holder(mem_sgmt, ZoneTableTree::create(mem_sgmt));
    void* p = mem_sgmt.allocate(sizeof(ZoneTable));
    ZoneTable* zone_table = new(p) ZoneTable(holder.get());
    holder.release();
    return (zone_table);
}

void
ZoneTable::destroy(util::MemorySegment& mem_sgmt, ZoneTable* ztable) {
    ZoneTableTree::destroy(mem_sgmt, ztable->zones_.get());
    mem_sgmt.deallocate(ztable, sizeof(ZoneTable));
}

ZoneTable::AddResult
ZoneTable::addZone(util::MemorySegment& mem_sgmt, const Name& zone_name) {
    // Create a new ZoneData instance first.  If the specified name already
    // exists in the table, the new data will soon be destroyed, but we want
    // to make sure if this allocation fails the tree won't be changed to
    // provide as strong guarantee as possible.  In practice, we generally
    // expect the caller tries to add a zone only when it's a new one, so
    // this should be a minor concern.
    Holder<ZoneData> holder(mem_sgmt, ZoneData::create(mem_sgmt));

    // Get the node where we put the zone
    ZoneTableNode* node(NULL);
    switch (zones_->insert(mem_sgmt, zone_name, &node)) {
    case ZoneTableTree::SUCCESS:
    case ZoneTableTree::ALREADYEXISTS:
        // These are OK
        break;
    default:
        // Can Not Happen
        assert(false);
    }
    // Can Not Happen
    assert(node != NULL);

    // Is it empty? We either just created it or it might be nonterminal
    if (node->isEmpty()) {
        node->setData(mem_sgmt, holder.get());
        return (AddResult(result::SUCCESS, holder.release()));
    } else { // There's something there already
        return (AddResult(result::EXIST, node->getData()));
    }
}

ZoneTable::FindResult
ZoneTable::findZone(const Name& name) const {
    ZoneTableNode* node(NULL);
    result::Result my_result;

    // Translate the return codes
    switch (zones_->find(name, &node)) {
    case ZoneTableTree::EXACTMATCH:
        my_result = result::SUCCESS;
        break;
    case ZoneTableTree::PARTIALMATCH:
        my_result = result::PARTIALMATCH;
        break;
    case ZoneTableTree::NOTFOUND:
        // We have no data there, so translate the pointer to NULL as well
        return (FindResult(result::NOTFOUND, NULL));
    default:
        // Can Not Happen
        assert(0);
        // Because of warning
        return (FindResult(result::NOTFOUND, NULL));
    }

    // Can Not Happen (remember, NOTFOUND is handled)
    assert(node != NULL);

    return (FindResult(my_result, node->getData()));
}

} // end of namespace memory
} // end of namespace datasrc
} // end of namespace isc