/**
 *    Copyright (C) 2013 10gen Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This program 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 Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#include "mongo/platform/basic.h"

#include "mongo/db/exec/working_set_common.h"

#include "mongo/db/catalog/collection.h"
#include "mongo/db/service_context.h"
#include "mongo/db/exec/working_set.h"
#include "mongo/db/service_context.h"
#include "mongo/db/index/index_access_method.h"
#include "mongo/db/query/canonical_query.h"

namespace mongo {

    // static
    bool WorkingSetCommon::fetchAndInvalidateLoc(OperationContext* txn,
                                                 WorkingSetMember* member,
                                                 const Collection* collection) {
        // Already in our desired state.
        if (member->state == WorkingSetMember::OWNED_OBJ) { return true; }

        // We can't do anything without a RecordId.
        if (!member->hasLoc()) { return false; }

        // Do the fetch, invalidate the DL.
        member->obj = collection->docFor(txn, member->loc);
        member->obj.setValue(member->obj.value().getOwned() );

        member->state = WorkingSetMember::OWNED_OBJ;
        member->loc = RecordId();
        return true;
    }

    void WorkingSetCommon::prepareForSnapshotChange(WorkingSet* workingSet) {
        dassert(supportsDocLocking());

        for (WorkingSet::iterator it = workingSet->begin(); it != workingSet->end(); ++it) {
            if (it->state == WorkingSetMember::LOC_AND_IDX) {
                it->isSuspicious = true;
            }
            else if (it->state == WorkingSetMember::LOC_AND_UNOWNED_OBJ) {
                // We already have the data so convert directly to owned state.
                it->obj.setValue(it->obj.value().getOwned());
                it->state = WorkingSetMember::LOC_AND_OWNED_OBJ;
            }
        }
    }

    // static
    bool WorkingSetCommon::fetch(OperationContext* txn,
                                 WorkingSetMember* member,
                                 unowned_ptr<RecordCursor> cursor) {
        // The RecordFetcher should already have been transferred out of the WSM and used.
        invariant(!member->hasFetcher());

        // We should have a RecordId but need to retrieve the obj. Get the obj now and reset all WSM
        // state appropriately.
        invariant(member->hasLoc());

        member->obj.reset();
        auto record = cursor->seekExact(member->loc);
        if (!record) {
            return false;
        }

        member->obj = {txn->recoveryUnit()->getSnapshotId(), record->data.releaseToBson()};

        if (member->isSuspicious) {
            // Make sure that all of the keyData is still valid for this copy of the document.
            // This ensures both that index-provided filters and sort orders still hold.
            // TODO provide a way for the query planner to opt out of this checking if it is
            // unneeded due to the structure of the plan.
            invariant(!member->keyData.empty());
            for (size_t i = 0; i < member->keyData.size(); i++) {
                BSONObjSet keys;
                member->keyData[i].index->getKeys(member->obj.value(), &keys);
                if (!keys.count(member->keyData[i].keyData)) {
                    // document would no longer be at this position in the index.
                    return false;
                }
            }

            member->isSuspicious = false;
        }

        member->keyData.clear();
        member->state = WorkingSetMember::LOC_AND_UNOWNED_OBJ;
        return true;
    }

    // static
    void WorkingSetCommon::initFrom(WorkingSetMember* dest, const WorkingSetMember& src) {
        dest->loc = src.loc;
        dest->obj = src.obj;
        dest->keyData = src.keyData;
        dest->state = src.state;

        // Merge computed data.
        typedef WorkingSetComputedDataType WSCD;
        for (WSCD i = WSCD(0); i < WSM_COMPUTED_NUM_TYPES; i = WSCD(i + 1)) {
            if (src.hasComputed(i)) {
                dest->addComputed(src.getComputed(i)->clone());
            }
        }
    }

    // static
    BSONObj WorkingSetCommon::buildMemberStatusObject(const Status& status) {
        BSONObjBuilder bob;
        bob.append("ok", status.isOK() ? 1.0 : 0.0);
        bob.append("code", status.code());
        bob.append("errmsg", status.reason());

        return bob.obj();
    }

    // static
    WorkingSetID WorkingSetCommon::allocateStatusMember(WorkingSet* ws, const Status& status) {
        invariant(ws);

        WorkingSetID wsid = ws->allocate();
        WorkingSetMember* member = ws->get(wsid);
        member->state = WorkingSetMember::OWNED_OBJ;
        member->obj = Snapshotted<BSONObj>(SnapshotId(), buildMemberStatusObject(status));

        return wsid;
    }

    // static
    bool WorkingSetCommon::isValidStatusMemberObject(const BSONObj& obj) {
        return obj.nFields() == 3 &&
               obj.hasField("ok") &&
               obj.hasField("code") &&
               obj.hasField("errmsg");
    }

    // static
    void WorkingSetCommon::getStatusMemberObject(const WorkingSet& ws, WorkingSetID wsid,
                                                 BSONObj* objOut) {
        invariant(objOut);

        // Validate ID and working set member.
        if (WorkingSet::INVALID_ID == wsid) {
            return;
        }
        WorkingSetMember* member = ws.get(wsid);
        if (!member->hasOwnedObj()) {
            return;
        }
        BSONObj obj = member->obj.value();
        if (!isValidStatusMemberObject(obj)) {
            return;
        }
        *objOut = obj;
    }

    // static
    Status WorkingSetCommon::getMemberObjectStatus(const BSONObj& memberObj) {
        invariant(WorkingSetCommon::isValidStatusMemberObject(memberObj));
        return Status(static_cast<ErrorCodes::Error>(memberObj["code"].numberInt()),
                      memberObj["errmsg"]);
    }

    // static
    Status WorkingSetCommon::getMemberStatus(const WorkingSetMember& member) {
        invariant(member.hasObj());
        return getMemberObjectStatus(member.obj.value());
    }

    // static
    std::string WorkingSetCommon::toStatusString(const BSONObj& obj) {
        if (!isValidStatusMemberObject(obj)) {
            Status unknownStatus(ErrorCodes::UnknownError, "no details available");
            return unknownStatus.toString();
        }
        Status status(ErrorCodes::fromInt(obj.getIntField("code")),
                      obj.getStringField("errmsg"));
        return status.toString();
    }

}  // namespace mongo