/**
 *    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/db/update/update_driver.h"


#include "mongo/base/error_codes.h"
#include "mongo/base/string_data.h"
#include "mongo/bson/mutable/algorithm.h"
#include "mongo/bson/mutable/document.h"
#include "mongo/db/field_ref.h"
#include "mongo/db/matcher/expression_leaf.h"
#include "mongo/db/matcher/extensions_callback_noop.h"
#include "mongo/db/ops/modifier_object_replace.h"
#include "mongo/db/update/log_builder.h"
#include "mongo/db/update/modifier_table.h"
#include "mongo/db/update/path_support.h"
#include "mongo/util/embedded_builder.h"
#include "mongo/util/mongoutils/str.h"

namespace mongo {

namespace str = mongoutils::str;
namespace mb = mongo::mutablebson;

using std::unique_ptr;
using std::vector;

using pathsupport::EqualityMatches;

UpdateDriver::UpdateDriver(const Options& opts)
    : _replacementMode(false),
      _indexedFields(NULL),
      _logOp(opts.logOp),
      _modOptions(opts.modOptions),
      _affectIndices(false),
      _positional(false) {}

UpdateDriver::~UpdateDriver() {
    clear();
}

Status UpdateDriver::parse(const BSONObj& updateExpr, const bool multi) {
    clear();

    // Check if the update expression is a full object replacement.
    if (*updateExpr.firstElementFieldName() != '$') {
        if (multi) {
            return Status(ErrorCodes::FailedToParse, "multi update only works with $ operators");
        }

        // Modifiers expect BSONElements as input. But the input to object replace is, by
        // definition, an object. We wrap the 'updateExpr' as the mod is expecting. Note
        // that the wrapper is temporary so the object replace mod should make a copy of
        // the object.
        unique_ptr<ModifierObjectReplace> mod(new ModifierObjectReplace);
        BSONObj wrapper = BSON("dummy" << updateExpr);
        Status status = mod->init(wrapper.firstElement(), _modOptions);
        if (!status.isOK()) {
            return status;
        }

        _mods.push_back(mod.release());

        // Register the fact that this driver will only do full object replacements.
        _replacementMode = true;

        return Status::OK();
    }

    // The update expression is made of mod operators, that is
    // { <$mod>: {...}, <$mod>: {...}, ...  }
    BSONObjIterator outerIter(updateExpr);
    while (outerIter.more()) {
        BSONElement outerModElem = outerIter.next();

        // Check whether this is a valid mod type.
        modifiertable::ModifierType modType = modifiertable::getType(outerModElem.fieldName());
        if (modType == modifiertable::MOD_UNKNOWN) {
            return Status(ErrorCodes::FailedToParse,
                          str::stream() << "Unknown modifier: " << outerModElem.fieldName());
        }

        // Check whether there is indeed a list of mods under this modifier.
        if (outerModElem.type() != Object) {
            return Status(ErrorCodes::FailedToParse,
                          str::stream() << "Modifiers operate on fields but we found type "
                                        << typeName(outerModElem.type())
                                        << " instead. For example: {$mod: {<field>: ...}}"
                                        << " not {"
                                        << outerModElem.toString()
                                        << "}");
        }

        // Check whether there are indeed mods under this modifier.
        if (outerModElem.embeddedObject().isEmpty()) {
            return Status(ErrorCodes::FailedToParse,
                          str::stream() << "'" << outerModElem.fieldName()
                                        << "' is empty. You must specify a field like so: "
                                           "{"
                                        << outerModElem.fieldName()
                                        << ": {<field>: ...}}");
        }

        BSONObjIterator innerIter(outerModElem.embeddedObject());
        while (innerIter.more()) {
            BSONElement innerModElem = innerIter.next();

            Status status = addAndParse(modType, innerModElem);
            if (!status.isOK()) {
                return status;
            }
        }
    }

    // Register the fact that there will be only $mod's in this driver -- no object
    // replacement.
    _replacementMode = false;

    return Status::OK();
}

inline Status UpdateDriver::addAndParse(const modifiertable::ModifierType type,
                                        const BSONElement& elem) {
    if (elem.eoo()) {
        return Status(ErrorCodes::FailedToParse,
                      str::stream() << "'" << elem.fieldName() << "' has no value in : " << elem
                                    << " which is not allowed for any $"
                                    << type
                                    << " mod.");
    }

    unique_ptr<ModifierInterface> mod(modifiertable::makeUpdateMod(type));
    dassert(mod.get());

    bool positional = false;
    Status status = mod->init(elem, _modOptions, &positional);
    if (!status.isOK()) {
        return status;
    }

    // If any modifier indicates that it requires a positional match, toggle the
    // _positional flag to true.
    _positional = _positional || positional;

    _mods.push_back(mod.release());

    return Status::OK();
}

Status UpdateDriver::populateDocumentWithQueryFields(OperationContext* opCtx,
                                                     const BSONObj& query,
                                                     const vector<FieldRef*>* immutablePaths,
                                                     mutablebson::Document& doc) const {
    // We canonicalize the query to collapse $and/$or, and the namespace is not needed.  Also,
    // because this is for the upsert case, where we insert a new document if one was not found, the
    // $where/$text clauses do not make sense, hence empty ExtensionsCallback.
    auto qr = stdx::make_unique<QueryRequest>(NamespaceString(""));
    qr->setFilter(query);
    auto statusWithCQ =
        CanonicalQuery::canonicalize(opCtx, std::move(qr), ExtensionsCallbackNoop());
    if (!statusWithCQ.isOK()) {
        return statusWithCQ.getStatus();
    }
    unique_ptr<CanonicalQuery> cq = std::move(statusWithCQ.getValue());

    return populateDocumentWithQueryFields(*cq, immutablePaths, doc);
}

Status UpdateDriver::populateDocumentWithQueryFields(const CanonicalQuery& query,
                                                     const vector<FieldRef*>* immutablePathsPtr,
                                                     mutablebson::Document& doc) const {
    EqualityMatches equalities;
    Status status = Status::OK();

    if (isDocReplacement()) {
        FieldRefSet pathsToExtract;

        // TODO: Refactor update logic, make _id just another immutable field
        static const FieldRef idPath("_id");
        static const vector<FieldRef*> emptyImmutablePaths;
        const vector<FieldRef*>& immutablePaths =
            immutablePathsPtr ? *immutablePathsPtr : emptyImmutablePaths;

        pathsToExtract.fillFrom(immutablePaths);
        pathsToExtract.insert(&idPath);

        // Extract only immutable fields from replacement-style
        status =
            pathsupport::extractFullEqualityMatches(*query.root(), pathsToExtract, &equalities);
    } else {
        // Extract all fields from op-style
        status = pathsupport::extractEqualityMatches(*query.root(), &equalities);
    }

    if (!status.isOK())
        return status;

    status = pathsupport::addEqualitiesToDoc(equalities, &doc);
    return status;
}

Status UpdateDriver::update(StringData matchedField,
                            mutablebson::Document* doc,
                            BSONObj* logOpRec,
                            FieldRefSet* updatedFields,
                            bool* docWasModified) {
    // TODO: assert that update() is called at most once in a !_multi case.

    // Use the passed in FieldRefSet
    FieldRefSet* targetFields = updatedFields;

    // If we didn't get a FieldRefSet* from the caller, allocate storage and use
    // the unique_ptr for lifecycle management
    unique_ptr<FieldRefSet> targetFieldScopedPtr;
    if (!targetFields) {
        targetFieldScopedPtr.reset(new FieldRefSet());
        targetFields = targetFieldScopedPtr.get();
    }

    _affectIndices = (isDocReplacement() && (_indexedFields != NULL));

    _logDoc.reset();
    LogBuilder logBuilder(_logDoc.root());

    // Ask each of the mods to type check whether they can operate over the current document
    // and, if so, to change that document accordingly.
    for (vector<ModifierInterface*>::iterator it = _mods.begin(); it != _mods.end(); ++it) {
        ModifierInterface::ExecInfo execInfo;
        Status status = (*it)->prepare(doc->root(), matchedField, &execInfo);
        if (!status.isOK()) {
            return status;
        }

        // If a mod wants to be applied only if this is an upsert (or only if this is a
        // strict update), we should respect that. If a mod doesn't care, it would state
        // it is fine with ANY update context.
        const bool validContext = (execInfo.context == ModifierInterface::ExecInfo::ANY_CONTEXT ||
                                   execInfo.context == _context);

        // Nothing to do if not in a valid context.
        if (!validContext) {
            continue;
        }


        // Gather which fields this mod is interested on and whether these fields were
        // "taken" by previous mods.  Note that not all mods are multi-field mods. When we
        // see an empty field, we may stop looking for others.
        for (int i = 0; i < ModifierInterface::ExecInfo::MAX_NUM_FIELDS; i++) {
            if (execInfo.fieldRef[i] == 0) {
                break;
            }

            // Record each field being updated but check for conflicts first
            const FieldRef* other;
            if (!targetFields->insert(execInfo.fieldRef[i], &other)) {
                return Status(ErrorCodes::ConflictingUpdateOperators,
                              str::stream() << "Cannot update '" << other->dottedField()
                                            << "' and '"
                                            << execInfo.fieldRef[i]->dottedField()
                                            << "' at the same time");
            }

            // We start with the expectation that a mod will be in-place. But if the mod
            // touched an indexed field and the mod will indeed be executed -- that is, it
            // is not a no-op and it is in a valid context -- then we switch back to a
            // non-in-place mode.
            //
            // TODO: make mightBeIndexed and fieldRef like each other.
            if (!_affectIndices && !execInfo.noOp && _indexedFields &&
                _indexedFields->mightBeIndexed(execInfo.fieldRef[i]->dottedField())) {
                _affectIndices = true;
                doc->disableInPlaceUpdates();
            }
        }

        if (!execInfo.noOp) {
            status = (*it)->apply();

            if (docWasModified)
                *docWasModified = true;

            if (!status.isOK()) {
                return status;
            }
        }

        // If we require a replication oplog entry for this update, go ahead and generate one.
        if (!execInfo.noOp && _logOp && logOpRec) {
            status = (*it)->log(&logBuilder);
            if (!status.isOK()) {
                return status;
            }
        }
    }

    if (_logOp && logOpRec)
        *logOpRec = _logDoc.getObject();

    return Status::OK();
}

size_t UpdateDriver::numMods() const {
    return _mods.size();
}

bool UpdateDriver::isDocReplacement() const {
    return _replacementMode;
}

bool UpdateDriver::modsAffectIndices() const {
    return _affectIndices;
}

void UpdateDriver::refreshIndexKeys(const UpdateIndexData* indexedFields) {
    _indexedFields = indexedFields;
}

bool UpdateDriver::logOp() const {
    return _logOp;
}

void UpdateDriver::setLogOp(bool logOp) {
    _logOp = logOp;
}

ModifierInterface::Options UpdateDriver::modOptions() const {
    return _modOptions;
}

void UpdateDriver::setModOptions(ModifierInterface::Options modOpts) {
    _modOptions = modOpts;
}

void UpdateDriver::setCollator(const CollatorInterface* collator) {
    for (auto&& mod : _mods) {
        mod->setCollator(collator);
    }

    _modOptions.collator = collator;
}

ModifierInterface::ExecInfo::UpdateContext UpdateDriver::context() const {
    return _context;
}

void UpdateDriver::setContext(ModifierInterface::ExecInfo::UpdateContext context) {
    _context = context;
}

BSONObj UpdateDriver::makeOplogEntryQuery(const BSONObj& doc, bool multi) const {
    BSONObjBuilder idPattern;
    BSONElement id;
    // NOTE: If the matching object lacks an id, we'll log
    // with the original pattern.  This isn't replay-safe.
    // It might make sense to suppress the log instead
    // if there's no id.
    if (doc.getObjectID(id)) {
        idPattern.append(id);
        return idPattern.obj();
    } else {
        uassert(16980,
                str::stream() << "Multi-update operations require all documents to "
                                 "have an '_id' field. "
                              << doc.toString(),
                !multi);
        return doc;
    }
}
void UpdateDriver::clear() {
    for (vector<ModifierInterface*>::iterator it = _mods.begin(); it != _mods.end(); ++it) {
        delete *it;
    }
    _mods.clear();
    _indexedFields = NULL;
    _replacementMode = false;
    _positional = false;
}

}  // namespace mongo