/**
 *    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/ops/modifier_current_date.h"

#include "mongo/base/error_codes.h"
#include "mongo/bson/mutable/document.h"
#include "mongo/db/ops/field_checker.h"
#include "mongo/db/ops/log_builder.h"
#include "mongo/db/ops/path_support.h"
#include "mongo/util/mongoutils/str.h"

namespace mongo {

    namespace str = mongoutils::str;

    namespace {
        const char kType[] = "$type";
        const char kDate[] = "date";
        const char kTimestamp[] = "timestamp";
    }

    struct ModifierCurrentDate::PreparedState {

        PreparedState(mutablebson::Document& doc)
            : doc(doc)
            , elemFound(doc.end())
            , idxFound(0) {
        }

        // Document that is going to be changed.
        mutablebson::Document& doc;

        // Element corresponding to _fieldRef[0.._idxFound].
        mutablebson::Element elemFound;

        // Index in _fieldRef for which an Element exist in the document.
        size_t idxFound;
    };

    ModifierCurrentDate::ModifierCurrentDate()
        : _pathReplacementPosition(0)
        , _typeIsDate(true) {
    }

    ModifierCurrentDate::~ModifierCurrentDate() {
    }

    Status ModifierCurrentDate::init(const BSONElement& modExpr, const Options& opts,
                                     bool* positional) {

        _updatePath.parse(modExpr.fieldName());
        Status status = fieldchecker::isUpdatable(_updatePath);
        if (!status.isOK()) {
            return status;
        }

        // If a $-positional operator was used, get the index in which it occurred
        // and ensure only one occurrence.
        size_t foundCount;
        bool foundDollar = fieldchecker::isPositional(_updatePath,
                                                      &_pathReplacementPosition,
                                                      &foundCount);

        if (positional)
            *positional = foundDollar;

        if (foundDollar && foundCount > 1) {
            return Status(ErrorCodes::BadValue,
                          str::stream() << "Too many positional (i.e. '$') elements found in path '"
                                        << _updatePath.dottedField() << "'");
        }

        // Validate and store the type to produce
        switch (modExpr.type()) {
            case Bool:
                _typeIsDate = true;
                break;
            case Object: {
                const BSONObj argObj = modExpr.embeddedObject();
                const BSONElement typeElem = argObj.getField(kType);
                bool badInput = typeElem.eoo() || !(typeElem.type() == String);

                if (!badInput) {
                    std::string typeVal = typeElem.String();
                    badInput = !(typeElem.String() == kDate || typeElem.String() == kTimestamp);
                    if (!badInput)
                        _typeIsDate = (typeVal == kDate);

                    if (!badInput) {
                        // Check to make sure only the $type field was given as an arg
                        BSONObjIterator i( argObj );
                        const bool onlyHasTypeField = ((i.next().fieldNameStringData() == kType)
                                                            && i.next().eoo());
                        if (!onlyHasTypeField) {
                            return Status(ErrorCodes::BadValue,
                                          str::stream() <<
                                          "The only valid field of the option is '$type': "
                                          "{$currentDate: {field : {$type: 'date/timestamp'}}}; "
                                          << "arg: " << argObj);
                        }

                    }

                }

                if (badInput) {
                    return Status(ErrorCodes::BadValue,
                                  "The '$type' string field is required "
                                  "to be 'date' or 'timestamp': "
                                  "{$currentDate: {field : {$type: 'date'}}}");
                }
                break;
            }
            default:
                return Status(ErrorCodes::BadValue,
                              str::stream() << typeName(modExpr.type())
                              << " is not valid type for $currentDate."
                                 " Please use a boolean ('true')"
                                 " or a $type expression ({$type: 'timestamp/date'}).");
        }

        return Status::OK();
    }

    Status ModifierCurrentDate::prepare(mutablebson::Element root,
                                const StringData& matchedField,
                                ExecInfo* execInfo) {

        _preparedState.reset(new PreparedState(root.getDocument()));

        // If we have a $-positional field, it is time to bind it to an actual field part.
        if (_pathReplacementPosition) {
            if (matchedField.empty()) {
                return Status(ErrorCodes::BadValue,
                              str::stream() << "The positional operator did not find the match "
                                               "needed from the query. Unexpanded update: "
                                            << _updatePath.dottedField());
            }
            _updatePath.setPart(_pathReplacementPosition, matchedField);
        }

        // Locate the field name in 'root'. Note that we may not have all the parts in the path
        // in the doc -- which is fine. Our goal now is merely to reason about whether this mod
        // apply is a noOp or whether is can be in place. The remaining path, if missing, will
        // be created during the apply.
        Status status = pathsupport::findLongestPrefix(_updatePath,
                                                root,
                                                &_preparedState->idxFound,
                                                &_preparedState->elemFound);

        // FindLongestPrefix may say the path does not exist at all, which is fine here, or
        // that the path was not viable or otherwise wrong, in which case, the mod cannot
        // proceed.
        if (status.code() == ErrorCodes::NonExistentPath) {
            _preparedState->elemFound = root.getDocument().end();
        }
        else if (!status.isOK()) {
            return status;
        }

        // We register interest in the field name. The driver needs this info to sort out if
        // there is any conflict among mods.
        execInfo->fieldRef[0] = &_updatePath;

        return Status::OK();
    }

    Status ModifierCurrentDate::apply() const {

        const bool destExists = (_preparedState->elemFound.ok() &&
                                 _preparedState->idxFound == (_updatePath.numParts() - 1));

        mutablebson::Document& doc = _preparedState->doc;
        StringData lastPart = _updatePath.getPart(_updatePath.numParts() - 1);
        // If the element exists and is the same type, then that is what we want to work with
        mutablebson::Element elemToSet = destExists ?
                                            _preparedState->elemFound:
                                            doc.end() ;

        if (!destExists) {
            // Creates the final element that's going to be $set in 'doc'.
            // fills in the value with place-holder/empty

            elemToSet = _typeIsDate ?
                            doc.makeElementDate(lastPart, Date_t()) :
                            doc.makeElementTimestamp(lastPart, OpTime());

            if (!elemToSet.ok()) {
                return Status(ErrorCodes::InternalError, "can't create new element");
            }

            // Now, we can be in two cases here, as far as attaching the element being set goes:
            // (a) none of the parts in the element's path exist, or (b) some parts of the path
            // exist but not all.
            if (!_preparedState->elemFound.ok()) {
                _preparedState->elemFound = doc.root();
                _preparedState->idxFound = 0;
            }
            else {
                _preparedState->idxFound++;
            }

            // createPathAt() will complete the path and attach 'elemToSet' at the end of it.
            Status s = pathsupport::createPathAt(_updatePath,
                                                 _preparedState->idxFound,
                                                 _preparedState->elemFound,
                                                 elemToSet);
            if (!s.isOK())
                return s;
        }

        dassert(elemToSet.ok());

        // By the time we are here the element is in place and we just need to update the value
        if (_typeIsDate) {
            const mongo::Date_t now = mongo::jsTime();
            Status s = elemToSet.setValueDate(now);
            if (!s.isOK())
                return s;
        }
        else {
            mutex::scoped_lock lk(OpTime::m);
            const OpTime timestamp = OpTime::now(lk);
            Status s = elemToSet.setValueTimestamp(timestamp);
            if (!s.isOK())
                return s;
        }

        // Set the elemFound, idxFound to the changed element for oplog logging.
        _preparedState->elemFound = elemToSet;
        _preparedState->idxFound = (_updatePath.numParts() - 1);

        return Status::OK();
    }

    Status ModifierCurrentDate::log(LogBuilder* logBuilder) const {
        // TODO: None of this checks should be needed unless someone calls if we are a noOp
        // When we cleanup we should build in testing that no-one calls in the noOp case
        const bool destExists = (_preparedState->elemFound.ok() &&
                                 _preparedState->idxFound == (_updatePath.numParts() - 1));

        // If the destination doesn't exist then we have nothing to log.
        // This would only happen if apply isn't called or fails when it had to create an element
        if (!destExists)
            return Status::OK();

        return logBuilder->addToSetsWithNewFieldName(_updatePath.dottedField(),
                                                     _preparedState->elemFound);
    }

} // namespace mongo
