/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    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
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    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 Server Side 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/pipeline/document_source_replace_root.h"

#include <boost/smart_ptr/intrusive_ptr.hpp>
#include <fmt/format.h>

#include "mongo/db/exec/document_value/value.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/pipeline/document_source_replace_root_gen.h"
#include "mongo/db/pipeline/lite_parsed_document_source.h"

namespace mongo {

using boost::intrusive_ptr;

Document ReplaceRootTransformation::applyTransformation(const Document& input) {
    // Extract subdocument in the form of a Value.
    Value newRoot = _newRoot->evaluate(input, &_expCtx->variables);
    // The newRoot expression, if it exists, must evaluate to an object.
    uassert(40228,
            fmt::format(kErrorTemplate.rawData(),
                        _errMsgContextForNonObject,
                        newRoot.toString(),
                        typeName(newRoot.getType()),
                        input.toString()),
            newRoot.getType() == BSONType::Object);

    // Turn the value into a document.
    MutableDocument newDoc(newRoot.getDocument());
    newDoc.copyMetaDataFrom(input);
    return newDoc.freeze();
}

REGISTER_DOCUMENT_SOURCE(replaceRoot,
                         LiteParsedDocumentSourceDefault::parse,
                         DocumentSourceReplaceRoot::createFromBson,
                         AllowedWithApiStrict::kAlways);
REGISTER_DOCUMENT_SOURCE(replaceWith,
                         LiteParsedDocumentSourceDefault::parse,
                         DocumentSourceReplaceRoot::createFromBson,
                         AllowedWithApiStrict::kAlways);

intrusive_ptr<DocumentSource> DocumentSourceReplaceRoot::createFromBson(
    BSONElement elem, const intrusive_ptr<ExpressionContext>& expCtx) {
    const auto stageName = elem.fieldNameStringData();
    auto newRootExpression = [&]() {
        if (stageName == kAliasNameReplaceWith) {
            return Expression::parseOperand(expCtx.get(), elem, expCtx->variablesParseState);
        }

        invariant(
            stageName == kStageName,
            str::stream() << "Unexpected stage registered with DocumentSourceReplaceRoot parser: "
                          << stageName);
        uassert(40229,
                str::stream() << "expected an object as specification for " << kStageName
                              << " stage, got " << typeName(elem.type()),
                elem.type() == Object);

        auto spec =
            ReplaceRootSpec::parse(IDLParserErrorContext(kStageName), elem.embeddedObject());

        // The IDL doesn't give us back the type we need to feed into the expression parser, and
        // the expression parser needs the extra state in 'vps' and 'expCtx', so for now we have
        // to adapt the two.
        BSONObj parsingBson = BSON("newRoot" << spec.getNewRoot());
        return Expression::parseOperand(
            expCtx.get(), parsingBson.firstElement(), expCtx->variablesParseState);
    }();

    // Whether this was specified as $replaceWith or $replaceRoot, always use the name $replaceRoot
    // to simplify the serialization process.
    const bool isIndependentOfAnyCollection = false;
    return new DocumentSourceSingleDocumentTransformation(
        expCtx,
        std::make_unique<ReplaceRootTransformation>(
            expCtx,
            newRootExpression,
            (stageName == kStageName) ? "'newRoot' expression " : "'replacement document' "),
        kStageName.rawData(),
        isIndependentOfAnyCollection);
}

boost::intrusive_ptr<DocumentSource> DocumentSourceReplaceRoot::create(
    const boost::intrusive_ptr<ExpressionContext>& expCtx,
    const boost::intrusive_ptr<Expression>& newRootExpression,
    std::string errMsgContextForNonObjects) {
    const bool isIndependentOfAnyCollection = false;
    return new DocumentSourceSingleDocumentTransformation(
        expCtx,
        std::make_unique<ReplaceRootTransformation>(
            expCtx, newRootExpression, std::move(errMsgContextForNonObjects)),
        kStageName.rawData(),
        isIndependentOfAnyCollection);
}
}  // namespace mongo