#
#  Copyright 2014 MongoDB, Inc.
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#  http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.
#

use strict;
use warnings;
package MongoDB::Role::_OpReplyParser;

# MongoDB interface for sending OP_QUERY|OP_GETMORE and parsing OP_REPLY

use version;
our $VERSION = 'v1.8.1';

use Moo::Role;

use MongoDB::Error;
use MongoDB::_Protocol;
use MongoDB::_Constants;

use namespace::clean;

# Sends a BSON query/get-more string, then read, parse and validate the reply.
# Throws various errors if the results indicate a problem.  Returns
# a "result" structure generated by MongoDB::_Protocol, but with
# the 'docs' field replaced with inflated documents.

# as this is the hot loop, we do a number of odd things in the name of
# optimization, such as chaining lots of operations with ',' to keep them
# in a single statement

# args are self, link, op_bson, request_id and not unpacked as they are only
# used briefly

sub _query_and_receive {
    my ($result, $doc_bson, $bson_codec, $docs, $len, $i);
    $_[1]->write( $_[2] ),
      ( $result   = MongoDB::_Protocol::parse_reply( $_[1]->read, $_[3] ) ),
      ( $doc_bson = $result->{docs} ),
      ( $docs     = $result->{docs} = [] ),
      ( ( $bson_codec, $i ) = ( $_[0]->bson_codec, 0 ) ),
      ( $#$docs = $result->{number_returned} - 1 );

    # XXX should address be added to result here?

    MongoDB::CursorNotFoundError->throw("cursor not found")
      if $result->{flags}{cursor_not_found};

    # XXX eventually, BSON needs an API to do this efficiently for us without a
    # loop here.  Alternatively, BSON strings could be returned as objects that
    # inflate lazily

    while ( length($doc_bson) ) {
        $len = unpack( P_INT32, $doc_bson );
        MongoDB::ProtocolError->throw("document in response at index $i was truncated")
          if $len > length($doc_bson);
        $docs->[ $i++ ] = $bson_codec->decode_one( substr( $doc_bson, 0, $len, '' ) );
    }

    MongoDB::ProtocolError->throw(
        sprintf(
            "unexpected number of documents: got %s, expected %s",
            scalar @$docs,
            $result->{number_returned}
        )
    ) if scalar @$docs != $result->{number_returned};

    return $result
      unless $result->{flags}{query_failure};

    # had query_failure, so pretend the query was a command and assert it here
    MongoDB::CommandResult->_new(
        output  => $result->{docs}[0],
        address => $_[1]->address
    )->assert;
}

1;