/********************************************************************
 * 2014 -
 * open source under Apache License Version 2.0
 ********************************************************************/
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */
#include "BigEndian.h"
#include "DataTransferProtocolSender.h"
#include "Exception.h"
#include "ExceptionInternal.h"
#include "HWCrc32c.h"
#include "RemoteBlockReader.h"
#include "SWCrc32c.h"
#include "WriteBuffer.h"

#include <inttypes.h>
#include <vector>

namespace Hdfs {
namespace Internal {

RemoteBlockReader::RemoteBlockReader(const ExtendedBlock& eb,
                                     DatanodeInfo& datanode,
                                     PeerCache& peerCache, int64_t start,
                                     int64_t len, const Token& token,
                                     const char* clientName, bool verify,
                                     SessionConfig& conf)
    : sentStatus(false),
      verify(verify),
      binfo(eb),
      datanode(datanode),
      checksumSize(0),
      chunkSize(0),
      position(0),
      size(0),
      cursor(start),
      endOffset(len + start),
      lastSeqNo(-1),
      peerCache(peerCache) {

    assert(start >= 0);
    readTimeout = conf.getInputReadTimeout();
    writeTimeout = conf.getInputWriteTimeout();
    connTimeout = conf.getInputConnTimeout();
    sock = getNextPeer(datanode);
    in = shared_ptr<BufferedSocketReader>(new BufferedSocketReaderImpl(*sock));
    sender = shared_ptr<DataTransferProtocol>(new DataTransferProtocolSender(
        *sock, writeTimeout, datanode.formatAddress()));
    sender->readBlock(eb, token, clientName, start, len);
    checkResponse();
}

RemoteBlockReader::~RemoteBlockReader() {
    if (sentStatus) {
        peerCache.addConnection(sock, datanode);
    } else {
        sock->close();
    }
}

shared_ptr<Socket> RemoteBlockReader::getNextPeer(const DatanodeInfo& dn) {
    shared_ptr<Socket> sock;
    try {
        sock = peerCache.getConnection(dn);

        if (!sock) {
            sock = shared_ptr<Socket>(new TcpSocketImpl);
            sock->connect(dn.getIpAddr().c_str(), dn.getXferPort(),
                          connTimeout);
            sock->setNoDelay(true);
        }
    } catch (const HdfsTimeoutException & e) {
        NESTED_THROW(HdfsIOException,
                     "RemoteBlockReader: Failed to connect to %s",
                     dn.formatAddress().c_str());
    }

    return sock;
}

void RemoteBlockReader::checkResponse() {
    std::vector<char> respBuffer;
    int32_t respSize = in->readVarint32(readTimeout);

    if (respSize <= 0 || respSize > 10 * 1024 * 1024) {
        THROW(HdfsIOException, "RemoteBlockReader get a invalid response size: %d, Block: %s, from Datanode: %s",
              respSize, binfo.toString().c_str(), datanode.formatAddress().c_str());
    }

    respBuffer.resize(respSize);
    in->readFully(&respBuffer[0], respSize, readTimeout);
    BlockOpResponseProto resp;

    if (!resp.ParseFromArray(&respBuffer[0], respBuffer.size())) {
        THROW(HdfsIOException, "RemoteBlockReader cannot parse BlockOpResponseProto from Datanode response, "
              "Block: %s, from Datanode: %s", binfo.toString().c_str(), datanode.formatAddress().c_str());
    }

    if (resp.status() != Status::DT_PROTO_SUCCESS) {
        std::string msg;

        if (resp.has_message()) {
            msg = resp.message();
        }

        if (resp.status() == Status::DT_PROTO_ERROR_ACCESS_TOKEN) {
            THROW(HdfsInvalidBlockToken, "RemoteBlockReader: block's token is invalid. Datanode: %s, Block: %s",
                  datanode.formatAddress().c_str(), binfo.toString().c_str());
        } else {
            THROW(HdfsIOException,
                  "RemoteBlockReader: Datanode return an error when sending read request to Datanode: %s, Block: %s, %s.",
                  datanode.formatAddress().c_str(), binfo.toString().c_str(),
                  (msg.empty() ? "check Datanode's log for more information" : msg.c_str()));
        }
    }

    const ReadOpChecksumInfoProto & checksumInfo = resp.readopchecksuminfo();
    const ChecksumProto & cs = checksumInfo.checksum();
    chunkSize = cs.bytesperchecksum();

    if (chunkSize < 0) {
        THROW(HdfsIOException,
              "RemoteBlockReader invalid chunk size: %d, expected range[0, %" PRId64 "], Block: %s, from Datanode: %s",
              chunkSize, binfo.getNumBytes(), binfo.toString().c_str(), datanode.formatAddress().c_str());
    }

    switch (cs.type()) {
    case ChecksumTypeProto::CHECKSUM_NULL:
        verify = false;
        checksumSize = 0;
        break;

    case ChecksumTypeProto::CHECKSUM_CRC32:
        THROW(HdfsIOException, "RemoteBlockReader does not support CRC32 checksum, Block: %s, from Datanode: %s",
              binfo.toString().c_str(), datanode.formatAddress().c_str());
        break;

    case ChecksumTypeProto::CHECKSUM_CRC32C:
        if (HWCrc32c::available()) {
            checksum = shared_ptr<Checksum>(new HWCrc32c());
        } else {
            checksum = shared_ptr<Checksum>(new SWCrc32c());
        }

        checksumSize = sizeof(int32_t);
        break;

    default:
        THROW(HdfsIOException, "RemoteBlockReader cannot recognize checksum type: %d, Block: %s, from Datanode: %s",
              static_cast<int>(cs.type()), binfo.toString().c_str(), datanode.formatAddress().c_str());
    }

    /*
     * The offset into the block at which the first packet
     * will start. This is necessary since reads will align
     * backwards to a checksum chunk boundary.
     */
    int64_t firstChunkOffset = checksumInfo.chunkoffset();

    if (firstChunkOffset < 0 || firstChunkOffset > cursor || firstChunkOffset <= cursor - chunkSize) {
        THROW(HdfsIOException,
              "RemoteBlockReader invalid first chunk offset: %" PRId64 ", expected range[0, %" PRId64 "], " "Block: %s, from Datanode: %s",
              firstChunkOffset, cursor, binfo.toString().c_str(), datanode.formatAddress().c_str());
    }
}

shared_ptr<PacketHeader> RemoteBlockReader::readPacketHeader() {
    try {
        shared_ptr<PacketHeader> retval;
        static const int packetHeaderLen = PacketHeader::GetPkgHeaderSize();
        std::vector<char> buf(packetHeaderLen);

        if (lastHeader && lastHeader->isLastPacketInBlock()) {
            THROW(HdfsIOException, "RemoteBlockReader: read over block end from Datanode: %s, Block: %s.",
                  datanode.formatAddress().c_str(), binfo.toString().c_str());
        }

        in->readFully(&buf[0], packetHeaderLen, readTimeout);
        retval = shared_ptr<PacketHeader>(new PacketHeader);
        retval->readFields(&buf[0], packetHeaderLen);
        return retval;
    } catch (const HdfsIOException & e) {
        NESTED_THROW(HdfsIOException, "RemoteBlockReader: failed to read block header for Block: %s from Datanode: %s.",
                     binfo.toString().c_str(), datanode.formatAddress().c_str());
    }
}

void RemoteBlockReader::readNextPacket() {
    assert(position >= size);
    lastHeader = readPacketHeader();
    int dataSize = lastHeader->getDataLen();
    int64_t pendingAhead = 0;

    if (!lastHeader->sanityCheck(lastSeqNo)) {
        THROW(HdfsIOException, "RemoteBlockReader: Packet failed on sanity check for block %s from Datanode %s.",
              binfo.toString().c_str(), datanode.formatAddress().c_str());
    }

    assert(dataSize > 0 || lastHeader->getPacketLen() == sizeof(int32_t));

    if (dataSize > 0) {
        int chunks = (dataSize + chunkSize - 1) / chunkSize;
        int checksumLen = chunks * checksumSize;
        size = checksumLen + dataSize;
        assert(size == lastHeader->getPacketLen() - static_cast<int>(sizeof(int32_t)));
        buffer.resize(size);
        in->readFully(&buffer[0], size, readTimeout);
        lastSeqNo = lastHeader->getSeqno();

        if (lastHeader->getPacketLen() != static_cast<int>(sizeof(int32_t)) + dataSize + checksumLen) {
            THROW(HdfsIOException, "Invalid Packet, packetLen is %d, dataSize is %d, checksum size is %d",
                  lastHeader->getPacketLen(), dataSize, checksumLen);
        }

        if (verify) {
            verifyChecksum(chunks);
        }

        /*
         * skip checksum
         */
        position = checksumLen;
        /*
         * the first packet we get may start at the position before we required
         */
        pendingAhead = cursor - lastHeader->getOffsetInBlock();
        pendingAhead = pendingAhead > 0 ? pendingAhead : 0;
        position += pendingAhead;
    }

    /*
     * we reach the end of the range we required, send status to datanode
     * if datanode do not sending data anymore.
     */

    if (cursor + dataSize - pendingAhead >= endOffset && readTrailingEmptyPacket()) {
        sendStatus();
    }
}

bool RemoteBlockReader::readTrailingEmptyPacket() {
    shared_ptr<PacketHeader> trailingHeader = readPacketHeader();

    if (!trailingHeader->isLastPacketInBlock() || trailingHeader->getDataLen() != 0) {
        return false;
    }

    return true;
}

void RemoteBlockReader::sendStatus() {
    ClientReadStatusProto status;

    if (verify) {
        status.set_status(Status::DT_PROTO_CHECKSUM_OK);
    } else {
        status.set_status(Status::DT_PROTO_SUCCESS);
    }

    WriteBuffer buffer;
    int size = status.ByteSize();
    buffer.writeVarint32(size);
    status.SerializeToArray(buffer.alloc(size), size);
    sock->writeFully(buffer.getBuffer(0), buffer.getDataSize(0), writeTimeout);
    sentStatus = true;
}

void RemoteBlockReader::verifyChecksum(int chunks) {
    int dataSize = lastHeader->getDataLen();
    char * pchecksum = &buffer[0];
    char * pdata = &buffer[0] + (chunks * checksumSize);

    for (int i = 0; i < chunks; ++i) {
        int size = chunkSize < dataSize ? chunkSize : dataSize;
        dataSize -= size;
        checksum->reset();
        checksum->update(pdata + (i * chunkSize), size);
        uint32_t result = checksum->getValue();
        uint32_t target = ReadBigEndian32FromArray(pchecksum + (i * checksumSize));

        if (result != target) {
            THROW(ChecksumException, "RemoteBlockReader: checksum not match for Block: %s, on Datanode: %s",
                  binfo.toString().c_str(), datanode.formatAddress().c_str());
        }
    }

    assert(0 == dataSize);
}

int64_t RemoteBlockReader::available() {
    return size - position > 0 ? size - position : 0;
}

int32_t RemoteBlockReader::read(char * buf, int32_t len) {
    assert(0 != len && NULL != buf);

    if (cursor >= endOffset) {
        THROW(HdfsIOException, "RemoteBlockReader: read over block end from Datanode: %s, Block: %s.",
              datanode.formatAddress().c_str(), binfo.toString().c_str());
    }

    try {
        if (position >= size) {
            readNextPacket();
        }

        int32_t todo = len < size - position ? len : size - position;
        memcpy(buf, &buffer[position], todo);
        position += todo;
        cursor += todo;
        return todo;
    } catch (const HdfsTimeoutException & e) {
        NESTED_THROW(HdfsIOException, "RemoteBlockReader: failed to read Block: %s from Datanode: %s.",
                     binfo.toString().c_str(), datanode.formatAddress().c_str());
    } catch (const HdfsNetworkException & e) {
        NESTED_THROW(HdfsIOException, "RemoteBlockReader: failed to read Block: %s from Datanode: %s.",
                     binfo.toString().c_str(), datanode.formatAddress().c_str());
    }
}

void RemoteBlockReader::skip(int64_t len) {
    int64_t todo = len;
    assert(cursor + len <= endOffset);

    try {
        while (todo > 0) {
            if (cursor >= endOffset) {
                THROW(HdfsIOException, "RemoteBlockReader: skip over block end from Datanode: %s, Block: %s.",
                      datanode.formatAddress().c_str(), binfo.toString().c_str());
            }

            if (position >= size) {
                readNextPacket();
            }

            int batch = size - position;
            batch = batch < todo ? batch : static_cast<int>(todo);
            position += batch;
            cursor += batch;
            todo -= batch;
        }
    } catch (const HdfsTimeoutException & e) {
        NESTED_THROW(HdfsIOException, "RemoteBlockReader: failed to read Block: %s from Datanode: %s.",
                     binfo.toString().c_str(), datanode.formatAddress().c_str());
    } catch (const HdfsNetworkException & e) {
        NESTED_THROW(HdfsIOException, "RemoteBlockReader: failed to read Block: %s from Datanode: %s.",
                     binfo.toString().c_str(), datanode.formatAddress().c_str());
    }
}

}
}