/************************************************************************
 *
 * Copyright (c) 2016 Alibaba.com, Inc. All Rights Reserved
 * $Id:  learner_client.cc,v 1.0 12/27/2016 10:42:18 AM jarry.zj(jarry.zj@alibaba-inc.com) $
 *
 ************************************************************************/

/**
 * @file learner_client.cc
 * @author jarry.zj(jarry.zj@alibaba-inc.com)
 * @date 12/27/2016 10:42:18 AM
 * @version 1.0
 * @brief
 *
 **/

#include <memory>
#include <cstdlib>
//#include <my_global.h>
#include <mysql.h>
#include "learner_client.h"
#include "paxos_log.h"
#include "mem_paxos_log.h"
#include "witness.h"

namespace alisql {

LearnerClient::LearnerClient(): node_(nullptr), lastLogIndex_(0), readTimeout_(0)
{
}

LearnerClient::~LearnerClient()
{
  close();
}

int LearnerClient::registerLearner(const RemoteLeader &leader, const string &addr)
{
  MYSQL *conn = mysql_init(NULL);
  if (!mysql_real_connect(conn, leader.ip.c_str(), leader.user.c_str(), leader.passwd.c_str(), NULL, leader.port, NULL, 0))
  {
    fprintf(stderr, "Failed to connect to database: Error: %s\n", mysql_error(conn));
    mysql_close(conn);
    return -1;
  }
  char query[100];
  snprintf(query, 100, "add consensus_learner \"%s\"", addr.c_str());
  if (mysql_query(conn, query) != 0)
  {
    fprintf(stderr, "Failed to execute query %s : Error: %s\n", query, mysql_error(conn));
    mysql_close(conn);
    return -1;
  }
  mysql_close(conn);
  return 0;
}

int LearnerClient::deregisterLearner(const RemoteLeader &leader, const string &addr)
{
  MYSQL *conn = mysql_init(NULL);
  if (!mysql_real_connect(conn, leader.ip.c_str(), leader.user.c_str(), leader.passwd.c_str(), NULL, leader.port, NULL, 0))
  {
    fprintf(stderr, "Failed to connect to database: Error: %s\n", mysql_error(conn));
    mysql_close(conn);
    return -1;
  }
  char query[100];
  snprintf(query, 100, "drop consensus_learner \"%s\"", addr.c_str());
  if (mysql_query(conn, query) != 0)
  {
    fprintf(stderr, "Failed to execute query %s : Error: %s\n", query, mysql_error(conn));
    mysql_close(conn);
    return -1;
  }
  mysql_close(conn);
  return 0;
}

int LearnerClient::open(const string &addr, uint64_t clusterId, uint64_t lastLogIndex, uint64_t readTimeout, uint64_t cacheSize)
{
  /* It will always use MemPaxosLog */
  std::shared_ptr<MemPaxosLog> memlog = std::make_shared<MemPaxosLog>(lastLogIndex, readTimeout, cacheSize);
  node_ = new Witness(addr, memlog, clusterId);
  lastLogIndex_ = lastLogIndex;
  readTimeout_ = readTimeout;
  return 0;
}

int LearnerClient::openWithTimestamp(const string &addr, uint64_t clusterId, const RemoteLeader &leader,
    uint64_t lastTimestamp, uint64_t readTimeout, uint64_t cacheSize) {
  /* TODO not implemented */
  /* step 1: Parse timestamp to logindex */
  uint64_t lastLogIndex = getLogIndexByTimestamp(leader, lastTimestamp);
  if (lastLogIndex == 0)
  {
    fprintf(stderr, "Get log index from timestamp fail.\n");
    return -1;
  }

  /* step 2: Open with lastLogIndex */
  open(addr, clusterId, lastLogIndex - 1, readTimeout, cacheSize);
  return 0;
}

uint64_t LearnerClient::getLogIndexByTimestamp(const RemoteLeader &leader, uint64_t lastTimestamp)
{
  MYSQL *conn = mysql_init(NULL);
  if (!mysql_real_connect(conn, leader.ip.c_str(), leader.user.c_str(), leader.passwd.c_str(), NULL, leader.port, NULL, 0))
  {
    fprintf(stderr, "Failed to connect to database: Error: %s\n", mysql_error(conn));
    mysql_close(conn);
    return 0;
  }
  char query[100];
  snprintf(query, 100, "show consensus_index %lu", lastTimestamp);
  if (mysql_query(conn, query) != 0)
  {
    fprintf(stderr, "Failed to execute query %s : Error: %s\n", query, mysql_error(conn));
    mysql_close(conn);
    return 0;
  }
  MYSQL_RES *myRes = mysql_store_result(conn);
  if (myRes == NULL)
  {
    fprintf(stderr, "Failed to fetch result: Error: %s\n", mysql_error(conn));
    mysql_close(conn);
    return 0;
  }
  MYSQL_ROW myRow = mysql_fetch_row(myRes);
  if (myRow == NULL || mysql_num_fields(myRes) == 0)
  {
    fprintf(stderr, "Failed to fetch logindex in the result\n");
    mysql_free_result(myRes);
    mysql_close(conn);
    return 0;
  }
  /* Should support ulonglong. */
  uint64_t lastLogIndex = strtoull(myRow[0], NULL ,10);
  mysql_free_result(myRes);
  mysql_close(conn);

  return lastLogIndex;
}

int LearnerClient::read(LogEntry &le)
{
  if (node_ == nullptr)
    return RET_ERROR;
  auto log = node_->getLog();
  int ret = log->getEntry(le);
  if (ret != 0)
  {
    return RET_TIMEOUT;
  }
  else
  {
    lastLogIndex_ = le.index();
    /* updateAppliedIndex after read */
    if (node_)
      node_->updateAppliedIndex(lastLogIndex_);
    /* extra check, avoid reading half blob */
    if ((le.info() & (Logentry_info_flag::FLAG_BLOB | Logentry_info_flag::FLAG_BLOB_END))
        && blobCache_.length() == 0
        && !(le.info() & Logentry_info_flag::FLAG_BLOB_START))
    {
      fprintf(stderr, "Current index may cause a broken blob data (index: %lu, flag: %lu). Try an early lastLogIndex to init LearnerClient lastLogIndex.\n", le.index(), le.info());
      node_->resetLastLogIndex(le.index() - 2);
      return RET_WAIT_BLOB;
    }
    if (le.info() & Logentry_info_flag::FLAG_BLOB_END)
    {
      blobCache_.append(le.value());
      le.set_value(blobCache_);
      blobCache_.clear();
    }
    else if (le.info() & Logentry_info_flag::FLAG_BLOB)
    {
      blobCache_.append(le.value());
      le.set_value("");
    }
    return RET_SUCCESS;
  }
}

int LearnerClient::close()
{
  if (node_ != nullptr)
  {
    delete node_;
    node_ = nullptr;
  }
  return 0;
}

ServerMeta LearnerClient::getRealCurrentLeader(const ServerMeta &meta)
{
  ServerMeta current = meta;
  while(1){
    MYSQL *conn = mysql_init(NULL);
    if (!mysql_real_connect(conn, current.ip.c_str(), current.user.c_str(), current.passwd.c_str(), NULL, current.port, NULL, 0))
    {
      fprintf(stderr, "Failed to connect to database: Error: %s\n", mysql_error(conn));
      mysql_close(conn);
      return current;
    }
    char query[100];
    snprintf(query, 100, "select current_leader from information_schema.alisql_cluster_local limit 1");
    if (mysql_query(conn, query) != 0)
    {
      fprintf(stderr, "Failed to execute query %s : Error: %s\n", query, mysql_error(conn));
      mysql_close(conn);
      return current;
    }
    MYSQL_RES *myRes = mysql_store_result(conn);
    if (myRes == NULL)
    {
      fprintf(stderr, "Failed to fetch result: Error: %s\n", mysql_error(conn));
      mysql_close(conn);
      return current;
    }
    MYSQL_ROW myRow = mysql_fetch_row(myRes);
    if (myRow == NULL || mysql_num_fields(myRes) == 0)
    {
      fprintf(stderr, "Failed to fetch current leader in the result\n");
      mysql_free_result(myRes);
      mysql_close(conn);
      return current;
    }
    /* Should support ulonglong. */
    string sqlres = myRow[0];
    auto pos = sqlres.find(":");
    if (pos == std::string::npos)
    {
      fprintf(stderr, "Failed to resolve ip:port\n");
      mysql_free_result(myRes);
      mysql_close(conn);
      return current;
    }
    string newIp = sqlres.substr(0, pos);
    /* alisql port = paxos port - 8000 */
    uint64_t newPort = strtoull(sqlres.substr(pos + 1).c_str(), NULL ,10) - 8000;
    fprintf(stderr, "Update Current ip(%s -> %s) port(%lu -> %lu)\n", current.ip.c_str(), newIp.c_str(), current.port, newPort);
    if (newIp == current.ip && newPort == current.port)
    {
      mysql_free_result(myRes);
      mysql_close(conn);
      break;
    }
    current.ip = newIp;
    current.port = newPort;
    mysql_free_result(myRes);
    mysql_close(conn);
  }
  return current;
}

}