/*
----
This file is part of SECONDO.

Copyright (C) 2021,
Faculty of Mathematics and Computer Science,
Database Systems for New Applications.

SECONDO is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

SECONDO 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with SECONDO; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
----

//[$][\$]

*/
#include "ConnectionMySQL.h"

using namespace std;

namespace BasicEngine {

/*
6 Class ~ConnectionPG~

Implementation.

6.1 ~Constructor~

*/
ConnectionMySQL::ConnectionMySQL(const std::string &_dbUser, 
  const std::string &_dbPass, const int _dbPort, 
  const std::string &_dbName) : ConnectionGeneric(
    _dbUser, _dbPass, _dbPort, _dbName) {
}

/*
6.1.1 Destructor

*/
ConnectionMySQL::~ConnectionMySQL() {
  if(conn != nullptr) {
    mysql_close(conn);
    conn = nullptr;
    mysql_library_end();
  }
}

/*
6.2 ~createConnection~

*/
bool ConnectionMySQL::createConnection() {

    if(conn != nullptr) {
        return false;
    }

    int mysqlInitRes = mysql_library_init(0, NULL, NULL);

    if(mysqlInitRes != 0) {
        BOOST_LOG_TRIVIAL(error) << "Unable to init MySQL client library";
        return false;
    }

    conn = mysql_init(conn);

    if(conn == nullptr) {
        BOOST_LOG_TRIVIAL(error) << "Unable to create MySQL connection object";
        return false;
    }

    if(mysql_real_connect(conn, "127.0.0.1", 
            dbUser.c_str(), dbPass.c_str(),
            dbName.c_str(), dbPort, NULL, 0) == nullptr) {

        BOOST_LOG_TRIVIAL(error) << "Unable to connect to MySQL server: "
            << mysql_error(conn);

        if(conn != nullptr) {
            mysql_close(conn);
            conn = nullptr;
        }

        return false;
    }

    return true;
}

/*
6.3 ~sendCommand~

*/
bool ConnectionMySQL::sendCommand(const std::string &command, 
    bool print) {

    int mysqlExecRes = mysql_query(conn, command.c_str());

    if(mysqlExecRes != 0) {
        if(print) {
            BOOST_LOG_TRIVIAL(error) 
                << "Unable to perform command: " << command
                << " / " << mysql_error(conn);
        }

        return false;
    }

    return true;
}

/*
6.4 ~sendQuery~

*/
MYSQL_RES* ConnectionMySQL::sendQuery(const std::string &query) {

 int mysqlExecRes = mysql_query(conn, query.c_str());

  if(mysqlExecRes != 0) {
    BOOST_LOG_TRIVIAL(error) 
      << "Unable to perform query" << query
      << " / " << mysql_error(conn);
    return nullptr;
  }

  MYSQL_RES *res = mysql_store_result(conn);

  return res;
}


/*
6.5 ~checkConnection~

*/
bool ConnectionMySQL::checkConnection() {

    if(conn == nullptr) {
        return false;
    }

    int pingResult = mysql_ping(conn);

    if(pingResult != 0) {
        BOOST_LOG_TRIVIAL(error) << "MySQL ping failed"
          << " / " << mysql_error(conn);
        return false;
    }

    return true;
}

/*
6.6 ~getCreateTableSQL~

*/
std::string ConnectionMySQL::getCreateTableSQL(const std::string &table) {

    string createTableSQL = "DROP TABLE IF EXISTS " + table +";\n";

    string getTableStructure = "SHOW CREATE TABLE " + table;

    MYSQL_RES* res = sendQuery(getTableStructure);

    if(res != nullptr) {
        MYSQL_ROW row = mysql_fetch_row(res);

        // 0 = Tablename
        // 1 = Create Statement
        char* createTable = row[1];
        createTableSQL = createTableSQL + createTable + ";";
    }

    if(res != nullptr) {
        mysql_free_result(res);
        res = nullptr;
    }

    BOOST_LOG_TRIVIAL(debug) 
      << "Create table statement is: " << createTableSQL;

    return createTableSQL;
}

/*
6.7 ~partitionRoundRobin~

*/
bool ConnectionMySQL::partitionRoundRobin(
    const std::string &table, const std::string &key, 
    const size_t slots, const std::string &targetTab) {
    
    // Apply sequence counter to the relation
    string selectSQL = "SELECT @n := ((@n + 1) % " 
        + to_string(slots) + ") Slot, t.* "
        + "FROM (SELECT @n:=0) AS initvars, " + table + " AS t";
    
    string createTableSQL = getCreateTabSQL(targetTab, selectSQL);

    bool res = sendCommand(createTableSQL);

    if(! res) {
        BOOST_LOG_TRIVIAL(error) << "Unable to create round robin table";
        return false;
    }

    return true;
}

/*
6.8 ~getPartitionHashSQL~

*/
std::string ConnectionMySQL::getPartitionHashSQL(const std::string &table, 
    const std::string &key, const size_t anzSlots, 
    const std::string &targetTab) {

  string usedKey(key);
  boost::replace_all(usedKey, ",", ",'%_%',");

  string selectSQL = "SELECT DISTINCT md5(" + usedKey + ") % " 
        + to_string(anzSlots) + " As slot, " + key
        + " FROM "+ table;

    BOOST_LOG_TRIVIAL(debug) 
      << "Partition hash statement is: " << selectSQL;

  return getCreateTabSQL(targetTab, selectSQL);
}

/*
6.9 ~getPartitionSQL~

*/
std::string ConnectionMySQL::getPartitionSQL(const std::string &table, 
    const std::string &key, const size_t anzSlots,
    const std::string &fun, const std::string &targetTab) {

    string usedKey(key);
    boost::replace_all(usedKey, ",", ",'%_%',");

    string selectSQL = "";
    
    if (boost::iequals(fun, "random")) {
        selectSQL = "SELECT DISTINCT rand() % " 
            + to_string(anzSlots) + " As slot, " + key
            + " FROM "+ table;
    } else {
        BOOST_LOG_TRIVIAL(error) 
                << "Unknown partitioning function: " << fun;
        return "";
    }

    BOOST_LOG_TRIVIAL(debug) 
        << "Partition hash statement is: " << selectSQL;

  return getCreateTabSQL(targetTab, selectSQL);
}

/*
6.10 ~getPartitionGridSQL~

*/
std::string ConnectionMySQL::getPartitionGridSQL(const std::string &table,
    const std::string &key, const std::string &geo_col, 
    const size_t anzSlots, const std::string &x0, 
    const std::string &y0, const std::string &size, 
    const std::string &targetTab) {
 
    
    // Drop old procedure
    string dropProcedure = "DROP PROCEDURE IF EXISTS ST_CREATE_STATIC_GRID;";

    bool res = sendCommand(dropProcedure.c_str());

    if(!res) {
        BOOST_LOG_TRIVIAL(error) 
        << "Unable to perform SQL query " << dropProcedure            
        << mysql_error(conn);
        return "";
    }

    // Create new procedure
    const char* createProcedure = R"ENDSQL(
CREATE PROCEDURE ST_CREATE_STATIC_GRID(IN rows INTEGER, IN columns INTEGER,
    IN xsize FLOAT, IN ysize FLOAT, IN x0 FLOAT, IN y0 FLOAT)

BEGIN

-- Declare variables
DECLARE cur_row INTEGER DEFAULT 0;
DECLARE cur_column INTEGER DEFAULT 0;
DECLARE polygon VARCHAR(255);
DECLARE cell_x0, cell_x1, cell_y0, cell_y1 FLOAT;
DECLARE cell_p0, cell_p1, cell_p2, cell_p3 VARCHAR(32);

DROP TABLE IF EXISTS grid_table;

CREATE TABLE grid_table ( 
    id BIGINT NOT NULL AUTO_INCREMENT, 
    cell POLYGON NOT NULL,
    PRIMARY KEY(id)
);

-- Create cells
START TRANSACTION;

WHILE cur_row < rows DO
   SET cur_column = 0;
   WHILE cur_column < columns DO
      SET cell_x0 = x0 + (cur_column * xsize);
      SET cell_y0 = y0 + (cur_row * ysize);

      SET cell_x1 = cell_x0 + xsize;
      SET cell_y1 = cell_y0 + ysize;

      SET cell_p0 = concat(cell_x0, ' ', cell_y0);
      SET cell_p1 = concat(cell_x1, ' ', cell_y0);
      SET cell_p2 = concat(cell_x1, ' ', cell_y1);
      SET cell_p3 = concat(cell_x0, ' ', cell_y1);
      
      SET polygon = concat('POLYGON((', cell_p0, ',', cell_p1, ',', cell_p2, 
        ',', cell_p3, ',', cell_p0, '))');
      INSERT INTO grid_table(cell) values(ST_PolyFromText(polygon, 4326));

      SET cur_column = cur_column + 1;
   END WHILE;
   SET cur_row = cur_row + 1;
END WHILE;

COMMIT;

END;
)ENDSQL";

    res = sendCommand(createProcedure);

    if(! res) {
        BOOST_LOG_TRIVIAL(error) 
        << "Unable to perform SQL query " << createProcedure;
        return "";
    }

    // Execute procedure to create table
    string createCell = "CALL ST_CREATE_STATIC_GRID(" + to_string(anzSlots) 
        + ", " + to_string(anzSlots) + ", " + size + " , " + size + ", " 
        + x0 + ", " + y0 + ");";

    res = sendCommand(createCell.c_str());

    if(!res) {
        BOOST_LOG_TRIVIAL(error) 
        << "Unable to perform SQL query " << createCell;
        return "";
    }

    string usedKey(key);
    boost::replace_all(usedKey, ",", ",r.");

    string query_exec = "SELECT r." + usedKey + ", "
               "g.id AS slot "
               "FROM grid_table g INNER JOIN "+ table + " r "
               "ON ST_INTERSECTS(g.cell, r."+ geo_col +")";

    return getCreateTabSQL(targetTab, query_exec);
}

/*
6.11 ~getExportDataSQL~

*/
std::string ConnectionMySQL::getExportDataSQL(const std::string &table, 
    const std::string &join_table, const std::string &key, 
    const std::string &nr, const std::string &path,
    size_t numberOfWorker) {
 
    string filename = getFilenameForPartition(table, nr);

    string exportSQL = "SELECT a.* FROM "+ table +" a INNER JOIN " 
        + join_table  + " b " + getjoin(key) 
        + " WHERE (slot % " + to_string(numberOfWorker) + ") = " + nr
        + " INTO OUTFILE '" + path + filename + "' CHARACTER SET utf8;";

    BOOST_LOG_TRIVIAL(debug) 
      << "Export partition statement is: " << exportSQL;

    return exportSQL;
}


/*
6.14 ~getjoin~

Returns the join-part of a join-Statement from a given key-list

*/
string ConnectionMySQL::getjoin(const string &key) {

  string res= "ON ";
  vector<string> result;
  boost::split(result, key, boost::is_any_of(","));

  for (size_t i = 0; i < result.size(); i++) {
    if (i>0) {
      res = res + " AND ";
    }

    string attribute = result[i];
    boost::replace_all(attribute," ","");

    res = res + "a." + attribute + " = b." + attribute;
  }

  return res;
}

/*
6.12 ~getImportTableSQL~

*/
std::string ConnectionMySQL::getImportTableSQL(const std::string &table, 
    const std::string &full_path) {
 
    return "LOAD DATA INFILE '" + full_path + "' INTO TABLE " + table 
        + " CHARACTER SET utf8;";
}

/*
6.12 ~getExportTableSQL~

*/
std::string ConnectionMySQL::getExportTableSQL(const std::string &table, 
    const std::string &full_path) {
 
    return "SELECT * INTO OUTFILE '" + full_path 
        + "' CHARACTER SET utf8 FROM " + table + ";";
}

/*
6.13 ~getTypeFromSQLQuery~

*/
std::vector<std::tuple<string, string>> 
    ConnectionMySQL::getTypeFromSQLQuery(const std::string &sqlQuery) {

  string usedSQLQuery = limitSQLQuery(sqlQuery);
  vector<tuple<string, string>> result;

  if( ! checkConnection()) {
    BOOST_LOG_TRIVIAL(error) 
      << "Connection is not ready in getTypeFromSQLQuery";
    return result;
  }
  
  MYSQL_RES *res = sendQuery(usedSQLQuery.c_str());

  if(res == nullptr) {
    BOOST_LOG_TRIVIAL(error) 
      << "Unable to perform SQL query" << usedSQLQuery;
      return result;
  }

  result = getTypeFromQuery(res);

  if(res != nullptr) {
     mysql_free_result(res);
     res = nullptr;
  }

  return result;
}


/*
6.14 ~getTypeFromQuery~

*/
vector<tuple<string, string>> ConnectionMySQL::getTypeFromQuery(
    MYSQL_RES* res) {

  vector<tuple<string, string>> result;
  int columns = mysql_num_fields(res);
  MYSQL_FIELD *fields = mysql_fetch_fields(res);

  for(int i = 0; i < columns; i++) {       
    enum_field_types columnType = fields[i].type;
        
    string attributeName = string(fields[i].name);

    // Ensure secondo is happy with the name
    attributeName[0] = toupper(attributeName[0]);

    string attributeType;

    // Convert to SECONDO attribute type
    switch(columnType) {
#if LIBMYSQL_VERSION_ID >= 80000
    case MYSQL_TYPE_BOOL:
        attributeType = CcBool::BasicType();
        break;
#endif
    
    case MYSQL_TYPE_STRING:
    case MYSQL_TYPE_VARCHAR:
    case MYSQL_TYPE_VAR_STRING:
        attributeType = FText::BasicType();
        break;

    case MYSQL_TYPE_DECIMAL:
    case MYSQL_TYPE_TINY:
    case MYSQL_TYPE_SHORT:
    case MYSQL_TYPE_LONG:
    case MYSQL_TYPE_TIMESTAMP:
    case MYSQL_TYPE_LONGLONG:
        attributeType = CcInt::BasicType();
        break;

    case MYSQL_TYPE_FLOAT:
    case MYSQL_TYPE_DOUBLE:
        attributeType = CcReal::BasicType();
        break;

    default:
        BOOST_LOG_TRIVIAL(warning) 
            << "Unknown column type: " << attributeName << " / " 
            << columnType << " will be mapped to text";
        attributeType = FText::BasicType();
    }

    // Attribute name and type
    auto tuple = std::make_tuple(attributeName, attributeType);
    result.push_back(tuple);
  }

  return result;
}

/*
6.15 ~performSQLSelectQuery~

*/
ResultIteratorGeneric* ConnectionMySQL::performSQLSelectQuery(
    const std::string &sqlQuery) {

    if( ! checkConnection()) {
        BOOST_LOG_TRIVIAL(error) 
             << "Connection check failed in performSQLSelectQuery()";
        return nullptr;
    }

    MYSQL_RES *res = sendQuery(sqlQuery.c_str());

    if(res == nullptr) {
        return nullptr;
    }    

    vector<std::tuple<std::string, std::string>> types = getTypeFromQuery(res);
    ListExpr resultList = convertTypeVectorIntoSecondoNL(types);

    if(nl->IsEmpty(resultList)) {
        BOOST_LOG_TRIVIAL(error) 
            << "Unable to get tuple type form query: " << sqlQuery;
            return nullptr;
    }

    return new ResultIteratorMySQL(res, resultList);
}

/*
6.16 Validate the given query

*/
bool ConnectionMySQL::validateQuery(const std::string &query) {

    if( ! checkConnection()) {
        BOOST_LOG_TRIVIAL(error) 
             << "Connection check failed in validateQuery()";
        return false;
    }

    string restrictedQuery = limitSQLQuery(query);

    MYSQL_RES *res = sendQuery(restrictedQuery.c_str());

    if(res == nullptr) {
        return false;
    }

    mysql_free_result(res);
    res = nullptr;

    return true;
}

}