/*
 * This file is a part of morm
 * and is distributed under the 2-Clause BSD licence.
 * Author: Tomasz Sowa <t.sowa@ttmath.org>
 */

/*
 * Copyright (c) 2018-2021, Tomasz Sowa
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

// for sleep()
#include <unistd.h>

#include "postgresqlconnector.h"
#include "utf8/utf8.h"
#include "postgresqlexpression.h"
#include "convert/strtoint.h"


namespace morm
{

PostgreSQLConnector::PostgreSQLConnector()
{
	pg_conn = nullptr;
}


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


void PostgreSQLConnector::close()
{
	if( pg_conn )
	{
		PQfinish(pg_conn);
		pg_conn = nullptr;
	}
}



void PostgreSQLConnector::allocate_default_expression()
{
	deallocate_expression();
	db_expression = new PostgreSQLExpression();
	expression_allocated = true;
}





QueryResult * PostgreSQLConnector::create_query_result()
{
	return new PostgreSQLQueryResult();
}


bool PostgreSQLConnector::do_query(const char * query_str, PostgreSQLQueryResult * psql_result)
{
	if( pg_conn && psql_result )
	{
		psql_result->clear();

		if( log_queries && log )
		{
			(*log) << pt::Log::log3 << "Morm: query: " << query_str << pt::Log::logend;
		}

		psql_result->psql_result = PQexec(pg_conn, query_str);

		if( !psql_result->psql_result )
		{
			if( PQstatus(pg_conn) != CONNECTION_OK )
			{
				assert_connection();
				psql_result->psql_result = PQexec(pg_conn, query_str);
			}
		}

		if( psql_result->psql_result )
		{
			psql_result->psql_status = PQresultStatus(psql_result->psql_result);
			psql_result->result_rows = static_cast<size_t>(PQntuples(psql_result->psql_result));
			psql_result->result_cols = static_cast<size_t>(PQnfields(psql_result->psql_result));
		}

		if( !psql_result->psql_result || psql_result->psql_status == PGRES_FATAL_ERROR )
		{
			const char * err_msg = PQerrorMessage(pg_conn);

			if( err_msg )
			{
				pt::UTF8ToWide(err_msg, psql_result->error_msg);
			}

			if( log )
			{
				(*log) << pt::Log::log1 << "Morm: Problem with this query: \"" << query_str << '\"' << pt::Log::logend;

				if( err_msg )
					(*log) << pt::Log::log1 << "Morm: " << err_msg << pt::Log::logend;
			}
		}
		else
		{
			psql_result->status = true;
		}
	}

	return (pg_conn && psql_result && psql_result->psql_result != nullptr && psql_result->status);
}



bool PostgreSQLConnector::query(const char * query_str, QueryResult & query_result)
{
	PostgreSQLQueryResult * psql_result = dynamic_cast<PostgreSQLQueryResult*>(&query_result);
	return do_query(query_str, psql_result);
}


const char * PostgreSQLConnector::query_last_sequence(const wchar_t * sequence_table_name)
{
	allocate_default_expression_if_needed();

	if( db_expression )
	{
		PostgreSQLQueryResult psql_result;

		stream.clear();
		stream << "select currval(E'";
		db_expression->esc(sequence_table_name, stream);
		stream << "');";

		if( query_select(stream, psql_result) )
		{
			if( psql_result.result_rows == 1 )
			{
				return psql_result.get_value_from_result(0, 0);
			}
			else
			{
				if( log )
				{
					(*log) << pt::Log::log1 << "Morm: expected only one row in sequence result, has: " << psql_result.result_rows
							  << pt::Log::logend;
				}
			}
		}
		else
		{
			if( pg_conn && log )
			{
				(*log) << pt::Log::log1 << "Morm: error (currval) for table: " << sequence_table_name << ", "
						  << PQerrorMessage(pg_conn) << pt::Log::logend;
			}
		}
	}

	return nullptr;
}



bool PostgreSQLConnector::query(const pt::TextStream & stream, QueryResult & query_result)
{
	stream.to_string(query_str);
	return query(query_str.c_str(), query_result);
}


bool PostgreSQLConnector::query(const std::string & query_str, QueryResult & query_result)
{
	return query(query_str.c_str(), query_result);
}


bool PostgreSQLConnector::query_select(const char * query_str, QueryResult & query_result)
{
	PostgreSQLQueryResult * psql_result = dynamic_cast<PostgreSQLQueryResult*>(&query_result);
	bool result = false;

	if( psql_result )
	{
		result = (do_query(query_str, psql_result) && psql_result->psql_status == PGRES_TUPLES_OK);
		psql_result->status = result;
	}

	return result;
}


bool PostgreSQLConnector::query_update(const char * query_str, QueryResult & query_result)
{
	PostgreSQLQueryResult * psql_result = dynamic_cast<PostgreSQLQueryResult*>(&query_result);
	bool result = false;

	if( psql_result )
	{
		result = (do_query(query_str, psql_result) && psql_result->psql_status == PGRES_COMMAND_OK);
		psql_result->status = result;
	}

	return result;
}


bool PostgreSQLConnector::query_insert(const char * query_str, QueryResult & query_result)
{
	PostgreSQLQueryResult * psql_result = dynamic_cast<PostgreSQLQueryResult*>(&query_result);
	bool result = false;

	if( psql_result )
	{
		result = (do_query(query_str, psql_result) && psql_result->psql_status == PGRES_COMMAND_OK);
		psql_result->status = result;
	}

	return result;
}


bool PostgreSQLConnector::query_remove(const char * query_str, QueryResult & query_result)
{
	PostgreSQLQueryResult * psql_result = dynamic_cast<PostgreSQLQueryResult*>(&query_result);
	bool result = false;

	if( psql_result )
	{
		result = (do_query(query_str, psql_result) && psql_result->psql_status == PGRES_COMMAND_OK);
		psql_result->status = result;
	}

	return result;
}


bool PostgreSQLConnector::query_select(const pt::TextStream & stream, QueryResult & query_result)
{
	stream.to_string(query_str);
	return query_select(query_str.c_str(), query_result);
}

bool PostgreSQLConnector::query_update(const pt::TextStream & stream, QueryResult & query_result)
{
	stream.to_string(query_str);
	return query_update(query_str.c_str(), query_result);
}

bool PostgreSQLConnector::query_insert(const pt::TextStream & stream, QueryResult & query_result)
{
	stream.to_string(query_str);
	return query_insert(query_str.c_str(), query_result);
}

bool PostgreSQLConnector::query_remove(const pt::TextStream & stream, QueryResult & query_result)
{
	stream.to_string(query_str);
	return query_remove(query_str.c_str(), query_result);
}






















//void PostgreSQLConnector::CreateIdList(const std::vector<long> & id_tab, std::wstring & list, bool add_parentheses)
//{
//wchar_t buffer[50];
//size_t buffer_len = sizeof(buffer) / sizeof(wchar_t);
//
//	list.clear();
//
//	if( add_parentheses )
//		list += '(';
//
//	for(size_t i=0 ; i<id_tab.size() ; ++i)
//	{
//		Toa((unsigned long)id_tab[i], buffer, buffer_len);
//		list += buffer;
//
//		if( i+1 < id_tab.size() )
//			list += ',';
//	}
//
//	if( add_parentheses )
//		list += ')';
//}




//Error PostgreSQLConnector::BeginTrans()
//{
//	return DoCommand("BEGIN;");
//}
//
//
//
//Error PostgreSQLConnector::RollbackTrans()
//{
//	return DoCommand("ROLLBACK;");
//}
//
//
//
//Error PostgreSQLConnector::CommitTrans()
//{
//	return DoCommand("COMMIT;");
//}
//
//
//
//bool PostgreSQLConnector::EndTrans(bool everything_ok)
//{
//bool result;
//
//	if( everything_ok )
//	{
//		result = (CommitTrans() == WINIX_ERR_OK);
//	}
//	else
//	{
//		RollbackTrans();
//		// we return the old err code
//		result = false;
//	}
//
//return result;
//}
//
//
//Error PostgreSQLConnector::EndTrans(Error err)
//{
//	if( err == WINIX_ERR_OK )
//	{
//		err = CommitTrans();
//	}
//	else
//	{
//		// we return the old err code
//		RollbackTrans();
//	}
//
//return err;
//}



void PostgreSQLConnector::set_conn_param(const std::wstring & database_name, const std::wstring & user, const std::wstring & pass)
{
	db_database = database_name;
	db_user     = user;
	db_pass     = pass;
}


void PostgreSQLConnector::overwrite(pt::TextStream & stream)
{
	pt::TextStream::iterator i = stream.begin();

	for( ; i != stream.end() ; ++i)
	{
		*i = 0;
	}

	stream.clear();
}




void PostgreSQLConnector::connect()
{
	// IMPROVEME
	// what about if reconnecting is made in the midle of queries?
	// e.g. in after_select? (the whole stack query_results will be cleared)
	close();

	allocate_default_expression_if_needed();

	if( db_expression )
	{
		stream.clear();
		stream << "dbname='";
		db_expression->esc(db_database, stream);

		stream << "' user='";
		db_expression->esc(db_user, stream);

		stream << "' password='";
		db_expression->esc(db_pass, stream);
		stream << "'";

		std::string str;
		stream.to_string(str);
		pg_conn = PQconnectdb(str.c_str());

		overwrite(stream);
	}
	// warning! pg_conn can be not null but there cannnot be a connection established
	// use PQstatus(pg_conn) to check whether the connection works fine
}

//
//
//

void PostgreSQLConnector::log_connection_socket()
{
	if( pg_conn && log )
	{
		(*log) << pt::Log::log2 << "Morm: connection to the database works fine" << pt::Log::logend;
		(*log) << pt::Log::log3 << "Morm: connection socket: " << PQsocket(pg_conn) << pt::Log::logend;
		(*log) << pt::Log::logsave;
	}
}

void PostgreSQLConnector::wait_for_connection()
{
	if( !pg_conn || PQstatus(pg_conn) != CONNECTION_OK )
	{
		if( log )
		{
			(*log) << pt::Log::log3 << "Morm: waiting for the db to be ready...." << pt::Log::logend << pt::Log::logsave;
		}

		while( !assert_connection(false) )
		{
			sleep(5);
		}

		log_connection_socket();
	}
}




// IMPROVE ME what about the exception now?
bool PostgreSQLConnector::assert_connection(bool put_log)
{
bool was_connection = true;


	if( !pg_conn )
	{
		was_connection = false;
		connect();
	}
	else
	if( PQstatus(pg_conn) != CONNECTION_OK )
	{
		if( put_log && log )
		{
			(*log) << pt::Log::log2 << "Morm: connection to the database is lost, trying to recover" << pt::Log::logend << pt::Log::logsave;
		}

		was_connection = false;
		PQreset(pg_conn);
	}


	if( pg_conn && PQstatus(pg_conn) == CONNECTION_OK )
	{
		if( !was_connection )
		{
			if( put_log )
				log_connection_socket();

			set_db_parameters();
		}

		return true;
	}
	else
	{
		if( put_log && log )
		{
			(*log) << pt::Log::log1 << "Morm: connection to db server cannot be established" << pt::Log::logend << pt::Log::logsave;
		}

//		if( throw_if_no_connection )
//		{
//			//throw Error(WINIX_ERR_DB_FATAL_ERROR_DURING_CONNECTING);
//			throw int(10);
//		}

		return false;
	}
}

void PostgreSQLConnector::set_db_parameters()
{
	if( pg_conn )
	{
		if( PQsetClientEncoding(pg_conn, "UTF8") == -1 )
		{
			if( log )
			{
				(*log) << pt::Log::log1 << "Morm: Can't set the proper client encoding" << pt::Log::logend << pt::Log::logsave;
			}
		}
	}
}


void PostgreSQLConnector::log_unsupported_bin_format()
{
	if( log )
	{
		(*log) << pt::Log::log1 << "Morm: unsupported binary format (skipping)" << pt::Log::logend;
	}
}



size_t PostgreSQLConnector::unescape_bin_char(const char * str, wchar_t & field_value, const FT & field_type)
{
	if( str[0]!='\\' || str[1]!='x' )
	{
		log_unsupported_bin_format();
		return 0;
	}
	else
	{
		return unescape_hex_char(str + 2, field_value, field_type);
	}
}



void PostgreSQLConnector::unescape_bin_string(const char * str, std::string & out)
{
	if( str[0]!='\\' || str[1]!='x' )
	{
		log_unsupported_bin_format();
	}
	else
	{
		unescape_hex_string(str + 2, out);
	}
}


void PostgreSQLConnector::unescape_bin_string(const char * str, std::wstring & out, const FT & field_type)
{
	if( str[0]!='\\' || str[1]!='x' )
	{
		log_unsupported_bin_format();
	}
	else
	{
		unescape_hex_string(str + 2, out, field_type);
	}
}


}