/*
	$Revision: 28 $
	$Date: 23/03/05 11:49 $
	Copyright © 2001-2006, FSL Technologies Limited. Contact "http://fost.3.felspar.com".
*/


#include "stdafx.h"
#include <FOST.id.hpp>


using namespace std;
using namespace FSLib;


namespace {


	Revision c_revision( L"$Archive: /FOST.3/F3Util/assign.cpp $", __DATE__, L"$Revision: 28 $", L"$Date: 23/03/05 11:49 $" );


	const Setting c_dsn( L"$Archive: /FOST.3/F3Util/assign.cpp $", L"ID", L"DSN", L"dsn=FostID", true );
	const Setting c_method( L"$Archive: /FOST.3/F3Util/assign.cpp $", L"ID", L"Method", L"FostID", true );

	const Setting c_table( L"$Archive: /FOST.3/F3Util/assign.cpp $", L"ID", L"Table", L"FSLib_Domain", true );
	const Setting c_column( L"$Archive: /FOST.3/F3Util/assign.cpp $", L"ID", L"Column", L"nextID", true );


	const wchar_t IDFaultMsg[]=L"Error in ID assignment.";

	
	Mutex g_dbc_mutex;

	inline
	DBConnection &g_dbConnectionRO() {
		Mutex::Lock lock( g_dbc_mutex );
		static DBConnection dbc( Setting::value( L"ID", L"DSN" ) );
		return dbc;
	}

	inline
	DBConnection &g_dbConnectionRW() {
		Mutex::Lock lock( g_dbc_mutex );
		static DBConnection dbc( Setting::value( L"ID", L"DSN" ), Setting::value( L"ID", L"DSN" ) );
		return dbc;
	}


	// Assignment methods
	ID fostID( const ID &domain );
	ID exclusive( const ID &domain );


}


/*
	Exceptions
*/


inline
Exceptions::IDFault::IDFault( const FSLib::wstring &msg )
: Exception( msg ) {
}


inline
const wchar_t * const Exceptions::IDFault::message() const {
	return IDFaultMsg;
}


/*
	Assignment
*/


inline
ID FSLib::nextID( const ID &domain ) {
	FSLib::wstring method( Setting::value( L"ID", L"Method" ) );
	if ( method == L"Exclusive" ) {
		return exclusive( domain );
	} else if ( method == L"FostID" ) {
		return fostID( domain );
	} else {
		throw Exceptions::IDFault( L"Method '" + method + L"' not recognised." );
	}
}


inline
ID FSLib::currentID( const ID &domain ) {
	try {
		Recordset rs( g_dbConnectionRO().execute( L"SELECT (" + c_column.value() + L" - 1) AS cur FROM " + c_table.value() + L" WHERE id=" + domain.asString() ) );
		if ( rs.eof() ) throw FSLib::Exceptions::IDFault( L"No ID number found for domain" );
		return field_cast< ID >( rs, L"cur" );
	} catch ( FSLib::Exceptions::Exception &e ) {
		e.info() << L"Fetching current ID for domain " << domain << std::endl;
		throw;
	}
}


/*
	Methods
*/


namespace {


	// FostID

	ID fostID( const ID &domain ) {
		// Uses the read only API despite doing a write as the write connection doesn't return a recordset
		Recordset rs( g_dbConnectionRO().execute(
				L"BEGIN TRAN\n"
				L"SET NOCOUNT ON\n"
				L"UPDATE " + c_table.value() + L" SET " + c_column.value() + L"=" + c_column.value() + L"+1 WHERE id=" + domain.asString() + L"\n"
				L"SET NOCOUNT OFF\n"
				L"SELECT (" + c_column.value() + L" - 1) AS next FROM " + c_table.value() + L" WHERE id=" + domain.asString() + L"\n"
				L"COMMIT TRAN" ) );
		return field_cast< ID >( rs, 0 );
	}


	// Exclusive

	Mutex exclusive_mutex;
	ID exclusive_nextID;

	ID exclusive( const ID &domain ) {
		Mutex::Lock lock( exclusive_mutex );
		if ( exclusive_nextID.isnull() ) {
			exclusive_nextID = field_cast< ID >( g_dbConnectionRW().execute( L"SELECT " + c_column.value() + L" AS next FROM " + c_table.value() + L" WHERE id=" + domain.asString() ), L"next" );
		}
		ID ret( exclusive_nextID );
		exclusive_nextID = _wtoi( exclusive_nextID.asString().c_str() ) + 1;
		g_dbConnectionRW().execute( e_writeCNX, L"UPDATE " + c_table.value() + L" SET " + c_column.value() + L"=" + exclusive_nextID.asString() + L" WHERE id=" + domain.asString() );
		return ret;
	}


}