//---------------------------------------------------------------------------------------------------------------------------------
// File: OdbcHandle.h
// Contents: Object to manage ODBC handles
// 
// Copyright Microsoft Corporation and contributors
//
// Licensed 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.
//---------------------------------------------------------------------------------------------------------------------------------

#pragma once

namespace mssql
{
    using namespace std;

    template<SQLSMALLINT HandleType>
    class OdbcHandle
    {
    public:

        OdbcHandle( void ) : handle(SQL_NULL_HANDLE)
        {
        }

        OdbcHandle(OdbcHandle&& orig) : handle(orig.handle)
        { 
            orig.handle = SQL_NULL_HANDLE;
        }

        ~OdbcHandle()
        {
            Free();
        }

        OdbcHandle& operator=(OdbcHandle&& orig)
        {
            handle = orig.handle;

            orig.handle = SQL_NULL_HANDLE;

            return *this;
        }

        bool Alloc()
        {
            assert(handle == SQL_NULL_HANDLE);
            SQLRETURN ret = SQLAllocHandle( HandleType, nullptr, &handle );
            if (!SQL_SUCCEEDED(ret))
            {
                return false;
            }
            return true;
        }

        template<SQLSMALLINT ParentType>
        bool Alloc(const OdbcHandle<ParentType>& parent)
        {
            assert(handle == SQL_NULL_HANDLE);
            SQLRETURN ret = SQLAllocHandle( HandleType, parent, &handle );
            if (!SQL_SUCCEEDED(ret))
            {
                return false;
            }
            return true;
        }

        void Free()
        {
            if (handle != SQL_NULL_HANDLE)
            {
                SQLFreeHandle( HandleType, handle );
                handle = SQL_NULL_HANDLE;
            }
        }

        operator SQLHANDLE() const { return handle; }

        operator bool() const { return handle != SQL_NULL_HANDLE; }

        shared_ptr<OdbcError> LastError( void )
        {
            vector<wchar_t> buffer;

            SQLWCHAR wszSqlState[6];
            SQLINTEGER nativeError;
            SQLSMALLINT actual;

            SQLRETURN ret = SQLGetDiagRec(HandleType, handle, 1, wszSqlState, &nativeError, NULL, 0, &actual);
            assert( ret != SQL_INVALID_HANDLE );
            assert( ret != SQL_NO_DATA );
            assert( SQL_SUCCEEDED( ret ));

            buffer.resize(actual+1);
            ret = SQLGetDiagRec(HandleType, handle, 1, wszSqlState, &nativeError, &buffer[0], actual + 1, &actual);
            assert( SQL_SUCCEEDED( ret ));

            string sqlstate = w2a(wszSqlState);
            string message = w2a(buffer.data());
            return make_shared<OdbcError>( sqlstate.c_str(), message.c_str(), nativeError );
        }

    private:

        void operator=(const OdbcHandle& orig) 
        {
            assert(false);
        }

        SQLHANDLE handle;
    };

    typedef OdbcHandle<SQL_HANDLE_ENV> OdbcEnvironmentHandle;
    typedef OdbcHandle<SQL_HANDLE_DBC> OdbcConnectionHandle;
    typedef OdbcHandle<SQL_HANDLE_STMT> OdbcStatementHandle;
}