/*
 * Copyright (c) Contributors, http://opensimulator.org/
 * See CONTRIBUTORS.TXT for a full list of copyright holders.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of the OpenSim Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``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 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.
 */

using System;
using System.Data;
using System.Data.Common;

namespace OpenSim.Data.Base
{
    public abstract class BaseTableMapper
    {
        private readonly BaseDatabaseConnector m_database;
        private readonly object m_syncRoot = new object();

        protected void WithConnection(Action<DbConnection> action)
        {
            lock (m_syncRoot)
            {
                DbConnection m_connection = m_database.GetNewConnection();

                if (m_connection.State != ConnectionState.Open)
                {
                    m_connection.Open();
                }

                action(m_connection);

                if (m_connection.State == ConnectionState.Open)
                {
                    m_connection.Close();
                }
            }
        }

        private readonly string m_tableName;
        public string TableName
        {
            get { return m_tableName; }
        }

        protected BaseSchema m_schema;
        public BaseSchema Schema
        {
            get { return m_schema; }
        }

        protected BaseFieldMapper m_keyFieldMapper;
        public BaseFieldMapper KeyFieldMapper
        {
            get { return m_keyFieldMapper; }
        }

        public BaseTableMapper(BaseDatabaseConnector database, string tableName)
        {
            m_database = database;
            m_tableName = tableName.ToLower(); // Stupid MySQL hack.
        }

        public string CreateParamName(string fieldName)
        {
            return m_database.CreateParamName(fieldName);
        }

        protected DbCommand CreateSelectCommand(DbConnection connection, string fieldName, object primaryKey)
        {
            return m_database.CreateSelectCommand(this, connection, fieldName, primaryKey);
        }

        public string CreateCondition(DbCommand command, string fieldName, object key)
        {
            return m_database.CreateCondition(this, command, fieldName, key);
        }

        public DbCommand CreateInsertCommand(DbConnection connection, object obj)
        {
            return m_database.CreateInsertCommand(this, connection, obj);
        }

        public DbCommand CreateUpdateCommand(DbConnection connection, object rowMapper, object primaryKey)
        {
            return m_database.CreateUpdateCommand(this, connection, rowMapper, primaryKey);
        }

        public object ConvertToDbType(object value)
        {
            return m_database.ConvertToDbType(value);
        }

        protected virtual BaseDataReader CreateReader(IDataReader reader)
        {
            return m_database.CreateReader(reader);
        }
    }

    public abstract class BaseTableMapper<TRowMapper, TPrimaryKey> : BaseTableMapper
    {
        public BaseTableMapper(BaseDatabaseConnector database, string tableName)
            : base(database, tableName)
        {
        }

        // HACK: This is a temporary function used by TryGetValue().
        // Due to a bug in mono 1.2.6, delegate blocks cannot contain
        // a using block.  This has been fixed in SVN, so the next
        // mono release should work.
        private void TryGetConnectionValue(DbConnection connection, TPrimaryKey primaryKey, ref TRowMapper result, ref bool success)
        {
            using (
                DbCommand command =
                CreateSelectCommand(connection, KeyFieldMapper.FieldName, primaryKey))
            {
                using (IDataReader reader = command.ExecuteReader())
                {
                    if (reader.Read())
                    {
                        result = FromReader(CreateReader(reader));
                        success = true;
                    }
                    else
                    {
                        success = false;
                    }
                }
            }
        }

        public bool TryGetValue(TPrimaryKey primaryKey, out TRowMapper value)
        {
            TRowMapper result = default(TRowMapper);
            bool success = false;

            WithConnection(delegate(DbConnection connection)
                           {
                               TryGetConnectionValue(connection, primaryKey, ref result, ref success);
                           });

            value = result;

            return success;
        }

        // HACK: This is a temporary function used by Remove().
        // Due to a bug in mono 1.2.6, delegate blocks cannot contain
        // a using block.  This has been fixed in SVN, so the next
        // mono release should work.
        protected virtual void TryDelete(DbConnection connection, TPrimaryKey id, ref int deleted)
        {
            using (
                DbCommand command =
                CreateDeleteCommand(connection, KeyFieldMapper.FieldName, id))
            {
                deleted = command.ExecuteNonQuery();
            }
        }

        public virtual bool Remove(TPrimaryKey id)
        {
            int deleted = 0;

            WithConnection(delegate(DbConnection connection)
                           {
                               TryDelete(connection, id, ref deleted);
                           });

            if (deleted == 1)
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        public DbCommand CreateDeleteCommand(DbConnection connection, string fieldName, TPrimaryKey primaryKey)
        {
            string table = TableName;

            DbCommand command = connection.CreateCommand();

            string conditionString = CreateCondition(command, fieldName, primaryKey);

            string query =
                String.Format("delete from {0} where {1}", table, conditionString);

            command.CommandText = query;
            command.CommandType = CommandType.Text;

            return command;
        }

        // HACK: This is a temporary function used by Update().
        // Due to a bug in mono 1.2.6, delegate blocks cannot contain
        // a using block.  This has been fixed in SVN, so the next
        // mono release should work.
        protected void TryUpdate(DbConnection connection, TPrimaryKey primaryKey, TRowMapper value, ref int updated)
        {
            using (DbCommand command = CreateUpdateCommand(connection, value, primaryKey))
            {
                updated = command.ExecuteNonQuery();
            }
        }

        public virtual bool Update(TPrimaryKey primaryKey, TRowMapper value)
        {
            int updated = 0;

            WithConnection(delegate(DbConnection connection)
                           {
                               TryUpdate(connection, primaryKey, value, ref updated);
                           });

            if (updated == 1)
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        // HACK: This is a temporary function used by Add().
        // Due to a bug in mono 1.2.6, delegate blocks cannot contain
        // a using block.  This has been fixed in SVN, so the next
        // mono release should work.
        protected void TryAdd(DbConnection connection, TRowMapper value, ref int added)
        {
            using (DbCommand command = CreateInsertCommand(connection, value))
            {
                added = command.ExecuteNonQuery();
            }
        }

        public virtual bool Add(TRowMapper value)
        {
            int added = 0;

            WithConnection(delegate(DbConnection connection)
                           {
                               TryAdd(connection, value, ref added);
                           });

            if (added == 1)
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        public abstract TRowMapper FromReader(BaseDataReader reader);
    }
}
