using System;

namespace Umbraco.Core.Persistence.SqlSyntax
{
    /// <summary>
    /// Singleton to handle the configuration of a SqlSyntaxProvider
    /// </summary>
    public static class SqlSyntaxContext
    {
        private static ISqlSyntaxProvider _sqlSyntaxProvider;

        public static ISqlSyntaxProvider SqlSyntaxProvider
        {
            get
            {
                if(_sqlSyntaxProvider == null)
                {
                    throw new ArgumentNullException("SqlSyntaxProvider",
                                                    "You must set the singleton 'Umbraco.Core.Persistence.SqlSyntax.SqlSyntaxContext' to use an sql syntax provider");
                }
                return _sqlSyntaxProvider;
            }
            set { _sqlSyntaxProvider = value; }
        }
    }

    internal static class SqlSyntaxProviderExtensions
    {
        /// <summary>
        /// This is used to generate a delete query that uses a sub-query to select the data, it is required because there's a very particular syntax that
        /// needs to be used to work for all servers: MySql, SQLCE and MSSQL
        /// </summary>
        /// <returns></returns>
        /// <remarks>
        /// See: http://issues.umbraco.org/issue/U4-3876
        /// </remarks>
        public static string GetDeleteSubquery(this ISqlSyntaxProvider sqlProvider, string tableName, string columnName, Sql subQuery)
        {
            return string.Format(@"DELETE FROM {0} WHERE {1} IN (SELECT {1} FROM ({2}) x)",
                                    sqlProvider.GetQuotedTableName(tableName),
                                    sqlProvider.GetQuotedColumnName(columnName),
                                    subQuery.SQL);
        }

    }
}