using Umbraco.Core.Persistence.Migrations.Model;

namespace Umbraco.Core.Persistence.SqlSyntax
{
    /// <summary>
    /// Static class that provides simple access to the Sql Server SqlSyntax Providers singleton
    /// </summary>
    internal static class SqlServerSyntax
    {
        public static ISqlSyntaxProvider Provider { get { return SqlServerSyntaxProvider.Instance; } }
    }

    /// <summary>
    /// Represents an SqlSyntaxProvider for Sql Server
    /// </summary>
    internal class SqlServerSyntaxProvider : SqlSyntaxProviderBase<SqlServerSyntaxProvider>
    {
        public static SqlServerSyntaxProvider Instance = new SqlServerSyntaxProvider();

        private SqlServerSyntaxProvider()
        {
            StringLengthColumnDefinitionFormat = StringLengthUnicodeColumnDefinitionFormat;
            StringColumnDefinition = string.Format(StringLengthColumnDefinitionFormat, DefaultStringLength);

            AutoIncrementDefinition = "IDENTITY(1,1)";
            StringColumnDefinition = "VARCHAR(8000)";
            GuidColumnDefinition = "UniqueIdentifier";
            RealColumnDefinition = "FLOAT";
            BoolColumnDefinition = "BIT";
            DecimalColumnDefinition = "DECIMAL(38,6)";
            TimeColumnDefinition = "TIME"; //SQLSERVER 2008+
            BlobColumnDefinition = "VARBINARY(MAX)";

            InitColumnTypeMap();
        }

        public override bool DoesTableExist(Database db, string tableName)
        {
            var result =
                db.ExecuteScalar<long>("SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = @TableName",
                                       new { TableName = tableName });

            return result > 0;
        }

        protected override string FormatIdentity(Migrations.Model.ColumnDefinition column)
        {
            return column.IsIdentity ? GetIdentityString(column) : string.Empty;
        }

        private static string GetIdentityString(Migrations.Model.ColumnDefinition column)
        {
            return "IDENTITY(1,1)";
        }

        protected override string FormatSystemMethods(SystemMethods systemMethod)
        {
            switch (systemMethod)
            {
                case SystemMethods.NewGuid:
                    return "NEWID()";
                case SystemMethods.NewSequentialId:
                    return "NEWSEQUENTIALID()";
                case SystemMethods.CurrentDateTime:
                    return "GETDATE()";
                case SystemMethods.CurrentUTCDateTime:
                    return "GETUTCDATE()";
            }

            return null;
        }

        public override string AddColumn { get { return "ALTER TABLE {0} ADD {1}"; } }
    }
}