using System.Text;

namespace Connected.Data.Schema.Sql
{
	internal class TableCreate : TableTransaction
	{
		public TableCreate(bool temporary)
		{
			Temporary = temporary;

			if (Temporary)
				TemporaryName = $"T{Guid.NewGuid().ToString().Replace("-", string.Empty)}";
		}

		private bool Temporary { get; }

		public string TemporaryName { get; }

		protected override async Task OnExecute()
		{
			await Context.Execute(CommandText);

			if (!Temporary)
			{
				await ExecutePrimaryKey();
				await ExecuteDefaults();
				await ExecuteIndexes();
			}
		}

		private async Task ExecutePrimaryKey()
		{
			var primaryKey = Context.Schema.Columns.FirstOrDefault(f => f.IsPrimaryKey);

			if (primaryKey is not null)
				await new PrimaryKeyAdd(primaryKey).Execute(Context);
		}

		private async Task ExecuteDefaults()
		{
			var name = Temporary ? TemporaryName : Context.Schema.Name;

			foreach (var column in Context.Schema.Columns)
			{
				if (!string.IsNullOrWhiteSpace(column.DefaultValue))
					await new DefaultAdd(column, name).Execute(Context);
			}
		}

		private async Task ExecuteIndexes()
		{
			var indexes = ParseIndexes(Context.Schema);

			foreach (var index in indexes)
				await new IndexCreate(index).Execute(Context);
		}

		private string CommandText
		{
			get
			{
				var text = new StringBuilder();

				var name = Temporary ? TemporaryName : Context.Schema.Name;

				text.AppendLine($"CREATE TABLE {Escape(Context.Schema.SchemaName(), name)}");
				text.AppendLine("(");
				var comma = string.Empty;

				for (var i = 0; i < Context.Schema.Columns.Count; i++)
				{
					text.AppendLine($"{comma} {CreateColumnCommandText(Context.Schema.Columns[i])}");

					comma = ",";
				}

				text.AppendLine(");");

				return text.ToString();
			}
		}
	}
}