using System;
using System.Data;

class Program {
	static void Main(string[] args) {
		var notes = NoteTaker.Load("testing");

		var newRow = notes.NewNote();
		newRow.SetField("Title", "Another Test");
		newRow.SetField("Contents", "Can I add rows to an existing table?");
		newRow.SetField("CreatedDate", DateTime.Now);
		newRow.SetField("LastModifiedDate", DateTime.Now);
		newRow.AcceptChanges();

		notes.Save("testing");
	}
}

public class NoteTaker : IDisposable {
	private const string NAMESPACE = "test";

	private DataSet _set;
	private DataTable _notesTable;

	private NoteTaker() {
		_set = new DataSet("NoteTakerDataSet");

		_notesTable = _set.Tables.Add("Notes", NAMESPACE);
		var idColumn = _notesTable.Columns.Add("Id", typeof(int), null);
		idColumn.AutoIncrement = true;
		idColumn.AutoIncrementSeed = 1;
		idColumn.AutoIncrementStep = 1;
		idColumn.ReadOnly = true;
		idColumn.Unique = true;
		_notesTable.PrimaryKey = new[] { idColumn };

		var titleColumn = _notesTable.Columns.Add("Title", typeof(string), null);
		var contentsColumn = _notesTable.Columns.Add("Contents", typeof(string), null);
		var createdDateColumn = _notesTable.Columns.Add("CreatedDate", typeof(DateTime), null);
		var lastModifiedDateColumn = _notesTable.Columns.Add("LastModifiedDate", typeof(DateTime), null);
	}

	private NoteTaker(string schemaPath, string dataPath) {
		_set = new DataSet();
		_set.ReadXmlSchema(schemaPath);
		_set.ReadXml(dataPath);

		_notesTable = _set.Tables["Notes"];
	}

	private NoteTaker(string databaseName)
		: this($"{databaseName}.xsd", $"{databaseName}.xml") {
	}

	public static NoteTaker CreateNew() {
		return new NoteTaker();
	}

	public static NoteTaker Load(string databaseName) {
		return new NoteTaker(databaseName);
	}

	public DataRow NewNote() {
		var row = _notesTable.NewRow();
		_notesTable.Rows.Add(row);
		return row;
	}

	public void Save(string databaseName) {
		Save($"{databaseName}.xsd", $"{databaseName}.xml");
	}

	public void Dispose() {
		_set.Dispose();
	}

	private void Save(string schemaPath, string dataPath) {
		_set.WriteXmlSchema(schemaPath);
		_set.WriteXml(dataPath);
	}
}